Prostate Cancer

5. DIAGNOSTIC EVALUATION

5.1. Screening and individual early detection

The diagnostic pathway for PCa aims for timely detection of significant PCa, while leaving insignificant PCa undetected, balancing diagnostic accuracy with the burden on an individual and healthcare provider. Patient-specific factors such as lower urinary tract symptoms (LUTS), family history, age, and comorbidity should always be considered.

Men may enter the diagnostic pathway through different indications, including clinical symptoms, opportunistic early detection (individual), or screening (population-based). The prevalence of PCa and significant PCa is different dependent on the indication, resulting in different yields of the subsequent diagnostic pathway.

5.1.1. Clinical Symptoms

Localised PCa is usually asymptomatic. Local progression may cause symptoms such as LUTS, erectile dysfunction (ED), retention, pain, or haematuria. Bone metastases may cause pain or spinal cord compression. Digital rectal examination (DRE) and PSA are usually part of the initial diagnostic work-up in these cases, after which a further diagnostic algorithm may be initiated. Definitive diagnosis normally depends on histopathological verification in prostate biopsy cores. However, men with high suspicion of malignancy (e.g. malignant feeling prostate, PSA >100 ng/mL and a positive bone scan might avoid a biopsy especially if pre-existing comorbidities would exclude second-line treatments.

5.1.2. Individual early detection

Early detection may be initiated on an individual level. Men with risk factors include age > 50 years; men from 45 years of age with a family history of PCa; men of African descent from 45 years of age; men carrying BRCA2 mutations from 40 years of age [130,131]. The risk of detecting clinically insignificant cancers and possible overtreatment should be discussed along with the possibility of improved disease-specific mortality. It is difficult to accurately estimate the individual benefit or harm due to early detection for the individual man but the effect may be larger as diluting effects from intention-to-treat analyses in screening trials are not applicable (i.e. non-participation: no participation after screening invitation; contamination: screening occurring in control arm) [132]. Nevertheless, a comparison of systematic and opportunistic screening suggested over-diagnosis and mortality reduction in the systematic screening group compared to a higher over-diagnosis with only a marginal survival benefit, at best, in the opportunistic screening regimen [133].

Baseline PSA may be used to predict PCa mortality after fifteen to twenty yrs. Follow-up intervals of two years may be offered to those initially at risk (PSA > 1 ng/mL at 40 years; PSA > 2 ng/mL at 60 years) [134,135].

The age at which attempts an early diagnosis should be stopped remains controversial, but an individual’s life expectancy must definitely be taken into account. Men who have less than a fifteen-year life expectancy are unlikely to benefit, based on data from the Prostate Cancer Intervention Versus Observation Trial (PIVOT) and the European Randomized Screening for Prostate Cancer (ERSPC) trials. Furthermore, although there is no simple tool to evaluate individual life expectancy, co-morbidity is at least as important as age. A detailed review can be found in Section 6.1 ‘Estimating life expectancy and health status’ and in the SIOG Guidelines [136]. Informed men with one of the risk factors above, a life expectancy of > fifteen years and requesting investigation should be given a PSA test and undergo a DRE, after which a further diagnostic algorithm may be initiated [137]. 

Figure 5.1 Presents a flow diagram for deciding on prostate biopsy

* PSA >50, cT3-4
** If MRI not available / possible

5.1.3. Population-based screening

Population or mass screening is defined as the ‘systematic examination of asymptomatic men to identify individuals at risk for a specific disease’ and is usually initiated by health authorities. The co-primary objectives are:

• reduction in mortality due to PCa;
• a maintained quality of life (QoL) as expressed by QoL-adjusted gain in life years (QALYs).

Screening for PCa remains one of the most controversial topics in the urological literature [138]. A Cochrane review of randomised PCa screening trials with PCa mortality as endpoint was published in 2013 [139] and updated in 2018 [140,141]. The main findings of the updated publication from the results of five RCTs, randomising more than 721,718 men, are:

• Screening is associated with an increased diagnosis of PCa (Incidence ratio [IR]: 1.23 95% CI: 1.03–1.48).
• Screening is associated with detection of more localised disease (RR: 1.39, [1.09–1.79]) and less advanced PCa (T3–4, N1, M1; RR: 0.85 [0.72–0.99]).
• No PCa-specific survival benefit was observed (IR: 0.96 [0.85–1.08]). This was the main endpoint in all trials.
• No overall survival (OS) benefit was observed (IR: 0.99, 95% CI: 0.98–1.01). None of the trials were designed/powered for this endpoint.

The included studies are different regarding multiple aspects including trial size, time periods, age groups, participation/compliance rates, previous screening rates (opportunistic testing in control arm, ‘contamination’), one-time vs. repeat screening, and the applied diagnostic pathway. These differences account for discrepancies in results between single studies and the Cochrane review aggregated findings.

