Prostate Cancer

6. TREATMENT

This chapter reviews the available treatment modalities, followed by separate sections addressing treatment for the various disease stages.

6.1. Treatment modalities

6.1.1. Deferred treatment (active surveillance/watchful waiting)

As PCa is such a common disease, and with the increased rate of early detection of small tumours after the introduction of PSA, there is a distinct risk of over-diagnosis and subsequent over-treatment of the disease [474]. As all available curative treatment options for PCa carry a risk of significant side effects there is a need for conservative treatment options for patients with low risk of dying from their PCa. Data from studies conducted on patients who did not undergo local treatment with up to 25 years of follow-up, with endpoints of OS and CSS, are available. Several series have shown a consistent CSS rate of 82–87% at 10 years [475-478], and 80–95% for T1/T2 and ISUP grade < 2 PCas [479]. In three studies with data beyond 15 years, the CSS was 80%, 79% and 58% respectively [475,477,478], and two reported 20-year CSS rates of 57% and 32% [475,477]. The observed heterogeneity in outcomes is due to different inclusion criteria, with some older studies from the pre-PSA era showing worse outcomes [477]. In addition, many patients classified as ISUP grade 1 would now be classified as ISUP grade 2–3 based on the 2005 Gleason classification, suggesting that the above-mentioned results should be considered as minimal. Patients with well-, moderately- and poorly-differentiated tumours had 10-year CSS rates of 91%, 90% and 74%, respectively, correlating with data from a pooled analysis [479]. Observation is most effective in men aged 65–75 years with low-risk PCa [480]. In screen-detected localised PCa there is also a lead-time bias, resulting in a higher rate of early detected PCa, but also an even higher risk of detecting clinically insignificant PCa that never would have caused any problems [474]. Cancer-specific survival from untreated screen-detected PCa in patients with ISUP grade 1–2 is therefore likely to be even higher than for PCa detected of other reasons. Consequently, a high proportion of men with PSA-detected PCa are suitable for conservative treatment.

The high CSS rates of localised PCa leads to a life expectancy of at least 10 years to be considered mandatory for any benefit from active treatment. Co-morbidity is as important as age in predicting life expectancy in men with PCa. Increasing co-morbidity greatly increases the risk of dying from non-PCa-related causes. In an analysis of 19,639 patients aged > 65 years who were not given curative treatment, most men with a CCI score > 2 had died from competing causes at 10 years follow-up regardless of their age at time of diagnosis. Tumour aggressiveness had little impact on OS suggesting that patients could have been spared biopsy and diagnosis of cancer. Men with a CCI score < 1 had a low risk of death at 10 years, especially for well- or moderately-differentiated lesions [457]. This highlights the importance of assessing co-morbidity even before considering a biopsy, but also before advising a patient with a PCa diagnosis on the optimal treatment for him.

There are two distinct strategies for conservative management that aim to reduce over-treatment: AS and WW (Table 6.1.1).

Table 6.1.1: Definitions of active surveillance and watchful waiting 

DRE = digital rectal examination; PSA = prostate-specific antigen; MRI = magnetic resonance imaging.

6.1.1.1. Active surveillance

Active surveillance aims to avoid unnecessary treatment, and consequently unnescessary side effects, in men with clinically localised PCa, and a life expectancy of 10 years or more, who do not require immediate treatment, but at the same time achieve the correct timing for curative treatment in those who eventually do [482]. Patients remain under close surveillance through structured surveillance programmes with regular follow-up consisting of PSA testing, clinical examination, MRI imaging and repeat prostate biopsies, with curative treatment being prompted by pre-defined thresholds indicative of potentially life-threatening disease, which is still curable, while considering individual life expectancy.

No formal RCT is available comparing AS to curative treatment. Several cohorts have investigated AS in organ-confined disease, the findings of which were summarised in a systematic review [483]. More recently, the largest prospective series of men with low-risk PCa managed by AS was published [484]. Table 6.1.2 summarises the results of selective AS cohorts. It is clear that the long-term OS and CSS of patients on AS are extremely good. However, more than one-third of patients are ‘reclassified’ during follow-up, most of whom undergo curative treatment due to disease upgrading, increase in disease extent, disease stage, progression or patient preference. There is considerable variation and heterogeneity between studies regarding patient selection and eligibility, follow-up policies (including frequency and type of imaging such as MRI imaging, type and frequency of repeat prostate biopsies, such as MRI-targeted biopsies or transperineal template biopsies, use of PSA kinetics and density, and frequency of clinical follow-up), when active treatment should be instigated (i.e., reclassification criteria) and which outcome measures should be prioritised [482]. For specific guidelines on inclusion criteria and follow-up strategies for AS, see Sections 6.2.1.1, 6.2.1.3 and 6.2.2.1 and 6.2.2.5.

In the ProtecT-trial, a RCT, 1,643 patients were randomised into one of three arms: active treatment with either RP or EBRT or active monitoring (AM) [485]. Even though the ProtecT trial is a RCT it does not include a formal AS strategy as described above and in Sections 6.2.1.1.4 and 6.2.1.3, but rather AM, a significantly less stringent surveillance strategy in terms of clinical follow-up, imaging and repeat biopsies. Fifty-six percent of the patients had low-risk disease, with 90% having a PSA < 10 ng/mL, 77% ISUP grade 1 (20% ISUP grade 2–3), and 76% had T1c disease. The remaining patients had mainly intermediate-risk disease. The key finding was that AM was as effective as active treatment at 10 years (CSS = 99% vs. 98.8%), but at a cost of increased metastatic progression risk (2.6% vs. 6%). Metastases, although rare, were more frequent than seen with comparable AS protocols [483]. Recently, a comprehensive characterisation of the ProtecT study cohort was performed, stratifying patients at baseline according to risk of progression using clinical stage, grade at diagnosis and PSA level [486]. Additionally, detailed clinico-pathological information on participants who received RP were analysed. The authors aimed to test the hypothesis that the clinico-pathological features of participants with disease progression differed from those with stable disease in order to identify prognostic markers. The results showed that out of all patients who had been randomised (n = 1,643), 34% (n = 505) had intermediate- or high-risk disease, and 66% (n = 973) had low-risk disease. Of all patients who had received AM, RP or RT within 12 months of randomisation (n = 1,607), 12% (n = 198) developed progression at a median follow-up of 10 years, of which 72% (n = 142) had undergone AM. Treatment received, age (65–69 vs. 50–64 years), PSA, ISUP grade at diagnosis, cT stage, risk group, number of PCa-involved biopsy cores, maximum length of tumour (median 5.0 vs. 3.0 mm), aggregate length of tumour (median 8.0 vs. 4.0 mm), and presence of perineural invasion were each associated with increased risk of disease progression (p < 0.001 for each). However, these factors could not reliably predict progression in individuals. Notably, 53% (n = 105) of patients who progressed had biopsy ISUP grade 1 disease, although, conversely, none of the participants who received RP and subsequently progressed had pathological ISUP grade 1 tumours. This discrepancy in progression and metastases rate between the AM arm of the ProtecT-study and comparable AS protocols can, most likely, be explained by inadequate sampling by PSA testing and 10-core TRUS-guided biopsies and differences in intensity of surveillance.

It is important to note that the AM arm in ProtecT represented an intermediate approach between contemporary AS protocols and WW in terms of a monitoring strategy based almost entirely on PSA measurements alone; there was no use of MRI scan, either at recruitment or during the monitoring period, nor were there any protocol-mandated repeat prostate biopsies at regular intervals. In addition, approximately 40% of randomised patients had intermediate-risk disease. Nevertheless, the ProtecT study has reinforced the role of deferred active treatment (i.e., either AS or some form of initial AM) as a feasible alternative to active curative interventions in patients with low-grade and low-stage disease. Beyond 10 years, no RCT-data is available, as yet, although AS is likely to give more reassurance especially in younger men, based on more accurate risk stratification at recruitment and more stringent criteria regarding follow-up, imaging, repeat biopsy and reclassification. Individual life expectancy must continuously be evaluated before considering any active treatment in low-risk patients and in those with up to 10 years’ individual life expectancy [486].

Table 6.1.2: Active surveillance in screening-detected prostate cancer (large cohorts with longer-term follow-up)

* Patients receiving active therapy following initial active surveillance.
CSS = cancer-specific survival; FU = follow-up; mo = months; n = number of patients; n.r. = not reported; OS = overall survival; RP = radical prostatectomy.

6.1.1.2. Watchful Waiting

Watchful waiting refers to conservative management for patients deemed unsuitable for curative treatment from the outset, and patients are clinically ‘watched’ for the development of local or systemic progression with (imminent) disease-related complaints, at which stage they are then treated palliatively according to their symptoms in order to maintain QoL.

There are two RCTs and one Cochrane review comparing the outcomes of WW to RP. The SPCG-4 study was a RCT from the pre-PSA era, randomising patients to either WW or RP [496]. The study found RP to provide superior CSS, OS and PFS compared to WW at a median follow-up of 23.6 years (range 3 weeks–28 years). However, the benefit in favour of RP over WW was only apparent after 10 years. The PIVOT trial, a RCT conducted in the early PSA era, made a similar comparison between RP vs. WW in 731 men (50% with non-palpable disease) but in contrast to the SPCG-4, it found little, to no, benefit of RP (cumulative incidence of all-cause death, RP vs. observation: 68% vs. 73%; RR: 0.92, 95% CI: 0.84–1.01) within a median follow-up period of 18.6 years (interquartile range, 16.6 to 20 years) [497]. Exploratory subgroup analysis showed that the borderline benefit from RP was most marked for intermediate-risk disease (RR: 0.84, 95% CI: 0.73–0.98) but there was no benefit in patients with low- or high-risk disease. Overall, no adverse effects on health-related QoL (HRQoL) and psychological well-being was apparent in the first 5 years [498]. However, one of the criticisms of the PIVOT trial is the relatively high overall mortality rate in the WW group compared with more contemporary series. A Cochrane review performed a pooled analysis of RCTs comparing RP vs. WW [499]. Three studies were included; the previously mentioned SPCG-4 [496] and PIVOT [497] and the Veteran’s Administration Cooperative Urological Research Group (VACURG) study which was conducted in the pre-PSA era [500]. The authors found that RP compared with WW reduced time to death by any cause (HR: 0.79, 95% CI: 0.70–0.90), time to death by PCa (HR: 0.57, 95% CI: 0.44–0.73) and time to metastatic progression (HR: 0.56, 95% CI: 0.46–0.70) at 29 years’ follow-up. However, RP was associated with higher rates of urinary incontinence (RR: 3.97, 95% CI: 2.34–6.74) and erectile dysfunction (ED) (RR: 2.67, 95% CI: 1.63–4.38).

The overall evidence indicates that for men with asymptomatic, clinically localised PCa, and with a life expectancy of < 10 years based on co-morbidities and/or age, the oncological advantages of active treatment over WW are unlikely to be relevant to them. Consequently, WW should be adopted for such patients. For assistance in estimating life expectancy and health status see Section 5.4.

6.1.2. Radical prostatectomy

6.1.2.1. Introduction

The goal of RP by any approach is the eradication of cancer while, whenever possible, preserving pelvic organ function [501]. The procedure involves removing the entire prostate with its capsule intact and SVs, followed by vesico-urethral anastomosis. Surgical approaches have expanded from perineal and retropubic open approaches to laparoscopic and robotic-assisted techniques; anastomoses have evolved from Vest approximation sutures to continuous suture watertight anastomoses under direct vision and mapping of the anatomy of the dorsal venous complex (DVC) and cavernous nerves has led to excellent visualisation and potential for preservation of erectile function [502]. The main results from multi-centre RCTs involving RP are summarised in Table 6.1.3.

Table 6.1.3: Oncological results of radical prostatectomy in organ-confined disease in RCTs

CSS = cancer-specific survival; FU = follow-up; mo = months; PSA = prostate-specific antigen; yr. = year.

6.1.2.2. Pre-operative preparation

6.1.2.2.1. Pre-operative patient education

As before any surgery appropriate education and patient consent is mandatory prior to RP. Peri-operative education has been shown to improve long-term patient satisfaction following RP [504]. Augmentation of standard verbal and written educational materials such as use of interactive multimedia tools [505,506] and pre-operative patient-specific 3D printed prostate models has been shown to improve patient understanding and satisfaction and should be considered to optimise patient-centred care [507].

6.1.2.2.2. Pre-operative pelvic floor exercises

Although many patients who have undergone RP will experience a return to urinary continence [508], temporary urinary incontinence is common early after surgery, reducing QoL. Pre-operative pelvic floor exercises (PFE) with, or without, biofeedback have been used with the aim of reducing this early post-operative incontinence. A systematic review and meta-analysis of the effect of pre-RP PFE on post-operative urinary incontinence showed a significant improvement in incontinence rates at 3 months post-operatively with an OR of 0.64 (p = 0.005), but not at 1 month or 6 months [509]. Pre-operative PFE may therefore provide some benefit, however the analysis was hampered by the variety of PFE regimens and a lack of consensus on the definition of incontinence.

6.1.2.2.3. Prophylactic antibiotics

Prophylactic antibiotics should be used; however, no high-level evidence is available to recommend specific prophylactic antibiotics prior to RP (See EAU Urological Infections Guidelines [510]). In addition, as the susceptibility of bacterial pathogens and antibiotic availability varies worldwide, any use of prophylactic antibiotics should adhere to local guidelines.

6.1.2.2.4. Neoadjuvant androgen deprivation therapy

Several RCTs have analysed the impact of neoadjuvant ADT before RP, most of these using a 3-month period. The main findings were summarised in a 2006 Cochrane review [511]. Neoadjuvant ADT is associated with a decreased rate of pT3 (downstaging), decreased positive margins, and a lower incidence of positive LNs. These benefits are greater with increased treatment duration (up to 8 months). However, since neither the PSA relapse-free survival nor CSS were shown to improve, neoadjuvant ADT should not be considered as standard clinical practice. These findings were supported by a 2021 systematic review and meta-analysis [512]

One recent RCT compared neoadjuvant luteinising hormone-releasing hormone (LHRH) alone vs. LHRH plus abiraterone acetate plus prednisone (AAP) prior to RP in 65 localised high-risk PCa patients [513]. Patients in the combination arm were found to have both significantly lower tumour volume and significantly lower BCR at > 4 years follow-up (p = 0.0014). A pooled analysis of 3 RCTs, including 117 patients and assessing the impact of intense neoadjuvant deprivation therapy has reported a complete pathological response rate of 9.4%, with improved BCR outcomes in complete responders [514]. Further supportive evidence is required before recommending combination neoadjuvant therapy including abiraterone prior to RP. Another RCT (CALGB 90203), comparing RP alone to RP with neoadjuvant chemo-hormonal therapy (CHT) including docetaxel for clinically high-risk localised PCa did not meet the study’s primary endpoint of biochemical PFS at 3 years post-operatively, due to contamination with early salvage RT (SRT). As a result, CHT is not currently recommended unless longer-term data show a survival benefit using clinical endpoints [515].

6.1.2.2.5. Timing of radical prostatectomy

The effect of the COVID-19 pandemic on healthcare prompted a systematic review of whether delayed surgery for intermediate and high-risk localised PCa affected oncological outcomes [516]. Evidence in the 19 studies included was hampered by variation in definitions of delay from diagnosis to surgery, but oncological outcomes, including adverse pathology, BCR, additional treatment and survival, were no worse with delays of up to 3 months. Heterogeneity of data prevented any meaningful analysis of delays beyond 3 months.

6.1.2.3. Surgical techniques

Prostatectomy can be performed by open-, laparoscopic- or robot-assisted (RARP) approaches. The initial open technique of RP described by Young in 1904 was via the perineum [502] but suffered from a lack of access to pelvic LNs. If lymphadenectomy is required during perineal RP it must be done via a separate open retropubic (RRP) or laparoscopic approach. The open retropubic approach was popularised by Walsh in 1982 following his anatomical description of the DVC, enabling its early control, and of the cavernous nerves, permitting a bilateral nerve-sparing procedure [517]. In 2002, RARP was introduced using the da Vinci Surgical System^® by Binder [518]. This technology combined the minimally-invasive advantages of laparoscopic RP with improved surgeon ergonomics and greater technical ease of suture reconstruction of the vesicourethral anastomosis and has now become the preferred minimally-invasive approach when available.

In a randomised phase III trial, RARP was shown to have reduced admission times and blood loss, but not earlier (12 weeks) functional or oncological outcomes compared to open RP [519]. An updated analysis with follow-up at 24 months did not reveal any significant differences in functional outcomes between the approaches [520]. Increased surgical experience has lowered the complication rates of RP and improved cancer cure [477-480]. Lower rates of positive surgical margins for high-volume surgeons suggest that experience and careful attention to surgical details, can improve cancer control with RP [521-523]. There is a lack of studies comparing the different surgical modalities for these longer-term outcomes [476,498,503,524]. A 2016 systematic review and meta-analysis included two small RCTs comparing RARP vs. laparoscopic RP (LRP) [525]. The results suggested higher rates of return of erectile function (RR: 1.51, 95% CI: 1.19–1.92) and return to continence function (RR: 1.14, 95% CI: 1.04–1.24) in the RARP group. However, a Cochrane review comparing either RARP or LRP vs. open RP included two RCTs and found no significant differences between the comparisons for oncological-, urinary- and sexual function outcomes, although RARP and LRP both resulted in statistically significant improvements in duration of hospital stay and blood transfusion rates over open RP [526]. Therefore, no surgical approach can be recommended over another.

Outcome after prostatectomy has been shown to be dependent on both surgeon [527] as well as hospital volume [528]. Although various volume criteria have been set worldwide, the level of evidence is insufficient to pinpoint a specific lower volume limit.

6.1.2.3.1. Robotic anterior versus Retzius-sparing dissection

Robot-assisted RP has typically been performed via the anterior approach, first dropping the bladder to expose the space of Retzius. However, the posterior approach (Retzius-sparing [RS-RARP]) has been used to minimise injury to support structures surrounding the prostate.

Galfano et al., first described RS-RARP in 2010 [529]. This approach commences dissection posteriorly at the pouch of Douglas, first dissecting the SVs and progressing caudally behind the prostate. All of the anterior support structures are avoided, giving rise to the hypothetical mechanism for improved early post-operative continence. RS-RARP thus offers the same potential advantage as the open perineal approach, but without disturbance of the perineal musculature.

Retzius-sparing-RARP has been recently investigated in RCTs leading to four systematic reviews and meta-analyses [530-532] including a 2020 Cochrane systematic review [533] and a large propensity score matched analysis [534]. The Cochrane review used the most rigorous methodology and analysed 5 RCTs with 502 patients. It found with moderate certainty that RS-RARP improved continence at 1 week post catheter removal compared to standard RARP (RR: 1.74). Continence may also be improved at 3 months post-operatively (RR: 1.33), but this was based on low-certainty data. Continence outcomes appeared to equalise by 12 months (RR: 1.01). These findings matched those of the other systematic reviews. However, a significant concern was that RS-RARP appears to increase the risk of positive margins (RR: 1.95) but this was also low-certainty evidence. A single-surgeon propensity score matched analysis of 1,863 patients reached the same conclusion as the systematic reviews regarding earlier return to continence but did not show data on margin status [534].

Based on these data, recommendations cannot be made for one technique over another. However, the trade-offs between the risks of a positive margin vs. earlier continence recovery should be discussed with prospective patients. Furthermore, no high-level evidence is available on high-risk disease with some concerns that RS-RARP may confer an increased positive margin rate based on pT3 results. In addition, RS-RARP may be more technically challenging in various scenarios such as anterior tumours, post-TURP, a grossly enlarged gland, or a bulky median lobe [535].

6.1.2.3.2. Pelvic lymph node dissection

A systematic review has demonstrated that performing PLND during RP failed to improve oncological outcomes, including survival [536]. Moreover, two RCTs have failed to show a benefit of an extended approach vs. a limited PLND on early oncologic outcomes [537,538].

Extended PLND includes removal of the nodes overlying the external iliac artery and vein, the nodes within the obturator fossa located cranially and caudally to the obturator nerve, and the nodes medial and lateral to the internal iliac artery. With this template, 94% of patients are correctly staged [539] and as such, ePLND provides the most accurate information for staging and prognosis [536].

The individual risk of patients harbouring positive LNs can be estimated based on validated nomograms. The Briganti [400,401], Partin and MSKCC nomograms [540] have shown similar diagnostic accuracy in predicting LN invasion [541-543]. However, these nomograms were developed in the pre-MRI setting based on systematic random biopsy.

An updated nomogram has been externally validated in men diagnosed based on MRI followed by MRI-targeted biopsy [401]. Using this nomogram, patients could be spared an ePLND if their risk of nodal involvement was less than 7%; which would result in missing only 1.5% of patients with nodal invasion [401,403]. However, 70% of patients would still undergo an unnecessary ePLND as they would have no LN involvement [364]. This is problematic due to the risk of complications of PLND (see below) as well as the additional operative time required.

A 2021 systematic review and meta-analysis of 27 studies showed that PSMA PET had a significantly higher sensitivity (93% vs. 54%, p = 0.008) and NPV (96% vs. 83%, p = 0.044) for LN positivity in intermediate-risk vs. high-risk groups [544]. This suggests that, given a lack of survival benefit of PLND, it might be safely omitted in intermediate-risk patients whose staging PSMA PET is negative. However, only 1 of the 27 studies with only 42 patients had focused on intermediate-risk cancer, indicating a need for further data in this risk group. The authors conclude that PLND should still be performed in high-risk patients with negative PSMA PET, however this should also be balanced against the risk of morbidity of PLND (see Section 5.3.2.4). For patients with positive pelvic LNs on PSMA PET only, evidence is currently unavailable on the best treatment strategy.

6.1.2.3.2.1. Early complications of extended pelvic lymph node dissection

Extended PLND increases morbidity in the treatment of PCa [536]. Overall complication rates of 19.8% vs. 8.2% were noted for ePLND vs. limited PLND, respectively, with lymphoceles (10.3% vs. 4.6%) being the most common adverse event (AE). Other authors have reported lower complication rates [545]. Similar rates of lymphoceles have been observed in RALP series; however, in one subgroup analysis lymphoceles were more common with the extraperitoneal approach (19%) vs. the transperitoneal approach (0%) [546,547]. Briganti et al., [548] also showed more complications after extended compared to limited PLND. Twenty percent of men suffer a complication of some sort after ePLND. Thromboembolic events occur in less than 1% of cases overall, but the RR of DVT and PE associated with PLND has been found to be 7.8 and 6.3, respectively [549] (See section 6.1.2.4.2)

6.1.2.3.2.2. Sentinel node biopsy analysis

The rationale for a sentinel node biopsy (SNB) is based on the concept that a sentinel node is the first to be involved by migrating tumour cells. Therefore, when this node is negative it is possible to avoid an ePLND [550]. Intraprostatic injections of indocyanine green (ICG) have been used to visualise prostate-related LNs for SNB. In a randomised comparison, Harke et al, found more cancer-containing LNs in men who underwent a PLND guided by ICG but no difference in BCR at 22.9-month follow-up [551]. A systematic review of 21 studies showed a sensitivity of 95.2% and NPV of 98.0% for SNB in detecting men with metastases at ePLND [552]. However, this review was hampered by widespread heterogeneity of both definitions and how SNB is performed. This prompted the development of an expert consensus report to guide further research [550]. There currently remains insufficient evidence supporting SNB for nodal staging.

6.1.2.3.3. Prostatic anterior fat pad dissection and histologic analysis

Several multi-centre and large single-centre series have shown the presence of lymphoid tissue within the fat pad anterior to the endopelvic fascia; the prostatic anterior fat pad (PAFP) [553-559]. This lymphoid tissue is present in 5.5–10.6% of cases and contains metastatic PCa in up to 1.3% of intermediate- and high-risk patients.

When positive, the PAFP is often the only site of LN metastasis. The PAFP is therefore a rare but recognised route of spread of disease. Unlike PLND, there is no morbidity associated with removal of the PAFP. The PAFP is always removed at RP for exposure of the endopelvic fascia and should be sent for histologic analysis as per all removed tissue.

6.1.2.3.4. Management of the dorsal venous complex

Since the description of the anatomical open RP by Walsh and Donker in the 1980s, various methods of controlling bleeding from the DVC have been proposed to optimise visualisation [517]. In the open setting, blood loss and transfusion rates have been found to be significantly reduced when ligating the DVC prior to transection [560]. However, concerns have been raised regarding the effect of prior DVC ligation on apical margin positivity and continence recovery due to the proximity of the DVC to both the prostatic apex and the urethral sphincter muscle fibres. In the robotic-assisted laparoscopic technique, due to the increased pressure of pneumoperitoneum, whether prior DVC ligation was used or not, blood loss was not found to be significantly different in one study [561]. In another study, mean blood loss was significantly less with prior DVC ligation (184 vs. 176 mL, p = 0.033), however it is debatable whether this was clinically significant [562]. The positive apical margin rate was not different, however, the latter study showed earlier return to full continence at 5 months post-operatively in the no prior DVC ligation group (61% vs. 40%, p < 0.01).

Ligation of the DVC can be performed with standard suture or using a vascular stapler. One study found significantly reduced blood loss (494 mL vs. 288 mL) and improved apical margin status (13% vs. 2%) when using the stapler [563].

Given the relatively small differences in outcomes, the surgeon’s choice to ligate prior to transection or not, or whether to use sutures or a stapler, will depend on their familiarity with the technique and the equipment available.

6.1.2.3.5. Nerve-sparing surgery

During prostatectomy, preservation of the neurovascular bundles (NVB) with parasympathetic nerve branches of the pelvic plexus can spare erectile function [564,565].

Extra-, inter-, and intra-fascial dissection planes can be planned, with those closer to the prostate and performed bilaterally associated with superior (early) functional outcomes [566-569]. Furthermore, many different techniques are propagated such as retrograde approach after anterior release (vs. antegrade), and athermal and traction-free handling of bundles [570-572]. Nerve-sparing (NS) surgery may be performed using clips or low bipolar energy without clear benefit favouring one technique over another regarding functional outcomes [573].

A 2021 large retrospective study of high-risk patients also found that NS did not affect BCR, risk of metastasis, or of death [574]. Notably, clinical and pathological stage T3 and ISUP Grade 5 did not impact these oncological outcomes. However, as a retrospective study, it was subject to selection bias, whereby patients with unfavourable characteristics were more likely to have undergone non-nerve-sparing surgery.

A 2021 systematic review of 19 studies analysing the parameters used for selection of NS found that individual clinical and radiological factors were poor at predicting EPE, and consequently, the appropriateness of NS. However, nomograms that incorporated mpMRI performed better. As with all nomograms, the question remains as to where to set the cut-off point [575].

A 2022 systematic review of 18 comparative studies (no RCTs) of NS vs. non-nerve-sparing RP showed a RR of side-specific positive margins of 1.5, but none of them included patients with high-risk PCa [576]. There was no effect seen of NS on BCR. However, follow-up was short and studies were subject to selection bias with mainly low-risk patients. For those patients with high-risk PCa, side-specific NS was avoided if disease was palpable or EPE was present on MRI. Indeed, a 2019 systematic review showed that MRI affected the decision to perform NS or not in 35% of cases without any negative impact on surgical margin rate [577] (See Section 5.3.1.2).

Although age and pre-operative function may remain the most important predictors for post-operative erectile function, NS has also been associated with improved continence outcomes and may therefore still be relevant for men with poor erectile function [578,579]. The association with continence may be mainly due to the dissection technique used during NS surgery, and not due to the preservation of the NVB themselves [578].

In summary, the quality of data is not adequate to permit a strong recommendation in favour of NS or non-nerve-sparing, but pre-operative risk factors for side-specific EPE such as PSA, PSA density, clinical stage, ISUP grade, and PI-RADS score, EPE and capsule contact length on MRI, should be taken into account.

6.1.2.3.6. Lymph-node-positive patients during radical prostatectomy

Although no RCTs are available, data from prospective cohort studies comparing survival of pN+ patients (as defined following pathological examination after RP) support that RP may have a survival benefit over abandonment of RP in node-positive cases [580]. As a consequence there is no role for performing frozen section of suspicious LNs.

6.1.2.3.7. Removal of seminal vesicles

The more aggressive forms of PCa may spread directly into the SVs. For oncological clearance, the SVs have traditionally been removed intact with the prostate specimen [581]. However, in some patients the tips of the SVs can be challenging to dissect free. Furthermore, the cavernous nerves run past the SV tips such that indiscriminate dissection of the SV tips could potentially lead to ED [582]. However, a RCT comparing nerve-sparing RP with and without a SV-sparing approach found no difference in margin status, PSA recurrence, continence or erectile function outcomes. Whilst complete SV removal should be the default, preservation of the SV tips may be considered in cases of low risk of involvement.

6.1.2.3.8. Techniques of vesico-urethral anastomosis

Following prostate removal, the bladder neck is anastomosed to the membranous urethra. The objective is to create a precisely aligned, watertight, tension-free, and stricture-free anastomosis that preserves the integrity of the intrinsic sphincter mechanism. Several methods have been described, based on the direct or indirect approach, the type of suture (i.e. barbed vs. non-barbed/monofilament), and variation in suturing technique (e.g., continuous vs. interrupted, or single-needle vs. double-needle running suture). The direct vesico-urethral anastomosis, which involves the construction of a primary end-to-end inter-mucosal anastomosis of the bladder neck to the membranous urethra by using 6 interrupted sutures placed circumferentially, has become the standard method of reconstruction for open RP [583].

The development of laparoscopic- and robotic-assisted techniques to perform RP have facilitated the introduction of new suturing techniques for the anastomosis. A systematic review and meta-analysis compared unidirectional barbed suture vs. conventional non-barbed suture for vesico-urethral anastomosis during robotic-assisted laparoscopic prostatectomy (RALP) [584]. The review included 3 RCTs and found significantly reduced anastomosis time, operative time and posterior reconstruction time in favour of the unidirectional barbed suture technique, but there were no differences in post-operative leak rate, length of catheterisation and continence rate. However, no definitive conclusions could be drawn due to the relatively low quality of the data. In regard to suturing technique, a systematic review and meta-analysis compared continuous vs. interrupted suturing for vesico-urethral anastomosis during RP [585]. The study included only one RCT with 60 patients [586]. Although the review found slight advantages for continuous suturing over interrupted suturing in terms of catheterisation time, anastomosis time and rate of extravasation, the overall quality of evidence was low and no clear recommendations were possible. A recent RCT [587] compared the technique of suturing using a single absorbable running suture vs. a double-needle single-knot running suture (i.e. Van Velthoven technique) in laparoscopic RP [588]. The study found slightly reduced anastomosis time with the single running suture technique, but anastomotic leak, stricture, and continence rates were similar.

Overall, although there are a variety of approaches, methods and techniques for performing the vesico-urethral anastomosis, no clear recommendations are possible due to the lack of high-certainty evidence. In practice, the chosen method should be based on surgeon experience and individual preference [583-588].

6.1.2.3.9. Bladder neck management

Bladder neck mucosal eversion

Some surgeons perform mucosal eversion of the bladder neck as its own step in open RP with the aim of securing a mucosa-to-mucosa vesico-urethral anastomosis and avoiding anastomotic stricture. Whilst bringing bladder and urethral mucosa together by the everted bladder mucosa covering the bladder muscle layer, this step may actually delay healing of the muscle layers. An alternative is to simply ensure bladder mucosa is included in the full thickness anastomotic sutures. A non-randomised study of 211 patients with and without bladder neck mucosal eversion showed no significant difference in anastomotic stricture rate [589]. The strongest predictor of anastomotic stricture in RP is current cigarette smoking [590], but it is also 2.2 higher in open RP than RARP [591].