The ERSPC study started in the early 90’s, included >182,000 European men, found a significant reduction in PCa mortality due to screening. ERSPC applied a mainly PSA-based screening protocol (cut-off 3.0–4.0 ng/mL followed by systematic sextant prostate biopsy, every two to four years in men aged 50–74) [142] The contamination rate was relatively low when compared to other large studies such as the Prostate Lung Colorectal and Ovarian (PLCO) screening trial [142]. A limitation is the heterogeneity in patient groups and the applied screening protocols. Since 2013, data have been updated with sixteen years of follow-up [142]. With extended follow-up, the mortality reduction (21% and 29% after non-compliance adjustment) remains unchanged. However, the number needed to screen (NNS) and to treat is decreasing and is now below the NNS observed in breast cancer trials [142,143] (Table 5.1).

Table 5.1: Follow-up data from the ERSPC study [142]

In the Rotterdam section of the ERSPC, with 21 years follow-up, the risk ratio of death due to PCa was 0.73 in the screening group, with number needed to invite of 246 and number needed to diagnose (NND) of fourteen to prevent one death due to PCa [144]. To prevent one metastasized case NNS was 121 and NND seven.

In the Goteborg screening trial, with eighteen years of follow-up, the ratio of death from PCa for the screening group compared with the control group was 0.65 (95% CI: 0.49–0.87) and for men starting screening at age 55–59 it was 0.47 (95% CI: 0.29–0.78) [145]. The number needed to invite was 231; the NND ten.

The benefit of screening in reducing PCa-specific mortality (PCSM) and the even more favourable impact on metastases rates, is counter-balanced by the side effects of screening such as increased diagnosis rates, which has led to over-treatment of low-risk PCa, and subsequent treatment-related side-effects [146]. Regarding QoL, the beneficial effects of screening and the side effects seem to balance out, resulting in limited overall impact on the invited population [146,147].

Recognition of the harms of over-diagnosis and over-treatment had led to a redesign in the pathway for early detection of PCa including identification of specific risk groups, individualised re-testing interval, improved indication for biopsy using risk calculators and/or MRI, targeted biopsies, and the application of AS for low-risk disease.

After a negative screening, PSA measurement and DRE need to be repeated [148], but the optimal intervals for PSA testing and DRE follow-up are unknown as they varied between several prospective screening trials. A risk-adapted strategy might be a consideration, based on the initial PSA level. Men with a baseline PSA < 1 ng/mL at 40 years or < 2 ng/mL at 60 years are at decreased risk of PCa metastasis or death from PCa several decades later [46,135]. The retesting interval can therefore be every two years for those initially at increased risk or postponed up to eight years for those at low-risk [149].

An analysis of ERSPC data supports a recommendation for an eight-year screening interval in men with an initial PSA concentration < 1 ng/mL; fewer than 1% of men with an initial PSA concentration < 1 ng/mL were found to have a concentration above the biopsy threshold of 3 ng/mL at four-year follow-up; the cancer detection rate by eight years was close to 1% [150]. The long-term survival and QoL benefits of extended PSA re-testing (every eight years) remain to be proven at a population level.

5.1.4. Screening in patients with BRCA mutations

The IMPACT study evaluates targeted PCa screening using PSA in men aged 40–69 years with germline BRCA1/2 mutations (annually, biopsy recommended if PSA > 3.0 ng/mL). After three years of screening, BRCA2 mutation carriers were associated with a higher incidence of PCa, a younger age of diagnosis, and more clinically significant tumours compared with non-carriers [131,151]. The influence of BRCA1 mutations on PCa remained unclear. No differences in age or tumour characteristics were detected between BRCA1 carriers and BRCA1 non-carriers. The mismatch repair cohort of IMPACT in men with MSH2 and MSH6 pathogenic variants found a higher incidence of significant PCa vs. non-carriers [152].

5.1.5. Guidelines for individual early detection

5.1.6. Genetic testing for inherited prostate cancer

Increasing evidence supports the implementation of genetic counselling and germline testing in early detection and PCa management [153]. Several commercial screening panels are now available to assess the main PCa risk genes [154]. However, it remains unclear when germline testing should be considered and how this may impact localised and metastatic disease management. Germline BRCA1 and BRCA2 mutations occur in approximately 0.2% to 0.3% of the general population [155]. It is important to understand the difference between somatic testing, which is performed on the tumour, and germline testing, which is performed on blood or saliva and identifies inherited mutations. Genetic counselling is required prior to and after undergoing germline testing.

Germline mutations can drive the development of aggressive PCa. Therefore, the consensus is the following men, with a personal or family history of PCa or other cancer types arising from DNA repair gene mutations should be considered for germline testing:

• Men with metastatic PCa who are candidates for targeted treatment;
• Men with BRCA mutations on somatic testing;
• Men with multiple family members diagnosed with csPCa at age < 60 years or a family member who died from PCa;
• Men with a family history of high-risk germline mutations or a family history of multiple cancers on the same side of the family.

Further research in this field (including not so well-known germline mutations) is needed to develop screening, early detection and treatment paradigms for mutation carriers and family members.

5.1.7. Guidelines for germline testing*

*Genetic counselling is required prior to germline testing.

5.2. Diagnostic tools

The different available diagnostic tools can be used separately, or in multiple-tier combinations and/or sequences to indicate prostate biopsy.

5.2.1. Digital rectal examination

In ~18% of cases, PCa is detected by suspect DRE alone, irrespective of PSA level [156]. A suspect DRE in patients with a PSA level ≤ 2 ng/mL has a positive predictive value (PPV) of 5–30% [156]. In the ERSPC trial, an abnormal DRE in conjunction with an elevated PSA more than doubled the risk of a positive biopsy (48.6% vs. 22.4%) [157]. An abnormal DRE is associated with an increased risk of a higher ISUP grade, predicts clinically significant PCa in men under AS (active surveillance) [158] and is an indication for MRI and biopsy [157,159]. Clinical T-staging is dependent on DRE, and it remains a strong predictor of advanced PCa (OR: 11.12 for cT3 and OR: 5.28 for cT4) [160].

5.2.2. Prostate-specific antigen

Prostate-specific antigen (a glycoprotein enzyme secreted by prostate epithelial cells) is the primary test in the suspicion of PCa. Its use as a serum marker has revolutionised PCa diagnosis [161]. Prostate-specific antigen is organ- but not cancer specific; therefore, it may be elevated in benign prostatic hyperplasia (BPH), prostatitis and other non-malignant conditions. There are no agreed standards for defining PSA thresholds [162]. It is a continuous parameter, with higher levels indicating greater likelihood of PCa. Some men may harbour PCa despite having low serum PSA [163]. Table 5.2 demonstrates the occurrence of any PCa and ISUP ≥ grade 2 PCa in systematic biopsies at low PSA levels, precluding an optimal PSA threshold for detecting non-palpable but csPCa.

Table 5.2: Risk of PCa identified by systemic PCa biopsy in relation to low prostate-specific antigen values [163]

In a screening situation, the most commonly applied threshold for PSA is ≥ 3.0 ng/ml, resulting in 16.5% of invited men returning a positive test [164]. The risk of finding PCa at a specific PSA threshold in a clinical cohort may be different than in a screening situation, due to differences in prevalence, protocol for referral, and diagnostic algorithm. PSA keeps its diagnostic value for cancer detection in symptomatic patients [165]. A review and meta-analysis on the diagnostic accuracy of PSA (≥ 4.0 ng/ml) for the detection of PCa transrectal ultrasound (TRUS) in clinical patients found an estimated combined sensitivity of 0.93 and specificity of 0.20 PSA production is androgen dependent and 5a-reductase inhibitors (e.g. finasteride, dutasteride) used for benign prostatic enlargement of the prostate such as finasteride or dutasteride will reduce PSA levels by 50% [166]. In such cases, PSA level should be corrected before a decision about further investigation is made.

In case of a moderately elevated PSA (up to 10 ng/mL), a repeated test after a few weeks should be considered to confirm the increase before going to continue the diagnostic analysis. Repeat PSA should be performed in the same laboratory using the same assay under standardised conditions (i.e. no ejaculation, manipulations, and urinary tract infections [UTIs]) [167,168]. The type of PSA assay used may impact PSA values and rates of PSA above certain fixed thresholds [169].

A repeat PSA test before prostate biopsies in men with an initial PSA 3–10 ng/mL reduced the indication for biopsies in 16.8% of men while missing 5.4% ISUP grade > 1 in the Stockholm3 trial [170]. Similarly, in the Prostate Testing for Cancer and Treatment (ProtecT) trial men with a more than 20% lower repeat-PSA analysis within seven weeks had a lower risk of PCa (OR: 0.43, 95% CI: 0.35–0.52) as well as a lower risk of ISUP grade ≥ 2 (OR: 0.29, 95% CI: 0.19–0.44) [171]. A study with a PSA interval of four weeks showed similar findings of a reduced risk of PCa and ISUP grade > 1 [172]. These observations indicate that an early repeat-PSA prior to the decision of prostate biopsies has prognostic information.

5.2.3. Prostate-specific antigen density

Prostate-specific antigen density (PSA-D) is the level of serum PSA divided by the prostate volume. The higher the PSA-D, the more likely it is that the PCa is clinically significant; in particular in smaller prostates when a PSA-D cut-off of 0.15 ng/mL/cc was applied [195]. Several studies found a PSA-D over 0.1–0.15 ng/mL/cc predictive of PCa [173,174]. Patients with a PSA-D below 0.09 ng/mL/cc were found unlikely (4%) to be diagnosed with csPCa [175]. PSA-D is one of the strongest predictors in risk calculators.