Bladder neck preservation

Whilst the majority of urinary continence is maintained by the external urethral sphincter at the membranous urethra (see below), a minor component is contributed by the internal lissosphincter at the bladder neck [592]. Preservation of the bladder neck has therefore been proposed to improve continence recovery post-RP. A RCT assessing continence recovery at 12 months and 4 years showed improved objective and subjective urinary continence in both the short- and long term without any adverse effect on oncological outcome [593]. These findings were confirmed by a systematic review [594]. However, concern remains regarding margin status for cancers located at the prostate base.

A systematic review addressing site-specific margin status found a mean base-specific positive margin rate of 4.9% with bladder neck preservation vs. only 1.9% without [592]. This study was inconclusive, but it would be sensible to exercise caution when considering bladder neck preservation if significant cancer is known to be at the prostate base. Bladder neck preservation should be performed routinely when the cancer is distant from the base. However, bladder neck preservation cannot be performed in the presence of a large median lobe or a previous TURP.

6.1.2.3.10. Urethral length preservation

The membranous urethra sits immediately distal to the prostatic apex and is chiefly responsible, along with its surrounding pelvic floor support structures, for urinary continence. It consists of the external rhabdosphincter which surrounds an inner layer of smooth muscle. Using pre-operative MRI, the length of membranous urethra has been shown to vary widely. Two systematic reviews and meta-analyses found that every extra millimetre of membranous urethral length seen on MRI pre-operatively improves early return to continence post-RP [595,596]. Therefore, it is likely that preservation of as much urethral length as possible during RP will maximise the chance of early return to continence. It may also be useful to measure urethral length pre-operatively to facilitate counselling of patients on their relative likelihood of early post-operative continence.

6.1.2.3.11. Cystography prior to catheter removal

Cystography may be used prior to catheter removal to check for a substantial anastomotic leak. If such a leak is found, catheter removal may then be deferred to allow further healing and sealing of the anastomosis. However, small comparative studies suggest that a cystogram to assess anastomotic leakage is not indicated as SOC before catheter removal 8 to 10 days after surgery [597]. If a cystogram is used, men with LUTS, large prostates, previous TURP or bladder neck reconstruction, may benefit as these factors have been associated with leakage [598,599]. Contrast-enhanced transrectal US is an alternative [600].

6.1.2.3.12. Urinary catheter

A urinary catheter is routinely placed during RP to enable bladder rest and drainage of urine while the vesicourethral anastomosis heals. Compared to a traditional catheter duration of around 1 week, some centres remove the transurethral catheter early (post-operative day 2–3), usually after thorough anastomosis with posterior reconstruction or in patients selected peri-operatively on the basis of anastomosis quality [601-604]. No higher complication rates were found. Although shorter catheterisation has been associated with more favourable short-term functional outcomes, no differences in long-term function were found [605]. One RCT has shown no difference in rate of UTI following indwelling catheter (IDC) removal whether prophylactic ciprofloxacin was given prior to IDC removal or not, suggesting antibiotics should not be given at catheter removal [606].

As an alternative to transurethral catheterisation, suprapubic catheter insertion during RP has been suggested. Some reports suggest less bother regarding post-operative hygiene and pain [607-611], while others did not find any differences [612,613]. No impact on long-term functional outcomes were seen.

6.1.2.3.13. Use of a pelvic drain

A pelvic drain has traditionally been used in RP for potential drainage of urine leaking from the vesico-urethral anastomosis, blood, or lymphatic fluid when a PLND has been performed. Two RCTs in the robotic-assisted laparoscopic setting have been performed [614,615]. Patients with urine leak at intra-operative anastomosis watertight testing were excluded. Both trials showed non-inferiority in complication rates when no drain was used. When the anastomosis is found to be watertight intra-operatively, it is reasonable to avoid inserting a pelvic drain. There is no evidence to guide usage of a pelvic drain in PLND.

6.1.2.4. Acute and chronic complications of radical protatectomy

Post-operative incontinence and ED are common problems following surgery for PCa. A key consideration is whether these problems are reduced by using newer techniques such as RALP. Systematic reviews have documented complication rates after RALP [616-620], and can be compared with contemporaneous reports after RRP [621]. A prospective controlled non-RCT of patients undergoing RP in 14 centres using RALP or RRP showed that 12 months after RALP, 21.3% of patients were incontinent, as were 20.2% after RRP (adjusted OR: 1.08, 95% CI: 0.87–1.34) [622]. Erectile dysfunction was observed in 70.4% after RALP and 74.7% after RRP. The adjusted OR was 0.81 (95% CI: 0.66–0.98) [622].

A systematic review and meta-analysis of unplanned hospital visits and re-admissions post-RP analysed 60 studies with over 400,000 patients over a 20-year period up to 2020. It found an emergency room visit rate of 12% and a hospital re-admission rate of 4% at 30 days post-operatively [623].

A RCT comparing RALP and RRP reported outcomes at 12 weeks in 326 patients and functional outcomes at 2 years [519]. Urinary function scores did not differ significantly between RRP vs. RALP at 6 and 12 weeks post-surgery (74–50 vs. 71–10, p = 0.09; 83–80 vs. 82–50, p = 0.48), with comparable outcomes for sexual function scores (30–70 vs. 32–70, p = 0.45; 35–00 vs. 38–90, p = 0.18). In the RRP group 14 (9%) patients had post-operative complications vs. 6 (4%) in the RALP group. The intra- and peri-operative complications of RRP and RALP are listed in Table 6.1.4. Table 6.1.5 lists the Clavien-Dindo definition of surgical complications. The early use of phosphodiesterase-5 (PDE5) inhibitors in penile rehabilitation remains controversial resulting in a lack of clear recommendations (see Section 8.3.2.1).

Table 6.1.4: Intra-and peri-operative complications of retropubic RP, laparoscopic RP and RALP (Adapted from )

RALP = robot-assisted laparoscopic prostatectomy; RP = radical prostatectomy; RRP = radical retropubicprostatectomy.

Table 6.1.5: Clavien-Dindo grading of surgical complications [624].

6.1.2.4.1. Effect of anterior and posterior reconstruction on continence

Preservation of integrity of the external urethral sphincter is critical for continence post-RP. Less clear is the effect of reconstruction of surrounding support structures to return to continence. Several small RCTs have been conducted, however, pooling analyses is hampered by variation in the definitions of incontinence and surgical approach, such as open vs. robotic and intra-peritoneal vs. extra-peritoneal. In addition, techniques used to perform both anterior suspension or reconstruction and posterior reconstruction are varied. For example, anterior suspension is performed either through periosteum of the pubis or the combination of ligated DVC and puboprostatic ligaments (PPL). Posterior reconstruction from rhabdosphincter is described to either Denonvilliers fascia posterior to bladder or to posterior bladder wall itself.

Two trials assessing posterior reconstruction in RALRP found no significant improvement in return to continence [625,626]. A third trial using posterior bladder wall for reconstruction showed only an earlier return to 1 pad per day (median 18 vs. 30 days, p = 0.024) [627]. When combining both anterior and posterior reconstruction, where for anterior reconstruction the PPL were sutured to the anterior bladder neck, another RCT found no improvement compared to a standard anastomosis with no reconstruction [628].

Four RCTs including anterior suspension have also shown conflicting results. Anterior suspension alone through the pubic periosteum, in the setting of extra-peritoneal RALRP, showed no advantage [629]. However, when combined with posterior reconstruction in RRP, one RCT showed significant improvement in return to continence at one month (7.1% vs. 26.5%, p = 0.047) and 3 months (15.4% vs. 45.2%, p = 0.016), but not at 6 months (57.9% vs. 65.4%, p = 0.609) [630]. Another anterior plus posterior reconstruction RCT using the Advanced Reconstruction of VesicoUrethral Support (ARVUS) technique and the strict definition of continence of ‘no pads‘, showed statistically significant improvement in continence at 2 weeks (43.8% vs. 11.8%), 4 weeks (62.5% vs. 14.7%), 8 weeks (68.8% vs. 20.6%), 6 months (75% vs. 44.1%) and 12 months (86.7% vs. 61.3%), when compared to standard posterior Rocco reconstruction [631]. Anterior suspension alone through the DVC and PPL combined without posterior construction in the setting of RRP has shown improvement in continence at one month (20% vs. 53%, p = 0.029), 3 months (47% vs. 73%, p = 0.034) and 6 months (83% vs. 100%, p = 0.02), but not at 12 months (97% vs. 100%, p = 0.313) [632]. Together, these results suggest a possible earlier return to continence, but no long-term difference.

As there is conflicting evidence on the effect of anterior and/or posterior reconstruction on return to continence post-RP, no recommendations can be made. However, no studies showed an increase in adverse oncologic outcome or complications with reconstruction.

6.1.2.4.2. Deep venous thrombosis prophylaxis

For EAU Guidelines recommendations on post-RP deep venous thrombosis prophylaxis, please see the Thromboprophylaxis Guidelines Section 3.1.6 [633]. However, these recommendations should be adapted based on national recommendations, when available.

6.1.3. Radiotherapy

Intensity-modulated RT (IMRT) or volumetric arc radiation therapy (VMAT) with image-guided RT (IGRT) is currently widely recognised as the standard treatment approach for EBRT.

6.1.3.1. External beam radiation therapy

6.1.3.1.1. Technical aspects

Intensity-modulated RT and VMAT employ dynamic multileaf collimators, which automatically and continuously adapt to the contours of the target volume seen by each beam. Viani et al., show significantly reduced acute and late grade > 2 genito-urinary (GU) and gastro-intestinal (GI) toxicity in favour of IMRT, while BCR-free rates did not differ significantly when comparing IMRT with three-dimensional conformal radiation therapy (3D-CRT) in a RCT comprising 215 patients [634]. A meta-analysis by Yu et al., (23 studies, 9,556 patients) concluded that IMRT significantly decreases the occurrence of grade 2–4 acute GI toxicity, late GI toxicity and late rectal bleeding, and achieves better PSA relapse-free survival in comparison with 3D-CRT. Intensity-modulated EBRT and 3D-CRT show comparable acute rectal toxicity, late GU toxicity and OS, while IMRT slightly increases the morbidity of acute GU toxicity [635]. Zapatero et al., found, based on 733 consecutive patients (295 IMRT vs. 438 3D-CRT), that compared with 3D-CRT, high-dose IMRT/IGRT is associated with a lower rate of late urinary complications despite a higher radiation dose [636]. In conclusion, IMRT plus IGRT remain the SOC for the treatment of PCa.

The advantage of VMAT over IMRT is shorter treatment times, generally two to three minutes in total. Both techniques allow for a more complex distribution of the dose to be delivered and provide concave isodose curves, which are particularly useful as a means of sparing the rectum. Radiotherapy treatment planning for IMRT and VMAT differs from that used in conventional EBRT, requiring a computer system capable of ‘inverse planning’ and the appropriate physics expertise. Treatment plans must conform to pre-specified dose constraints to critical organs at risk of normal tissue damage and a formal quality assurance process should be routine.

With dose escalation using IMRT/VMAT, organ movement becomes a critical issue in terms of both tumour control and treatment toxicity. Techniques will therefore combine IMRT/VMAT with some form of IGRT (usually gold marker or cone-beam CT), in which organ movement can be visualised and corrected for in real time, although the optimum means (number of applications per week) of achieving this is still unclear [637,638]. Tomotherapy is another technique for the delivery of IMRT, using a linear accelerator mounted on a ring gantry that rotates as the patient is delivered through the centre of the ring, analogous to spiral CT scanning.

While image-guided radiotherapy (IGRT) for PCa has resulted in lower rates of toxicity, the use of MR-guided adapted RT is still investigational [639]. Planning studies confirm that MR-based adaptive RT significantly reduces doses to organs at risk (OAR) and this should translate into a meaningful clinical benefit in due course [640]. Although the rates of acute GI- and GU toxicity appear low, mostly on the basis of patients treated with stereotactic RT [641], follow-up is too short for definitive conclusions [639]. Of interest, in one series, 36% of patients treated with SBRT needed a catheter insertion for acute grade 2 urinary retention [642]. Above that, the daily fraction time of up to 45 minutes [639,641], the heavy MR-workflow and the limited field size (rendering most pelvic fields too large) make its implementation not yet a routine [639]. Results of prospective RCTs such as the MIRAGE trial (CT-guided Stereotactic Body Radiation Therapy and MRI-guided Stereotactic Body Radiation Therapy for Prostate Cancer) will have to be awaited [643].

6.1.3.1.2. Dose escalation

Local control is a critical issue for the outcome of RT of PCa. It has been shown that local failure due to insufficient total dose is prognostic for death from PCa as a second wave of metastases is seen 5 to 10 years later on [644]. Several RCTs have shown that dose escalation (range 74–80 Gy) has a significant impact on 10-year biochemical relapse as well as metastases and disease-specific mortality [645-652]. These trials have generally included patients from several risk groups, and the use of neoadjuvant/adjuvant HT has varied (see Table 6.1.6). The best evidence of an OS benefit in patients with intermediate- or high-risk PCa, but not with low-risk PCa, derives from a non-randomised but well conducted propensity-matched retrospective analysis of the U.S. National Cancer Database by Kalbasi et al., including a total of 42,481 patients [653]. The concept of a focal boost to the dominant intraprostatic lesion visible on MRI has been successfully validated in a RCT of 571 intermediate- and high-risk patients [654]. Patients were randomised between 77 Gy in 35 fractions of 2.2 Gy and the same dose plus a focal boost up to 18 Gy. Additional ADT was given to 65% of patients in both arms. However, the duration of the ADT was not reported. With a median follow-up of 72 months there was a moderate improvement of biochemical PFS (primary endpoint). In addition, focal boosting decreased local failure (HR: 0.33) and increased the rate of regional + distant MFS (HR: 0.58) [655]. No significant difference for late GU- or GI toxicity grade > 2 (23% and 12% vs. 28% and 13%) was documented. For grade > 3 GU-toxicity these numbers were 3.5% and 5.6% (p > 0.05). However, longer follow-up is needed to assess late GU-toxicity [655]. Of note, there was a clear decrease in biochemical failure with increasing boost dose, individually given up to 18 Gy. If IMRT/VMAT and IGRT are used for dose escalation, rates of severe late side effects (> grade 3) for the rectum are 2–4% and for the GU tract 2–6% [647,654]. These data do not apply to focal boost therapy.

Table 6.1.6: Randomised trials of dose escalation in localised PCa

BF = biochemical failure; BFS = biochemical progression-free survival; DM = distant metastases; DSM = disease specific mortality; FFF = freedom from biochemical or clinical failure; HT = hormone therapy; MFS = metastasis-free survival; mo. = months; n = number of patients; OS = overall survival; PSA = prostate-specific antigen; yr. = year.

6.1.3.1.3. Hypofractionation

Fractionated RT utilises differences in the DNA repair capacity of normal and tumour tissue and slowly proliferating cells are very sensitive to an increased dose per fraction [656]. A meta-analysis of 25 studies including > 14,000 patients concluded that since PCa has a slow proliferation rate, hypofractionated RT could be more effective than conventional fractions of 1.8–2 Gy [657]. Hypofractionation (HFX) has the added advantage of being more convenient for the patient at lower cost.

Moderate HFX is defined as RT with 2.5–3.4 Gy/fx. Several studies report on moderate HFX applied in various techniques also including HT in part [658-665]. A systematic review concluded that studies on moderate HFX (2.5–3.4 Gy/fx) delivered with conventional 3D-CRT/IMRT have sufficient follow-up to support the safety of this therapy but long-term efficacy data are still lacking [664]. These results were confirmed by a recent Cochrane review on moderate HFX for clinically localised PCa [666]. Eleven studies were included (n = 8,278) with a median follow-up of 72 months showing little or no difference in PCa-specific survival (HR: 1.00). Based on 4 studies (n = 3,848), HFX probably makes little or no difference to late radiation GU toxicity (RR: 1.05) or GI toxicity (RR: 1.1), but this conclusion is based on relatively short follow-up, and 10 to 15-year data will be required to confirm these findings.

Moderate HFX should only be done by experienced teams using high-quality EBRT using IGRT and IMRT/VMAT and published phase III protocols should be adhered to (Table 6.1.7).

Table 6.1.7: Major phase III randomised trials of moderate hypofractionation for primary treatment

ADT = androgen deprivation therapy; BCDF = biochemical or clinical disease failure; BED = biologicallyequivalent dose, calculated to be equivalent in 2 Gy fractions using an α/ß of 1.5 Gy; DFS = disease-free survival; EBRT = external beam radiotherapy; FU = follow-up; fx = fractions; HR = hazard ratio; ISUP = International Society of Urological Pathology; mo. = month; n = number of patients; NCCN = National Comprehensive Cancer Network; n.s. = not significant; TF = treatment failure; yr. = year.

Ultra-HFX has been defined as RT with > 3.4 Gy per fraction [665]. It requires IGRT and (ideally) stereotactic body RT (SBRT). Table 6.1.8 provides an overview of selected studies. Short-term biochemical control (5-years) is comparable to conventional fractionation. However, there are concerns about high-grade GU and rectal toxicity and full long-term side effects may not yet be known [664,668]. In the HYPO-RT-PC randomised trial by Widmark et al., (n = 1,200), no difference in failure-free survival was seen for conventional or ultra-HFX but acute grade > 2 GU toxicity was 23% vs. 28% (p = 0.057), favouring conventional fractionation. There were no significant differences in long-term toxicity [668]. A systematic review by Jackson et al., included 38 studies with 6,116 patients who received RT with < 10 fractions and > 5 Gy per fraction. Five and 7-year biochemical recurrence-free survival (BRFS) rates were 95.3% and 93.7%, respectively, and estimated late grade > 3 GU and GI toxicity rates were 2.0% and 1.1%, respectively [669]. The authors conclude that there is sufficient evidence to support SBRT as a standard treatment option for localised PCa, even though the median follow-up in this review was only 39 months and it included at least one trial (HYPO-RT-PC) which used 3D-CRT in 80% and IMRT/VMAT in the remainder for ultra-HFX. In their review on SBRT, Cushman et al., evaluated 14 trials, including 2,038 patients and concluded that despite a lack of long-term follow-up and the heterogeneity of the available evidence, prostate SBRT affords appropriate biochemical control with few high-grade toxicities [670]. In the Intensity-modulated fractionated RT vs. stereotactic body RT for PCa (PACE-B) trial, acute grade > 2 GU or GI toxicities did not differ significantly between conventional fractionation and ultra- HFX [671]. Adopting planning dose constraints to the penile bulb might minimise ED, especially in younger patients (Table 6.1.8) [672].

First results of a small (n = 30) randomised phase-II trial in intermediate-risk PCa of ‘ultra-high single dose RT’ (SDRT) with 24 Gy compared with an ultra HFX stereotactic body RT regime with 5x9 Gy, have been published recently [673].

Table 6.1.8: Selected trials on ultra-hypofractionation for intact localised PCa

FFS = failure-free survival; FU = follow-up; fx = number fractions; GI = gastro-intestinal toxicity; GU = genito-urinary toxicity; mo. = months; n = number of patients; TD = total dose; SBRT = stereotactic body radiotherapy; wk. = weeks; yr. = years.

6.1.3.1.4. Neoadjuvant or adjuvant hormone therapy plus radiotherapy

The combination of RT with LHRH ADT has definitively proven its superiority compared with RT alone followed by deferred ADT on relapse, as shown by phase III RCTs [674-678] (Table 6.1.9). The main message is that for all intermediate-risk disease a short duration of 4-6 months is optimal while a longer one, around 3 years, is needed for high-risk patients. The OS impact of adding short-term ADT for favourable intermediate-risk disease, however, remains a matter of debate [121].

Table 6.1.9: Selected studies of use and duration of ADT in combination with RT for PCa

ADT = androgen deprivation therapy; CI = confidence interval; EBRT = external beam radiotherapy in standardfractionation; HR = hazard ratio; LHRH = luteinising hormone-releasing hormone; mo. = months; n = number of patients; OS = overall survival; RP = radical prostatectomy; RT = radiotherapy; wk = week; yr. = year.

The question of the added value of EBRT combined with ADT has been clarified by 3 RCTs. All showed a clear benefit of adding EBRT to long-term ADT (Table 6.1.10).

Table 6.1.10: Selected studies of ADT in combination with, or without, RT for PCa

ADT = androgen deprivation therapy; CSM = cancer-specific mortality; EBRT = external beam radiotherapy;HR = hazard ratio; LHRH = luteinising hormone-releasing hormone; mo. = months; n = number of patients; OS = overall survival; RT = radiotherapy; 3D-CRT = three-dimensional conformal radiotherapy.

6.1.3.1.5. Combined dose-escalated radiotherapy and androgen-deprivation therapy

The combination of ADT with various forms of RT has been extensively studied, with extremely strong evidence for the use of such combined modality therapy in several settings. The MARCAP (Individual Patient Data Meta-Analysis of Randomized Trials in Cancer of the Prostate) consortium recently conducted a meta-analysis of trials using individual patient data (IPD), and a primary endpoint of MFS, a validated surrogate for OS. Trials were eligible if they studied the use or prolongation of ADT in patients receiving definitive RT, and included 12 trials with 10,853 patients. Median follow-up was over 11 years. The use of ADT was clearly associated with significant improvements in BCR, metastatic recurrence, MFS, and OS. The benefits of ADT were independent of RT dose, age, and risk groups comparing NCCN unfavourable intermediate-risk (see Sections 4.2 and 6.2.2.3), high-risk and locally-advanced disease. There were no demonstrable benefits from the extension of duration of neoadjuvant ADT [687].

Three RCTs have shown that the benefits of ADT are independent of dose escalation, and that the use of ADT would not compensate for a lower RT dose:

1.The GICOR study shows a better biochemical DFS in high-risk patients for 3D-CRT radiation dose > 72 Gy when combined with long-term ADT [688].

2.DART01/05 GICOR shows improved OS in high-risk patients after ten years if 2 years of adjuvant ADT is combined with high-dose RT [689].

3.EORTC trial 22991 shows that 6 months ADT improves biochemical and clinical DFS irrespective of the dose (70, 74, 78 Gy) in intermediate-risk and low-volume high-risk localised PCa patients [690].

A meta-analysis based on IPD from two RCTs (RTOG 9413 and Ottawa 0101) has compared neoadjuvant/concomitant vs. adjuvant ADT (without substratifying between favourable- and unfavourable intermediate-risk disease) in conjunction with prostate RT and reported superior PFS with adjuvant ADT, but the data heterogeneity means that this observation is hypothesis-generating only [691].

In addition, a Canadian two-arm dose-escalated (76 Gy) RCT compared neoadjuvant and concomitant with adjuvant short-term ADT in 432 patients with intermediate-risk PCa. After 10 years no significant difference in OS or RT-related grade > 3 GI or GU toxicity was seen [692]. Therefore both regimen in combination with dose escalation are reasonable standards.

6.1.3.2. Proton beam therapy

In theory, proton beams are an attractive alternative to photon-beam RT for PCa, as they deposit almost all their radiation dose at the end of the particle’s path in tissue (the Bragg peak), in contrast to photons which deposit radiation along their path. There is also a very sharp fall-off for proton beams beyond their deposition depth, meaning that critical normal tissues beyond this depth could be effectively spared. In contrast, photon beams continue to deposit energy until they leave the body, including an exit dose.

One RCT on dose escalation (70.2 vs. 79.2 Gy) has incorporated protons for the boost doses of either 19.8 or 28.8 Gy. This trial shows improved outcome with the higher dose but it cannot be used as evidence for the superiority of proton therapy [646]. Thus, unequivocal information showing an advantage of protons over IMRT photon therapy is still not available. Studies from the SEER database and from Harvard describing toxicity and patient-reported outcomes do not point to an inherent superiority of protons [693,694]. In terms of longer-term GI toxicity, proton therapy might even be inferior to IMRT [694].

A RCT comparing equivalent doses of proton-beam therapy with IMRT is underway. Meanwhile, proton therapy must be regarded as an experimental alternative to photon-beam therapy.

6.1.3.3. Spacer during external beam radiation therapy

Biodegradable spacer insertion involves using a liquid gel or balloon to increase the distance between the prostate and rectum and consequently reduce the amount of radiation reaching the rectum. Various materials have been used with most evidence available for CE-marked hydrogel spacers [695]. A meta-analysis including one RCT and six cohort studies using the hydrogel spacer demonstrated a 5–8% reduction in the rectal volume receiving high-dose radiation, although heterogeneity between studies is found [696]. In the final analysis of the RCT with a median follow-up of 37 months and with approximately two-thirds of patients evaluable, those treated with spacer in situ had no deterioration from baseline bowel function whilst those treated without spacer had a lower mean bowel summary score of 5.8 points which met the threshold for a minimally important difference of 4–6 points [697].

This meta-analysis highlights inconsistent reporting of procedural complications. In addition, with more widespread clinical use safety reports describe uncommon, but severe and life changing, complications including prostatic abscess, fistulae and sepsis [698]. Implantation is associated with a learning curve and should only be undertaken by teams with experience of TRUS and transperineal procedures with robust audit reporting in place [699]. Its role in the context of moderate or extreme HFX is as yet unclear.

6.1.3.4. Brachytherapy

6.1.3.4.1. Low-dose rate brachytherapy

Low-dose rate (LDR) brachytherapy uses radioactive seeds permanently implanted into the prostate. In patients declining or unsuitable for AS LDR monotherapy [700] can be offered to those with low-risk or NCCN favourable intermediate-risk (see Section 4.2) and good urinary function defined as an International Prostatic Symptom Score (IPSS) < 12 and maximum flow rate > 15 mL/min on urinary flow tests [701]. In addition, with due attention to dose distribution, patients having had a previous TURP can undergo brachytherapy without an increase in risk of urinary toxicity. A minimal channel TURP is recommended, leaving at least 1 cm rim of prostate tissue around the post-TURP urethral defect at the postero-lateral sides of the prostate and there should be at least a 3-month interval between TURP and brachytherapy to allow for adequate healing [702-705].

The only available RCT comparing RP and LDR brachytherapy as monotherapy was closed due to poor accrual [706]. Outcome data are available from a number of large population cohorts with mature follow-up [707-711]. The biochemical DFS for ISUP grade 1 patients after 5 and 10 years has been reported to range from 71% to 93% and 65% to 85%, respectively [707-711]. A significant correlation has been shown between the implanted dose and biochemical control [712]. A D90 (dose covering 90% of the prostate volume) of > 140 Gy leads to a significantly higher biochemical control rate (PSA < 1.0 ng/mL) after 4 years (92 vs. 68%). There is no OS benefit in adding neoadjuvant or adjuvant ADT to LDR monotherapy [713].

Low-dose rate brachytherapy can be combined with EBRT in NCCN unfavourable intermediate-risk PCa (see Section 4.2) and high-risk patients. External beam RT (total dose of 78 Gy) has been compared with EBRT (total dose 46 Gy) followed by LDR brachytherapy boost (prescribed dose 115 Gy) in intermediate-risk and high-risk patients in the ASCENDE-RT randomised trial with 12 months of ADT in both arms [714]. The LDR boost resulted in 5- and 7-year PSA PFS increase (89% and 86%, respectively, compared to 84% and 75%). This improvement was achieved at a cost of increased late grade 3+ GU toxicity (18% compared to 8%) [715]. Toxicity resulted mainly in the development of urethral strictures and incontinence and great care should be taken during treatment planning.

6.1.3.4.2. High-dose rate brachytherapy

High-dose rate (HDR) brachytherapy uses a radioactive source temporarily introduced into the prostate to deliver radiation. The technical differences are outlined in Table 6.1.11. The use of the GEC (Groupe Europeen de Curietherapie)/ESTRO Guidelines is strongly recommended [716]. High-dose rate brachytherapy can be delivered in single or multiple fractions and is often combined with EBRT of at least 45 Gy [717]. A systematic review of non-RCTs and data from population studies suggest outcomes with EBRT plus HDR brachytherapy are superior to EBRT alone [718,719].

A single-centre RCT of EBRT (55 Gy in 20 fractions) vs. EBRT (35.75 Gy in 13 fractions), followed by HDR brachytherapy (17 Gy in two fractions over 24 hours) has been reported [720]. In 218 patients with T1–3 N0M0 PCa the combination of EBRT and HDR brachytherapy showed a significant improvement in the biochemical disease-free rate (p = 0.04) at 5 and 10 years (75% and 46% compared to 61% and 39%). However, an unexpectedly high rate of early recurrences was observed in the EBRT arm alone, even after 2 years, possibly due to a dose lower than the current standard used [720].

Supporting, but not definitive, evidence of the benefit of HDR boost is available from the TROG 03.04 RADAR trial. This multi-centre study had upfront radiation dose escalation (non-randomised) with dosing options of 66, 70, or 74 Gy EBRT, or 46 Gy EBRT plus HDR brachytherapy boost and randomised men with locally-advanced PCa to 6 or 18 months ADT. After a minimum follow-up of 10 years HDR boost significantly reduced distant progression, the study primary endpoint (sub HR: 0.68, 95% CI: 0.57–0.80; p < 0.0001), when compared to EBRT alone and, independent of duration of ADT, HDR boost was associated with increased IPSS of 3 points at 18 months post-treatment resolving by 3 years but decreased rectal symptoms when compared to EBRT [721].

Although radiation dose escalation using brachytherapy boost provides much higher biological doses, the TROG 03.04 RADAR RCT and systematic reviews show ADT use independently predicts better outcomes regardless of radiation dose intensification [713,721,722]. Omitting ADT may result in inferior OS and based on current evidence ADT use and duration should be in line with that used when delivering EBRT alone.

Fractionated HDR brachytherapy as monotherapy can be offered to patients with low- and intermediate-risk PCa, who should be informed that results are only available from limited series in very experienced centres. Five-year PSA control rates of 97.5% and 93.5% for low- and intermediate-risk PCa, respectively, are reported, with late grade 3+ GU toxicity rates < 5% and no, or very minimal, grade 3+ GI toxicity rates [723]. Single fraction HDR monotherapy should not be used as it has inferior biochemical control rates compared to fractionated HDR monotherapy [724].

Table 6.1.11: Difference between LDR and HDR brachytherapy

6.1.3.5. Acute side effects of external beam radiotherapy and brachytherapy

Gastro-intestinal and urinary side effects are common during and after EBRT. In the EORTC 22991 trial, approximately 50% of patients reported acute GU toxicity of grade 1, 20% of grade 2, and 2% grade 3. In the same trial, approximately 30% of patients reported acute grade 1 GI toxicity, 10% grade 2, and less than 1% grade 3. Common toxicities included dysuria, urinary frequency, urinary retention, haematuria, diarrhoea, rectal bleeding and proctitis [725]. In addition, general side effects such as fatigue are common. It should be noted that the incidence of acute side effects is greater than that of late effects (see Section 8.2.2.1), implying that most acute effects resolve. In a RCT of conventional dose EBRT vs. EBRT and LDR brachytherapy the incidence of acute proctitis was reduced in the brachytherapy arm, but other acute toxicities were equivalent [714]. Acute toxicity of HDR brachytherapy has not been documented in a RCT, but retrospective reports confirm lower rates of GI toxicity compared with EBRT alone and grade 3 GU toxicity in 10%, or fewer, patients, but a higher incidence of urinary retention [726]. Similar findings are reported using HFX; in a pooled analysis of 864 patients treated using extreme HFX and stereotactic RT, declines in urinary and bowel domains were noted at 3 months which returned to baseline, or better, by 6 months [727].

6.1.4. Hormonal therapy

6.1.4.1. Introduction

6.1.4.1.1. Different types of hormonal therapy

Androgen deprivation can be achieved by suppressing the secretion of testicular androgens in different ways. This can be combined with inhibiting the action of circulating androgens at the level of their receptor which has been known as complete (or maximal or total) androgen blockade (CAB) using the old-fashioned antiandrogens [728].