PSA-D remains currently limited due to the lack of standardisation of prostate volume estimation that can be assessed by DRE or by imaging (TRUS or MRI using various techniques such as ellipsoid formula or planimetry). Nonetheless, one study involving seven radiologists who assessed prostate volume on 40 MRI scans using two different ellipsoid methods and a manual planimetry method suggested that intra and inter-reader reproducibility of the three methods were excellent with intraclass correlation coefficient > 0.90 [176]. In a series of 640 men, TRUS found prostate volumes on average 8% smaller than MRI; in the 109 men who underwent RP, MRI-derived prostate volume was better correlated to the volume of the surgical specimen than TRUS-derived volume [177].

Transabdominal ultrasound overestimated the prostate volume by 9.9 ml [178]. Therefore, the use of transabdominal ultrasound to evaluate prostate volume is discouraged.

5.2.4. Imaging

5.2.4.1. Magnetic resonance imaging

Multi-parametric MRI combines T2-weighted, diffusion-weighted, and dynamic contrast-enhanced imaging. Although MRI is mainly initiated after suspicion of PCa based on PSA and/or DRE, it has also been analysed as an initial test [179]. Besides suggesting the presence of PCa, imaging also allows targeted prostate biopsy and provides staging information.

Prostate cancer appears as areas with low signal intensity on T2-weighted imaging, restriction of diffusion and early and intense enhancement on perfusion imaging. However, there is substantial overlap between the appearances of PCa and some prostate benign conditions. The Prostate Imaging-Reporting and Data System (PI-RADS) has been proposed to standardize interpretation and stratify men with suspected PCa on a 1- to 5- risk scale of having csPCa [180,181].

Correlation with RP specimens shows that MRI has good sensitivity for the detection and localisation of ISUP grade group ≥ 2 cancers, especially when their diameter is larger than 10 mm [182]. MRI is less sensitive in identifying ISUP grade group 1 PCa. It identifies less than 30% of ISUP grade 1 cancers smaller than 0.5 cc identified on RP specimens by histopathology analysis [182-185].

The good sensitivity of magnetic resonance imaging for ISUP grade group ≥ 2 cancer was further confirmed in patients who underwent template biopsies. In a Cochrane meta-analysis which compared MRI to template biopsies (≥ 20 cores) in biopsy-naïve and repeat-biopsy settings, MRI had a pooled sensitivity of 0.91 (95% CI: 0.83–0.95) and a pooled specificity of 0.37 (95% CI: 0.29–0.46) for ISUP grade group > 2 cancers. For ISUP grade ≥ 3 cancers, MRI pooled sensitivity and specificity were 0.95 (95% CI: 0.87–0.99) and 0.35 (95% CI: 0.26–0.46), respectively [186].

In a meta-analysis of seventeen studies involving men with suspected or biopsy-proven PCa, the average PPVs for ISUP grade group ≥ 2 cancers of lesions with a PI-RADS version 2.1 score of 3, 4 and 5 were 16% (7–27%), 59% (39–78%), and 85% (73–94%), respectively, but with significant heterogeneity among studies [187].

In biopsy naïve men, an MRI-based indication for biopsy after referral, leads to lower rates of biopsy, lower rates of men diagnosed with PCa labelled as insignificant, and more men with PCa labelled as csPCa [121,186,188-190]. This is also true in men with prior negative biopsy [186,191] (see section 5.4.2).

5.2.4.2. Transrectal ultrasound and ultrasound-based techniques

Standard TRUS is not reliable at detecting PCa [192] and the diagnostic yield of additional biopsies performed on hypoechoic lesions is negligible [190]. New sonographic modalities such as micro-Doppler, sonoelastography or contrast-enhanced US provided promising preliminary findings, either alone, or combined into the so-called ‘multi-parametric US’ [193,194]. In the multi-parametric US vs. multi-parametric MRI to diagnose PCa (CADMUS) trial, 306 patients underwent both multi-parametric MRI and multi-parametric US composed of B-mode, Colour Doppler, real-time elastography, and contrast-enhanced US. Patients with at least one positive test underwent targeted biopsy. Multi-parametric US detected 4.3% fewer csPCa while submitting 11.1% more patients to biopsy than MRI [195].

High-resolution micro-US shows improved spatial resolution but struggles to assess the anterior part of large prostates. Two prospective trials assessed MRI and micro-US interpreted in a blinded manner before combined targeted and systematic biopsy. In one, MRI and micro-US detected respectively 60 (76%) and 58 (73%) of the 79 csPCas, while systematic sampling detected 45/79 cases (57%). MRI-targeted biopsy detected seven csPCas missed by micro-US; of these three were anterior lesions. Micro-US-guided biopsy detected five csPCas missed by MRI; of these, three were at the apex [196]. In the other study, MRI- and micro-US-targeted biopsy depicted csPCa in 37 (39%) and 33 (35%) of the 94 men, respectively while the MRI- plus micro-US-targeted pathway detected 38 csPCa [197]. These findings suggest that MRI and micro-US could complement each other. Micro-US could also be an interesting alternative to MRI/fusion since biopsy operators who are aware of MRI findings can localise most MRI lesions on micro-US and, thus, target them with direct US image guidance [198]. Of note, evaluation of micro-US inter-operator variability is currently lacking.

5.2.4.3. Prostate-specific antigen-Positron emission tomography/Computed tomography (or Magnetic resonance imaging)

Though mainly used for staging purposes, PSMA-PET/CT (or -PET/MRI) prostate expression may be used to indicate and target biopsies. For csPCa detection, a pooled sensitivity of 0.89 and a pooled specificity of 0.56 have been reported [199]. In a prospective trial of 291 patients, combined PSMA + MRI improved negative predicted value (NPV) compared with MRI alone (91% vs. 72%, test ratio = 1.27 [1.11–1.39], p < 0.001). Sensitivity also improved (97% vs. 83%, p < 0.001), but specificity was reduced (40% vs. 53%, p = 0.011) [122].

5.2.5. Blood and urine biomarkers

Urine and serum biomarkers as well as tissue-based biomarkers have been proposed for improving detection and risk stratification of PCa patients, potentially avoiding unnecessary biopsies. However, further studies are necessary to validate their efficacy [200].

5.2.5.1. Blood based biomarkers: PHI/4K score/IsoPSA/Stockholm3/Proclarix

The use of biomarkers (included in a nomogram) may help in predicting indolent PCa [201,202]. Several assays measuring a panel of kallikreins in serum or plasma are now commercially available, including the U.S. Food and Drug Administration (FDA) approved Prostate Health Index (PHI) test (combining free and total PSA and the [-2]pro-PSA isoform [p2PSA]), and the four kallikrein (4K) score test (measuring free, intact and total PSA and kallikrein-like peptidase 2 [hK2] in addition to other parameters age, DRE and prior biopsy status). Both tests are intended to reduce the number of unnecessary prostate biopsies in PSA-tested men. A few prospective multi-centre studies demonstrated that both the PHI and 4K score test out-performed f/t PSA PCa detection, with an improved prediction of csPCa in men with a PSA between 2–10 ng/mL [203,204]. In a head-to-head comparison both tests performed equally [205].

In contrast to the 4K score and PHI, which focus on the concentration of PSA isoforms, IsoPSA utilises a technology which focuses on the structure of PSA. In a multi-centre prospective validation in 271 men the assay area under curve (AUC) was 0.784 for high-grade vs. low-grade cancer/benign histology, which was superior to the AUCs of total PSA and percent free PSA [208]. In men with a negative mpMRI, PSA-D, 4K score and family history predicted the risk of csPCa on biopsy and using a nomogram reduced the number of negative biopsies and indolent cancers by 47% and 15%, respectively, while missing 10% of csPCa [206].

The Stockholm3 test is a prediction model that is based on several clinical variables (age, first-degree family history of PCa, and previous biopsy), blood biomarkers (total PSA, free PSA, ratio of free PSA to total PSA, human kallikrein 2, macrophage inhibitory cytokine-1, and microseminoprotein-β ), and a polygenic risk score for predicting the risk of PCa with ISUP grade group ≥ 2, and was shown to reduce the percent of clinically insignificant cancers when used in combination with MRI in a PSA screening population [207]. It also has the potential to decrease the number of mpMRI scans required in prostate cancer screening [208].

The Proclarix^® test is a blood-based test that estimates the likelihood of csPCa according to measurement results for thrombospondin-1, cathepsin D, total PSA, percentage free PSA and patient age. This test has been correlated with the detection of significant PCa, notably in case of equivocal MRI (PI-RADS 3 lesions) [209].

5.2.5.2. Urine biomarkers: PCA3/SelectMDX/Mi Prostate score (MiPS)/ExoDX

Prostate cancer gene 3 (PCA3) is an overexpressed long non-coding RNA (lncRNA) biomarker that is detectable in urine sediments obtained after three strokes of prostatic massage during DRE. However, the clinical utility of the commercially available Progensa urine test for PCA3 for biopsy decision-making remains uncertain. Still, combining MRI findings with the PCA3 score may improve risk stratification [210].

The SelectMDX test is similarly based on mRNA biomarker isolation from urine. The presence of HOXC6 and DLX1 mRNA levels is assessed to provide an estimate of the risk of both presence of PCa on biopsy as well as presence of high-risk cancer [211]. A multi-centre trial evaluated SelectMDX in men with an MRI PI-RADS score < 4 or PI-RADS score < 3, and the percentage of missed csPCas was 6.5% and 3.2%, respectively, whereas 45.8% and 40% of biopsies were avoided [212]. Hendriks et al., found more biopsies were avoided and more high-grade PCas detected in an MRI-based biopsy strategy compared to a SelectMDX strategy. When both tests were combined, more Gleason grade > 1 lesions were found, but the number of negative or low-grade cancer biopsies more than doubled [202]. Combining SelectMDX and MRI in men with a PSA between 3–10 ng/mL had a negative predictive value (NPV) of 93% [213]. The clinically added value of SelectMDX in the era of upfront MRI and targeted biopsies remains unclear [214].