6.1.4.1.1.1. Testosterone-lowering therapy (castration)

6.1.4.1.1.1.1. Castration level

The castration level of testosterone is < 50 ng/dL (1.7 nmol/L), which was defined more than 40 years ago when testosterone testing was less sensitive. Current methods have shown that the mean value after surgical castration is 15 ng/dL [729]. Therefore, a more appropriate level should be defined as < 20 ng/dL
(< 0.7 nmol/L). This definition is important as better results are repeatedly observed with lower testosterone levels compared to 50 ng/dL [730-732]. However, the castrate level considered by the regulatory authorities and in clinical trials addressing castration in PCa is still the historical < 50 ng/dL (1.7 nmol/L).

6.1.4.1.1.1.2. Bilateral orchiectomy

Bilateral orchiectomy or subcapsular pulpectomy is still considered the primary treatment modality for ADT. It is a simple, cheap and virtually complication-free surgical procedure. It is easily performed under local anaesthesia, and it is the quickest way to achieve a castration level which is usually reached within less than twelve hours. It is irreversible and therefore does not allow for intermittent treatment [733].

6.1.4.1.1.1.3. Oestrogens

Treatment with oestrogens results in testosterone suppression and is not associated with bone loss [734]. Early studies tested oral diethylstilboestrol (DES) at several doses. Due to severe side effects, especially thromboembolic complications, even at lower doses these drugs are not considered as standard first-line treatment [735,736]. Oestrogen patches are under investigation [737].

6.1.4.1.1.1.4. Luteinising-hormone-releasing hormone agonists

Long-acting LHRH agonists are currently the main forms of ADT. These synthetic analogues of LHRH are delivered as depot injections on a 1-, 2-, 3-, 6-monthly, or yearly basis. The first injection induces a transient rise in luteinising hormone (LH) and follicle-stimulating hormone (FSH) leading to the ‘testosterone surge’ or ‘flare-up’ phenomenon which starts two to three days after administration and lasts for about one week. This may lead to detrimental clinical effects (the clinical flare) such as increased bone pain, acute bladder outlet obstruction, obstructive renal failure, spinal cord compression, and cardiovascular death due to hypercoagulation status [738]. Patients at risk are usually those with high-volume symptomatic bony disease. Concomitant therapy with an anti-androgen decreases the incidence of clinical flare but does not completely remove the risk. Anti-androgen therapy is usually continued for 4 weeks but neither the timing nor the duration of anti-androgen therapy are based on strong evidence. In addition, the long-term impact of preventing ‘flare up’ is unknown [739].

Chronic exposure to LHRH agonists results in the down-regulation of LHRH-receptors, suppressing LH and FSH secretion and therefore testosterone production. A castration level is usually obtained within 2 to 4 weeks [740]. Although there is no formal direct comparison between the various compounds, they are considered to be equally effective [741]. So far, no survival difference between LHRH agonists and orchiectomy has been reported due to the lack of high-quality trials [742].

The different products have practical differences that need to be considered in everyday practice, including the storage temperature, whether a drug is ready for immediate use or requires reconstitution, and whether a drug is given by subcutaneous or intramuscular injection.

6.1.4.1.1.1.5. Luteinising-hormone-releasing hormone antagonists

Luteinising-hormone-releasing hormone antagonists immediately bind to LHRH receptors, leading to a rapid decrease in LH, FSH and testosterone levels without any flare. The practical shortcoming of these compounds is the lack of a long-acting depot formulation with, so far, only monthly formulations being available. Degarelix is a LHRH antagonist. The standard dosage is 240 mg in the first month followed by monthly injections of 80 mg. Most patients achieve a castrate level at day three [740]. A phase III RCT compared degarelix to monthly leuprorelin following up patients for 12 months, suggesting a better PSA PFS for degarelix 240/80 mg compared to monthly leuprorelin [743]. A systematic review did not show a major difference between agonists and degarelix and highlighted the paucity of on-treatment data beyond 12 months as well as the lack of survival data [744]. Its definitive superiority over the LHRH analogues remains to be proven. Short-term follow-up data from a meta-analysis indicate that the use of LHRH antagonist is associated with significantly lower overall mortality and cardiovascular events as compared with agonists. On the other hand, other adverse effects such as decreased libido, hot flushes, ED, weight gain, and injection site reactions are seen less often with the agonists [745,746].

Relugolix is an oral LHRH antagonist. It was compared to the LHRH agonist leuprolide in a randomised phase III trial [747]. The primary endpoint was sustained testosterone suppression to castrate levels through 48 weeks. There was a significant difference of 7.9 percentage points (95% CI: 4.1–11.8) showing non-inferiority and superiority of relugolix. The incidence of major adverse cardiovascular events was significantly lower with relugolix (prespecified safety analysis). Relugolix has been approved by the FDA [748] and EMA [749] for hormone sensitive PCa.

6.1.4.1.1.1.6. Anti-androgens

These oral compounds are classified according to their chemical structure as:

• steroidal, e.g., cyproterone acetate (CPA), megestrol acetate and medroxyprogesterone acetate;
• non-steroidal or pure, e.g., nilutamide, flutamide and bicalutamide.

Both classes compete with androgens at the receptor level. This leads to an unchanged or slightly elevated testosterone level. Conversely, steroidal anti-androgens have progestational properties leading to central inhibition by crossing the blood-brain barrier.

6.1.4.1.1.1.6.1. Steroidal anti-androgens

These compounds are synthetic derivatives of hydroxyprogesterone. Their main pharmacological side effects are secondary to castration (gynaecomastia is quite rare) whilst the non-pharmacological side effects are cardiovascular toxicity (4–40% for CPA) and hepatotoxicity.

Cyproterone acetate was the first licensed anti-androgen but the least studied. Its most effective dose as monotherapy is still unknown. Although CPA has a relatively long half-life (31–41 hours), it is usually administered in two or three fractionated doses of 100 mg each. In one RCT CPA showed a poorer OS when compared with LHRH analogues [750]. An underpowered RCT comparing CPA monotherapy with flutamide in M1b PCa did not show any difference in DSS and OS at a median follow-up of 8.6 years [751]. Other CPA monotherapy studies suffer from methodological limitations preventing firm conclusions.

6.1.4.1.1.1.6.2. Non-steroidal anti-androgens

Non-steroidal anti-androgen monotherapy with e.g., nilutamide, flutamide or bicalutamide does not suppress testosterone secretion and it is claimed that libido, overall physical performance and bone mineral density (BMD) are frequently preserved [752]. Non-androgen-related pharmacological side effects differ between agents. Bicalutamide shows a more favourable safety and tolerability profile than flutamide and nilutamide [753]. The dosage licensed for use in CAB is 50 mg/day, and 150 mg/day for monotherapy. The non-steroidal anti-androgens pharmacological side effects are mainly gynaecomastia (70%) and breast pain (68%). However, non-steroidal anti-androgen monotherapy offers clear bone protection compared with LHRH analogues and probably LHRH antagonists [752,754]. All three agents share the potential for liver toxicity (occasionally fatal), requiring regular monitoring of patients’ liver enzymes.

6.1.4.1.1.2. New androgen receptor pathway inhibitors (ARPis)

Once on ADT the development of castration-resistance (CRPC) is only a matter of time. It is considered to be mediated through two main overlapping mechanisms: androgen-receptor (AR)-independent and AR-dependent mechanisms (see Section 6.5 - Castrate-resistant PCa). In CRPC, the intracellular androgen level is increased compared to androgen sensitive cells and an over-expression of the AR has been observed, suggesting an adaptive mechanism [755]. This has led to the development of several new compounds targeting the androgen axis. In mCRPC, abirateron acetate and enzalutamide have been approved. In addition to ADT (sustained castration), abiraterone acetate, apalutamide and enzalutamide have been approved for the treatment of metastatic hormone sensitive PCa (mHSPC) by the FDA and the EMA. For the updated approval status see EMA and FDA websites [756-760]. Finally, apalutamide, darolutamide and enzalutamide have been approved for non-metastatic CRPC (nmCRPC) at high risk of further metastases [761-765].

6.1.4.1.1.2.1. Abiraterone acetate

Abiraterone acetate is a CYP17 inhibitor (a combination of 17α-hydrolase and 17,20-lyase inhibition). By blocking CYP17, abiraterone acetate significantly decreases the intracellular testosterone level by suppressing its synthesis at the adrenal level and inside the cancer cells (intracrine mechanism). This compound must be used together with prednisone/prednisolone to prevent drug-induced hyperaldosteronism [756,759].

6.1.4.1.1.2.2. Apalutamide, darolutamide, enzalutamide (alphabetical order)

These agents are novel non-steroidal anti-androgens with a higher affinity for the AR receptor than bicalutamide. While previous non-steroidal anti-androgens still allow transfer of ARs to the nucleus and would act as partial agonists, all three agents also block AR transfer and therefore suppress any possible agonist-like activity [760-762]. Darolutamide has structurally unique properties [761]. In particular, in preclinical studies, it showed not to cross the blood-brain barrier [766,767].

6.1.4.2. Non-hormonal non-cytotoxic drug treatments

6.1.4.2.1. PARP inhibitors

Poly (ADP-ribose) polymerase inhibitors (PARPi) block the enzyme poly ADP-ribose polymerase (PARP) and were developed aiming to selectively target cancer cells harbouring BRCA mutations and other mutations inducing homologous recombination deficiency and high level of replication pressure with a sensitivity to PARPi treatment. Due to the oncogenic loss of some DNA repair effectors and incomplete DNA repair repertoire, some cancer cells are addicted to certain DNA repair pathways such as Poly (ADP-ribose) polymerase (PARP)-related single-strand break repair pathway. The interaction between BRCA and PARP is a form of synthetic lethal effect which means the simultaneously functional loss of two genes leads to cell death, while a defect in any single gene only has a limited effect on cell viability [768]. The therapeutic indication for PCa is discussed in Section 6.5.8.1.

6.1.4.2.2. Immune checkpoint inhibitors

Checkpoint inhibitors target the molecules CTLA4, programmed cell death protein 1 (PD-1), and programmed death-ligand 1 (PD-L1). For advanced PCa patients that are microsatellite instability-high/deficient mismatch repair (MSI-H/dMMR), the PD-1 inhibitor pembrolizumab has been approved by the FDA but not by the EMA. The label is tumour agnostic [769,770]. See also Section 6.5.2.1

AKT inhibitors are small molecules which are designed to target and bind to all three isoforms of AKT, which is a key component of the PI3K/AKT pathway. In clinical trials, ipatasertib, an oral, highly specific, AKT inhibitor was used and showed significant activity when combined with abiraterone acetate in patients with loss of the tumour suppressor protein PTEN on immunohistochemistry within the tumour [771,772]. Currently, there are no approved AKT inhibitors.

6.1.4.3. Radiopharmaceutical therapy

Radiopharmaceutical therapy (RPT) is based on the delivery of radioactive atoms to tumour-associated targets. The mechanism of action for RPT is radiation-induced killing of cells. Radionuclides with different emission properties are used to deliver radiation. The most commonly used radionuclides are represented by β-particles (e.g., ¹⁷⁷Lu) or α-particles (e.g., ²²³Ra, ²²⁵Ac). ¹⁷⁷Lu is increasingly used because of its optimal imaging range (100–200 keV), favourable half time (6.6 days) and appropriate β-particle energy for therapy. The short path of the α-particle (0.05–0.08 mm) results in minimal toxic effects in adjacent healthy tissue. These properties enable such radionuclides to be used as theranostics (i.e., the same radionuclide may be used for both diagnostic and therapeutic purposes). However, an essential requirement prior to any RPT is to assess the targeting of the agent, mainly using PET techniques which show the tumour expression and the extent of cancer [773]. ¹⁷⁷Lu has been approved by the FDA for the treatment of adult patients with PSMA-positive mCRPC who have been treated with ARPI and taxane-based chemotherapy [774]. Clinical details are discussed in Section 6.5.6.

6.1.5. Investigational therapies

6.1.5.1. Background

Besides RP, EBRT and brachytherapy, other modalities have emerged as potential therapeutic options in patients with clinically localised PCa [775-777]. These new modalities have been developed as minimally-invasive procedures with the aim of providing equivalent oncological safety, reduced toxicity, and improved functional outcomes. In this section, both whole gland- and focal treatment [778,779] will be considered, looking particularly at high-intensity focused US (HIFU), cryotherapeutic ablation of the prostate (cryotherapy) and focal photodynamic therapy (PDT), as sufficient data are available to form the basis of some initial judgements. Other options such as radiofrequency ablation (RFA) and electroporation, among others, are considered to be in the early phases of evaluation [778].

6.1.5.2. Whole-gland therapies

6.1.5.2.1. Cryotherapy for whole-gland treatment

Cryotherapy uses freezing techniques to induce cell death by dehydration resulting in protein denaturation, direct rupture of cellular membranes by ice crystals and vascular stasis and microthrombi, resulting in stagnation of the microcirculation with consecutive ischaemic apoptosis [775-777]. Freezing of the prostate is ensured by the placement of 17 gauge cryo-needles under TRUS guidance, placement of thermosensors at the level of the external sphincter and rectal wall, and insertion of a urethral warmer. Two freeze-thaw cycles are used under TRUS guidance resulting in a temperature of -40°C in the mid-gland and at the neurovascular bundle. Currently, third and fourth generation cryotherapy devices are mainly used. Since its inception, cryotherapy has been used for whole-gland treatment in PCa either as a primary or salvage treatment option.

The main adverse effects of whole-gland cryosurgery are ED (18%), urinary incontinence (2–20%), urethral sloughing (0–38%), rectal pain and bleeding (3%) and recto-urethral fistula formation (0–6%) [780]. There is a lack of prospective comparative data regarding oncological outcomes of whole-gland cryosurgery as a curative treatment option for men with localised PCa, with most studies being non-comparative single-arm case series with short follow-up [780].

6.1.5.2.2. High-intensity focused ultrasound for whole-gland treatment

High-intensity focused US consists of focused US waves emitted from a transducer that cause tissue damage by mechanical and thermal effects as well as by cavitation [781]. The goal of HIFU is to heat malignant tissue above 65°C, so that it is destroyed by coagulative necrosis. High-intensity focused US is performed under general or spinal anesthesia, with the patient lying in the lateral or supine position. High-intensity focused US has previously been widely used for whole-gland therapy with the following adverse effects: acute urinary retention (10%), ED (23%), urethral stricture (8%), rectal pain or bleeding (11%), recto-urethral fistula (0–5%) and urinary incontinence (10%) [780].

Since the ultrasound energy is most often delivered from the rectal cavity, HIFU faces challenges in delivering energy to the anterior part in large prostates.

Similar to cryosurgery, the lack of any long-term prospective comparative data on oncological outcomes, without significant reduction of side effects, prevents whole-gland HIFU from being considered as a reasonable alternative to the established curative treatment options [780].

6.1.5.3. Focal therapy for whole-gland treatment

During the past two decades, there has been a trend towards earlier diagnosis of PCa as a result of greater public and professional awareness leading to the adoption of both formal and informal screening strategies. The effect of this has been that men are identified at an earlier stage with smaller tumours, with a greater propensity for unifocal disease potentially suitable for focal therapy [782-784]. There is also greater awareness of the risks of over-treatment leading to attempts to ablate only a region of the prostate containing the tumour thereby limiting toxicity by sparing the neurovascular bundles, sphincter and urethra [785-787]. Most focal therapies to date have been achieved with ablative technologies: cryotherapy, HIFU, PDT, irreversible electroporation (IRE), and focal RT.

Despite these therapies having less impact on urogenital function, AS should remain the primary option for patient with low-risk PCa.

A recent systematic review included data from 5,827 patients across 72 studies and covered different energy sources including HIFU, cryotherapy, PDT, laser interstitial thermotherapy, focal brachytherapy, IRE and radiofrequency ablation (RFA) [788]. The review favours HIFU and PDT for their higher quality data, over 95% of pad-free incontinence and 85–90% of patients without clinical significant cancer in short-term analysis.

This has to be critically analysed, because 45% of all patients with a focal approach included in this systematic review had an ISUP 1 cancer. The overall quality of the evidence was low, due to the majority of studies being single-centre, non-comparative and retrospective in design, heterogeneity of definitions and approaches, follow-up strategies, outcomes, and duration of follow-up. Although the review finds high-quality evidence that focal therapy has favourable functional outcomes and minimises AEs, definitive proof of oncological effectiveness of focal therapy compared to standard treatments remains unavailable.

The currently largest analysis on oncologic outcomes following focal HIFU includes 625 patients, with 70% having ISUP 2/3 disease, followed for 5 years with an 88% failure-free survival (FFS), defined as the need for salvage treatment or systemic therapy [789]. In this study one repeated focal HIFU session was allowed and performed in 25% of all patients. Follow-up was driven by PSA and clinics, with re-biopsies performed only in 36% of patients after a significant PSA rise and suspicious MRI.

The guideline Panel acknowledges the challenges for interventional RCTs [790-792]. The interim analysis and meeting reports demonstrate slow recruitment, patients declining consent and rejecting their treatment allocation into the RP group.

Propensity-matched analysis using prospective multi-centre databases are available for comparison of focal therapy vs. radical therapy [793,794]. Oncological follow-up data up to 8 years can be used to counsel patients in treatment decisions [793]. Patients were managed by focal therapy had a HIFU or cryotherapy, with one retreatment, if needed. 17.1% of patients in the focal arm received a retreatment. The primary outcome was FFS defined as “need for local or systemic salvage treatment or metastasis”. Both groups included 246 patients with an average PSA of 7.9 ng/mL and 60% ISUP 2/3 cancers. The cancer core length was 5–6 mm with 45% having bilateral cancer. The authors report similar cancer control 8 years after therapy, with FFS and BCR of 83% and 23.9% for focal therapy vs. 79% and 24.8% for RP, respectively. Similar results were demonstrated in a cohort-based analysis with a follow-up of 6 years [794].

The use of different definitions for oncological failure in the two arms is a limitation of these studies. While any recurrence after RP was seen as failure, a second HIFU was permitted in the focal group. The current data from the HIFU Evaluation and Assessment of Treatment (HEAT) registry indicates that a repeat-HIFU does not significantly decrease urinary or erectile function [795]. However, this change of failure definition will have to be re-evaluated.

It is important to note, that these results were achieved in centres with a dedicated focal program where all patients had a mpMRI with targeted and systematic biopsies or full template mapping biopsies.

The prospective HEAT registry recently analysed over 800 men undergoing focal HIFU for localised PCa [795]. The functional data indicate low treatment-related toxicity with less than 4% decrease in pad-free incontinence and a reduction in IIEF of 0.4 points. The low percentage of side effects was also maintained if a second round of focal therapy was needed.

One comparative RCT was conducted in a very-low risk population, for which there is currently a strong movement away from any form of active treatment. This study was comparing padeliporfin-based vascular-targeted PDT vs. AS and found at a median follow-up of 24 months that less patients progressed in the PDT arm compared with the AS arm (adjusted HR: 0.34, 95% CI: 0.24–0.46), and needed less radical therapy (6% vs. 29%, p < 0.0001). Updated results were published in 2018 showing that these benefits were maintained after four years [796]. Nevertheless, limitations of the study include an unusually high observed rate of disease progression in the AS arm (58% in two years) and more patients in the AS arm chose to undergo radical therapy without a clinical indication which may have introduced confounding bias. Finally, the AS arm did not undergo any confirmatory biopsy or any MRI scanning, which is not representative of contemporary practice.

In order to update the evidence base, a systematic review incorporating a narrative synthesis was performed by the Panel, including comparative studies assessing focal ablative therapy vs. radical treatment, AS or alternative focal ablative therapy, published between 1^st January 2000 and 12^th June 2020 [797]. In brief, out of 1,119 articles identified, 4 primary studies (1 RCT and 3 retrospective cohort studies) [796,798-801] recruiting 3,961 patients, and 10 systematic reviews were included [780]. Only qualitative synthesis was possible due to clinical heterogeneity. Comparative effectiveness data regarding focal therapy were inconclusive. Data quality and applicability were poor due to clinical heterogeneity, RoB and confounding, lack of long-term data, inappropriate outcome measures and poor external validity.

The impact of salvage therapies after focal therapy was investigated in smaller series [802,803]. If a salvage RP is necessary, the reported functional and oncological outcomes are comparable to treatment-naïve patients [802,803].

The available evidence indicates that focal therapy is associated with less AEs than whole gland or radical treatments. Robust prospective trials reporting standardised 10-year oncological outcomes [804] are needed before unrestricted recommendations in support of focal therapy for routine clinical practice can be made [778,789,804]. Currently, focal therapy using HIFU or cryotherapy should be performed within the context of a prospective registry. All other ablative modalites should only be offered in well-designed prospective trial setting.

6.1.6. General guidelines for the treatment of prostate cancer*

*All recommendations are based on conventional imaging with isotope bone scan and CT/MR abdomen/pelvis.

6.2. Treatment by disease stages

6.2.1. Treatment of low-risk disease

6.2.1.1. Active surveillance

The main risk for men with low-risk disease is over-treatment (see Sections 6.1.1.2 and 6.1.1.4); AS should therefore be considered as first treatment for all such patients.

6.2.1.1.1. Active surveillance - inclusion criteria

Guidance regarding selection criteria for AS is limited by the lack of data from prospective RCTs. As a consequence, the Panel undertook an international collaborative study involving healthcare practitioners and patients to develop consensus statements for deferred treatment with curative intent for localised PCa, covering all domains of AS (DETECTIVE Study) [273], as well as a formal systematic review on the various AS protocols [805]. The criteria most often published include: ISUP grade 1, clinical stage cT1c or cT2a, PSA < 10 ng/mL and PSA-D < 0.15 ng/mL/cc, as based on systematic biopsy schemes [483,806]. The latter threshold remains controversial [806,807]. These criteria were supported by the DETECTIVE study consensus. There was no agreement on the maximum number of systematic cores that can be involved with cancer or the maximum percentage core involvement (CI), although there was recognition that extensive disease on MRI should exclude men from AS, even though there is no firm definition on this, especially when targeted biopsies confirm ISUP grade 1 [273]. A systematic review and meta-analysis found three clinico-pathological variables which were significantly associated with reclassification, high PSA-D, > 2 positive cores (on systematic biopsies) and African-American descent [808]. In addition, a previous pathology consensus group suggested excluding men from AS when any of the following features were present: predominant ductal carcinoma (including pure intraductal carcinoma), cribriform histology, sarcomatoid carcinoma, small cell carcinoma, EPE or LVI in needle biopsy [809] and perineural invasion [810].

Recently, a multidisciplinary consensus conference on germline testing attempted to develop a genetic implementation framework for the management of PCa [178]. Based on consensus, BRCA2-gene testing was recommended for AS discussions and could be performed in men with family history of prostate, breast or ovarian cancers. However, the nature of such discussions and how a positive result influences management were beyond the scope of the project. Currently, BRCA2 mutation does not exclude a patient from AS if tumour factors are otherwise favourable. Furthermore, if included in AS programmes, patients with a known BRCA2 mutation should be cautiously monitored until such time that more robust data are available.

6.2.1.1.2. Tissue-based prognostic biomarker testing for selection for active surveillance

Biomarkers, including Oncotype Dx^®, Prolaris^®, Decipher^®, PORTOS and ProMark^® are promising (see Section 5.2.8.3). However, further data will be needed before such markers can be used in standard clinical practice [221].

6.2.1.1.3. Magnetic resonance imaging for selection for active surveillance

In men eligible for AS based upon systematic biopsy findings alone who did not have a pre-biopsy MRI, a re-biopsy within 6–12 months (usually referred to as ‘confirmatory biopsy’) seems mandatory to exclude sampling error. A large body of literature including two RCTs showed that adding MRI-targeted biopsy to systematic sampling at confirmatory biopsy improved detection of ISUP grade > 2 cancers and thus, patient selection for AS [123,811-815]. Adding MRI-targeted biopsy to systematic sampling at confirmatory biopsy improved upgrade detection by increments of 0-7.9 per 100 men depending on the series [813]. In a meta-analysis of 6 studies, the rate of upgrading to ISUP grade > 2 cancer increased from 20% (95% CI: 16–25%) to 27% (95% CI: 22–34%) when MRI-targeted biopsy was added to systematic biopsy [811]. The Active Surveillance Magnetic Resonance Imaging Study (ASIST) randomised men on AS scheduled for confirmatory biopsy to either 12-core systematic biopsy or to MRI with targeted biopsy (when indicated), combined with systematic biopsy (up to 12 cores in total). After 2 years of follow-up, use of MRI before confirmatory biopsy resulted in fewer failures of surveillance (19% vs. 35%, p = 0.017) and in fewer patients progressing to ISUP grade > 2 cancer (9.9% vs. 23%, p = 0.048) [812]. However, systematic biopsy retains its additional value, which argues for a combined biopsy approach [811,813]. The DETECTIVE study agreed that men eligible for AS after combined systematic- and MRI-targeted biopsy do not require a confirmatory biopsy [273].

If the PCa diagnosis is made on MRI-targeted biopsy alone (recommended in some countries national guidelines, e.g., the Nordic countries [816] in order to lower the risk of over-detection of insignificant tumours) a confirmative systematic biopsy should be performed before definite decision of AS to rule out more widespread cancer growth in the prostate.

6.2.1.1.4. Follow-up during active surveillance

Based on the DETECTIVE consensus study, the follow-up strategy should be based on serial DRE (at least once yearly), PSA (at least once, every 6 months) and repeated biopsy. It was also agreed that PSA progression or change in PSA kinetics alone should lead to reclassification only if accompanied by changes in histology on repeat biopsy [273].

Yerram et al., analysed a prospectively-maintained AS cohort of 369 patients (272 with ISUP grade 1 cancer and 97 with ISUP grade 2 cancer) who had been selected for AS after combined systematic and MRI-targeted sampling during confirmatory biopy. At two years, systematic biopsy, MRI-targeted biopsy and combined biopsy detected grade progression in 44 patients (15.9%), 73 patients (26.4%) and 90 patients (32.5%), respectively. This suggests that both biopsy approaches retain added value, not only for confirmatory biopsy, but also during AS [817].

In 2016, the Prostate Cancer Radiological Estimation of Change in Sequential Evaluation (PRECISE) criteria were established to standardise the assessment of tumour progression on serial MRI [818]. Progression on MRI, or not, as defined by PRECISE criteria, is a strong predictor of histological upgrading [819,820]. Two independent meta-analyses assessed the value of MRI progression criteria for predicting histological progression (mostly defined as progression to ISUP grade > 2). The pooled histological progression rate was 27% in both reviews. If biopsies were triggered only by MRI progression findings, approximately two thirds of the biopsies would be avoided, at the cost of missing 40% of men with histological progression. In addition, at least half of biopsied men would have had negative findings for histological progression and thus would have undergone unnecessary biopsies. If histological progression was restricted to progression to ISUP grade > 3, approximately 30% of histological progression would be missed and approximately 80% of the biopsies performed would be unnecessary. The use of the PRECISE criteria did not seem to change these results [821,822]. This supports maintaining protocol-mandated follow-up biopsies during the course of AS.

However, several factors have been found to be associated with low re-classification rates and long PFS: negative baseline or follow-up MRI [823-830], low PSA-D [825,826,828,829], low PSA velocity [831,832] or negative biopsy (i.e., no cancer at all) at confirmatory or follow-up biopsy [833]. In patients with stable (PRECISE 3) follow-up MRI, a low PSA-D may be associated with a low rate of progression [834]. Using these criteria, it might be possible, in the future, to create risk-based personalised AS biopsy schedules.

A Panel systematic review incorporating 263 surveillance protocols showed that 78.7% of protocols mandated per-protocol confirmatory biopsies within the first 2 years and that 57.7% of the protocols performed repeat biopsy at least every 3 years for 10 years after the start of AS [805]. In another recent review it was concluded that a negative follow-up biopsy was associated with a 50% decrease in the risk of future reclassification and upgrading [835]. In a single-centre AS cohort of 514 patients who underwent at least three protocol-mandated biopsies after diagnosis (the confirmatory biopsy and at least two additional surveillance biopsies), men with one negative biopsy (i.e., no cancer at all) at confirmatory or second biopsy, or men with two consecutive negative biopsies had a lower likelihood of a positive third biopsy and significantly better 10-year treatment-free survival [833]. This suggests that men with repetitive negative biopsies may pursue AS with at least less frequent untriggered biopsies.

6.2.1.1.5. Active Surveillance - change in treatment

Men may remain on AS whilst they continue to consent, have a life expectancy of > 10 years and the disease remains indolent. Patient anxiety about continued surveillance occurs in around 10% of patients on AS [836] and was recognised as a valid reason for active treatment [273]. A thorough discussion on pros/cons of AS vs. active treatment already at the time of diagnosis is therefore of outmost importance. More common is the development of other co-morbidities which may result in a decision to transfer to a WW strategy.

A PSA change alone (including PSA-DT < 3 years) should not change management based on its weak link with grade progression [837,838] but rather trigger further investigation. There was clear agreement in the DETECTIVE consensus meeting that a change in PSA should lead to repeat-MRI and repeat-biopsy. It was also agreed that changes on follow-up MRI needed a confirmatory biopsy before considering active treatment [273].

However, the histopathology criteria required to trigger a change in management in the targeted biopsy era remain debated. Magnetic resonance imaging-targeted biopsy induces a grade shift and ISUP 2–3 cancers detected by MRI-targeted biopsy have, on average, a better prognosis than those detected by systematic sampling (see Section 5.2.4.2.6.4). As an increasing number of men with favourable intermediate-risk disease are managed with AS (see section 6.2.2.1), it seems illogical to use progression to ISUP grade 2 based on targeted biopsies as the sole criterion for reclassification. In addition, as acknowledged in the DETECTIVE consensus meeting, the number of positive cores is not an indicator of tumour volume anymore if targeted biopsies are performed [273,839]. No agreement could be reached on the pathological criteria required to trigger a change in management during the DETECTIVE consensus meeting [273]. However, based on the findings of a systematic review incorporating 271 reclassification protocols, patients with low-volume ISUP 2 disease at recruitment, and with increased systematic core positivity (> 3 cores involvement [> 50% per core]) on repeat systematic biopsies not using MRI, should be reclassified [805].

6.2.1.2. Alternatives to active surveillance

In terms of alternatives to AS in the management of patients with low-risk disease there is some data from randomised studies. In the PIVOT trial (Section 6.1.1) which compared surgery vs. observation, only 42% of patients had low-risk disease [497]. Sub-group analysis revealed that for low-risk disease there was no statistically significant difference in all-cause mortality between surgery vs. observation (RR: 0.93, 95% CI: 0.78–1.11). In the ProtecT study (Section 6.1.1) which compared the far less organised follow-up of active monitoring (PSA follow-up only) vs. surgery vs. EBRT, 56% of patients had low-risk disease [485]. However, no sub-group analysis on disease risk was performed on this population. The study found no difference between the three arms in terms of OS and CSS, but AM had higher metastatic progression compared with surgery or EBRT (6.0% vs. 2.6%). There are no robust data comparing contemporary AS protocols with either surgery or EBRT in patients with low-risk disease. Active surveillance should be considered SOC in patients with low-risk disease and a life expectancy > 10 years. Surgery and EBRT should only be considered as alternatives to AS in patients suitable for such treatments after thorough information on pros and cons of AS and active treatment, and who after such information refuse or for some other reason are deemed unfit for AS, and who accept a trade-off between toxicity and prevention of disease progression.

Other treatments such as whole-gland ablative therapy (f.i., cryotherapy or HIFU) or focal ablative therapy remain unproven in the setting of localised low-risk disease compared with AS or radical treatment options and should not be used outside a trial setting or well-designed prospective cohort setting. These treatments are discussed in detail in Section 6.1.5.