TMPRSS2-ERG fusion, a fusion of the trans-membrane protease serine 2 (TMPRSS2) and the ERG gene can be detected in 50% of PCas [215]. When detection of TMPRSS2-ERG in urine was added to PCA3 expression and serum PSA (Mi(chigan)Prostate Score [MiPS]), cancer prediction improved [216]. Exosomes secreted by cancer cells may contain mRNA diagnostic for high-grade PCa [217,218]. Use of the ExoDx Prostate IntelliScore urine exosome assay resulted in avoiding 27% of unnecessary biopsies when compared to standard of care (SOC). However, currently, both the MiPS-score and ExoDx assay are considered investigational.

In the screening population of the ERSPC study the use of both PCA3 and 4K panel when added to the risk calculator led to an improvement in AUC of less than 0.03 [219]. Based on the available evidence, some biomarkers could help in discriminating between aggressive and non-aggressive tumours with an additional value compared to the prognostic parameters currently used by clinicians [220]. However, upfront MRI is also likely to affect the utility of above-mentioned biomarkers (see Section 5.2.3.2).

5.2.6. Guidelines for screening and individual early detection

5.3. Pathology of prostate needle biopsies

5.3.1. Processing

Prostate core biopsies from different sites are processed separately, as delivered by the biopsy operator. Before processing, the number and length of the cores are recorded. The length of biopsy tissue significantly correlates with the PCa detection rate [221]. In case individual cores can clearly be identified in submitted jars, a maximum of three cores should be embedded per tissue cassette, and sponges or paper should be used to keep the cores stretched and flat to achieve optimal flattening and alignment [222,223]. To optimise detection of small lesions and improve accuracy of grading, paraffin blocks should be cut at three levels and intervening unstained sections may be kept for immunohistochemistry (IHC) [224].

5.3.2. Microscopy and reporting

Diagnosis of PCa is based on histology. The diagnostic criteria include features pathognomonic of cancer, major and minor features favouring cancer and features against cancer. Ancillary staining and additional (deeper) sections should be considered if a suspect lesion is identified [224]. Diagnostic uncertainty is resolved by intradepartmental or external consultation [224]. Sections 5.3.2.1 and 5.3.2.2 list the recommended terminology and item list for reporting prostate biopsies [223]. Type and subtype of PCa should be reported such as for instance acinar adenocarcinoma, ductal adenocarcinoma and small or large cell neuroendocrine carcinoma, even if representing a small proportion of the PCa. The distinct aggressive nature of small/large cell neuroendocrine carcinoma should be commented upon in the pathology report [223]. Apart from grading acinar and ductal adenocarcinoma, the percentage of Gleason grade 4 component should be reported in Gleason score 7 (3+4 and 4+3) PCa biopsies. Percentage Gleason grade 4 has additional prognostic value and is considered in some AS protocols [225,226]. Considerable evidence has been accumulated in recent years supporting that among the Gleason grade 4 patterns, cribriform pattern carries an increased risk of biochemical recurrence, metastatic disease and death of disease [227,228]. Reporting of this sub-pattern based on established criteria is recommended [101,229]. Intraductal carcinoma, defined as an extension of cancer cells into pre-existing prostatic ducts and acini, distending them, with preservation of basal cells [101], should be distinguished from high-grade prostatic intraepithelial neoplasia (PIN) [230] as it conveys unfavourable prognosis in terms of biochemical recurrence and cancer-specific survival (CSS) [231,232]. Its presence should be reported whether occurring in isolation or associated with adenocarcinoma [101]. Some intra-epithelial lesions have architectural complexity and/or cytological atypia exceeding those of high-grade PIN but fall short for a definitive diagnosis of IDC. These lesions have been referred to as Atypical Intraductal Proliferation (AIP) and amongst others encompass lesions that were previously classified as cribriform high-grade PIN. Small retrospective series suggest that AIP at biopsy is associated with unsampled IDC [233,234]. Therefore, presence of AIP should be reported and commented on in non-malignant biopsies and biopsies with ISUP grade group 1 and 2 cancers in the absence of overt invasive cribriform and IDC.