6.2.1.2.1. Androgen deprivation monotherapy

Data regarding the use of ADT monotherapy in men with low-risk localised disease may be inferred indirectly from the Early Prostate Cancer (EPC) Trial Programme which published its findings in 2006 [840]. The EPC programme comprises three large RCTs including 8,113 men with localised (cT1–2, N0/NxM0) or locally-advanced (cT3–4, any N; or any T, N+, M0) PCa. The intervention was oral bicalutamide 150 mg monotherapy vs. placebo following standard care (defined as RP, radical EBRT or WW). The primary endpoints were PFS and OS. Patients were stratified according to clinical stage only; data regarding PSA and Gleason score were not assessed. The authors found in patients with localised disease, ADT monotherapy did not improve PFS nor OS in any of the subgroups, compared with placebo. Instead, there was a statistically insignificant numerical trend towards worse OS with ADT in the WW sub-group (HR: 1.16, 95% CI: 0.99–1.37; p = 0.07). Although the trial did not directly address men with low-risk disease, it offered some evidence suggesting that otherwise asymptomatic men with localised disease should not receive ADT monotherapy. Currently, there is no evidence supporting the use of ADT monotherapy in asymptomatic men with low-risk disease who are not eligible for any local/radical treatment; these men should simply be offered WW alone.

Other treatments such as whole-gland ablative therapy (f.i., cryotherapy or HIFU) or focal ablative therapy remain unproven in the setting of localised low-risk disease compared with AS or radical treatment options; these have been discussed in detail in Section 6.1.5.

6.2.1.3. Summary of evidence and guidelines for follow-up during active surveillance

6.2.1.4. Summary of evidence and guidelines for the management of low-risk disease*

*All recommendations are based on conventional imaging with isotope bone scan and CT/MR abdomen/pelvis.

6.2.2. Treatment of intermediate-risk disease

When managed with non-curative intent, intermediate-risk PCa is associated with 10-year and 15-year PCSM rates of 13.0% and 19.6%, respectively [841]. These estimates are based on systematic biopsies and may be overestimated in the era of MRI-targeted biopsies.

6.2.2.1. Active Surveillance

In the ProtecT trial, where 34% of the randomised patients had intermediate- or high-risk disease, there was no statistically significant difference in CSS at 10 years [485]. In the comprehensive characterisation of the patients in the ProtecT trial, treatment received, PSA, ISUP grade at diagnosis, cT stage, risk group, number of PCa-involved biopsy cores, maximum length of tumour (median 5.0 vs. 3.0 mm), aggregate length of tumour (median 8.0 vs.  4.0 mm), and presence of perineural invasion were each associated with increased risk of disease progression  (p < 0.001 for each). However, these factors could not reliably predict progression in individuals [483].

The outcomes of AS in intermediate-risk PCa has also been analysed in two recent systematic reviews and meta-analyses, summarising available data on its oncological outcomes and comparing patients with intermediate-risk PCa to patients with low-risk disease [842,843]. The definition of AS was not strictly defined in either of the reviews: instead the search strategies included ‘active surveillance’ as a search term, and no a priori study protocol was available. The primary outcome was the proportion of patients who remained on AS, whilst secondary outcomes included CSS, OS, and metastasis-free survival in both studies.

In the first review 17 studies were included, incorporating 6,591 patients with intermediate-risk disease. Sixteen studies included patients with low- and intermediate-risk disease, hence enabling comparative outcome assessment via pooled analysis. Only one study performed MRI at recruitment and follow-up. There was significant clinical heterogeneity in terms of inclusion criteria for intermediate-risk disease. The results showed the proportion of patients who remained on AS was comparable between the low- and intermediate-risk groups after 10 and 15 years’ follow-up (OR: 0.97, 95% CI: 0.83–1.14; and OR: 0.86, 95% CI: 0.65–1.13, respectively). Cancer-specific survival was worse in the intermediate-risk group after 10 years (OR: 0.47, 95% CI: 0.31–0.69) and 15 years (OR: 0.34, 95% CI: 0.2–0.58). Overall survival was not statistically significantly different at 5 years’ follow-up (OR: 0.84, 95% CI: 0.45–1.57) but was significantly worse in the intermediate-risk group after 10 years (OR: 0.43, 95% CI: 0.35–0.53). Metastases-free survival did not significantly differ after 5 years (OR: 0.55, 95% CI: 0.2–1.53) but was worse in the intermediate-risk group after 10 years (OR: 0.46, 95% CI: 0.28–0.77).

The slightly more recent review, including 25 studies and a total of 29,673 low- or intermediate-risk patients, showed similar results in terms of treatment-free survival at 10 years (RR: 1.16, 95% CI: 0.99-1.36), risk of developing metastases (RR: 5.79, 95% CI: 4.61-7.29), risk of dying from PCa (RR: 3.93, 95% CI: 2.93-5.27) and risk of dying from any cause (RR: 1.44, 95% CI: 1.11-1.86).

In a subgroup analyses of four studies comparing outcomes of patients with intermediate- and low-risk PCa of ISUP < 2 (n = 1,900) no statistically significant difference could be found in terms of treatment-free survival or risk of developing metastases (RR: 1.03, 95% CI: 0.62-1.71 and RR: 2.09, 95% CI: 0.75-5.82, respectively). Both reviews indicate that AS in unselected intermediate-risk patients implies a higher risk of progression over time. It remains unclear whether this difference only reflects the inborne difference in outcome, that can also be seen when comparing immediate treatment of low- and intermediate-risk PCa, or if the delay in treatment caused any worsenening of the outcomes in the intermediate-risk group in any way. Both reviews conclude that AS could be offered to patients with intermediate-risk disease, but they should be informed of a higher risk of progression and the latter study suggests limiting the inclusion of intermediate-risk patients to those with low-volume ISUP 2 disease.

A Canadian consensus group proposes that low volume ISUP grade 2 (< 10% Gleason pattern 4 on systematic biopsies) may also be considered for AS. These recommendations have been endorsed by the American Society of Clinical Oncology (ASCO) [338] and the DETECTIVE study consensus [273] for those patients with a PSA < 10 ng/mL and low core positivity. The DETECTIVE Study concluded that men with favourable ISUP 2 cancer (PSA < 10 ng/mL, low density, clinical stage < cT2a and a low number of positive systematic cores) should also be considered for deferred treatment [273]. In this setting, re-biopsy within 6 to 12 months to exclude sampling error is even more relevant than in low-risk disease [806,844]. The DETECTIVE Study-related qualitative systematic review aimed to determine appropriate criteria for inclusion of intermediate-risk disease into AS protocols [805]. Out of 371 AS protocols included in the review, more than 50% included patients with intermediate-risk disease on the basis of PSA up to 20 ng/mL (25.3%), ISUP 2 or 3 (27.7%), clinical stage cT2b/c (41.6%) and/or direct use of D’Amico risk grouping of intermediate risk or above (51.1%). The DETECTIVE study reached consensus that patients with ISUP 3, or patients with intraductal or cribriform histology, should not be considered for AS. The presence of any grade 4 pattern is associated with a 3-fold increased risk of metastases compared to ISUP grade 1, while a PSA up to 20 ng/mL might be an acceptable threshold [844-846], especially in the context of low PSA-D. In addition, it is likely that MRI and targeted biopsies will detect small foci of Gleason grade 4 cancer that might have been missed with systematic biopsy. Therefore, care must be taken when explaining this treatment strategy, especially to patients with the longest life expectancy.

There are no clear concensus on how to interpret MRI and targeted biopsies for AS but the DETECTIVE study concensus was that if targeted biopsies based upon mpMRI images are performed, the number of positive cores of the targeted biopsies are not an indicator of the extent of disease or tumour volume. Indicator of the tumour volume may be either the number of positive cores, and the length of cancer in each core, based on systematic biopsies, or the volume of the dominant lesion seen on mpMRI [273].

In summary, AS can be considered in patients with low-volume ISUP 2 (defined as < 3 positive systematic cores and < 50% core involvement) or another single element of intermediate-risk disease (i.e. favourable intermediate-risk disease). Patients with ISUP 3 disease, or patients with intraductal or cribriform histology, should be excluded. The monitoring schedule should be diligent, given the potential higher risk of progression, development of regional or distant metastases and death of this group compared with patients with low-risk disease. During monitoring, if repeat non-MRI-based systematic biopsies reveal > 3 positive cores or maximum CI > 50%/core of ISUP 2 disease, patients should be reclassified (i.e., actively treated).

6.2.2.2. Radical prostatectomy

Patients with intermediate-risk PCa should be informed about the results of two RCTs (SPCG-4 and PIVOT) comparing RRP vs. WW in localised PCa. In the SPCG-4 study, death from any cause (RR: 0.71, 95% CI: 0.53–0.95), death from PCa (RR: 0.38, 95% CI: 0.23–0.62) and distant metastases (RR: 0.49, 95% CI: 0.32–0.74) were significantly reduced in intermediate-risk PCa at 18 years. In the PIVOT trial, according to a pre-planned subgroup analysis among men with intermediate-risk tumours, RP significantly reduced all-cause mortality (HR: 0.69, 95% CI: 0.49–0.98), but not death from PCa (0.50, 95% CI: 0.21–1.21) at 10 years. A meta-analysis based on the findings of SPCG-4, PIVOT and ProtecT demonstrated a benefit from RP over observation with a significantly decreased risk of death of 9% and of disease progression of 43% [847]. However, no stratification by disease stages was performed. The risk of having positive LNs in intermediate-risk PCa is between 3.7–20.1% [848]. An ePLND should be considered in intermediate-risk PCa if the estimated risk for pN+ exceeds 5% [400] or 7% if using the nomogram by Gandaglia et al., which incorporates MRI-guided biopsies [364]. However, preliminary data show a high NPV (96%) for LN-positivity when using PSMA PET for staging (See Section 6.1.2.3.2). In all other cases ePLND can be omitted, which means accepting a low risk of missing positive nodes. Nerve sparing surgery is discussed in Section 6.1.2.3.5.

6.2.2.3. Radiation therapy

6.2.2.3.1. Recommended IMRT/VMAT for intermediate-risk PCa

Patients suitable for ADT can be given combined IMRT/VMAT with short-term ADT (4–6 months) [849-851]. For adjuvant RT of the pelvic lymphatics (45-50 Gy) for NCCN unfavourable intermediate risk (cN0) see Section 6.2.3.2.1 - Radiotherapy for localised high-risk PCa. For patients unsuitable (e.g., due to co-morbidities) or unwilling to accept ADT (e.g., to preserve their sexual health) the recommended treatment is IMRT/VMAT (76–78 Gy or equivalent moderate HFX) or a combination of IMRT/VMAT and brachytherapy as described below (see Section 6.2.2.3.2). A secondary analysis of the PCS III trial has suggested that patients with NCCN favourable intermediate-risk disease (see Section 4.4) can safely omit ADT if their RT dose is 76 Gy, but this is based on an unplanned subgroup analysis and only 138 patients had favourable intermediate-risk disease. An individual discussion between the physician and the patient of the possible benefits and harms of omitting ADT in this group is essential [852]. In the absence of higher quality data, SOC will remain short-term ADT + IMRT/VMAT.

6.2.2.3.2. Brachytherapy for intermediate-risk PCa

Systematic review recommends LDR brachytherapy monotherapy can be offered to patients with NCCN favourable intermediate-risk disease and good urinary function (see Section 4.4) [853]. Fractionated HDR brachytherapy as monotherapy can be offered to selected patients with intermediate-risk PCa although they should be informed that results are only available from small series in very experienced centres. Five-year PSA control rates over 90% are reported, with late grade 3+ GU toxicity rates < 5% and no, or very minimal, grade 3+ GI toxicity rates [723]. There are no direct data to inform on the use of ADT in this setting. Trimodality therapy with IMRT plus brachytherapy boost and short-term ADT can be considered for NCCN unfavourable intermediate-risk PCa (see Section 4.4) but patients should be made aware that the potential improvements in biochemical control are accompanied with an increased risk of long-term urinary problems [714,715,719].

6.2.2.4. Other options for the primary treatment of intermediate-risk PCa (experimental therapies)

6.2.2.4.1. Focal therapy

A prospective study on focal therapy using HIFU in patients with localised intermediate-risk disease was published but the data was derived from an uncontrolled single-arm case series [789]. There is a paucity of high-certainty data for either whole-gland or focal ablative therapy in the setting of intermediate-risk disease. Consequently, neither whole-gland ablative treatment nor focal treatment can be considered as standard therapy for intermediate-risk patients and, if offered, it should only be in the setting of clinical trials or prospective registries [778].

6.2.2.4.2. Androgen deprivation therapy monotherapy

Data regarding the use of ADT monotherapy for intermediate-risk disease have been inferred indirectly from the EORTC 30891 trial, which was a RCT comparing deferred ADT vs. immediate ADT in 985 patients with T0–4 N0–2 M0 disease [848]. The trial showed a small, but statistically significant, difference in OS in favour of immediate ADT monotherapy but there was no significant difference in CSS, predominantly because the risk of cancer-specific mortality was low in patients with PSA < 8 ng/mL. Consequently, the use of ADT monotherapy for this group of patients is not considered as standard, even if they are not eligible for radical treatment.

6.2.2.5. Guidelines for the treatment of intermediate-risk disease*

*All recommendations are based on conventional imaging with isotope bone scan and CT/MR abdomen/pelvis.

6.2.3. Treatment of high-risk localised disease

Patients with high-risk PCa are at an increased risk of PSA failure, need for secondary therapy, metastatic progression and death from PCa. Nevertheless, not all high-risk PCa patients have a uniformly poor prognosis after RP [854]. When managed with non-curative intent, high-risk PCa is associated with 10-year and 15-year PCSM rates of 28.8 and 35.5%, respectively [855]. There is no consensus regarding the optimal treatment of men with high-risk PCa.

Some evidence suggests that radical treatment for high-risk PCa can be delayed up to 3 months after the diagnosis without any oncological consequences [516,856]. Systematic reviews suggest that there is a higher risk of biochemical recurrence and worse pathological outcomes when definitive treatment is given beyond a 6 to 9 months delay. However, there is no conclusive data regarding stronger endpoints (CSS or OS).

6.2.3.1. Radical prostatectomy

Provided that the tumour is not fixed to the pelvic wall or there is no invasion of the urethral sphincter, RP is a standard option in selected patients with a low tumour volume. Extended PLND should be performed in all high-risk PCa cases [400,401]. Patients should be aware pre-operatively that surgery may be part of multi-modal treatment, with adjuvant or SRT or ADT. Neoadjuvant therapy using ADT with or without new generation HT or docetaxel is not indicated. (See Section 6.1.2.2.4) [511,513]. Nerve sparing management is discussed in Section 6.1.2.3.5.

6.2.3.1.1. ISUP grade 4–5

The incidence of organ-confined disease is 26–31% in men with an ISUP grade > 4 on systematic biopsy. A high rate of downgrading exists between the biopsy ISUP grade and the ISUP grade of the resected specimen [855]. Several retrospective case series have demonstrated CSS rates over 60% at 15 years after RP in the context of a multi-modal approach (adjuvant or salvage ADT and/or RT) in patients with a biopsy ISUP grade 5 [441,519,857,858].

6.2.3.1.2. Prostate-specific antigen > 20 ng/mL

Reports in patients with a PSA > 20 ng/mL who underwent surgery as initial therapy within a multi-modal approach demonstrated a CSS at 15 years of over 70% [441,519,525,859-861].

6.2.3.1.3. Radical prostatectomy in cN0 patients with pathologically confirmed LN invasion (pN1)

At 15 years follow-up cN0 patients who undergo RP but who were found to have pN1 were reported to have an overall CSS and OS of 45% and 42%, respectively [862-867]. A systematic review has reported 10-year BCR-free, CSS, and OS rates ranging from 28% to 56%, 72% to 98%, and 60% to 87.6%, respectively, in pN1 patients [868]. These findings highlight that pN1 patients represent a very heterogeneous patient group and further treatment must be individualised based on risk factors (see Sections 6.2.5.2 and 6.2.5.6).

6.2.3.2. External beam radiation therapy

For high-risk localised PCa, a combined modality approach should be used consisting of IMRT/VMAT plus long-term ADT. The duration of ADT has to take into account PS, co-morbidities and the number of poor prognostic factors. It is important to recognise that in several studies EBRT plus short-term ADT did not improve OS in high-risk localised PCa and long-term ADT (at least 2 to 3 years) is currently recommended for these patients [676,677,687]. Moderate HFX is an option in selected high-risk patients with localised disease. The CHHiP study included 12% high-risk patients (n = 386) but limited entry to those with a PSA < 30 ng/mL and a Roach formula risk of SV involvement < 30% [661]. Patients were ineligible if they had both T3a tumours and ISUP grade 4 or higher.

6.2.3.2.1. Lymph node irradiation in cN0

There is no clear evidence for prophylactic irradiation of the pelvic LNs in intermediate- and high-risk disease. The long-term results of the NRG/RTOG 9413-trial which randomised intermediate-risk and high-risk localised PCa patients (1,322 cN0 patients were enrolled), showed that neoadjuvant HT plus whole pelvic RT improved PFS only compared with neoadjuvant ADT plus prostate RT and whole pelvic RT plus adjuvant ADT [869]. However, at the increased risk of > grade 3 GI-toxicity.

A well-conducted single-centre RCT randomised 224 patients comparing prostate-only RT (PORT) vs. whole pelvic RT (WPRT) in localised high-risk- and locally-advanced tumours (cN0) with a risk of > 20% of positive nodes (Roach formula). With a median follow-up of 68 months there was a significant improvement of distant metastasis-free survival (95.9% vs. 89.2%, HR: 0.35, p = 0.01) and DFS (89.5% vs.77.2%, p = 0.02). However, there was a significant higher rate of late GU > 2 effects (17.7% vs. 7.5%, p = 0.02), the trial was relatively small in size with additional limitations and these findings are therefore insufficient to define a change in practice [870,871]. The benefits of pelvic nodal irradiation using IMRT/VMAT merit further investigation in large scale RCTs as conducted by the RTOG or the UK National Cancer Research Institute (NCRI).

6.2.3.2.2. Brachytherapy boost

In men with NCCN unfavourable intermediate- or high-risk PCa, brachytherapy boost with supplemental EBRT and HT may be considered. See Sections 6.1.3.4.1 and 6.1.3.4.2 for details on RCTs comparing EBRT alone and EBRT with LDR or HDR boost, respectively.

6.2.3.3. Options other than surgery or radiotherapy for the primary treatment of localised PCa

Currently there is a lack of evidence supporting any other treatment option apart from RP and radical RT in localised high-risk PCa. The use of ADT monotherapy was addressed by the EORTC 30891 trial [848] (see Section 6.2.4.4.2). Immediate ADT may only benefit patients with a PSA-DT < 12 months, and either a PSA > 50 ng/mL or a poorly-differentiated tumour [848,872].

6.2.3.4. Guidelines for radical and palliative treatment of high-risk localised disease*

*All recommendations are based on conventional imaging with isotope bone scan and CT/MR abdomen/pelvis.

6.2.4. Treatment of locally-advanced PCa

In the absence of high-level evidence, a recent systematic review could not define the most optimal treatment option [873]. Randomised controlled trials are only available for EBRT. A local treatment combined with a systemic treatment provides the best outcome, provided the patient is fit enough to receive both. The initial results of the SCPG-15 trials suggested that randomisation between surgery and EBRT is feasible, but oncologic outcomes are awaited [874].

6.2.4.1. Radical prostatectomy

Surgery for locally-advanced disease as part of a multi-modal therapy has been reported [855,875,876]. However, the comparative oncological effectiveness of RP as part of a multi-modal treatment strategy vs. upfront EBRT with ADT for locally-advanced PCa remains unknown, although a prospective phase III RCT (SPCG-15) comparing RP (with or without adjuvant or salvage EBRT) against primary EBRT and ADT among patients with locally-advanced (T3) disease is currently recruiting [877]. Data from retrospective case series demonstrated over 60% CSS at 15 years and over 75% OS at 10 years [855,875,876,878-881]. For cT3b–T4 disease, PCa cohort studies showed 10-year CSS of over 87% and OS of 65% [882,883]. The indication for RP in all previously described stages assumes the absence of clinically detectable nodal involvement (cN0), based on conventional imaging. In case of suspected positive LNs during RP (initially considered cN0) the procedure should not be abandoned since RP may have a survival benefit in these patients. Intra-operative frozen section analysis is not justified in this case [580]. An ePLND is considered standard if a RP is planned.

6.2.4.2. Radiotherapy for locally-advanced PCa

In locally-advanced disease RCTs have clearly established that the additional use of long-term ADT combined with RT produces better OS than ADT or RT alone (see Section 6.1.3.1.4 and Tables 6.1.9 and 6.1.10) [873]. See Sections 6.1.3.4.1 and 6.1.3.4.2 for LDR and HDR brachytherapy boost in T3N0M0 PCa.

6.2.4.3. Treatment of cN1 M0 PCa

Lymph-node metastasised PCa is where options for local therapy and systemic therapies overlap. Approximately 5% to 10% of newly diagnosed PCa patients have synchronous suspected pelvic nodal metastases on conventional imaging (CT/bone scan) without bone or visceral metastases (cN1 M0 stage). Meta-analyses have shown that PSMA-PET/CT prior to primary treatment in advanced PCa detected disease outside the prostate in 32% of cases despite prior negative conventional imaging using bone scan and pelvic CT/MRI [416]. A RCT assessing PSMA-PET/CT as staging tool in high-risk PCa confirmed these findings and showed a 32% increase in accuracy compared with conventional imaging for the detection of pelvic nodal metastases [433]. Notably, more sensitive imaging also causes a stage shift with more cases classified as cN1, but with, on average, lower nodal disease burden.

The management of cN1M0 PCa is historically based on long-term ADT combined with a local treatment. The benefit of adding local treatment has been assessed in various retrospective studies, summarised in one systematic review [884] including 5 studies only [885-889]. The findings suggested an advantage in both OS and CSS after local treatment (RT or RP) combined with ADT as compared to ADT alone. The main limitations of this analysis were the lack of randomisation, of comparisons between RP and RT, as well as the value of the extent of PLND and of RT fields. Only limited evidence exists supporting RP for cN1 patients. Moschini et al., compared the outcomes of 50 patients with cN+ with those of 252 patients with pN1, but cN0 at pre-operative staging. cN+ was not a significant predictor of CSS [890].

Based on the consistent benefit seen in retrospective studies including cN1 patients, local therapy is recommended in patients with cN1 disease at diagnosis in addition to long-term ADT (see Table 6.2.4.1).

The addition of a brachytherapy boost to ADT plus EBRT was not associated with improved OS in a retrospective study of 1,650 cN1 patients after multivariable adjustment and propensity score matching [891].

The intensification of systemic treatment (abiraterone acetate, docetaxel, zoledronic acid) has been assessed in unplanned sub-group analyses from the STAMPEDE multi-arm RCT by stratifying for cN1 and M1 status [888,892]. The analyses were balanced for nodal involvement and for planned RT use in STAMPEDE at randomisation and at analysis. Abiraterone acetate was associated with a non-significant OS improvement (HR: 0.75, 95% CI: 0.48–1.18) in non-metastatic patients (N0/N+M0), but OS data were still immature with a low number of events. Furthermore, this was an underpowered subgroup analysis and hypothesis generating at best. Moreover, subgroup analyses were performed according to the metastatic/non-metastatic status and to the nodal status (any M) without specific data for the N1M0 population (n = 369; 20% of the overall cohort). The same would apply for the docetaxel arm in the STAMPEDE trial for which no specific subgroup analysis of newly diagnosed N1M0 PCa (n = 171, 14% of the overall cohort) was performed. However, the addition of docetaxel, zoledronic acid, or their combination, did not provide any OS benefit when stratifying by M0 and N+ status.

In the AFU-GETUG 12 trial comparing the impact of docetaxel plus estramustine in addition to ADT, 29% of included high-risk non-metastatic PCa patients had a nodal involvement (pN1) at randomisation [893]. A non-significant trend towards better relapse-free survival rates was reported in the treatment arm (HR 0.66; 0.43–1.01) without OS benefit. A meta-analysis of docetaxel trials in N0/N1-M0 patients concluded to an 8% 4-year survival advantage for docetaxel compared with ADT alone in terms of failure-free survival without OS
benefit [894].

Two RCTs from the STAMPEDE platform protocol reported on men with de novo high-risk/locally-advanced M0 disease, or relapse after primary curative therapy with high-risk features. Thirty-nine percent of patients (n = 774) were N1 on conventional imaging [895]. Radiotherapy in addition to long-term ADT was administered in 71% of these patients. Given the MFS and OS benefits observed in the overall population (see Section 6.2.4.2), combined ADT (for 3 years) and additional abiraterone (for 2 years) should be a SOC in cN1 patients in addition to prostate- and whole pelvic RT.

Table 6.2.4.1: Selected studies assessing local treatment in (any cT) cN1 M0 prostate cancer patients

ADT = androgen deprivation therapy; CSS = cancer-specific survival; EBRT = external beam radiotherapy; FFS = failure-free survival; HR = hazard ratio; mo = months; n = number of patients; OS = overall survival; RP = radical prostatectomy; RT = radiotherapy; yr = year.

6.2.4.4. Options other than surgery or radiotherapy for primary treatment

6.2.4.4.1. Investigational therapies

Currently cryotherapy, HIFU or focal therapies have no place in the management of locally-advanced PCa.

6.2.4.4.2. Androgen deprivation therapy monotherapy

The deferred use of ADT as single treatment modality has been answered by the EORTC 30891 trial [848]. Nine hundred and eighty-five patients with T0–4 N0–2 M0 PCa received ADT alone, either immediately or after symptomatic progression or occurrence of serious complications. After a median follow-up of 12.8 years, the OS favoured immediate treatment (HR: 1.21, 95% CI: 1.05–1.39). Surprisingly, no different disease-free or symptom-free survival was observed, raising the question of survival benefit. In locally-advanced T3–T4 M0 HSPC unsuitable for surgery or RT, immediate ADT may only benefit patients with a PSA > 50 ng/mL and a PSA-DT < 12 months or those that are symptomatic [848,872]. The median time to start deferred treatment was 7 years. In the deferred treatment arm 25.6% of patients died without needing treatment.

6.2.4.5. Guidelines for radical- and palliative treatment of locally-advanced disease*

*All recommendations are based on conventional imaging with isotope bone scan and CT/MR abdomen/pelvis.

6.2.5. Adjuvant treatment after radical prostatectomy

6.2.5.1. Introduction

Adjuvant treatment is by definition additional to the primary or initial therapy with the aim of decreasing the risk of relapse, despite the apparent full control following surgery. A post-operative detectable PSA is an indication of persistent prostate cells (see Section 6.2.6). All information listed below refers to patients with a post-operative undetectable PSA.

6.2.5.2. Risk factors for relapse

Patients with ISUP grade > 2 in combination with EPE (pT3a) and particularly those with SV invasion (pT3b) and/or positive surgical margins are at high risk of progression, which can be as high as 50% after 5 years [898]. Irrespective of the pT stage, the number of removed nodes [899-906], tumour volume within the LNs and capsular perforation of the nodal metastases are predictors of early recurrence after RP for pN1 disease [907]. A LN density (defined as ‘the percentage of positive LNs in relation to the total number of analysed/removed LNs’) of over 20% was found to be associated with poor prognosis [908]. The number of involved nodes seems to be a major factor for predicting relapse [901,902,909]; the threshold considered is less than 3 positive nodes from an ePLND [536,901,909]. However, prospective data are needed before defining a definitive threshold value.

6.2.5.2.1. Biomarker-based risk stratification after radical prostatectomy

The Decipher^® gene signature consists of a 22-gene panel representing multiple biological pathways and was developed to predict systemic progression after definitive treatment. A meta-analysis of five studies analysed the performance of the Decipher^® Genomic Classifier (GC) test on men post-RP. The authors showed in multivariable analysis that Decipher^® GC remained a statistically significant predictor of metastasis (HR: 1.30, 95% CI: 1.14–1.47, p < 0.001) per 0.1 unit increase in score and concluded that it can independently improve prognostication of patients post-RP within nearly all clinicopathologic, demographic, and treatment subgroups [910]. A systematic review of the evidence for the Decipher^® GC has confirmed the clinical utility of this test in post-RP decision-making [911]. Further studies are needed to establish how to best incorporate Decipher^® GC in clinical decision-making.

6.2.5.3. Immediate (adjuvant) post-operative external irradiation after RP (cN0 or pN0)

Four prospective RCTs have assessed the role of immediate post-operative RT (adjuvant RT [ART]) (undetectable PSA mostly defined as PSA < 0.1 ng/mL), demonstrating an advantage (endpoint, development of BCR) in high-risk patients (e.g., pT2 with positive surgical margins and ISUP 3–5 or pT3/4 with- or without positive surgical margins and ISUP 3–5) post-RP (Table 6.2.5.1). In the ARO 96-02 trial, 80% of the pT3/R1/GS 8–10 patients randomised to observation developed BCR within 10 years [912]. It must be emphasised that PSA was undetectable at inclusion only in the ARO 96-02 trial which presents a major limitation interpreting these findings as patients with a detectable PSA would now be considered for salvage therapy rather than ART [912].

Table 6.2.5.1: Overview of all four randomised trials for adjuvant surgical bed radiation therapy after RP* (without ADT)

*See Section 6.3.5.1 for delayed (salvage) post-radical prostatectomy external irradiation.

BCR = biochemical recurrence; FU = follow-up; mo = months; n = number of patients; n.s. = not significant; OS = overall survival; PSA = prostate-specific antigen; RP = radical prostatectomy; SM = surgical margin; SRT = salvage radiotherapy.

6.2.5.4. Comparison of adjuvant- and salvage radiotherapy

Two retrospective matched studies (510 and 149 patients receiving ART) failed to show an advantage for metastasis-free survival [916,917]. However, both studies were underpowered for high-risk patients (pT3b/R1/ISUP grade 4–5 PCa). In contrast to these studies, a propensity score-matched retrospective analysis of two cohorts of 366 pT3 and/or R1 patients found that compared to SRT at a PSA between 0.1 and 0.5 ng/mL, ART given at an undetectable PSA (< 0.1 ng/mL) improved all three endpoints; BCR, metastasis-free survival, and OS [918].

Both approaches (ART and early SRT) together with the efficacy of adjuvant ADT are compared in three prospective RCTs: the Medical Research Council (MRC) Radiotherapy and Androgen Deprivation In Combination After Local Surgery (RADICALS) trial [919], the Trans-Tasman Oncology Group (TROG) Radiotherapy Adjuvant Versus Early Salvage (RAVES) trial [920], and the Groupe d’Etude des Tumeurs Uro- Genitales (GETUG-AFU 17) trial [921]. In addition, a pre-planned meta-analysis of all three trials has been published (Table 6.2.5.2) [922].

Two trials closed early after randomising 333/470 patients (RAVES) and 424/718 (GETUG-AFU-17) patients. RADICALS-RT included 1,396 patients with the option of subsequent inclusion in RADICALS-HT; 154/649 (24%) of patients starting in the adjuvant RT group also received neoadjuvant or adjuvant HT; 90 patients for 6 months/45 for 2 years/19 patients outside RADICALS-HT. From the SRT group, 61/228 (27%) received neoadjuvant or adjuvant HT for 6 months (n = 33) and 2 years (n = 13). Fifteen of these patients were treated outside the trial [919]. All men in the GETUG-AFU-17 trial (n = 424) received 6 months of HT. All together, 684 out of 2,153 patients received additional ADT for at least 6 months across both trials [922]. Radiotherapy to the pelvic lymphatics was allowed in the GETUG-AFU and in the RADICALS-RT trials.

The primary endpoint for RAVES and GETUG-AFU 17 was biochemical PFS, and for RADICALS-RT metastasis-free survival. So far only PFS data has been reported, and not metastasis-free survival- or OS data. With a median follow-up between 4.9 years and 6.25 years there was no statistically significant difference for biochemical PFS for both treatments in all three trials (see Table 6.2.5.2) indicating that in the majority of patients adjuvant irradiation should be avoided. Additionally, there was a significant lower rate of grade > 2 GU late side effects and grade 3–4 urethral strictures in favour of early SRT; which may also be caused by the low number of patients with PSA-progression and subsequent need for early SRT at the time of analysis (40% of patients).

It is important to note that the indication for ART changed over the last ten years with the introduction of ultra-sensitive PSA-tests, favouring early SRT. Therefore many patients, randomised in these 3 trials (accruing 2006–2008) are not likely to benefit from ART as there is a low risk of biochemical progression (~20–30%) in, for example, pT3R0 or pT2R1-tumours. The median pre-SRT PSA in all 3 trials was 0.24 ng/mL. Therefore, patients with ‘low-risk factors’ of biochemical progression after RP should be closely followed up with ultra-sensitive assays and SRT should be discussed, if needed, as soon as PSA starts to rise, which has to be confirmed by a second PSA measurement (see Section 6.3). The proportion of patients with adverse pathology at RP (ISUP grade group 4–5 and pT3 with or without positive margins) in all 3 trials was low (between 10–20%) and therefore even the meta-analysis may be underpowered to show an outcome in favour of SRT [922]. In addition, the side-effect profile may have been impacted with a larger proportion of ART patients receiving treatment with older 3D-treatment planning techniques as compared to SRT patients (GETUG-AFU 17: ART, 69% 3D vs. 46% SRT) and patients treated more recently were more likely to undergo IMRT techniques with a proven lower rate of late side effects [634].

For these reasons, 10-year OS and metastasis-free survival endpoints results should be awaited before drawing final conclusions. Due to the small number of patients with adverse pathology (ISUP grade group 4–5 and pT3) included in these 3 trials (between 10–20%), ART remains a recommended treatment option in highly selected patients with adverse pathology (‘high-risk patients’) i.e. ISUP grade group 4–5 and pT3 with or without positive margins [923,924]. This recommendation was supported by a published retrospective multi-centre study comparing ART and SRT in patients with high-risk features (pN1 or ISUP 4–5 and pT3/4-tumours) after RP [925]. After a median follow-up of 8.2 years of the 26,118 men included in the study, 2,104 patients died, 25.62% from PCa (n = 539) and 2,424 patients had adverse pathology compared with 23,694 who did not. After excluding men with persistent PSA after RP, ART when compared with early SRT showed a significantly lower acute mortality risk (p = 0.02, HR: 0.33).

Table 6.2.5.2: Overview of all three randomised trials and one meta-analysis for patients treated with adjuvant vs. early salvage RT after RP

ART = adjuvant radiotherapy; BCR = biochemical recurrence; BPFS = biochemical progression-free survival; ED = erectile dysfunction; FU = follow-up; Fx = fraction; GU = genito-urinary; LHRH = luteinising hormone-releasing hormone; LT = late toxicity; mo = months; med = median; MFS = metastasis-free survival; n.r. = not reported; OS = overall survival; PSA = prostate-specific antigen; RP = radical prostatectomy; RT = radiotherapy; SR = self reported; SRT = salvage radiotherapy; + = positive; yr = year.

6.2.5.5. Adjuvant systemic therapy in N0 disease

Adjuvant androgen ablation with bicalutamide 150 mg daily did not improve PFS in localised disease while it did for locally-advanced disease after RT. However, this never translated to an OS benefit [926]. A systematic review showed a possible benefit for PFS but not OS for adjuvant androgen ablation [511].

The TAX3501 trial comparing the role of leuprolide (18 months) with and without docetaxel (6 cycles) ended prematurely due to poor accrual. A phase III RCT comparing adjuvant docetaxel against surveillance after RP for locally-advanced PCa showed that adjuvant docetaxel did not confer any oncological benefit [927]. Consequently, adjuvant chemotherapy after RP should only be considered in a clinical trial [928].

6.2.5.6. Adjuvant treatment in pN1 disease

6.2.5.6.1. Adjuvant androgen ablation alone

The combination of RP and early adjuvant HT in pN+ PCa has been shown to achieve a 10-year CSS rate of 80% and has been shown to significantly improve CSS and OS in prospective RCTs [929,930]. However, these trials included mostly patients with high-volume nodal disease and multiple adverse tumour characteristics and these findings may not apply to men with less extensive nodal metastases.

6.2.5.6.2. Adjuvant radiotherapy combined with ADT in pN1 disease

In a retrospective multi-centre cohort study, maximal local control with RT to the prostatic fossa appeared to be beneficial in PCa patients with pN1 after RP, treated ‘adjuvantly‘ with continuous ADT (within 6 months after surgery irrespective of PSA). The beneficial impact of adjuvant RT on survival in patients with pN1 PCa was highly influenced by tumour characteristics. Men with low-volume nodal disease (< 3 LNs), ISUP grade 2–5 and pT3–4 or R1, as well as men with 3 to 4 positive nodes were more likely to benefit from RT after surgery, while the other subgroups did not [931]. In contrast, a recent retrospective multi-centre study including 1,614 patients and a median follow-up of 7,02 years assessed ART + ADT. Adjuvant RT compared to SRT was associated with a decreased all-cause mortality and this reduction increased with each additional positive pelvic LN, from the first one on and the highest effect was for more than 3 positive nodes [932]. These data are in agreement with a US National Cancer Database analysis based on 5,498 patients [933]. Another US National Cancer Database study including 8,074 pN1 patients reports improved OS after ADT plus EBRT (including pelvic LNs) vs. observation and vs. ADT alone in all men with single or multiple adverse pathological features. Men without any adverse pathological features did not benefit from immediate adjuvant therapy [934].

In a systematic review of the literature, RT with or without ADT was associated with improved survival in men with locally-advanced disease and a higher number of positive nodes [868]. Radiotherapy to the pelvic lymphatics and the prostate fossa plus long-term ADT can be offered to patients with pN1 disease [931,935]. However, the optimal duration of ADT is still unkown.

6.2.5.6.3. Observation of pN1 patients after radical prostatectomy and extended lymph node dissection

Several retrospective studies and a systematic review addressed the management of patients with pN1 PCa at RP [868,909,931,935,936]. A subset of patients with limited nodal disease (1–2 positive LNs) showed favourable oncological outcomes and did not require additional treatment.

An analysis of 209 pN1 patients with one or two positive LNs at RP showed that 37% remained metastasis-free without need of salvage treatment at a median follow-up of 60.2 months [936]. Touijer et al., reported their results of 369 pN1-positive patients (40 with and 329 without adjuvant treatment) and showed that higher pathologic grade group and > 3 positive LNs were significantly associated with an increased risk of BCR on multivariable analysis [909]. Biochemical-free survival rates in pN1 patients without adjuvant treatment ranged from 43% at 4 years to 28% at 10 years [868]. Reported CSS rates were 78% at 5 years and 72% at 10 years. The majority of these patients were managed with initial observation after surgery, had favourable disease characteristics, and 63% had only one positive node [868]. Initial observation followed by early salvage treatment at the time of recurrence may represent a safe option in selected patients with a low disease
burden [868].

6.2.5.7. Guidelines for adjuvant treatment for pN0 and pN1 disease after radical prostatectomy*

*All recommendations are based on conventional imaging with isotope bone scan and CT/MR abdomen/pelvis.

6.2.6. Persistent PSA after radical prostatectomy

Between 5 and 20% of men continue to have detectable or persistent PSA after RP (when defined in the majority of studies as detectable post-RP PSA of > 0.1 ng/mL within 4 to 8 weeks of surgery) [937,938]. It may result from persistent local disease, pre-existing metastases or residual benign prostate tissue.

6.2.6.1. Natural history of persistently elevated PSA after RP

Several studies have shown that persistent PSA after RP is associated with more advanced disease (such as positive surgical margins, pathologic stage > T3a, positive nodal status and/or pathologic ISUP grade > 3) and poor prognosis. Initially defined as > 0.1 ng/mL, improvements in the sensitivity of PSA assays now allow for the detection of PSA at much lower levels.

Moreira et al., demonstrated that failure to achieve a PSA of less than 0.03 ng/mL within 6 months of surgery was associated with an increased risk of BCR and overall mortality [939,940]. However, since the majority of the published literature is based on the 0.1 ng/mL PSA cut-off, there is significantly more long-term data for this definition. Predictors of PSA persistence were higher BMI, higher pre-operative PSA and ISUP grade > 3 [940]. In patients with PSA persistence, one and 5-year BCR-free survival were 68% and 36%, compared to 95% and 72%, respectively, in men without PSA persistence [939]. Ten-year OS in patients with and without PSA persistence was 63% and 80%, respectively.

Spratt et al., confirmed that a persistently detectable PSA after RP represents one of the worst prognostic factors associated with oncological outcome [941]. Of 150 patients with a persistent PSA, 95% received RT before detectable metastasis. In a multivariable analysis the presence of a persistently detectable PSA post-RP was associated with a 4-fold increase in the risk of developing metastasis. This was confirmed by data from Preisser et al., who showed that persistent PSA is prognostic of an increased risk of metastasis and death [942]. At 15 years after RP, metastasis-free survival rates, OS and CSS rates were 53.0 vs. 93.2% (p < 0.001), 64.7 vs. 81.2% (p < 0.001) and 75.5 vs. 96.2% (p < 0.001) for persistent vs. undetectable PSA, respectively. The median follow-up was 61.8 months for patients with undetectable PSA vs. 46.4 months for patients with persistent PSA. In multivariable Cox regression models, persistent PSA represented an independent predictor for metastasis (HR: 3.59, p < 0.001), death (HR: 1.86, p < 0.001) and cancer-specific death (HR: 3.15, p < 0.001).

However, not all patients with persistent PSA after RP experience disease recurrence. Xiang et al., showed a 50% 5-year BCR-free survival in men who had a persistent PSA level > 0.1 but < 0.2 ng/mL at 6–8 weeks after RP [943].

Rogers et al., assessed the clinical outcome of 160 men with a persistently detectable PSA level after RP [944]. No patient received adjuvant therapy before documented metastasis. In their study, 38% of patients had no evidence of metastases for > 7 years while 32% of the patients were reported to develop metastases within 3 years. Noteworthy is that a significant proportion of patients had low-risk disease. In multivariable analysis the PSA slope after RP (as calculated using PSA levels 3 to 12 months after surgery) and pathological ISUP grade were significantly associated with the development of distant metastases.

6.2.6.2. Imaging in patients with persistently elevated PSA after RP

Standard imaging with bone scan and MRI has a low detection rate in men with a PSA below 2 ng/mL. However, PSMA PET/CT has been shown to identify residual cancer with positivity rates of 33%, 46%, 57%, 82%, and 97%, in men with post-RP PSA ranges of 0–0.19, 0.2–0.49, 0.5–0.99, 1–1.99, and > 2 ng/mL, respectively [945-950] which can guide SRT planning [951]. Based on these post-RP PSA ranges, Schmidt-Hegemann et al., studied 129 patients who had either persistent PSA (52%) or BCR (48%) after RP, showing that men with a persistent PSA had significantly more pelvic nodal involvement on PSMA PET/CT than those developing a detectable PSA [952]. In a multi-centre retrospective study including 191 patients, ⁶⁸Ga-PSM localised biochemical persistence after RP in more than two-thirds of patients with high-risk PCa features. The obturator and presacral/mesorectal nodes were identified as high risk for residual disease [953]. Another retrospective study included 150 patients with persistent PSA after RARP who were re-staged with both ⁶⁸Ga-PSMA and ¹⁸F-DCFPyL PSMA. The authors found that in the presence of persistent PSA the majority of patients already had metastatic pelvic LNs or distant metastases which would support a role of PSMA PET/CT imaging in guiding (salvage) treatment strategies [954]. At present there is uncertainty regarding the best treatment if PSMA PET/CT shows metastatic disease outside the pelvis.

6.2.6.3. Impact of post-operative RT and/or ADT in patients with persistent PSA

The benefit of SRT in patients with persistent PSA remains unclear due to a lack of RCTs, however, it would appear that men with a persistent PSA do less well than men with BCR undergoing RT.

Preisser et al., compared oncological outcomes of patients with persistent PSA who received SRT vs. those who did not [942]. In the subgroup of patients with persistent PSA, after 1:1 propensity score matching between patients with SRT vs. no RT, OS rates at 10 years after RP were 86.6 vs. 72.6% in the entire cohort (p < 0.01), 86.3 vs. 60.0% in patients with positive surgical margin (p = 0.02), 77.8 vs. 49.0% in pT3b disease (p < 0.001), 79.3 vs. 55.8% in ISUP grade 1 disease (p < 0.01) and 87.4 vs. 50.5% in pN1 disease (p < 0.01), respectively. Moreover, CSS rates at 10 years after RP were 93.7 vs. 81.6% in the entire cohort (p < 0.01), 90.8 vs. 69.7% in patients with positive surgical margin (p = 0.04), 82.7 vs. 55.3% in pT3b disease (p < 0.01), 85.4 vs. 69.7% in ISUP grade 1 disease (p < 0.01) and 96.2 vs. 55.8% in pN1 disease (p < 0.01), for SRT vs. no RT, respectively. In multivariable models, after 1:1 propensity score matching, SRT was associated with lower risk of death (HR: 0.42, p = 0.02) and lower cancer-specific death (HR: 0.29, p = 0.03). These survival outcomes in patients with persistent PSA who underwent SRT suggest they benefit but outcomes are worse than for men experiencing BCR [955].

It is clear from a number of studies that poor outcomes are driven by the level of pre-RT PSA, the presence of ISUP grade > 4 in the RP histology and pT3b disease [956-961]. Fossati et al., suggested that only men with a persistent PSA after RP and ISUP grade < 3 benefit significantly [962], although this is not supported by Preisser et al. [942]. The current data do not allow making any clear treatment decisions.

Addition of ADT may improve PFS [957]. Choo et al., studied the addition of 2-year ADT to immediate RT to the prostate bed in patients with pT3 and/or positive surgical margins after RP [957]. Twenty-nine of the 78 included patients had persistently detectable post-operative PSA. The relapse-free rate was 85% at 5 years and 68% at 7 years, which was superior to the 5-year progression-free estimates of 74% and 61% in the post-operative RT arms of the EORTC and the SWOG studies, respectively, which included patients with undetectable PSA after RP [913,914]. Patients with persistently detectable post-operative PSA comprised approximately 50% and 12%, respectively, of the study cohorts in the EORTC and the SWOG studies.

In the ARO 96-02, a prospective RCT, 74 patients with PSA persistence (20%) received immediate SRT only (66 Gy per protocol [arm C]). The 10-year clinical relapse-free survival was 63% [956]. The GETUG-22 trial comparing RT with RT plus short-term ADT for post-RP PSA persistence (0.2–2.0 ng/mL) reported good tolerability of the combined treatment. The oncological endpoints are yet to be published [963].

Two systematic reviews addressing persistent PSA confirmed a strong correlation of PSA persistence with poor oncologic outcomes [937,938]. Ploussard et al., also reported that SRT was associated with improved survival outcomes, although the available evidence is of low quality [938].

6.2.6.4. Conclusion

The available data suggest that patients with PSA persistence after RP may benefit from early aggressive multimodality treatment, however, the lack of prospective RCTs makes firm recommendations difficult.

6.2.6.5. Recommendations for the management of persistent PSA after radical prostatectomy

6.3. Management of PSA-only recurrence after treatment with curative intent

Follow-up will be addressed in Chapter 7 and is not discussed in this section.

6.3.1. Background

Between 27% and 53% of all patients undergoing RP or RT develop a rising PSA (PSA recurrence). Whilst a rising PSA level universally precedes metastatic progression, physicians must inform the patient that the natural history of PSA-only recurrence may be prolonged and that a measurable PSA may not necessarily lead to clinically apparent metastatic disease. Physicians treating patients with PSA-only recurrence face a difficult set of decisions in attempting to delay the onset of metastatic disease and death while avoiding over-treating patients whose disease may never affect their OS or QoL. It should be emphasised that the treatment recommendations for these patients should be given after discussion in a multidisciplinary team.

6.3.1.1. PSA velocity and doubling time

Various PSA kinetics definitions have been proposed with different methods of calculation (log transformed or not) and eligible PSAs:

• PSA velocity (PSAV): absolute annual increase in serum PSA (ng/mL/year);
• PSA doubling time (PSA-DT): which measures the exponential increase in serum PSA over time.

Prostate-specific antigen velocity is more simple to calculate by subtracting the initial value from the final value, dividing by time. However, by ignoring middle values, not all PSA values are accurately taken into account.

Prostate-specific antigen-DT is calculated assuming an exponential rise in serum PSA. The formula takes into account the natural logarithm of 2 divided by the slope obtained from fitting a linear regression of the natural log of PSA over time [964]. However, many different PSA-DT calculations have been assessed according to the mathematical formula used and to the included PSA values (number, time period, intervals) [965]. For example, the ‘MSKCC’ method calculates a regression slope integrating all PSA values. Other methods transform PSA before calculating the slope and do not include all PSA values (different time frames and minimal intervals) [966]. O’Brien and colleagues identified more than 20 different definitions of PSAV and PSA-DT and demonstrated that obtained values could vary widely between definitions [966].

However, some rules can be considered for PSA-DT calculation [964]:

• At least 3 PSA measurements are required;
• A minimum time period between measurements (4 weeks) is preferable due to potential statistical ‘noise’ when PSA values are obtained too close together (this statement can be reconsidered in case of very active disease);
• All included PSA values should be obtained within the past 12 months at most, to reflect the current disease activity;
• PSA-DT is often mentioned in months, or in weeks in very active disease.

These measurements do not provide additional information compared with PSA alone [966-969]. In the post-local therapy relapse setting, PSA-DT has been correlated with distant progression and with poorer outcomes after salvage treatments [970,971]. Prostate-specific antigen-DT has been linked with metastasis-free- and OS in non-metastatic CRPC (nmCRPC) and identifies patients with high-risk nmCRPC who benefit from intensified therapy (PSA-DT threshold < 10 months) [972].

6.3.2. Controversies in the definitions of clinically relevant PSA relapse

The PSA level that defines treatment failure depends on the primary treatment. Patients with rising PSA after RP or primary RT have different risks of subsequent symptomatic metastatic disease based on various parameters, including the PSA level. Therefore, physicians should carefully interpret BCR endpoints when comparing treatments. Clinicians should interpret a PSA rise in light of the EAU BCR risk groups (see Section 6.3.3).

After RP, the threshold that best predicts further metastases is a PSA > 0.4 ng/mL and rising [973-975]. However, with access to ultra-sensitive PSA testing, a rising PSA much below this level will be a cause for concern for patients.

After primary RT, with or without short-term hormonal manipulation, the RTOG-ASTRO Phoenix Consensus Conference definition of PSA failure (with an accuracy of > 80% for clinical failure) is ‘any PSA increase > 2 ng/mL higher than the PSA nadir value, regardless of the serum concentration of the nadir’ [976].

After HIFU or cryotherapy no endpoints have been validated against clinical progression or survival; therefore, it is not possible to give a firm recommendation of an acceptable PSA threshold after these alternative local treatments [977].

6.3.3. Natural history of biochemical recurrence

Once a PSA recurrence has been diagnosed, it is important to determine whether the recurrence has developed at local or distant sites. A systematic review and meta-analysis investigated the impact of BCR on hard endpoints and concluded that patients experiencing BCR are at an increased risk of developing distant metastases, PCa-specific and overall mortality [977]. However, the effect size of BCR as a risk factor for mortality is highly variable. After primary RP its impact ranges from HR 1.03 (95% CI: 1.004–1.06) to HR 2.32 (95% CI: 1.45–3.71) [978,979]. After primary RT, OS rates are approximately 20% lower at 8 to 10 years follow-up even in men with minimal co-morbidity [980,981]. Still, the variability in reported effect sizes of BCR remains high and suggests that only certain patient subgroups with BCR might be at an increased risk of mortality.

The risk of subsequent metastases, PCa-specific- and overall mortality may be predicted by the initial clinical and pathologic factors (e.g., T-category, PSA, ISUP grade) and PSA kinetics (PSA-DT and interval to PSA failure), which was further investigated by the systematic review [977].

For patients with BCR after RP, the following outcomes were found to be associated with significant prognostic factors:

• distant metastatic recurrence: positive surgical margins, high RP specimen pathological ISUP grade, high pT category, short PSA-DT, high pre-SRT PSA;
• prostate-cancer-specific mortality: high RP specimen pathological ISUP grade, short interval to biochemical failure as defined by investigators, short PSA-DT;
• overall mortality: high RP specimen pathological ISUP grade, short interval to biochemical failure, high PSA-DT.

For patients with BCR after RT, the corresponding outcomes are:

• distant metastatic recurrence: high biopsy ISUP grade, high cT category, short interval to biochemical failure;
• prostate-cancer-specific mortality: short interval to biochemical failure;
• overall mortality: high age, high biopsy ISUP grade, short interval to biochemical failure, high initial (pre-treatment) PSA.

Based on this meta-analysis, proposal is to stratify patients into two risk categories since not all patients with BCR will have similar outcomes (see Table 6.3.1). The stratification into ‘EAU Low-Risk’ or ‘EAU High-Risk’ BCR has recently been validated in a European cohort [982].

Table 6.3.1: EAU risk categories for biochemical recurrence

6.3.4. The role of imaging in PSA-only recurrence

Imaging is only of value if it leads to a treatment change which results in an improved outcome. In practice, however, there are very limited data available regarding the outcomes consequent on imaging at recurrence.

6.3.4.1. Assessment of metastases (including nodal)

6.3.4.1.1. Bone scan and abdominopelvic CT

Because BCR after RP or RT precedes clinical metastases by 7 to 8 years on average [903,983], the diagnostic yield of conventional imaging techniques (bone scan and abdominopelvic CT) is low in asymptomatic patients [984]. In men with PSA-only recurrence after RP the probability of a positive bone scan is < 5%, when the PSA level is < 7 ng/mL [985,986]. Only 11–14% of patients with BCR after RP have a positive CT [985]. In a series of 132 men with BCR after RP the mean PSA level and PSA velocity associated with a positive CT were
27.4 ng/mL and 1.8 ng/mL/month, respectively [987].

6.3.4.1.2. Choline PET/CT

In two different meta-analyses the combined sensitivities and specificities of choline PET/CT for all sites of recurrence in patients with BCR were 86–89% and 89–93%, respectively [988,989].

Choline PET/CT may detect multiple bone metastases in patients showing a single metastasis on bone scan [990] and may be positive for bone metastases in up to 15% of patients with BCR after RP and negative bone scan [991]. The specificity of choline PET/CT is also higher than bone scan, with fewer false-positive and indeterminate findings [420]. Detection of LN metastases using choline PET/CT remains limited by the relatively poor sensitivity of the technique (see Section 5.3.2.3). Choline PET/CT sensitivity is strongly dependent on the PSA level and kinetics [429,992,993]. In patients with BCR after RP, PET/CT detection rates are only 5–24% when the PSA level is < 1 ng/mL but rises to 67–100% when the PSA level is > 5 ng/mL. Despite its limitations, choline PET/CT may change medical management in 18–48% of patients with BCR after primary treatment [994-996].

Choline PET/CT should only be recommended in patients fit enough for curative loco-regional salvage treatment.

6.3.4.1.3. Fluoride PET/CT

¹⁸F-NaF PET/CT has a higher sensitivity than bone scan in detecting bone metastases [997]. However, ¹⁸F -NaF PET/CT is limited by a relative lack of specificity and by the fact that it does not assess soft-tissue metastases [998].

6.3.4.1.4. Fluciclovine PET/CT

¹⁸F-Fluciclovine PET/CT has been approved in the U.S. and Europe and it is therefore one of the PCa-specific radiotracers widely commercially available [999-1001].

¹⁸F-Fluciclovine PET/CT has a slightly higher sensitivity than choline PET/CT in detecting the site of relapse in BCR [1002]. In a multi-centre trial evaluating 596 patients with BCR in a mixed population fluciclovine PET/CT showed an overall detection rate of 67.7%; lesions could be visualised either at local level (38.7%) or in LNs and bones (9%) [1003]. As for choline PET/CT, fluciclovine PET/CT sensitivity is dependent on the PSA level, with a sensitivity likely inferior to 50% at PSA < 1 ng/mL.

In a prospective RCT evaluating the impact of ¹⁸F-fluciclovine PET/CT on SRT management decisions in patients with recurrence post-prostatectomy, in 28 of 79 (35.4%) patients overall radiotherapeutic management changed following ¹⁸F-fluciclovine PET/CT [1004]. ¹⁸F-Fluciclovine PET/CT had a significantly higher positivity rate than conventional imaging (abdominopelvic CT or MRI plus bone scan) for whole body (79.7% vs. 13.9%, p < 0.001), prostate bed (69.6% vs. 5.1%, p < 0.001), and pelvic LNs (38.0% vs. 10.1%, p < 0.001) [1004]. However, as yet, no data demonstrating that these changes translate into a survival benefit are available.

6.3.4.1.5. Prostate-specific membrane antigen based PET/CT

PSMA PET/CT has shown good potential in patients with BCR, although most studies are limited by their retrospective design. Reported predictors of ⁶⁸Ga-PSMA PET in the recurrence setting were recently updated based on a high-volume series (see Table 6.3.2) [945]. High sensitivity (75%) and specificity (99%) were observed on per-lesion analysis.

Table 6.3.2: PSMA-positivity separated by PSA level category [945]

PSA = prostate-specific antigen; 68Ga-PSMA PET = Gallium-68 prostate-specific membrane antigen positron emission tomography.

PSMA PET/CT seems substantially more sensitive than choline PET/CT, especially for PSA levels < 1 ng/mL [1005,1006]. In a study of 314 patients with BCR after treatment and a median PSA level of 0.83 ng/mL, ⁶⁸Ga-PSMA PET/CT was positive in 197 patients (67%) [1007]. In another prospective multi-centre trial including 635 patients with BCR after RP (41%), RT (27%), or both (32%), PPV for ⁶⁸Ga-PSMA PET/CT was 0.84 (95% CI: 0.75–0.90) by histopathologic validation (primary endpoint, n = 87) and 0.92 (95% CI: 0.75–0.90) by a composite reference standard. Detection rates significantly increased with PSA value [1008].

A prospective multi-centre, multi-reader, open-label, phase II/III trial (OSPREY) evaluated the diagnostic performance of ¹⁸F-DCFPyL in patients with presumptive radiologic evidence of recurrent or metastatic PCa on conventional imaging [415]. Median sensitivity and median PPV were 95.8% (95% CI: 87.8%–99.0%) and 81.9% (95% CI: 73.7%–90.2%), respectively.

Another prospective study evaluated the diagnostic performance of ¹⁸F-DCFPyL in 208 men with BCR after RP or RT. The primary endpoint, the correct localisation rate was achieved, demonstrating positive findings on ¹⁸F-DCFPyL PET/CT in the setting of negative standard imaging [1009]. At present there are no conclusive data about comparison of such tracers [1010].

6.3.4.1.6. Whole-body and axial MRI

Whole body MRI has not been widely evaluated in BCR because of its limited value in the detection of early metastatic involvement in normal-sized LNs [418,431,1011]. In a prospective series of 68 patients with BCR, the diagnostic performance of DW-MRI was significantly lower than that of ⁶⁸Ga-PSMA PET/CT and ¹⁸NaF PET/CT for diagnosing bone metastases [1012].

6.3.4.2. Assessment of local recurrences

6.3.4.2.1. Local recurrence after radical prostatectomy

Because the sensitivity of anastomotic biopsies is low, especially for PSA levels < 1 ng/mL [984], SRT is usually decided on the basis of BCR without histological proof of local recurrence. The dose delivered to the prostatic fossa tends to be uniform since it has not been demonstrated that a focal dose escalation at the site of recurrence improves the outcome. Therefore, most patients undergo SRT without local imaging.

Magnetic resonance imaging can detect local recurrences in the prostatic bed. The PSA threshold for MRI positivity seems between 0.3 and 0.5 ng/mL; PSA kinetics also influence the MRI positivity, even at low PSA values [1013]. Two single-centre studies found that a negative MRI was an independent predictor of failure of SRT [1014,1015].

Choline PET/CT is less sensitive for local relapse than MRI but detects more regional and distant metastases [1016].

The detection rates of ⁶⁸Ga-PSMA PET/CT in patients with BCR after RP increase with the PSA level [1017]. PSMA PET/CT studies showed that a substantial part of recurrences after RP were located outside the prostatic fossa, even at low PSA levels [946,1018]. Combining ⁶⁸Ga-PSMA PET and MRI may improve the detection of local recurrences, as compared to ⁶⁸Ga-PSMA PET/CT alone [1019-1021].

The EMPIRE-1, a single-centre, open-label, phase II/III RCT included 365 patients with detectable PSA after RP, but negative results on conventional imaging. They were randomised to RT directed by conventional imaging alone or to conventional imaging plus ¹⁸F-fluciclovine-PET/CT; patients with M1 disease in the PET/CT group (n = 4) were excluded. Patients with cN1 were irradiated to the pelvic lymphatics but without a boost to the metastasis. After a median follow-up of 3.5 years,the PET/CT group was significantly associated with longer event-free survival (HR: 2.04, 95% CI: 1.06–3.93, p = 0.0327) [1022].

6.3.4.2.2. Local recurrence after radiation therapy

In patients with BCR after RT, biopsy status is a major predictor of outcome, provided the biopsies are obtained 18–24 months after initial treatment. Given the morbidity of local salvage options it is necessary to obtain histological proof of the local recurrence before treating the patient [984].

MRI has yielded excellent results in identifying local recurrence and can be used for biopsy targeting and guiding local salvage treatment [984,1023-1026], even if it slightly underestimates the volume of the local recurrence [1027]. Prostate-specific membrane antigen PET/CT can also detect local recurrences after RT [945] and concordance between PSMA PET/CT and MRI is highly suggestive of cancer recurrence [1028].

6.3.4.3. Summary of evidence of imaging in case of biochemical recurrence

In patients with BCR imaging can detect both local recurrences and distant metastases, however, the sensitivity of detection depends on the PSA level. After RP, PSMA PET/CT seems to be the imaging modality with the highest sensitivity at low PSA levels (< 0.5 ng/mL) and may help distinguishing patients with recurrences confined to the prostatic fossa from those with distant metastases which may impact the design and use of post-RP SRT. After RT, MRI has shown excellent results at detecting local recurrences and guiding prostate biopsy. Given the substantial morbidity of post-RT local salvage treatments, distant metastases must be ruled out in patients with local recurrences and who are fit for these salvage therapies. Choline-, fluciclovine- or PSMA-PET/CT can be used to detect metastases in these patients but for this indication PSMA PET/CT seems the most sensitive technique.

6.3.4.4. Summary of evidence and guidelines for imaging in patients with biochemical recurrence

6.3.5. Treatment of PSA-only recurrences

The timing and treatment modality for PSA-only recurrences after RP or RT remain a matter of controversy based on the limited evidence.

6.3.5.1. Treatment of PSA-only recurrences after radical prostatectomy

6.3.5.1.1. Salvage radiotherapy for PSA-only recurrence after radical prostatectomy (cTxcN0M0, without PET/CT)

Early SRT provides the possibility of cure for patients with an increasing PSA after RP. Boorjian et al., reported a 75% reduced risk of systemic progression with SRT when comparing 856 SRT patients with 1,801 non-SRT patients [1029]. The RAVES and RADICAL trials assessing SRT in post-RP patients with PSA levels exceeding 0.1–0.2 ng/mL showed 5-year freedom from BCR and BCR-free survival rates of 88% [919,1030].