5.3.2.1. Recommended terminology for reporting prostate biopsies [235]

Each biopsy site should be reported individually, including its location (in accordance with the sampling site) and histopathological findings, which include the histological type and the ISUP 2019 grade group [101,236,237]. For MRI targeted biopsies consisting of multiple cores per target the aggregated (or composite) ISUP grade group should be reported per targeted lesion [101]. If the targeted biopsies are negative, presence of specific benign pathology should be mentioned, such as dense inflammation, fibromuscular hyperplasia or granulomatous inflammation [101,238]. A global ISUP grade group comprising all systematic (non-targeted) and targeted biopsies is also reported (see Section 4.2). The global ISUP grade group takes into account all biopsies positive for carcinoma, by estimating the total extent of each Gleason grade present. For instance, if three biopsy sites are entirely composed of Gleason grade 3 and one biopsy site of Gleason grade 4 only, the global ISUP grade group would be 2 (i.e. GS 7[3+4]) or 3 (i.e. GS 7[4+3]), dependent on whether the extent of Gleason grade 3 exceeds that of Gleason grade 4, whereas the worst grade would be ISUP grade group 4 (i.e. GS 8[4+4]). Neither global nor worst ISUP grade group is clearly superior over the other [239]. The majority of clinical studies have not specified whether global or worst biopsy grade was taken into account. In addition to GS /ISUP grade group, the presence/absence of intraductal/invasive cribriform pattern should be reported [101,236,237]. Furthermore, in biopsy GS 7 (ISUP grade group 2 and 3) percentage Gleason grade 4 should be monitored at the case and/or biopsy level [101,237]. Lymphovascular invasion (LVI), EPE and ejaculatory duct/seminal vesicle involvement must each be reported, if identified, since they carry unfavourable prognostic information [240,241].

Recently, a series of studies have demonstrated that computer-assisted PCa grading artificial intelligence algorithms can perform grading at the level of experienced genito-urinary pathologists. These algorithms have potential in supporting grading of less experienced pathologists, by reducing inter-observer variability, and in quantitative analyses. However, more extensive and prospective validation of these algorithms is needed for implementation in daily clinical practise [101,236,237,242]. The proportion of systematic (non-targeted) carcinoma-positive cores as well as the extent of tumour involvement per biopsy core correlate with the ISUP grade group, tumour volume, surgical margins and pathological stage in RP specimens and predict BCR, post-prostatectomy progression and RT failure. These parameters are included in nomograms created to predict pathological stage and SV invasion after RP and RT failure [243,244]. A pathology report should therefore provide both the number of carcinoma positive cores and the extent of cancer involvement for each core. The length in mm and percentage of carcinoma in the biopsy have equal prognostic impact [245]. An extent of >50% of adenocarcinoma in a single core is used as a cut-off in some AS protocols [246] triggering immediate treatment vs. AS in patients with ISUP grade group 1 (see Section 6.1.1.1).

5.3.2.2. Recommended item list for reporting prostate cancer biopsies [101,236,237]

5.3.3. Tissue-based prognostic biomarker testing

After a comprehensive literature review and several panel discussions an American Society of Clinical Oncology (ASCO)-EAU-American Urological Association (AUA) multi-disciplinary expert panel made recommendations regarding the use of tissue-based PCa biomarkers. The recommendations were limited to five commercially available tests (Oncotype Dx, Prolaris, Decipher, Decipher PORTOS and ProMark) with extensive validation in large retrospective studies and evidence that their test results might actually impact clinical decision-taking. The selected commercially available tests significantly improved the prognostic accuracy of clinical multi-variable models for identifying men who would benefit of AS and those with csPCa requiring curative treatment, as well as for guidance of patient management after RP. Few studies showed that tissue biomarker tests and MRI findings independently improved the detection of csPCa in an AS setting, but it remains unclear which men would benefit of both tests. Decipher^® test outcome has been associated with presence of intraductal/invasive cribriform carcinoma but retains independent value in multi-variable analysis. Since the long-term impact of the use of these commercially available tests on oncological outcome remains unproven and prospective trials are largely lacking, the Panel concluded that these tests should not be offered routinely but only in subsets of patients where the test result provides clinically actionable information, such as for instance in men with favourable intermediate-risk PCa who might opt for AS or men with unfavourable intermediate-risk PCa scheduled for RT to decide on treatment intensification with hormone therapy (HT) [247].

5.3.4. Tissue samples for homologous recombination repair (HRR)-testing

Homologous recombination repair-testing in the PROfound trial was conducted on archival or recent biopsy tissue from primary or metastatic disease with successful sequencing in 69% [248]. Alterations in HRR genes are relatively unchanged comparing matched treatment-naïve diagnostic and mCRPC biopsies [249,250]. Whereas there is no preference for use of archival or new metastatic biopsies for HRR-testing, bone biopsies might be associated with lower success rates related to decalcification of tissue [251]. Testing of circulating tumour DNA might be a good alternative if tumour tissue is not available [250,252]. With tissue as reference, ctDNA showed 81% positive and 92% negative percentage agreement [253].

5.3.5. Histopathology of radical prostatectomy specimens

5.3.5.1. Processing of radical prostatectomy specimens

Histopathological examination of RP specimens describes the pathological stage, histopathological type, grade and surgical margins of PCa. It is recommended that RP specimens are totally embedded to enable assessment of cancer location, multi-focality and heterogeneity. For cost-effectiveness, partial embedding may also be considered, particularly for prostates >60 g. The most widely accepted method includes complete embedding of the posterior prostate and a single mid-anterior left and right section. Compared with total embedding, partial embedding with this method missed 5% of positive margins and 7% of EPE [254].