The PSA level at BCR was shown to be prognostic [1029]. More than 60% of patients who are treated before the PSA level rises to > 0.5 ng/mL will achieve an undetectable PSA level [1031-1034], corresponding to a ~80% chance of being progression-free 5 years later [1035]. A retrospective analysis of 635 patients who were followed after RP and experienced BCR and/or local recurrence and either received no salvage treatment (n = 397) or SRT alone (n = 160) within 2 years of BCR showed that SRT was associated with a 3-fold increase in PCa-specific survival relative to those who received no salvage treatment (p < 0.001). Salvage RT has been shown to be effective mainly in patients with a short PSA-DT [1036]. For an overview of SRT see Table 6.3.3.

The EAU BCR definitions have been externally validated and may be helpful for individualised treatment decisions [977,982]. Despite the indication for SRT, a ‘wait and see‘ strategy remains an option for the EAU BCR ‘Low-Risk’ group [977,982].

Although biochemical progression is now widely accepted as a surrogate marker of PCa recurrence; metastatic disease, disease-specific and OS are more meaningful endpoints to support clinical decision-making. A systematic review and meta-analysis on the impact of BCR after RP reports SRT to be favourable for OS and PCSM. In particular SRT should be initiated in patients with rapid PSA kinetics after RP and with a PSA cut-off of 0.4 ng/mL [977]. An international multi-institutional analysis of pooled data from RCTs has suggested that metastasis-free survival is the most valid surrogate endpoint with respect to impact on OS [1037,1038]. Table 6.3.4 summarises results of recent studies on clinical endpoints after SRT.

Table 6.3.3: Selected studies of post-prostatectomy salvage radiotherapy, stratified by pre-salvage radiotherapy PSA level* (cTxcN0M0, without PET/CT)

*Androgen deprivation therapy can influence the outcome ‘biochemically no evidence of disease (bNED)’ or ‘progression-free survival’. To facilitate comparisons, 5-year bNED/PFS read-outs from Kaplan-Meier plots are included.
ADT = androgen deprivation therapy; bNED = biochemically no evidence of disease; FU = follow up; mo = months; n = number of patients; PFS = progression-free survival; PSA = prostate-specific antigen; SRT = salvage radiotherapy; yr = year.

Table 6.3.4: Recent studies reporting clinical endpoints after SRT (cTxcN0M0, without PET/CT) (the majority of included patients did not receive ADT)

ADT = androgen deprivation therapy; DM = distant metastasis; DSM = disease specific mortality; FU = follow up; mo. = month; n = number of patients; OS = overall survival; PSA = prostate specific antigen; SRT = salvage radiotherapy.

6.3.5.1.2. Salvage radiotherapy combined with androgen deprivation therapy (cTxcN0, without PET/CT)

Data from RTOG 9601 suggest both CSS and OS benefit when adding 2 years of bicalutamide (150 mg o.d.)
to SRT [1043]. According to GETUG-AFU 16 also 6-months treatment with a LHRH-analogue can significantly improve 10-year BCR, biochemical PFS and, modestly, metastasis-free survival. However, SRT combined with either goserelin or placebo showed similar DSS and OS rates [1044]. In addition, Pollack et al., reported on the results of a randomised 3-arm phase III trial (NRG Oncology/RTOG 0534 SPPORT) adding six months treatment with a LHRH-analogue to SRT of the prostate bed (PBRT) (group 2) compared with PBRT alone (group 1) or the former combination with PBRT-RT and pelvic LN RT (PLNRT) (group 3) [1045]). The primary endpoint was freedom from progression (FFP) after 5 years. However, using the phoenix-definition of biochemical progression (nadir + 2 ng/mL used for definitive RT), and not the criterion of nadir + 0.2, as is used commonly (but without clear evidence) will have resulted in a later diagnosis of progression in the SPPORT trial.

With a median follow-up of 8.2 years of the surviving patients FFP increased significant for group 3 (87.4%) compared with group 2 (81.3%) (p = 0.0027) and group 1 (70.9%) (p < 0.0001) The difference between group 2 and group 1 was also significant (p < 0.0001). Distant metastasis incidence rates were lowest in group 3 and were lower compared with group 1 (PBRT only, HR: 0.52) similar to the rate of PCa deaths (HR: 0.51). No significant difference was seen for OS. There was a significantly higher risk of both acute- and late side effects in group 3. In conclusion, the role of additional PLNRT remains unclear and should be further proven in RCTs including PSMA PET-CT [1046]. Table 6.3.5 provides an overview of these three RCTs.

These RCTs support adding ADT to SRT. However, when interpreting these data it has to be kept in mind that RTOG 9601 used outdated radiation dosages (< 66 Gy) and technique. The question with respect to the patient risk profile, whether to offer combination treatment or not, and the optimal combination (LHRH or bicalutamide) remains, as yet, unsolved. The EAU BCR risk classification may offer guidance in this respect [977].

One of these RCTs reports improved OS (RTOG 96-01) and the other (GETUG-AFU 16) improved metastasis-free survival but due to methodological discrepancies and also related to follow-up and risk patterns, it is, as yet, not evident which patients should receive ADT, which type of ADT, and for how long. Men at high risk of further progression (e.g., with a PSA > 0.7 ng/mL and GS > 8) may benefit from SRT combined with two years of ADT; for those at lower risk (e.g., PSA < 0.7 ng/mL and GS = 8) SRT combined with 6 months of ADT may be sufficient. Men with a low-risk profile (PSA < 0.5 ng/mL and GS < 8) may receive SRT alone. In a sub-analysis of men with a PSA of 0.61 to 1.5 (n = 253) there was an OS benefit associated with anti-androgen assignment (HR: 0.61, 95% CI: 0.39–0.94) [1047]. In those receiving early SRT (PSA 0.6 ng/mL, n = 389), there was no improvement in OS (HR: 1.16, 95% CI: 0.79–1.70), with increased other-cause mortality (sub-distribution HR: 1.94, 95% CI: 1.17–3.20, p = 0.01) and increased odds of late grades 3–5 cardiac and neurologic toxic side effects (OR: 3.57, 95% CI: 1.09–15.97, p = 0.05). These results suggest that pre-SRT PSA level may be a prognostic biomarker for outcomes of anti-androgen treatment with SRT. In patients receiving late SRT (PSA > 0.6 ng/mL), HT was associated with improved outcomes. In men receiving early SRT (PSA < 0.6 ng/mL), long-term anti-androgen treatment was not associated with improved OS [1047].

A systematic review addressing the benefit from combining HT with SRT suggested risk stratification of patients based on the pre-SRT PSA (< 0.5, 0.6–1, > 1 ng/mL), margin status and ISUP grade as a framework to individualise treatment [1048].

Table 6.3.5: Randomised controlled trials comparing salvage radiotherapy combined with androgen deprivation therapy vs. salvage radiotherapy alone

ADT = androgen deprivation therapy; DM = distant metastasis; DSM = disease specific mortality; PFS = progression free survival; FFP = Freedom From Progression; FU = follow-up; LHRH = luteinising hormone-releasing hormone; MFS = metastasis-free survival; OS = overall survival; PFS = progression-free survival; mo = months; n = number of patients; RT = radiotherapy; yr = year, PBRT = prostate bed radiotherapy; PLNRT = pelvic lymph node radiotherapy.

6.3.5.1.2.1. Target volume, dose, toxicity

There have been various attempts to define common outlines for ‘clinical target volumes‘ for pN0 PCa [1049-1051] and for organs at risk of normal tissue complications [1050,1051]. However, given the variations of techniques and dose-constraints, a satisfactory consensus has not yet been achieved. A benefit in biochemical PFS but not metastasis-free survival has been reported in patients receiving whole pelvis SRT (± ADT) but the advantages must be weighed against possible side effects [1046]. This is supported by data from the SPPORT-Trial (NRG Oncology/RTOG 0534 SPPORT) but it remains controversial [1045].

The optimal SRT dose has not been well defined. It should be at least 64 Gy to the prostatic fossa (± the base of the SVs, depending on the pathological stage after RP) [924,1032,1052]. In a systematic review, the pre- SRT PSA level and SRT dose both correlated with BCR, showing that relapse-free survival decreased by 2.4% per 0.1 ng/mL PSA and improved by 2.6% per Gy, suggesting that the treatment dose above 70 Gy should be administered at the lowest possible PSA level [1053]. The combination of pT stage, margin status and ISUP grade and the PSA at SRT seems to define the risk of biochemical progression, metastasis and overall mortality [916,1054,1055]. In a study on 894 node-negative PCa patients, doses ranging from 64 to > 74 Gy were assigned to twelve risk groups defined by their pre-SRT PSA classes < 0.1, 0.1–0.2, 0.2–0.4, and > 0.4 ng/mL and ISUP grade, < 1 vs. 2/3 vs. > 4 [1056]. The updated Stephenson nomograms incorporate the SRT and ADT doses as predictive factors for biochemical failure and distant metastasis [1041].

Two RCT’s were recently published (Table 6.3.6). Intensity-modulated radiation therapy plus IGRT was used in 57% of the patients in the SAKK-trial [924] and in all patients of a Chinese trial [1057]. No patient had a PSMA PET/CT before randomisation. The primary endpoint in both trials was ‘freedom from biochemical progression’, which was not significantly improved with higher doses. However, in the Chinese trial a subgroup analysis showed a significant improvement of this endpoint for patients with Gleason 8-10 tumours (79.7% vs. 55%,
p = 0.049). In this trial, patients were treated with ART or SRT and the number of patients was relatively small (n = 144). At this time it seems difficult to draw final conclusions about the optimal total RT-dose and longer follow-up should be awaited.

Table 6.3.6: Randomized trials investigating dose escalation for SRT without ADT and without PET-CT

ADT = androgen deprivation therapy; ART = adjuvant radiotherapy; FFBP = freedom from biochemical failure;GI = gastro-intestinal; GU = genito-urinary; Gy = Gray; IGRT = image guided radiotherapy; mo = month; n = number of patients; PSA = prostate-specific antigen; RT = radiotherapy; SRT = y = year; vs. = versus; VMAT = volumetric arc radiation therapy.

Salvage RT is associated with toxicity. In one report on 464 SRT patients receiving median 66.6 (max. 72) Gy, acute grade 2 toxicity was recorded in 4.7% for both the GI and GU tract. Two men had late grade 3 reactions of the GI tract, but overall, severe GU tract toxicity was not observed. Late grade 2 complications occurred in 4.7% (GI tract) and 4.1% (GU tract), respectively, and 4.5% of the patients developed moderate urethral stricture [1039].

In a RCT on dose escalation for SRT (n = 350), acute grade 2 and 3 GU toxicity was observed in 13.0% and 0.6%, respectively, with 64 Gy and in 16.6% and 1.7%, respectively, with 70 Gy. Gastro-intestinal tract grades 2 and 3 toxicity occurred in 16.0% and 0.6%, respectively, with 64 Gy, and in 15.4% and 2.3%, respectively, with 70 Gy. Late effects have yet to be reported [1058,1059]. Late grade 2 and 3 GI toxicity was significantly increased with higher doses but without significant differences in QoL. In this study, however, the rectal wall dose constraints were rather permissive and in 44% of the patients outdated 3-D-techniques were used [924].

With dose escalation over 72 Gy and/or up to a median of 76 Gy, the rate of severe side effects, especially GU symptoms, clearly increases, even with newer planning and treatment techniques [1060,1061]. In particular, when compared with 3D-CRT, IMRT was associated with a reduction in grade 2 GI toxicity from 10.2 to 1.9% (p = 0.02) but no effect on the relatively high level of GU toxicity was shown (5-year, 3D-CRT 15.8% vs. IMRT 16.8%) [1060]. However, in a RCT comparing 66 Gy and 72 Gy with all patients having IMRT plus IGRT (n = 144), no significant differences for GI and GU-toxicity was demonstrated [1057]. After a median salvage IMRT dose of 76 Gy, however, the 5-year risk of grade 2–3 toxicity rose to 22% for GU and 8% for GI symptoms, respectively [1061]. Doses of at least 64 Gy and up to 72 Gy in patients without PET/CT can be recommended [1039,1058].

6.3.5.1.2.2. Salvage radiotherapy with or without ADT (cTx cN0/1) with PET/CT

In a prospective multi-centre study of 323 patients with BCR, PSMA PET/CT changed the management intent in 62% of patients as compared to conventional staging. This was due to a significant reduction in the number of men in whom the site of disease recurrence was unknown (77% vs. 19%, p < 0.001) and a significant increase in the number of men with metastatic disease (11% vs. 57%) [1062].

A prospective study in a subgroup of 119 BCR patients with low PSA (< 0.5 ng/mL) reported a change in the intended treatment in 30.2% of patients [946]; however, no data exist on the impact on final outcome.

Another prospective study in 272 patients with early biochemical recurrent PCa after RP showed that ⁶⁸Ga-PSMA PET/CT may tailor further therapy decisions (e.g., local vs. systemic treatment) at low PSA values (0.2–1 ng/mL) [948].

A single-centre study retrospectively assessed 164 men who underwent imaging with PSMA PET/CT for a rising PSA after RP with PSA levels < 0.5 ng/mL. In men with a negative PSMA PET/CT who received SRT, 85% (23 out of 27) demonstrated a treatment response compared to a further PSA increase in 65% of those not treated (22 out of 34). In the 36/99 men with disease confined to the prostate fossa on PSMA, 83% (29 out of 36) responded to SRT [1063]. Thus, PSMA PET/CT might stratify men into a group with high response (negative findings or recurrence confined to the prostate) and poor response (positive nodes or distant disease) to SRT.

A recent multi-centre retrospective study evaluated patients who underwent SRT for BCR after RP, without any signs of distant metastatic disease on PET/CT. After case-controle matching, 2 cohorts (n = 108 patients each), with and without PSMA PET/CT prior to SRT were analysed. In the cohort without PSMA PET/CT, 23 patients (21%) had BCR at 1 year after SRT vs. 9 patients (8%) who underwent restaging with PSMA PET/C prior to SRT (p = 0.007). PSMA-PET/CT was found to be associated with an improved oncological outcome in patients with BCR after RP, receiving SRT to the prostatic fossa [1064]. It is worth mentioning that in this study the median biologically effective radiation dose administered in the PSMA-cohort was significantly higher than in the historical cohort (70 Gy vs. 66 Gy, respectively, p < 0.001). However, another publication showed that the biochemical progression rate after SRT between patients who underwent 64 Gy or 70 Gy to the prostate bed, without HT for BCR, did not differ significantly [1065]. Therefore, it is questionable whether this difference in administered radiation dose influenced the outcome in both cohorts. As there are no prospective phase III data (in particular not for PCa-specific survival or OS) these results have to be confirmed before a recommendation can be provided.

A single-centre open-label, phase II/III RCT (EMPIRE-1) evaluated the role of ¹⁸F-fluciclovine-PET/CT compared with conventional imaging for SRT. Three hundred and sixty five patients with detectable PSA after RP but negative results on conventional imaging, were randomised to RT directed by conventional imaging alone or to conventional imaging plus PET/CT; patients with M1 disease in the PET/CT group (n = 4) were excluded. Patients with cN1 were irradiated to the pelvic lymphatics but without a boost to the metastasis. Median follow-up was 3.5 years. In adjusted analyses, the study group was significantly associated with event-free survival (HR: 2.04, 95% CI: 1.06–3.93, p = 0.0327) [1022].

6.3.5.1.2.3. Nodal-directed therapy for rcN1 (with PET/CT)

Radiolabelled PSMA PET/CT is increasingly used as a diagnostic tool to assess metastatic disease burden in patients with BCR following prior definitive therapy. A review including 30 studies and 4,476 patients showed overall estimates of positivity in a restaging setting of 38% in pelvic LNs and 13% in extra-pelvic LN metastases [945]. The percentage positivity of PSMA PET/CT was proven to increase with higher PSA values [945]. Results of this review demonstrated a high sensitivity and specificity of ⁶⁸Ga-PSMA in advanced PCa, with a per-lesion-analysed sensitivity and specificity of 75% and 99%, respectively.

A large retrospective international study included patients with LN-recurrent PCa (cN1 and M1a) and PSA progression following multi-modality treatment (surgery and post-operative RT) [1066]. The aim of the study was to compare standard of care (SOC) with nodal metastasis-directed therapy (MDT). The nodal MDT-group showed significantly better CSS than the SOC control group (5-year survival 98.6% vs. 95.7%, p < 0.01, respectively) [1066].

Another retrospective study compared SABR with elective nodal irradiation (ENRT) in nodal oligo-recurrent PCa (n = 506 patients, 365 of which with N1 pelvic recurrence). With a median follow-up of 36 months, ENRT (n = 197) was associated with a significant reduction of nodal recurrences (p < 0.001), compared with SABR (n = 309) of 2% vs. 18%, respectively. In a a multi-variable analysis, patients with one LN at recurrence had longer adjusted MFS after ENRT (HR: 0.50, 95% CI: 0.30–0.85, p = 0.009). The tendency to relapse was higher for pelvic- than extra-pelvic nodes (p < 0.001) [1067]. For patients presenting with two or more (extra)pelvic LNs, adjusted MFS was not significantly different (HR: 0.92, 95% CI: 0.54– 1.59, p = 0.8). In these situations, SABR should be used in highly selected patients in prospective cohorts or clinical trials only, before any recommendations can be made. For MDT in M1 patients see Section 6.4.7.

6.3.5.1.3. Salvage lymph node dissection

The surgical management of recurrent nodal metastases in the pelvis has been the topic of several retrospective analyses [1068-1070] and a systematic review [1071]. The reported 5-year BCR-free survival rates ranged from 6% to 31%. Five-year OS was approximately 84% [1071]. Biochemical recurrence rates were found to be dependent on PSA at salvage surgery and location and number of positive nodes [1072]. Addition of RT to the lymphatic template after salvage LN dissection may improve the BCR rate [1073]. In a multi-centre retrospective study long-term outcomes of 189 patients who underwent salvage LN dissection were reported to be worse than previously described in studies with shorter follow-up [1074]. Biochemical recurrence (BCR)-free survival at 10 years was 11%. Patients with a PSA response after salvage LN dissection and patients receiving ADT within 6 months from salvage LN dissection had a lower risk of death from PCa [1074]. The majority of the patients (81%) had received a choline PET and median PSA at salvage LN dissection was 2.5 ng/mL. In a cohort study including patients treated with salvage LN dissection via PSMA-radio-guided surgery (PSMA-RGS), 2-year BCR-free survival rate was 32% [1075]. In multi-variable analyses, higher pre-operative PSA, higher number of PSMA-avid lesions, multiple (pelvic plus retroperitoneal), and retroperitoneal localisation of lesions at pre-operative imaging were independent predictors of BCR after PSMA-RGS. High-level evidence for the oncological value of salvage LN dissection (including adjuvant RT of the LNs) is still lacking [1071].

6.3.5.2. Management of PSA failures after radiation therapy

Therapeutic options in these patients are ADT or salvage local procedures, as well as a ‘wait and see’ approach, based on EAU BCR risk categories at relapse. A systematic review and meta-analysis included studies comparing the efficacy and toxicity of salvage RP, salvage HIFU, salvage cryotherapy, SBRT, salvage LDR brachytherapy, and salvage HDR brachytherapy in the management of locally recurrent PCa after primary radical EBRT [1076]. The outcomes were BCR-free survival at 2 and 5 years. No significant differences with regards to recurrence-free survival (RFS) between these modalities was found. Five-year RFS ranged from 50% after cryotherapy to 60% after HDR brachytherapy and SBRT. The authors reported that severe GU toxicity exceeded 21% for HIFU and RP, whereas it ranged from 4.2% to 8.1% with re-irradiation. Differences in severe GI toxicity also appeared to favour re-irradiation, particularly HDR brachytherapy [1076]. Due to the methodological limitations of this review (the majority of the included studies were uncontrolled single-arm case series and there was considerable heterogeneity in the definitions of core outcomes) the available evidence for these treatment options is of low quality and strong recommendations regarding the choice of any of these techniques cannot be made. The following is an overview of the most important findings for each of these techniques.

6.3.5.2.1. Salvage radical prostatectomy

Salvage RP after RT is associated with a higher likelihood of AEs compared to primary surgery because of the risk of fibrosis and poor wound healing due to radiation [1077].

6.3.5.2.1.1. Oncological outcomes

In a systematic review of the literature, Chade, et al., showed that SRP provided 5- and 10-year BCR-free survival estimates ranging from 47–82% and from 28–53%, respectively. The 10-year CSS and OS rates ranged from 70–83% and from 54–89%, respectively. The pre-SRP PSA value and prostate biopsy ISUP grade were the strongest predictors of the presence of organ-confined disease, progression, and CSS [1078]. In a multi-centre analysis including 414 patients, 5-year BCR-free survival, CSS and OS were 56.7%, 97.7% and 92.1%, respectively [1079]. Pathological T stage > T3b (OR: 2.348) and GS (up to OR 7.183 for GS > 8) were independent predictors for BCR (see Table 6.3.7).

Table 6.3.7: Oncological results of selected salvage radical prostatectomy case series

*Percentage of patients without BCR.

BCR = biochemical recurrence; CSS = cancer-specific survival; FU = follow-up; mo = months; n = number of patients; PSM = positive surgical margin; yr. = year.

6.3.5.2.1.2. Morbidity

Compared to primary open RP, SRP is associated with a higher risk of later anastomotic stricture (47 vs. 5.8%), urinary retention (25.3% vs. 3.5%), urinary fistula (4.1% vs. 0.06%), abscess (3.2% vs. 0.7%) and rectal injury (9.2 vs. 0.6%) [1083]. In more recent series, these complications appear to be less common [1077,1078,1081].

Functional outcomes are also worse compared to primary surgery, with urinary incontinence ranging from 21% to 90% and ED in nearly all patients [1078,1081].

6.3.5.2.1.3.Summary of salvage radical prostatectomy

In general, SRP should be considered only in patients with low co-morbidity, a life expectancy of at least 10 years, a pre-SRP PSA < 10 ng/mL and initial biopsy ISUP grade < 2/3, no LN involvement or evidence of distant metastatic disease pre-SRP, and those whose initial clinical staging was T1 or T2 [1078].

6.3.5.2.2. Salvage cryoablation of the prostate

6.3.5.2.2.1. Oncological outcomes

Salvage cryoablation of the prostate (SCAP) has been proposed as an alternative to salvage RP, as it has a potentially lower risk of morbidity and equal efficacy.

In a systematic review a total of 32 studies assessed SCAP, recruiting a total of 5,513 patients. The overwhelming majority of patients (93%) received whole-gland SCAP. The adjusted pooled analysis for 2-year BCR-free survival for SCAP was 67.49% (95% CI: 61.68–72.81%), and for 5-year BCR-free survival was 50.25% (95% CI: 44.10–56.40%). However, the certainty of the evidence was low. Table 6.3.8 summarises the results of a selection of the largest series on SCAP to date in relation to oncological outcomes (BCR only) [1076].

Table 6.3.8: Oncological results of selected salvage cryoablation of the prostate case series, including at least 250 patients

ASTRO = American Society for Therapeutic Radiology and Oncology; BCR = biochemical recurrence; FU = follow-up; mo. = months; n = number of patients; PSA = prostate-specific antigen; yr. = year.

6.3.5.2.3. Salvage re-irradiation

6.3.5.2.3.1. Salvage brachytherapy for radiotherapy failure

Carefully selected patients with a good PS, primary localised PCa, good urinary function and histologically proven local recurrence are candidates for salvage brachytherapy using either HDR or LDR.

In a systematic review a total of 16 studies (4 prospective) and 32 studies (2 prospective) assessed salvage HDR and LDR brachytherapy, respectively, with the majority (> 85%) receiving whole-gland brachytherapy rather than focal treatment [1076]. The adjusted pooled analysis for 2-year BCR-free survival for HDR was 77% (95% CI: 70–83%) and for LDR was 81% (95% CI:74–86%). The 5-year BCR-free survival for HDR was 60% (95% CI: 52–67%) and for LDR was 56% (95% CI: 48–63%). As noted above, brachytherapy techniques are associated with lower rates of severe GU toxicity when compared to RP or HIFU, at 8% for HDR (95% CI: 5.1–11%) and 8.1% for LDR (95% CI: 4.3–13%). Rates of severe GI toxicity are reported to be very low at 0% for HDR (95% CI: 0–0.2%) and 1.5% for LDR (95% CI: 0.2–3.4%). High-dose-rate or LDR brachytherapy are effective treatment options with an acceptable toxicity profile. However, the published series are small and likely under-report toxicity. Consequently, this treatment should be offered in experienced centres ideally within randomised clinical trials or prospective registry studies (see Table 6.3.9).

Table 6.3.9: Treatment-related toxicity and BCR-free probability in selected salvage brachytherapy studies including at least 100 patients.

BT = brachytherapy; CI = confidence interval; G = grade; GI = gastro-intestinal; GU = genito-urinary; HDR = high-dose rate; LDR = low-dose rate; mo = months; n = number of patients; n.r. = not reported; yr = year.

6.3.5.2.3.2. Salvage stereotactic ablative body radiotherapy for radiotherapy failure

6.3.5.2.3.2.1.Oncological outcomes and morbidity

Stereotactic ablative body radiotherapy (CyberKnife^® or linac-based treatment) is a potentially viable new option to treat local recurrence after RT. Carefully selected patients with good IPSS-score, without obstruction, good PS and histologically proven localised local recurrence are potential candidates for SABR. In a meta-analysis and systematic review five mostly retrospective studies including 206 patients were treated with CyberKnife^® or linac-based treatment showing 2-year RFS estimates (61.6%, 95% CI: 52.6–69.9%) [1076]. In a retrospective multi-centre study (n = 100) the median pre-salvage PSA was 4.3 ng/mL with 34% of patients having received ADT for twelve months (median). All recurrences were biopsy proven. Patients were treated with the CyberKnife^® with a single dose of 6 Gy in six daily fractions (total dose 36 Gy). With a median follow-up of 30 months the estimated 3-year second BCR-free survival was 55% [1094].

In a smaller retrospective series including 50 men with histologically proven local recurrence with a median pre-salvage PSA of 3.9 ng/mL only 15% had received additional ADT. The estimated 5-year second BCR-free survival was 60% (median follow-up of 44 months) which is an outcome comparable to series treating patients with RP, HIFU or brachytherapy [1095]. Table 6.3.10 summarises the results of the two larger SABR series addressing oncological outcomes and morbidity.

Table 6.3.10: Treatment-related toxicity and BCR-free survival in selected SABR studies

BCR = biochemical recurrence; FU = follow-up; mo = months; n = number of patients; RT-type = type of radio-therapy; SD = single dose; TD = total dose; yr = year.

6.3.5.2.3.2.2.Morbidity

In a retrospective single-centre study with 50 consecutive patients chronic significant toxicity was only seen for the GU domain with 5-year grade 2+ and grade 3+ GU rates of 17% and 8%, respectively. No GI toxicity > grade 1 was seen. Of note, of the fifteen patients who were sexually potent pre-salvage SBRT, twelve subsequently lost potency [1095]. In a retrospective French (GETUG) multi-centre series (n = 100) the 3-year late grade 2+ GU and GI toxicity was 20.8% (95% CI: 13–29%) and 1% (95% CI: 0.1–5.1%), respectively [1094].

6.3.5.2.3.2.3.Summary of salvage stereotactic ablative body radiotherapy

Despite the encouraging results so far the number of patients treated with SABR is relatively limited. In view of the rates of higher grade 2+ GU side effects, SABR should only be offered to selected patients, in experienced centres as part of a clinical trial or well-designed prospective study.

6.3.5.2.4. Salvage high-intensity focused ultrasound

6.3.5.2.4.1. Oncological outcomes

Salvage HIFU has emerged as an alternative thermal ablation option for radiation-recurrent PCa. Being relatively newer than SCAP the data for salvage HIFU are even more limited. A systematic review and meta-analysis included 20 studies (n = 1,783) assessing salvage HIFU [1076]. The overwhelming majority of patients (86%) received whole-gland salvage HIFU. The adjusted pooled analysis for 2-year BCR-free survival for salvage HIFU was 54.14% (95% CI: 47.77–60.38%) and for 5-year BCR-free survival 52.72% (95% CI: 42.66– 62.56%). However, the certainty of the evidence was low. Table 6.3.11 summarises the results of a selection of the largest series on salvage HIFU to date in relation to oncological outcomes (BCR only).

Table 6.3.11: Oncological results of selected salvage cryoablation of the prostate case series, including at least 250 patients

*Results stratified by pre-EBRT D’Amico risk groups.BCR = biochemical recurrence; FU = follow-up; mo = months; n = number of patients; yr = year.

6.3.5.2.4.2. Morbidity

The main adverse effects and complications relating to salvage HIFU include urinary incontinence, urinary retention due to bladder outflow obstruction, rectourethral fistula and ED. The systematic review and meta-analysis showed an adjusted pooled analysis for severe GU toxicity for salvage HIFU of 22.66% (95% CI: 16.98–28.85%) [1076]. The certainty of the evidence was low. Table 6.3.12 summarises the results of a selection of the largest series on salvage HIFU to date in relation to GU outcomes.

Table 6.3.12: Peri-operative morbidity, erectile function and urinary incontinence in selected salvage HIFU case series, including at least 100 patients

*Incontinence was heterogeneously defined; figures represent at least 1 pad usage.ED = erectile dysfunction; n.r. = not reported; n = number of patients.

6.3.5.2.4.3. Summary of salvage high-intensity focused ultrasound

There is a lack of high-certainty data which prohibits any recommendations regarding the indications for salvage HIFU in routine clinical practice. There is also a risk of significant morbidity associated with its use in the salvage setting. Consequently, salvage HIFU should only be performed in selected patients in experienced centres as part of a clinical trial or well-designed prospective cohort study.

6.3.6. Hormonal therapy for relapsing patients

The Panel conducted a systematic review including studies published from 2000 onwards [1101]. Conflicting results were found on the clinical effectiveness of HT after previous curative therapy of the primary tumour. Some studies reported a favourable effect of HT, including the only RCT addressing the research question of this review (86% vs. 79% advantage in OS in the early HT group) [1102]. Other studies did not find any differences between early vs. delayed, or no, HT. One study found an unfavourable effect of HT [1103]. This may be the result of selecting clinically unfavourable cases for (early) HT and more intensive diagnostic workup and follow-up in these patients.

The studied population is highly heterogeneous regarding their tumour biology and therefore clinical course. Predictive factors for poor outcomes were; CRPC, distant metastases, CSS, OS, short PSA-DT, high ISUP grade, high PSA, increased age and co-morbidities. In some studies, such as the Boorjian, et al., study [1104], high-risk patients, mainly defined by a high ISUP grade and a short PSA-DT (most often less than 6 months) seem to benefit most from (early) HT, especially men with a long life expectancy.

No data were found on the effectiveness of different types of HT, although it is unlikely that this will have a significant impact on survival outcomes in this setting. Non-steroidal anti-androgens have been claimed to be inferior compared to castration, but this difference was not seen in M0 patients [1036]. One of the included RCTs suggested that intermittent HT is not inferior to continuous HT in terms of OS and CSS [1105]. A small advantage was found in some QoL domains but not overall QoL outcomes. An important limitation of this RCT is the lack of any stratifying criteria such as PSA-DT or initial risk factors. Based on the lack of definitive efficacy and the undoubtedly associated significant side effects, patients with recurrence after primary curative therapy should not receive standard HT since only a minority of them will progress to metastases or PCa-related death. The objective of HT should be to improve OS, postpone distant metastases, and improve QoL. Biochemical response to only HT holds no clinical benefit for a patient. For older patients and those with co-morbidities the side effects of HT may even decrease life expectancy; in particular cardiovascular risk factors need to be considered [1106,1107]. Early HT should be reserved for those at the highest risk of disease progression defined mainly by a short PSA-DT at relapse (< 6–12 months) or a high initial ISUP grade (> 2/3) and a long life expectancy.

6.3.7. Observation

In unselected relapsing patients the median actuarial time to the development of metastasis will be 8 years and the median time from metastasis to death will be a further 5 years [903]. For patients with EAU Low-Risk BCR features (see Section 6.3.3), unfit patients with a life expectancy of less than 10 years or patients unwilling to undergo salvage treatment, active follow-up may represent a viable option.

6.3.8. Guidelines for second-line therapy after treatment with curative intent

6.4. Treatment: Metastatic prostate cancer

6.4.1. Introduction

All prospective data available rely on the definition of M1 disease based on CT scan or MRI and bone scintigraphy. The influence on treatment and outcome of newer, more accurate, imaging has not been assessed yet.

6.4.2. Prognostic factors

Median survival of patients with newly diagnosed metastases (synchronous mHSPC) is approximately 42 months with ADT alone, however, it is highly variable since the M1 population is heterogeneous [1108]. Several prognostic factors for survival have been suggested including the number and location of bone metastases, presence of visceral metastases, ISUP grade, PS status and initial PSA and alkaline phosphatase level, but only few have been validated [1109-1112].

‘Volume‘ of disease as a potential predictor was introduced by CHAARTED (Chemo-hormonal Therapy versus Androgen Ablation Randomized Trial for Extensive Disease in Prostate Cancer) [1112-1114] (see table 6.4.1) and subsequently, in STAMPEDE, was shown to be predictive in an adequately powered subgroup analysis for benefit of addition of prostate RT to ADT in the subgroup of patients with low volume/burden disease [1115] (See table 6.4.1).

‘Metachronous’ metastatic disease (after radical local treament of the primary tumour) vs. synchronous (or de novo) metastatic disease has also been shown to have generally a better prognosis [1116].

Based on a large SWOG 9346 cohort, the PSA level after 7 months of ADT was used to create 3 prognostic groups (see Table 6.4.2) [1117]. A PSA < 0.2 ng/mL at 7 months has been confirmed as a prognostic marker for men receiving ADT for metastatic disease in the CHAARTED study independent of the addition of docetaxel [1118].

Table 6.4.1 Definition of high- and low-volume in CHAARTED  [1112-1114] and high- and low-risk in LATITUDE [765]

*Lymph nodes are not considered as visceral metastases.

Table 6.4.2: Prognostic factors based on the SWOG 9346 study  [1117]

6.4.3. First-line hormonal treatment

Primary ADT has been the SOC for over 50 years [728]. There is no high-level evidence in favour of a specific type of ADT for oncological outcomes, neither for orchiectomy nor for a LHRH agonist or antagonist. The level of testosterone is reduced much faster with orchiectomy and LHRH antagonist, therefore patients with impending spinal cord compression or other potential impending complications from the cancer should be treated with either a bilateral orchidectomy or LHRH antagonists as the preferred options.

There is a suggestion in some studies that cardiovascular side effects are less frequent in patients treated with LHRH antagonists than patients treated with LHRH agonists [747,1119,1120]; therefore, patients with pre-existing cardiovascular disease or other cardio-vascular risk factors might be considered to be treated with antagonists if a chemical castration is chosen.

6.4.3.1. Non-steroidal anti-androgen monotherapy

Based on a Cochrane review comparing non-steroidal anti-androgen (NSAA) monotherapy to ADT (either medical or surgical), NSAA was considered to be less effective in terms of OS, clinical progression, treatment failure and treatment discontinuation due to AEs [1121] and is generally not recommended also because ADT-based combination treatments have become SOC.

6.4.3.2. Intermittent versus continuous androgen deprivation therapy

Three independent reviews [1122-1124] and two meta-analyses [1125,1126] looked at the clinical efficacy of intermittent androgen deprivation (IAD) therapy. All of these reviews included 8 RCTs of which only 3 were conducted in patients with exclusively M1 disease.

So far, the SWOG 9346 is the largest trial addressing IAD in M1b patients [1127]. Of 3,040 screened patients, only 1,535 patients met the inclusion criteria. This highlights that only about 50% of M1b patients can be expected to be candidates for IAD, i.e. the best PSA responders. This was a non-inferiority trial leading to inconclusive results: the actual upper limit was above the pre-specified 90% upper limit of 1.2 (HR: 1.1, CI: 0.99–1.23), the pre-specified non-inferiority limit was not achieved, and the results did not show a significant inferiority for any treatment arm. However, based on this study inferior survival with IAD cannot be completely ruled out even in this highly selected subgroup. The use of intermittent ADT has been superseeded as continuous ADT has become SOC.

6.4.3.3. Early versus deferred androgen deprivation therapy

Early treatment before the onset of symptoms is recommended in the majority of patients with metastatic hormone-sensitive disease despite lack of randomised phase III data in this specific setting and specifically not with the combination therapies that are standard nowadays.

A Cochrane analysis from 2019 about the topic concluded that early ADT probably extends time to death of any cause and time to death from PCa [1128]. Since the analysis included only a very limited number of biochemical recurrence patients, the benefit of early ADT in this setting remains unproven. All of the trials testing the combination therapies in the metastatic hormone-sensitive setting also included asymptomatic patients.

The only candidates with metastatic disease who may possibly be considered for deferred treatment are asymptomatic patients with a strong wish to avoid treatment-related side effects. The risk of developing symptoms, and even dying from PCa, without receiving the benefit from HT with deferred treatment has been highlighted [841,1129], but in the era before next generation imaging was used.

Patients with deferred treatment for advanced PCa must be amenable to close follow-up. Another potential exception are patients with recurrent oligometastatic disease who have a strong wish to postpone the start of ADT (see Section 6.4.7).

6.4.4. Combination therapies

All of the following combination therapies have been studied with continuous ADT, not intermittent ADT.

6.4.4.1.‘Combined’ androgen blockade with older generation NSAA (bicalutamide, flutamide, nilutamide)

Systematic reviews have shown that CAB using a NSAA appears to provide a small survival advantage (< 5%) vs. monotherapy (surgical castration or LHRH agonists) [1130,1131] but this minimal survival advantage must be balanced against the increased side effects. In addition, the newer combination therapies (see Tables 6.4.3, 6.4.4, 6.4.5) are more effective as shown specifically for enzalutamide which was tested against. NSAA in a phase III trial [1132]. More recently another trial has demonstrated a significant OS benefit for the addition of rezvilutamide vs. addition of bicalutamide to ADT in patients with high-volume mHSPC [1133]. Therefore, combination with NSAAs should only be considered if other combination therapies are not available.

6.4.4.2. Androgen deprivation combined with other agents

6.4.4.2.1. Androgen deprivation therapy combined with chemotherapy

Three large RCTs were conducted [849,1112,1134]. All trials compared ADT alone as the SOC with ADT combined with immediate docetaxel (75 mg/sqm, every 3 weeks within 3 months of ADT initiation). The primary objective in all three studies was to assess OS. The key findings are summarised in Table 6.4.3.

Table 6.4.3: Key findings - Hormonal treatment combined with chemotherapy

ADT = androgen deprivation therapy; CI = confidence interval; ECOG = Eastern Cooperative Oncology Group; HR = hazard ratio; ISUP = International Society for Urological Pathology; mo = month; n = number of patients; OS = overall survival; P = prednisone; PSA-DT = prostate-specific antigen-doubling time.

In the GETUG 15 trial, all patients had M1 PCa, either de novo or after a primary treatment [1134]. They were stratified based on previous treatment and Glass risk factors [1109]. In the CHAARTED trial the same inclusion criteria applied, and patients were stratified according to disease volume (see Table 6.4.1) [1112].

STAMPEDE is a multi-arm multi-stage trial in which the reference arm (ADT monotherapy) included 1,184 patients. One of the experimental arms was docetaxel combined with ADT (n = 593), another was docetaxel combined with zoledronic acid (n = 593). Patients were included with either M1 or N1 or having two of the following 3 criteria: T3/4, PSA > 40 ng/mL or ISUP grade 4–5. Also relapsed patients after local treatment were included if they met one of the following criteria: PSA > 4 ng/mL with a PSA-DT < 6 months or a PSA > 20 ng/mL, N1 or M1. No stratification was used regarding metastatic disease volume (high/low volume) [849]. In all 3 trials toxicity was mainly haematological with around 12–15% grade 3–4 neutropenia, and 6–12% grade 3–4 febrile neutropenia. The use of granulocyte colony-stimulating factor receptor (GCSF) was shown to be beneficial in reducing febrile neutropenia. Primary or secondary prophylaxis with GCSF should be based on available guidelines [1136,1137].

Docetaxel in all three trials was used at the standard dose of 75 mg/sqm every 3 weeks, 6 cycles in CHAARTED and STAMPEDE and up to 9 cycles in GETUG-AFU-15.

In subgroup analyses from GETUG-AFU 15 and CHAARTED the beneficial effect of the addition of docetaxel to ADT was most evident in men with de novo metastatic high-volume disease [1113,1114], while it was in the same range whatever the volume in the post-hoc analysis from STAMPEDE [1135]. The effect of adding docetaxel was less apparent in men who had prior local radical treatment although the numbers were small and the event rates lower. A systematic review and meta-analysis which included these 3 trials showed that the addition of docetaxel to SOC improved survival [1137]. The HR of 0.77 (95% CI: 0.68–0.87, p < 0.0001) translates into an absolute improvement in 4-year survival of 9% (95% CI: 5–14).

Based on these data, upfront docetaxel combined with ADT was considered as a standard in men presenting with metastases at first presentation, provided they are fit enough to receive docetaxel [1137]. More recently two large Phase 3 studies have now shown an OS benefit by adding an ARPI to ADT and docetaxel. Therefore adding docetaxel alone to ADT should only be considered if no ARPI is available or all available ones are contra-indicated (see Section 6.4.4.2.3).

6.4.4.2.2. Combination with an ARPI alone (abiraterone, apalutamide, enzalutamide)

In two large RCTs (STAMPEDE, LATITUDE) the addition of abiraterone acetate (1000 mg daily) plus prednisone (5 mg daily) to ADT in men with mHSPC was studied [765,892,1138] (see table 6.4.4). The primary objective of both trials was an improvement in OS. Both trials showed a significant OS benefit. In LATITUDE with only de novo high-risk metastatic patients included, the HR reached 0.62 (0.51–0.76) [765]. The HR in STAMPEDE was very similar with 0.63 (0.52–0.76) in the total patient population (metastatic and non-metastatic) and a HR of 0.61 in the subgroup of metastatic patients [892]. While only high-risk patients were included in the LATITUDE trial a post-hoc analysis from STAMPEDE showed the same benefit whatever the risk or the volume stratification [1139].

All secondary objectives such as PFS, time to radiographic progression, time to pain, or time to chemotherapy were positive and in favour of the combination. No difference in treatment-related deaths was observed with the combination of ADT plus AAP compared to ADT monotherapy (HR: 1.37 [0.82–2.29]). However, twice as many patients discontinued treatment due to toxicity in the combination arms in STAMPEDE (20%) compared to LATITUDE (12%) [1138]. Based on these data upfront AAP combined with ADT should be considered as a standard in men presenting with metastases at first presentation, provided they are fit enough to receive the drug.

In three large RCTs (ENZAMET, ARCHES and TITAN) the addition of AR antagonists to ADT in men with mHSPC was tested [763,764,1132]. In ARCHES the primary endpoint was radiographic PFS (rPFS). In the primary analysis rPFS was significantly improved for the combination of enzalutamide and ADT with a HR of 0.39 (0.3–0.5). Approximately 36% of the patients had low-volume disease; around 25% had prior local therapy and 18% of the patients had received prior docetaxel. In the final prespecified analysis the key secondary enpoint OS was significantly improved with a HR of 0.66 (0.53-0.81) and a significant benefit for rPFS was maintained with a HR of 0.63 (0,52–0.76) [1140]. In ENZAMET the primary endpoint was OS. The addition of enzalutamide to ADT in the first analysis improved OS with a HR of 0.67 (0.52–0.86) compared to ADT plus a non-steroidal antiandrogen. Approximately half of the patients had concomitant docetaxel; about 40% had prior local therapy and about half of the patients had low-volume disease [764]. In the TITAN trial, ADT plus apalutamide was used and rPFS and OS were co-primary endpoints. In the primary analysis rPFS was significantly improved by the addition of apalutamide with a HR of 0.48 (0.39–0.6); OS at 24 months was improved for the combination with a HR of 0.67 (0.51–0.89). In the final analysis the HR for OS was 0.65 (0.53–0.79) without adjustment for cross-over. In this trial 16% of patients had prior local therapy, 37% had low-volume disease and 11% received prior docetaxel [763,1141]. In the more recently published CHART trial, ADT plus rezvilutamide was tested vs. ADT plus bicalutamide in patients with high-volume de novo metastatic disease. Ninety percent of the patients were recruited in China. Overall survival and rPFS were co-primary endpoints. At the pre-planned interim analysis rezvilutamide significantly improved rPFS compared with bicalutamide with a HR of 0.44 (0.33–0.58) and OS with a HR of 0.58 (0.44–0.77) [1133].

In summary, the addition of the new AR antagonists significantly improves clinical outcomes with no convincing evidence of differences between subgroups. The majority of patients had de novo metastatic disease and the evidence is most compelling in this situation. In the trials with the new AR antagonists, a proportion of patients had metachronous disease (see Table 6.4.5); in the subgroup analyses the effect seemed to be consistent and therefore, a combination should also be offered for men progressing after radical local therapy [1142].

Table 6.4.4: Results from the STAMPEDE arm G and LATITUDE studies

AA = abiraterone acetate; ADT = androgen deprivation therapy; CI = confidence interval; FFS = failure-free survival; HR = hazard ratio; ISUP = International Society of Urological Pathology; mo = month; n = number of patients; NA = not available; OS = overall survival; P = prednisone; rPFS = radiographic progression-free survival; PSA = prostate-specific antigen; yr. = year.

Table 6.4.5: Results from the ENZAMET and TITAN studies with OS as primary endpoint

ADT = androgen deprivation therapy; CI = confidence interval; HR = hazard ratio; mo = month; n = number of patients; OS = overall survival; SOC = standard of care; rPFS = radiographic progression-free survival; yr = year.

Table 6.4.6: Results from the ARCHES and CHART studies 

HR = hazard ratio; mo = month; n = number of patients; OS = overall survival; rPFS = radiographic progression-free survival; yr = year.

6.4.4.2.3. Combination with docetaxel and an ARPI

The addition of abiraterone to ADT and docetaxel has been reported to have a benefit in rPFS and in OS in the PEACE-1 trial [1143,1144]. The trial has a 2x2 factorial design and participants with de novo (synchronous) metastatic PCa were randomised to SOC; at the beginning of the trial ADT, later ADT plus docetaxel for 6 cycles if chemotherapy-fit) vs. SOC plus radiotherapy vs. SOC plus abiraterone vs. SOC plus radiotherapy plus abiraterone. Co-primary endpoints were rPFS and OS, both were statistically significantly improved in the total population. Also in the group of patients who received ADT plus docetaxel as SOC (n = 710) both rPFS and OS were increased with a HR: 0.5 (0.34–0.71) and 0.75 (0.59–0.95), respectively. Of note; in this population about 35% had low-volume disease. Toxicity was modestly increased, mostly hypertension.

In the ARASENS Phase 3 trial all patients received ADT and docetaxel for 6 cycles as SOC plus darolutamide or placebo [1145]. 1,306 metastatic patients were included, 14 % of them with relapsed disease after radical local treatment (metachronous). Primary endpoint was OS and this was statistically significanty increased by the addition of darolutamide with a HR of 0.68 (0.57–0.8).

Until now no subgroup analysis for high- and low-volume disease was reported. Interestingly, in this trial the occurrence of AEs was similar in both arms. In both trials docetaxel and the ARPI have been given concomitantly.

Also in ENZAMET, TITAN and ARCHES there were patients who received docetaxel as a part of SOC, thus not all concommitantly, but the percentage of patients receiving docetaxel in these trials was much lower [763,764,1132].

6.4.5. Treatment selection and patient selection

There have been several network meta-analyses of the published data concluding that combination therapy is more efficient than ADT alone, but none of the combination therapies has been clearly proven to be superior over another [1146,1147]. As a consequence, patients should be offered combination treatment unless there are clear contra-indications or they present with asymptomatic disease and a very short life expectancy (based on non-cancer co-morbidities).

Since the data of the above mentioned Phase III trials of the triplet therapies have been reported, docetaxel as sole addition to ADT is not longer a valid option in the majority of patients if an androgen receptor pathway inhibitor (ARPI) is available and there are no contra-indiactions to use one. From subgroup analysis of all the above-mentioned RCTs we know that probably all subgroups (high vs. low volume and synchronous vs. metachronous) can profit from the addition of an ARPI to ADT. Therefore, in view of the current data the recommendation is using ADT plus ARPI as the sole additional therapy or the triplet with an ARPI plus docetaxel. Formally the question what the added value of adding docetaxel to ADT plus an ARPI has not been evaluated, but since triplet therapy seems not to add a lot of unexpected overlapping toxicities, the data should be discussed with patients who are fit for chemotherapy and an ARPI, realising that most of the toxicity is caused by adding the chemotherapy. There is more evidence for using the triplet in synchronous disease and the OS benefit in PEACE-1 seemed to be driven mostly by the high volume patients at the time point of the analysis for the publication. In summary, the choice will most likely be driven by fitness for docetaxel, the nature of the disease (low/high volume; synchronous/metachronous), patient preference, the specific side effects, availability, logistics and cost.

6.4.6. Treatment of the primary tumour in newly diagnosed metastatic disease

The first reported trial evaluating prostate RT in men with metastatic castration-sensitive disease was the HORRAD trial. Four hundred and thirty-two patients were randomised to ADT alone or ADT plus IMRT with IGRT to the prostate. Overall survival was not significantly different (HR: 0.9 [0.7–1.14]), median time to PSA progression was significantly improved in the RT arm (HR: 0.78 [0.63–0.97]) [1148]. The STAMPEDE trial evaluated 2,061 men with metastatic castration-sensitive PCa (mCSPC) who were randomised to ADT alone vs. ADT plus RT to the prostate. This trial confirmed that RT to the primary tumour did not improve OS in unselected patients [1115]. However, following the results from CHAARTED and prior to analysing the data, the original screening investigations were retrieved, and patients categorised as low- or high volume. In the low-volume subgroup (n = 819) there was a significant OS benefit by the addition of prostate RT. This was confirmed by the latest analysis of long-term follow-up (median follow-up of 61 months [HR: 0.64 for OS benefit in the low-volume group]) [1149].

A secondary, not pre-planned, analysis of the STAMPEDE trial confirmed the benefit of prostate RT in patients with < 3 bone metastases, but also showed a benefit in patients with M1a disease [1150]. No evidence of difference in time to symptomatic local events was found with median follow-up of over 5 years [1149]. The dose used in these indications should be equivalent of up to 72 Gy in 2 Gy fractions.

Therefore, RT of the prostate only in patients with low-volume metastatic disease should be considered. Of note, only 18% of these patients had additional docetaxel and no patients had additional AAP, so no clear recommendation can be made about triple combinations. In addition, it is not clear if these data can be extrapolated to RP as local treatment as results of ongoing trials are awaited.

In a systematic review and meta-analysis including the above two RCTs, the authors found that, overall, there was no evidence that the addition of prostate RT to ADT improved survival in unselected patients (HR: 0.92, 95% CI: 0.81–1.04, p = 0.195) [1151]. However, there was a clear difference in the effect of metastatic burden on survival with an absolute improvement of 7% in 3-year survival in men who had four or fewer bone metastases.

6.4.7. Metastasis-directed therapy in M1-patients

In patients relapsing after a local treatment, a metastases-targeting therapy has been proposed, with the aim to delay systemic treatment. There are two randomised phase II trials testing metastasis-directed therapy (MDT) using surgery ± SABR vs. surveillance [1152] or SABR vs. surveillance in men with oligo-recurrent PCa [1153]. Oligo-recurrence was defined as < 3 lesions on choline-PET/CT only [1152] or conventional imaging with MRI/CT and/or bone scan [1153]. The sample size was small with 62 and 54 patients, respectively, and a substantial proportion of them had nodal disease only [1152]. Androgen deprivation therapy-free survival was the primary endpoint in one study which was longer with MDT than with surveillance [1152]. The primary endpoint in the ORIOLE trial was progression after 6 months which was significantly lower with SBRT than with surveillance (19% vs. 61%, p = 0.005) [1153].

Recently the combined results of STOMP and ORIOLE confirmed the significant improvement in PFS in favour of MDT (HR: 0.44, p < 0.001) [1154].

A phase II trial assessed the biochemical response after ¹⁸F-DCFPyL PET/MRI and subsequent MDT. Overall biochemical response rate, defined as > 50% PSA decline, was 60%, including 22% of patients with complete biochemical response [1155].

Currently there are no data to suggest an improvement in OS. Two comprehensive reviews highlighted MDT (SABR) as a promising therapeutic approach that must still be considered as investigational until the results of the ongoing RCT are available [1156,1157]. Thus far, the toxicity of MDT appears to be low, but this also needs to be confirmed [1158,1159].

6.4.8. Guidelines for the first-line treatment of hormone-sensitive metastatic disease*

*All the following statements are based on metastatic disease defined by bone scintigraphy and CT scan/MRI.

6.5. Treatment: Castration-resistant PCa (CRPC)

6.5.1. Definition of CRPC

Castrate serum testosterone < 50 ng/dL or 1.7 nmol/L plus either:

a. Biochemical progression: Three consecutive rises in PSA at least one week apart resulting in two 50% increases over the nadir, and a PSA > 2 ng/mL

or

b. Radiological progression: The appearance of new lesions: either two or more new bone lesions on bone scan or a soft tissue lesion using RECIST (Response Evaluation Criteria in Solid Tumours) [1160]. Symptomatic progression alone must be questioned and subject to further investigation. It is not sufficient to diagnose CRPC.

6.5.2. Management of mCRPC - general aspects

Selection of treatment for mCRPC is multifactorial and in general dependent on:

• previous treatment for mHSPC and for non-mHSPC;
• previous treatment for nmCRPC and mCRPC;
• quality of response and pace of progression on previous treatment;
• known cross resistance between androgen receptor pathway inhibitor (ARPI);
• co-medication and known drug interactions (see approved summary of product characteristics);
• known genetic alterations and microsatellite instability–high (MSI-H)/mismatch repair–deficient (dMMR) status;
• known histological variants and DNA repair deficiency (to consider platinum or targeted therapy like PARPi);
• local approval status of drugs and reimbursement situation;
• available clinical trials;
• the patient and his co-morbidities.

6.5.2.1. Molecular diagnostics

All metastatic patients should be offered somatic genomic testing for homologous repair and MMR defects, preferably on metastatic carcinoma tissue but testing on primary tumour may also be performed. Alternatively, but still less common, genetic testing on circulating tumour DNA (ctDNA) is an option and has been used in some trials. One test, the FoundationOne^® Liquid CDx, has been FDA approved [1161]. Defective MMR assessment can be performed by IHC for MMR proteins (MSH2, MSH6, MLH1 and PMS2) and/or by next-generation sequencing (NGS) assays [1162]. Germline testing for BRCA1/2, ATM and MMR is recommended for high-risk- and particularly for metastatic PCa if clinically indicated.

Molecular diagnostics should be performed by a certified (accredited) institution using a standard NGS multiplication procedure (minimum depth of coverage of 200 X). The genes and respective exons should be listed; not only DNA for mutations but RNA needs to be examined for fusions and protein expression to obtain all clinically relevant information. A critical asset is the decision support helping to rate the mutations according to their clinical relevance [1163,1164].

Level 1 evidence for the use of PARP-inhibitors has been reported [1165-1167]. Microsatellite instability (MSI)-high (or MMR deficiency) is rare in PCa, but for those patients, pembrolizumab has been approved by the FDA and could be a valuable additional treatment option [770,1168]. Germline molecular testing is discussed in Section 5.1.3 - Genetic testing for inherited PCa. Recommendations for germline testing are provided in Section 5.1.4.

6.5.3. Treatment decisions and sequence of available options

Approved agents for the treatment of mCRPC in Europe are docetaxel, abiraterone/prednisolone, enzalutamide, cabazitaxel, olaparib and radium-223. In general, sequencing of ARPIs like abiraterone and enzalutamide is not recommended particularly if the time of response to ADT and to the first ARPI was short (< 12 months) and high-risk features of rapid progression are present (see detailed discussion in Section 6.5.7) [1169,1170].

The use of chemotherapy with docetaxel and subsequent cabazitaxel in the treatment sequence is recommended and should be applied early enough when the patient is still fit for chemotherapy. This is supported by high-level evidence [1169].

6.5.4. Non-metastatic CRPC

Frequent PSA testing in men treated with ADT has resulted in earlier detection of biochemical progression. Of these men approximately one-third will develop bone metastases within two years, detected by conventional imaging [972].

In men with CRPC and no detectable clinical metastases using bone scan and CT-scan, baseline PSA level, PSA velocity and PSA-DT have been associated with time to first bone metastasis, bone metastasis-free survival and OS [972,1171]. These factors may be used when deciding which patients should be evaluated for metastatic disease. A consensus statement by the PCa Radiographic Assessments for Detection of Advanced Recurrence (RADAR) group suggested a bone scan and a CT scan when the PSA reached 2 ng/mL and if this was negative, it should be repeated when the PSA reached 5 ng/mL, and again after every doubling of the PSA based on PSA testing every three months in asymptomatic men [1172]. Symptomatic patients should undergo relevant investigations regardless of PSA level. With more sensitive imaging techniques like PSMA PET/CT or whole-body MRI, more patients are diagnosed with early mCRPC [1173]. It remains unclear if the use of PSMA PET/CT in this setting improves outcome.

Three large phase III RCTs, PROSPER [1174], SPARTAN [1175] and ARAMIS [1176], evaluated metastasis-free survival as the primary endpoint in patients with nmCRPC (M0 CRPC) treated with enzalutamide (PROSPER) vs. placebo or apalutamide (SPARTAN) vs. placebo or darolutamide vs. placebo (ARAMIS), respectively (see Table 6.5.1). The M0 status was established by CT and bone scans. Only patients at high risk for the development of metastasis with a short PSA-DT of < 10 months were included. Patient characteristics in trials revealed that about two-thirds of participants had a PSA-DT of < 6 months. All trials showed a significant metastasis-free survival benefit. All three trials showed a survival benefit after a follow-up of more than 30 months. In view of the long-term treatment with these AR targeting agents in asymptomatic patients, potential AEs need to be taken into consideration and the patient informed accordingly.

Table 6.5.1: Randomised phase III controlled trials – nmCRPC

ADT = androgen-deprivation therapy; CI = confidence interval; HR = hazard ratio; MFS = metastasis-freesurvival; nmCRPC = non-metastatic castrate-resistent prostate cancer; PSA-DT = prostate-specific antigen doubling time.

6.5.5. Metastatic CRPC

The remainder of this section focuses on the management of men with proven mCRPC on conventional imaging.

6.5.5.1. Conventional androgen deprivation in CRPC

Eventually men with PCa will show evidence of disease progression despite castration. Two trials have shown only a marginal survival benefit for patients remaining on LHRH analogues during second- and third-line therapies [1180,1181]. However, in the absence of prospective data, the modest potential benefits of continuing castration outweigh the minimal risk of treatment. In addition, all subsequent treatments have been studied in men with ongoing androgen suppression, therefore, it should be continued in these patients.

6.5.6. First-line treatment of metastatic CRPC

6.5.6.1. Abiraterone

Abiraterone was evaluated in 1,088 chemo-naive, asymptomatic or mildly symptomatic mCRPC patients in the phase III COU-AA-302 trial. Patients were randomised to abiraterone acetate or placebo, both combined with prednisone [1182]. Patients with visceral metastases were excluded. The main stratification factors were ECOG PS 0 or 1 and asymptomatic or mildly symptomatic disease. Overall survival and rPFS were the co-primary endpoints. After a median follow-up of 22.2 months there was significant improvement of rPFS (median 16.5 vs. 8.2 months, HR: 0.52, p < 0.001) and the trial was unblinded. At the final analysis with a median follow-up of 49.2 months, the OS endpoint was significantly positive (34.7 vs. 30.3 months, HR: 0.81, 95% CI: 0.70–0.93, p = 0.0033) [1183]. Adverse events related to mineralocorticoid excess and liver function abnormalities were more frequent with abiraterone, but mostly grade 1–2. Subset analysis of this trial showed the drug to be equally effective in an elderly population (> 75 years) [1184].

6.5.6.2. Enzalutamide

A randomised phase III trial (PREVAIL) included a similar patient population and compared enzalutamide and placebo [1185]. Men with visceral metastases were eligible but the numbers included were small. Corticosteroids were allowed but not mandatory. PREVAIL was conducted in a chemo-naive mCRPC population of 1,717 men and showed a significant improvement in both co-primary endpoints, rPFS (HR: 0.186, CI: 0.15–0.23, p < 0.0001), and OS (HR: 0.706, CI: 0.6–0.84, p < 0.001). A > 50% decrease in PSA was seen in 78% of patients. The most common clinically relevant AEs were fatigue and hypertension. Enzalutamide was equally effective and well tolerated in men > 75 years [1186] as well as in those with or without visceral metastases [1187]. However, for men with liver metastases, there seemed to be no discernible benefit [1187,1188].

Enzalutamide has also been compared with bicalutamide 50 mg/day in a randomised double-blind phase II study (TERRAIN) showing a significant improvement in PFS (15.7 months vs. 5.8 months, HR: 0.44, p < 0.0001) in favour of enzalutamide [1188]. With extended follow-up and final analysis the benefit in OS and rPFS were confirmed [1189].

6.5.6.3. Docetaxel

A statistically significant improvement in median survival of 2.0–2.9 months has been shown with docetaxel-based chemotherapy compared to mitoxantrone plus prednisone [1190,1191]. The standard first-line chemotherapy is docetaxel 75 mg/m², 3-weekly doses combined with prednisone 5 mg twice a day (BID), up to 10 cycles. Prednisone can be omitted if there are contra-indications or no major symptoms. The following independent prognostic factors: visceral metastases, pain, anaemia (Hb < 13 g/dL), bone scan progression, and prior estramustine may help stratify the response to docetaxel. Patients can be categorised into three risk groups: low risk (0 or 1 factor), intermediate (2 factors) and high risk (3 or 4 factors), and show three significantly different median OS estimates of 25.7, 18.7 and 12.8 months, respectively [1192].

Age by itself is not a contra-indication to docetaxel [1193] but attention must be paid to careful monitoring and co-morbidities as discussed in Section 5.4 - Estimating life expectancy and health status [1194]. In men with mCRPC who are thought to be unable to tolerate the standard dose and schedule, docetaxel 50 mg/m² every two weeks seems to be well tolerated with less grade 3–4 AEs and a prolonged time to treatment failure [1195].

6.5.6.4. Sipuleucel-T

In 2010 a phase III trial of sipuleucel-T showed a survival benefit in 512 asymptomatic or minimally symptomatic mCRPC patients [1196]. After a median follow-up of 34 months, the median survival was 25.8 months in the sipuleucel-T group compared to 21.7 months in the placebo group, with a HR of 0.78 (p = 0.03). No PSA decline was observed and PFS was similar in both arms. The overall tolerance was very good, with more cytokine-related AEs grade 1–2 in the sipuleucel-T group, but the same grade 3–4 AEs in both arms. Sipuleucel-T is not available in Europe.

6.5.6.5. Ipatasertib

The AKT inhibitor ipatasertib in combination with AAP was studied in asymptomatic or mildly symptomatic patients with and without PTEN loss by IHC and previously untreated for mCRPC. The randomised phase III trial (IPAtential) showed a significant benefit for the first endpoint rPFS in the PTEN loss (IHC) 18.5 vs. 16.5 mo; p = 0.0335, HR: 0.77, 95% CI: 0.61–0,98) but not in the intention to treat (ITT) population. The OS results are still pending. Side effects of the AKT inhibitor ipatasertib include rash and diarrhoea [771]. Grade 3 or higher AEs occurred nearly double as often in the combination group and the discontinuation rate due to AEs was
4 times higher. This combination is still investigational [1197].

6.5.6.6. Combinations

Based on the suggestion that there is a synergistic antitumour effect when combining abiraterone with a PARP inhibitor, several such combination trials were conducted with conflicting results.

Abiraterone/prednisone plus olaparib

A randomised double-blind, phase 3 trial (PROpel) of abiraterone (1000 mg once daily) plus prednisone 5 mg/twice daily (AAP) and olaparib (300 mg twice/daily) or placebo in patients with mCRPC in the first-line setting was conducted [1198]. Of note, 796 patients met the eligibility criteria and were randomly assigned 1:1 to study treatment regardless of homologous recombination repair gene mutation (HRRm) status which was retrospectively evaluated and determined by tumour tissue and circulating tumour DNA tests. The primary end point was imaging-based PFS (ibPFS) by investigator assessment. The result was significantly positive in favour of the combination with ibPFS of 24.8 vs. 16.6 mo (HR 0.66; 95% CI: 0.54 to 0.81; p = 0.001). The subgroup of patients with positive HRRm status showed a HR of 0.50 (CI: 0.34 to 0.73) which seems to be a major driver of the overall result. Survival data are still immature. The most common side effects with the combination were anaemia, fatigue/asthenia, and nausea.

Abiraterone/prednisone plus niraparib

At ASCO 2022, a randomised, double-blind, phase 3 trial (MAGNITUDE) evaluating abiraterone (1,000 mg once daily) plus prednisone 5 mg twice/daily plus niraparib 200 mg once/daily or placebo, was presented [1199]. The final paper has not yet been published.

Table 6.5.2: Randomised phase III controlled trials - first-line treatment of mCRPC

BID = twice a day; CI = confidence interval; ECOG = Eastern Cooperative Oncology Group; EMP = estramustine; FU = follow-up; HR = hazard ratio; mets. = metastases; mo = month; ib (imaging based); (r)PFS = (radiographic) progression-free survival; OS = overall survival; IHC = immunohistochemistry ; HRRm = homologour recombination repair genes mutation; ITT = intention to treat; BICR = blinded independent central review.

6.5.7. Second-line treatment for mCRPC and sequence

All patients who receive treatment for mCRPC will eventually progress. All treatment options in this setting are presented in Table 6.5.3. High-level evidence exists for second-line treatments after first-line treatment with docetaxel and for third-line therapy.

6.5.7.1. Cabazitaxel

Cabazitaxel is a novel taxane with activity in docetaxel-resistant cancers. It was studied in a large prospective, randomised, phase III trial (TROPIC) comparing cabazitaxel plus prednisone vs. mitoxantrone plus prednisone in 755 patients with mCRPC, who had progressed after or during docetaxel-based chemotherapy [1204]. Patients received a maximum of ten cycles of cabazitaxel (25 mg/m²) or mitoxantrone (12 mg/m²) plus prednisone (10 mg/day). Overall survival was the primary endpoint which was significantly longer with cabazitaxel (median: 15.1 vs. 12.7 months, p < 0.0001). There was also a significant improvement in PFS (median: 2.8 vs. 1.4 months, p < 0.0001), objective RECIST response (14.4% vs. 4.4%, p < 0.005), and PSA response rate (39.2% vs. 17.8%, p < 0.0002). Treatment-associated WHO grade 3–4 AEs developed significantly more often in the cabazitaxel arm, particularly haematological (68.2% vs. 47.3%, p < 0.0002) but also non-haematological (57.4 vs. 39.8%, p < 0.0002) toxicity. In two post-marketing randomised phase III trials, cabazitaxel was shown not to be superior to docetaxel in the first-line setting; in the second-line setting in terms of OS, 20 mg/m² cabazitaxel was not inferior to 25 mg/m², but less toxic. Therefore, the lower dose should be preferred [1205,1206]. Cabazitaxel should preferably be given with prophylactic granulocyte colony-stimulating factor (G-CSF) and should be administered by physicians with expertise in handling neutropenia and sepsis [1207].

6.5.7.2. Abiraterone acetate after docetaxel

Positive results of the large phase III trial (COU-AA-301) were reported after a median follow-up of 12.8 months [1208] and confirmed by the final analysis [1209]. A total of 1,195 patients with mCRPC were randomised 2:1 to AAP or placebo plus prednisone. All patients had progressive disease based on the Prostate Cancer Clinical Trials Working Group 2 (PCWG2) criteria after docetaxel therapy (with a maximum of two previous chemotherapeutic regimens). The primary endpoint was OS, with a planned HR of 0.8 in favour of AAP. After a median follow-up of 20.2 months, the median survival in the AAP group was 15.8 months compared to 11.2 months in the placebo arm (HR: 0.74, p < 0.0001). The benefit was observed in all subgroups and all the secondary objectives were in favour of AAP (PSA, radiologic tissue response, time to PSA or objective progression). The incidence of the most common grade 3–4 AEs did not differ significantly between arms, but mineralocorticoid-related side effects were more frequent in the AAP group, mainly grade 1–2 (fluid retention, oedema and hypokalaemia).

6.5.7.3. Enzalutamide after docetaxel

The planned interim analysis of the AFFIRM study was published in 2012 [1210]. This trial randomised 1,199 patients with mCRPC in a 2:1 fashion to enzalutamide or placebo. The patients had progressed after docetaxel treatment, according to the PCWG2 criteria. Corticosteroids were not mandatory, but could be prescribed, and were received by about 30% of the patients. The primary endpoint was OS, with an expected HR benefit of 0.76 in favour of enzalutamide. After a median follow-up of 14.4 months, the median survival in the enzalutamide group was 18.4 months compared to 13.6 months in the placebo arm (HR: 0.63, p < 0.001). This led to the recommendation to halt and unblind the study. The benefit was observed irrespective of age, baseline pain intensity, and type of progression. In the final analysis with longer follow-up the OS results were confirmed despite crossover and extensive post-progression therapies [1189]. Enzalutamide was active also in patients with visceral metastases.

All the secondary objectives were in favour of enzalutamide (PSA, soft tissue response, QoL, time to PSA, or objective progression). No difference in terms of side effects was observed in the two groups, with a lower incidence of grade 3–4 AEs in the enzalutamide arm. There was a 0.6% incidence of seizures in the enzalutamide group compared to none in the placebo arm.

6.5.7.4. Radium-223

The only bone-specific drug that is associated with a survival benefit is the α-emitter radium-223. In a large phase III trial (ALSYMPCA) 921 patients with symptomatic mCRPC, who failed or were unfit for docetaxel, were randomised to six injections of 50 kBq/kg radium-223 or placebo plus SOC. The primary endpoint was OS. Radium-223 significantly improved median OS by 3.6 months (HR: 0.70, p < 0.001) and was also associated with prolonged time to first skeletal event, improvement in pain scores and improvement in QoL [1211]. The associated toxicity was mild and, apart from slightly more haematologic toxicity and diarrhoea with radium-223, which did not differ significantly from that in the placebo arm [1211]. Radium-223 was effective and safe whether or not patients were docetaxel pre-treated [1212]. Due to safety concerns, use of radium-223 was recently restricted to after docetaxel and at least one AR targeted agent [1213]. In particular, the use of radium-223 in combination with AAP showed significant safety risks related to fractures and more deaths. This was most striking in patients without the concurrent use of bone health agents [1214].

6.5.8. Treatment after docetaxel and one line of hormonal treatment for mCRPC

6.5.8.1. Hormonal treatment

For men progressing quickly on AR targeted therapy (< 12 months) it is now clear that cabazitaxel is the treatment supported by the best data. The CARD trial, an open label randomised phase III trial, evaluated cabazitaxel after docetaxel and one line of ARPI (either AAP or enzalutamide) [1169]. It included patients progressing in less than 12 months on previous abiraterone or enzalutamide for mCRPC. Cabazitaxel more than doubled rPFS vs. another ARPI and reduced the risk of death by 36% vs. ARPI. The rPFS with cabazitaxel remained superior regardless of the ARPI sequence and if docetaxel was given before, or after, the first ARPI.

The choice of further treatment after docetaxel and one line of HT for mCRPC is open for patients who have a > 12 months response to first-line abiraterone or enzalutamide for mCRPC [1215]. Either radium-223 or second-line chemotherapy (cabazitaxel) are reasonable options. In general, subsequent treatments in unselected patients are expected to have less benefit than with earlier use [1216,1217] and there is evidence of cross-resistance between enzalutamide and abiraterone [1218,1219].

In this context, radioligand therapy has been discussed for many years. In pre-treated and highly selected patients, based on PSMA- and FDG PET scan results, ¹¹⁷Lu-PSMA-617 was compared with cabazitaxel in a randomised phase II trial. The primary endpoint PSA reduction > 50% was in favour of the radioligand therapy [1220]. Pivotal phase III data for ¹¹⁷Lu-PSMA-617 are discussed in Section 6.5.8.2.2.

Poly (ADP-ribose) polymerase inhibitors have shown high rates of response in men with somatic homologous recombination repair (HRR) deficiency in initial studies. Men previously treated with both docetaxel and at least one ARPI and whose tumours demonstrated homozygous deletions or deleterious mutations in DNA-repair genes showed an 88% response rate to olaparib [1221] and in another confirmatory trial a confirmed composite response of 54.3% (95% CI: 39.0–69.1) in the 400 mg cohort and in 18 of 46 (39.1%; 25.1–54.6) evaluable patients in the 300 mg cohort [1222]. See also section ‘Second-line management’).

6.5.8.2. Radiopharmaceuticals

6.5.8.2.1. Introduction

Historically, several radiopharmaceuticals including phosphorous-32, strontium-89, yttrium-90, samarium-153, and rhenium-186 were developed for the treatment of bone pain secondary to metastasis from PCa [1223]. They proved effective in a palliation setting, by relieving pain and improving QoL, especially in the setting of diffuse bone metastases. However, they never gained widespread adoption. The first radioisotope to demonstrate a survival benefit was radium-223 (see Section 6.5.7.4).

6.5.8.2.2. PSMA-based therapy

The increasing use of PSMA PET as a diagnostic tracer and the realisation that this allowed identification of a greater number of metastatic deposits led to attempts to treat cancer by replacing the imaging isotope with a therapeutic isotope which accumulates where the tumour is demonstrated (theranostics) [1224]. Therefore, after identification of the target, usually with diagnostic ⁶⁸Gallium-labelled PSMA, therapeutic radiopharmaceuticals labelled with β(lutetium-177 or yttrium-90) or α(actinium-225)-emitting isotopes could be used to treat metastatic PCa.

The PSMA therapeutic radiopharmaceutical supported by the most robust data is ¹⁷⁷Lu-PSMA-617. The first patient was treated in 2014 and early clinical studies evaluating the safety and efficacy of ¹⁷⁷Lu-PSMA therapy have demonstrated promising results, despite the fact that a significant proportion of men had already progressed on multiple therapies [1225]. The early data were based on single-centre experience [1226]. Data from uncontrolled prospective phase II trials reported high response rates with low toxic effects [1227,1228]. Positive signals are also coming from a randomised trial (TheraP) [1220].

In TheraP, a randomised phase II trial, patients for whom cabazitaxel was considered the next appropriate standard treatment after docetaxel and who were highly selected by ⁶⁸Ga-PSMA-11 and ¹⁸FDG PET-CT scans, were randomised to receive ¹⁷⁷Lu-PSMA-617 (6.0–8.5 GBq intravenously every 6 weeks for up to 6 cycles) or cabazitaxel (20 mg/m² for up to ten cycles). The primary endpoint was a reduction of at least 50% in PSA. The first endpoint was met (66% vs. 37% for ¹⁷⁷Lu–PSMA-617 vs. cabazitaxel, respectively, by ITT; difference 29% (95% CI: 16–42; p < 0.0001; and 66% vs. 44% by treatment received; difference 23% [9–37]; p = 0.0016) [1220].

An open-label phase III trial (VISION) compared ¹⁷⁷Lu–PSMA-617 radioligand therapy with protocol-permitted SOC (i.e., excluded chemotherapy, immunotherapy, radium-223 and investigational drugs) in mCRPC patients, with PSMA expressing metastases on PET/CT, previously treated with at least one ARPI and one (around 53%) or two taxanes. Imaging-based PFS and OS were the alternate primary endpoints. More than 800 patients were randomised. ¹⁷⁷Lu-PSMA-617 plus SOC significantly prolonged both imaging-based PFS and OS, as compared with SOC alone (see Table 6.5.3). Grade 3 or above AEs were higher with ¹⁷⁷Lu-PSMA-617 than without (52.7% vs. 38.0%), but QoL was not adversely affected. ¹⁷⁷Lu–PSMA-617 has shown to be a valuable additional treatment option in this mCRPC population [1229].

Recently, a systematic review and meta-analysis was updated, investigating the proportion of patients with any or more than 50% PSA decrease, and OS. The review, including 69 articles and a total of 4,157 patients, showed that patients treated with ¹⁷⁷Lu–PSMA 617 had a significantly higher response to therapy compared to controls, based on > 50% PSA decrease (OR = 5.33, 95% CI: 1.24–22.90, p < 0.05). Meta-analysis revealed an OS of 0.26 according to pooled HRs for any PSA decline, which was significant after ¹⁷⁷Lu–PSMA-617 therapy (95% CI: 0.18–0.37, p < 0.00001) and an OS of 0.52 for > 50% PSA decrease, also significant after radioligand (RLT) (95% CI: 0.40–0.67, p < 0.00001) [1230].

Currently, an increased interest for PSMA-targeted alpha therapy (²²⁵Ac-PSMA) is observed, due to the ability to deliver potent higher local radiation more selectively to cancer cells than PSMA-targeted beta therapy, while minimising unwanted damage to the surrounding normal tissues. Additionally, the intensive radiation to cancer cells results in more effective DNA strand breakage and reduces the development of treatment resistance. A meta-analysis, including 9 studies with 263 patients, investigated the therapeutic effects of ²²⁵Ac-PSMA RLT in patients with metastatic CRPC, pre-treated with chemotherapy, ¹⁷⁷Lu-PSMA and/or radium-223. The pooled proportions of patients with more than 50% PSA decline and any PSA decline were 60.99% (95% CI: 54.92%–66.83%) and 83.57% (95% CI: 78.62%–87.77%), respectively. The estimated mean PFS and mean OS were 9.15 months (95% CI: 6.69–11.03 months) and 11.77 months (95% CI: 9.51–13.49 months), respectively. These findings suggests that ²²⁵Ac-PSMA RLT may be an effective treatment option for patients with mCRPC [1231]. Despite the encouraging therapeutic response and survival of patients who received ²²⁵Ac-PSMA RLT, major AEs like xerostomia and severe haematotoxicity have to be considered as possible reasons for dose reduction or discontinuation of the therapy.

6.5.8.3. PARP inhibitors for mCRPC

So far, two PARP inhibitors, olaparib and rucaparib, are licenced by the FDA (EMA only approved olaparib) and several other PARP inhibitors are under investigation (e.g., talazoparib, niraparib).

A randomised phase III trial (PROfound) compared the PARP inhibitor olaparib to an alternative ARPI in mCRPC with alterations in > 1 of any qualifying gene with a role in HRR and progression on an ARPI. Most patients were heavily pre-treated with 1–2 chemotherapies and up to 2 ARPIs [1166,1167]. Radiographic PFS by blinded independent central review in the BRCA1/2 or ATM mutated population (Cohort A) was the first endpoint and significantly favoured olaparib (HR: 0.49, 95% CI: 0.38–0.63). The final results for OS demonstrated a significant improvement among men with BRCA1/2 or ATM mutations (Cohort A) (p = 0.0175; HR: 0.69, 95% CI: 0.50– 0.97). This was not significant in men with any (other) HRR alteration (Cohort B) (HR: 0.96, 95% CI: 0.63–1.49). Of note, patients in the physician’s choice of enzalutamide/abiraterone-arm who progressed, 66% (n = 86/131) crossed over to olaparib.

The most common AEs were anaemia (46.1% vs. 15.4%), nausea (41.4% vs. 19.2%), decreased appetite (30.1% vs. 17.7%) and fatigue (26.2% vs. 20.8%) for olaparib vs. enzalutamide/abiraterone. Among patients receiving olaparib 16.4% discontinued treatment secondary to an AEs, compared to 8.5% of patients receiving enzalutamide/abiraterone. Interestingly, 4.3% of patients receiving olaparib had a pulmonary embolism, compared to 0.8% among those receiving enzalutamide/abiraterone, none of which were fatal. There were no reports of myelodysplastic syndrome or acute myeloid leukaemia. This is the first trial to show a benefit for genetic testing and precision medicine in mCRPC.

The olaparib approval by the FDA is for patients with deleterious or suspected deleterious germline- or somatic HRR gene-mutated mCRPC, who have progressed following prior treatment with enzalutamide or abiraterone. The EMA approved olaparib for patients with BRCA1 and BRCA2 alterations [1232]. The recommended olaparib dose is 600 mg daily (300 mg taken orally twice daily), with or without food.

Rucaparib has been approved by the FDA for patients with deleterious BRCA mutations (germline and/or somatic) who have been treated with ARPI and a taxane-based chemotherapy [1233]. Approval was not based on OS data but on the results of the single-arm TRITON2 trial (NCT02952534). The confirmed ORR per independent radiology review in 62 patients with deleterious BRCA mutations was 43.5% (95% CI: 31–57) [1234].

6.5.8.4. Sequencing treatment

6.5.8.4.1. ARPI -> ARPI (chemotherapy-naive patients)

The use of sequential ARPIs in mCRPC showed limited benefit in retrospective series as well as in one prospective trial [1235-1242]. In particular in patients who had a short response to the first ARPI for mCRPC (< 12 months), this sequence should be avoided because of known cross resistance and the availability of chemotherapy and PARP inhibitors (if a relevant mutation is present).

In highly selected patients treated for more than 24 weeks with AAP, the sequence with enzalutamide showed some activity with a median rPFS of 8.1 months (95% CI: 6.1–8.3) and an unconfirmed PSA response rate of 27% [1243]. In case the patient is unfit for chemotherapy and a PARP inhibitor, best supportive care should be considered in case no other appropriate treatment option is available (clinical trial or immunotherapy if MSI-high). An ARPI-ARPI sequence should never be the preferred option but might be considered in such patients if the PS still allows for active treatment and the potential side effects seem manageable.

First prospective cross-over data on an ARPI-ARPI sequence [1235] and a systematic review and meta-analysis suggest that for the endpoints PFS and PSA PFS, but not for OS, abiraterone followed by enzalutamide is the preferred choice [1244].

6.5.8.4.2. ARPI -> PARP inhibitor/olaparib

This sequence in patients with deleterious or suspected deleterious germline or somatic HRR gene-mutated mCRPC is supported by data from the randomised phase III PROfound trial [1167]. A subgroup of patients in this trial was pre-treated with one or two ARPIs and no chemotherapy (35%). The ARPI – docetaxel - PARP inhibitor vs. ARPI – PARP inhibitor - docetaxel sequences are still under investigation.

6.5.8.4.3. Docetaxel for mHSPC -> docetaxel rechallenge

There is limited evidence for second- or third-line use of docetaxel after treatment with docetaxel for mHSPC. Docetaxel seems to be less active than ARPI at progression to mCRPC following docetaxel for mHSPC [1245].

6.5.8.4.4. ARPI -> docetaxel or docetaxel -> ARPI followed by PARP inhibitor

Both olaparib and rucaparib are active in biomarker-selected mCRPC patients after ARPI and docetaxel in either sequence [1167,1233].

6.5.8.4.5. ARPI before or after docetaxel

There is level 1 evidence for both sequences (see Table 6.5.3).

6.5.8.4.6. ARPI –> docetaxel -> cabazitaxel or docetaxel –> ARPI -> cabazitaxel

Both third-line treatment sequences are supported by level 1 evidence. Of note, there is high-level evidence favouring cabazitaxel vs. a second ARPI after docetaxel and one ARPI. CARD is the first prospective randomised phase III trial addressing this question (see Table 6.5.3) [1169].

Table 6.5.3: Randomised controlled phase II/III - second-line/third-line trials in mCRPC

*Only studies reporting survival outcomes as primary endpoints have been included.

ARPI = androgen receptor pathway inhibitor; CI = confidence interval; ECOG = Eastern Cooperative Oncology Group; FU = follow-up; GBq = gigabecquerel; HR = hazard ratio; Lu = lutetium; mo = months OS = overall survival; OR = odds ratio; ORR = objective response rate; PSA = prostate-specific antigen; PSMA = prostate-specific membrane antigen; (r)PFS = (radiographic) progression-free survival; SOC = standard of care; yr = year; HRR= homologous recombination repair.

6.5.8.5. Platinum chemotherapy

Cisplatin or carboplatin as monotherapy or combinations have shown limited activity in unselected patients in the pre-docetaxel era [1249]. More recently, the combination of cabazitaxel and carboplatin was evaluated in pre-treated mCRPC patients in a randomised phase I/II trial. The combination improved the median PFS from 4.5 months (95% CI: 3.5–5.7) to 7.3 months (95% CI: 5.5–8.2; HR: 0.69, 95% CI: 0.50–0.95, p = 0.018) and the combination was well tolerated [1250]. On a histopathological and molecular level, there is preliminary evidence that platinum adds efficacy in patients with aggressive variant PCa molecular signatures including TP53, RB1, and PTEN [1251].

Patients with mCRPC and alterations in DDR genes are more sensitive to platinum chemotherapy than unselected patients [1252], also after progression on PARP inhibitors. Interestingly, in contemporary retrospective series, unselected patients as well as patients without DDR gene alterations also showed a 50% PSA decline in up to 36% of patients [1253]. In view of the excellent tolerability of e.g., carboplatin monotherapy, platinum could be offered to patients with far advanced mCRPC harbouring DDR gene aberrations after having progressed on standard treatment options. Prospective controlled trials are ongoing.

6.5.9. Monitoring of treatment

Baseline examinations should include a medical history, clinical examination as well as baseline blood tests (PSA, total testosterone level, full blood count, renal function, baseline liver function tests, alkaline phosphatase), bone scan and CT of chest, abdomen and pelvis [1254,1255]. The use of choline or PSMA PET/CT scans for progressing CRPC is unclear and most likely not as beneficial as for patients with BCR or hormone-naive disease. Flares, PSMA upregulation and discordant results compared with PSA response or progression on ARPI have been described [1256]. Prostate-specific antigen alone is not reliable enough [1257] for monitoring disease activity in advanced CRPC since visceral metastases may develop in men without rising PSA [1258]. Instead, the PCWG2 recommends a combination of bone scintigraphy and CT scans, PSA measurements and clinical benefit in assessing men with CRPC [1191]. A majority of experts at the 2015 Advanced Prostate Cancer Consensus Conference (APCCC) suggested regular review and repeating blood profile every two to three months with bone scintigraphy and CT scans at least every six months, even in the absence of a clinical indication [1254]. This reflects that the agents with a proven OS benefit all have potential toxicity and considerable cost and patients with no objective benefit should have their treatment modified. The APCCC participants stressed that such treatments should not be stopped for PSA progression alone. Instead, at least two of the three criteria (PSA progression, radiographic progression and clinical deterioration) should be fulfilled to stop treatment. For trial purposes, the updated PCWG3 put more weight on the importance of documenting progression in existing lesions and introduced the concept of no longer ‘clinically benefiting‘ to underscore the distinction between first evidence of progression and the clinical need to terminate or change treatment [1259]. These recommendations also seem valid for clinical practice outside trials.

6.5.10. When to change treatment

The timing of mCRPC treatment change remains a matter of debate in mCRPC although it is clearly advisable to start or change treatment immediately in men with symptomatic progressing metastatic disease. Preferably, any treatment change should precede development of de novo symptoms or worsening of existing symptoms. Although, the number of effective treatments is increasing, head-to-head comparisons are still rare, as are prospective data assessing the sequencing of available agents. Therefore it is not clear how to select the most appropriate ‘second-line‘ treatment, in particular in patients without HRR alterations or other biomarkers. A positive example, however, is the CARD trial which clearly established cabazitaxel as the better third-line treatment in docetaxel pre-treated patients after one ARPI compared to the use of a second ARPI [1169].

The ECOG PS has been used to stratify patients. Generally men with a PS of 0–1 are likely to tolerate treatments and those with a PS of > 2 are less likely to benefit. However, it is important that treatment decisions are individualised, in particular when symptoms related to disease progression are impacting on PS. In such cases, a trial of active life-prolonging agents to establish if a given treatment will improve the PS may be appropriate. Sequencing of treatment is discussed in a summary paper published following the 2019 APCCC Conference [1260].

6.5.11. Symptomatic management in metastatic CRPC

Castration-resistant PCa is usually a debilitating disease often affecting the elderly male. A multidisciplinary approach is required with input from urologists, medical oncologists, radiation oncologists, nurses, psychologists and social workers [1260,1261]. Critical issues of palliation must be addressed when considering additional systemic treatment, including management of pain, constipation, anorexia, nausea, fatigue and depression.

6.5.11.1. Common complications due to bone metastases

Most patients with CRPC have painful bone metastases. External beam RT is highly effective, even as a single fraction [1262,1263]. A single infusion of a third generation bisphosphonate could be considered when RT is not available [1264]. Common complications due to bone metastases include vertebral collapse or deformity, pathological fractures and spinal cord compression. Cementation can be an effective treatment for painful spinal fracture whatever its origin, clearly improving both pain and QoL [1265]. It is important to offer standard palliative surgery, which can be effective for managing osteoblastic metastases [1266,1267]. Impending spinal cord compression is an emergency. It must be recognised early and patients should be educated to recognise the warning signs. Once suspected, high-dose corticosteroids must be given and MRI performed as soon as possible. A systematic neurosurgery or orthopaedic surgeon consultation should be planned to discuss a possible decompression, followed by EBRT [1268]. Otherwise, EBRT with, or without, systemic therapy, is the treatment of choice.

6.5.11.2. Preventing skeletal-related events

6.5.11.2.1. Bisphosphonates

Zoledronic acid has been evaluated in mCRPC to reduce skeletal-related events (SRE). This study was conducted when no active anti-cancer treatments, but for docetaxel, were available. Six hundred and forty three patients who had CRPC with bone metastases were randomised to receive zoledronic acid, 4 or 8 mg every three weeks for 15 consecutive months, or placebo [1269]. The 8 mg dose was poorly tolerated and reduced to 4 mg but did not show a significant benefit. However, at 15 and 24 months of follow-up, patients treated with 4 mg zoledronic acid had fewer SREs compared to the placebo group (44 vs. 33%, p = 0.021) and in particular fewer pathological fractures (13.1 vs. 22.1%, p = 0.015). Furthermore, the time to first SRE was longer in the zoledronic acid group. No survival benefit has been seen in any prospective trial with bisphosphonates.

6.5.11.2.2. RANK ligand inhibitors

Denosumab is a fully human monoclonal antibody directed against RANKL (receptor activator of nuclear factor κ-B ligand), a key mediator of osteoclast formation, function, and survival. In M0 CRPC, denosumab has been associated with increased bone-metastasis-free survival compared to placebo (median benefit: 4.2 months, HR: 0.85, p = 0.028) [1262]. This benefit did not translate into a survival difference (43.9 compared to 44.8 months, respectively) and neither the FDA or the EMA have approved denosumab for this indication [1270].

The efficacy and safety of denosumab (n = 950) compared with zoledronic acid (n = 951) in patients with mCRPC was assessed in a phase III trial. Denosumab was superior to zoledronic acid in delaying or preventing SREs as shown by time to first on-study SRE (pathological fracture, radiation or surgery to bone, or spinal cord compression) of 20.7 vs. 17.1 months, respectively (HR: 0.82, p = 0.008). Both urinary N-telopeptide and bone-specific alkaline phosphatase were significantly suppressed in the denosumab arm compared with the zoledronic acid arm (p < 0.0001 for both). However, these findings were not associated with any survival benefit and in a post-hoc re-evaluation of endpoints, denosumab showed identical results when comparing SREs and symptomatic skeletal events [1271].

The potential toxicity (e.g., osteonecrosis of the jaw, hypocalcaemia) of these drugs must always be kept in mind (5–8.2% in M0 CRPC and mCRPC, respectively) [1272,1273]]. Patients should have a dental examination before starting therapy as the risk of jaw necrosis is increased by several risk factors including a history of trauma, dental surgery or dental infection [1274]. Also, the risk for osteonecrosis of the jaw increased numerically with the duration of use in a pivotal trial [1275] (one year vs. two years with denosumab), but this was not statistically significant when compared to zoledronic acid [1270]. According to the EMA, hypocalcaemia is a concern in patients treated with denosumab and zoledronic acid. Hypocalcaemia must be corrected by adequate intake of calcium and vitamin D before initiating therapy [1276]. Hypocalcaemia should be identified and prevented during treatment with bone protective agents (risk of severe hypocalcaemia is 8% and 5% for denosumab and zoledronic acid, respectively) [1273]. Serum calcium should be measured in patients starting therapy and monitored during treatment, especially during the first weeks and in patients with risk factors for hypocalcaemia or on other medication affecting serum calcium. Daily calcium (> 500 mg) and vitamin D (> 400 IU equivalent) are recommended in all patients, unless in case of hypercalcaemia [1273,1277,1278].

6.5.12. Summary of evidence and guidelines for life-prolonging treatments of castrate-resistant disease

6.5.13. Guidelines for systematic treatments of castrate-resistant disease

6.5.14. Guideline for non-metastatic castrate-resistant disease

6.5.15. Guidelines for supportive care of castrate-resistant disease

These recommendations are in addition to appropriate systemic therapy.

6.6. Summary of guidelines for the treatment of prostate cancer

Table 6.6.1: EAU risk groups for biochemical recurrence of localised and locally-advanced prostate Cancer

GS = Gleason score; ISUP = International Society for Urological Pathology; PSA = prostate-specific antigen.
* Based on digital rectal examination.
** Based on CT/bone scan.

6.6.1. General guidelines recommendations for the treatment of prostate cancer

6.6.2. Guidelines recommendations for fist-line treatment of various disease stages*

*All recommendations are based on conventional imaging with isotope bone scan and CT/MR abdomen/pelvis.

6.6.3. Guidelines for metastatic disease, second-line and palliative treatments

Figure 6.1: Treatment non-metastasized (M0) – asymptomatic disease#

* Rule of thumb: Life expectancy 10 years. **Recommendation based on clinical staging using digital rectal examination, not imaging. *** Recommendation based on staging using combination of bone scan and CT. **** See text, dependent on GG and (biopsy) volume.¹EBRT: IMRT/VMAT + IGRT of the prostate. = weak recommendation.

ADT = androgen deprivation therapy; EBRT =external beam radiotherapy; ECE = extracapsular extension; ePLND = extended pelvic lymph node dissection; GG = grade group; HDR = high-dose rate; IDC = intraducal carcinoma; IGRT = image-guided radiotherapy; IMRT = intensity-modulated radiotherapy; LDR = low-dose rate; VMAT = volumetric modulated arc therapy.

Figure 6.2: Treatment of metastasized (M1*) – disease, M+HSPC

* Based on staging using combination of bone scan and CT. ** Alphabetical order.

¹EBRT: IMRT/VMAT + IGRT of the prostate (equivalent of up to 72 Gy in 2 Gy fractions). = weak recommendation. EBRT = external beam radiotherapy; IGRT = image-guided radiotherapy; IMRT = intensity-modulated radio-therapy.

#Note: Please be aware that the various options in the following flowcharts present a generalised approach only, and cannot take the management of individual patients into account, nor the availability of resources.