The entire RP specimen should be inked upon receipt in the laboratory to demonstrate the surgical margins. Specimens are fixed by immersion in buffered formalin for at least 24 hours, preferably before slicing. After fixation, the apex and the base (bladder neck) are removed and cut into (para)sagittal or radial sections; the shave method is not recommended [99]. The remainder of the specimen is cut in transverse, 3–4 mm sections, perpendicular to the long axis of the urethra. The resultant tissue slices can be embedded and processed as whole-mounts or after quadrant sectioning. Whole-mounts provide better topographic visualisation, faster histopathological examination and better correlation with pre-operative imaging, although they are more time-consuming and require specialist handling. For routine sectioning, the advantages of whole mounts do not outweigh their disadvantages.

5.3.5.2. Radical prostatectomy specimen report

The pathology report provides essential information on the prognostic characteristics relevant for clinical decision-making (Table 5.6). As a result of the complex information to be provided for each RP specimen, the use of synoptic(-like) or checklist reporting is recommended. Synoptic reporting results in more transparent and complete pathology reporting [255].

Table 5.3: Mandatory elements provided by the pathology report

5.3.5.3. ISUP grade group in prostatectomy specimens

Grading of conventional prostatic adenocarcinoma using the Gleason system is the strongest prognostic factor for clinical behaviour and treatment response [100]. The GS is incorporated in nomograms that predict disease-specific survival (DSS) after prostatectomy [256,257]. The ISUP grade group in prostatectomy specimens is determined mostly in a similar way as in biopsies, with a minor exception, i.e. the exclusion of minor (< 5%) high-grade components from the ISUP grade group. For instance, in a carcinoma almost entirely composed of Gleason grade 3 the presence of a minor (< 5%) Gleason grade 4 or 5 component is not included in the GS (ISUP grade group 1), but its presence is commented upon [101]. In case of multi-focality the ISUP grade group of the index lesion i.e. the tumour having the highest grade, stage or volume, is given.

5.3.5.4. Definition of extra-prostatic extension

Extra-prostatic extension is defined as carcinoma mixed with peri-prostatic adipose tissue, or tissue that extends beyond the prostate gland boundaries (e.g., neurovascular bundle, anterior prostate). Microscopic bladder neck invasion is considered EPE. It is useful to report the location and extent of EPE because the latter is related to recurrence risk [258]. There are no internationally accepted definitions of focal or microscopic, vs. non-focal or extensive EPE. Some describe focal as a few glands [259] or <1 high-power field in one or at most two sections whereas others measure the depth of extent in millimetres [259]. At the apex of the prostate, tumour mixed with skeletal muscle does not constitute EPE. In the bladder neck, microscopic invasion of smooth muscle fibres is not equated to bladder wall invasion, i.e. not as pT4, because it does not carry independent prognostic significance for PCa recurrence and should be recorded as EPE (pT3a) [260,261]. Stage pT4 is assigned when the tumour invades the bladder muscle wall as determined macroscopically [94].

5.3.5.5. PCa volume

Although PCa volume at RP correlates with tumour grade, stage and surgical margin status, the independent prognostic value of PCa volume has not been established [259,262,263]. Improvement in prostatic radio-imaging allows more accurate pre-operative measurement of cancer volume. Since the independent value of pathological tumour volume at RP has not been established, reporting of the diameter/volume of the dominant tumour nodule, or a rough estimate of the percentage of cancer tissue, is optional [264].

5.3.5.6. Surgical margin status

Surgical margin status is an independent risk factor for BCR. Margin status is positive if tumour cells are in contact with the ink on the specimen surface. Margin status is negative if tumour cells are close to the inked surface [265] or at the surface of the tissue lacking ink. In tissues that have severe crush artefacts, it may not be possible to determine margin status [266]. Surgical margin is separate from pathological stage, and a positive margin is not evidence of EPE [267]. There is evidence for a relationship between margin extent and recurrence risk [268,269]. Some indication must be given of the multi-focality and extent of margin positivity, such as the linear extent in mm of involvement: focal, ≤ 1 mm vs. extensive, > 1 mm [270], or number of blocks with positive margin involvement. Gleason score at the positive margin was found to correlate independently with outcome and should be reported [255,268,271].

5.3.5.7. Intra-operative assessment of surgical margin status

Intra-operative surgical margin assessment can be performed during RP to reduce positive margins and increase neurovascular bundle preservation. A SR reported a 1-15% decrease of positive surgical margins in eight out of ten studies [272]. Intra-operative evaluation of the posterolateral prostatic margin according to the neurovascular structure-adjacent frozen section examination (NeuroSAFE) technique is a systematic way of intra-operative surgical margin evaluation [273]. Non-randomised studies showed that men subjected to NeuroSAFE had lower positive surgical margin rates and more frequently underwent uni- or bilateral nerve-sparing surgery [273-276]. Pending the results on long-term oncological and functional outcome as well as the outcome of the randomised NeuroSAFE PROOF trial, intra-operative frozen section analysis should not be considered standard of care [277].

5.4. Biopsy indication

5.4.1. Risk assessment before MRI and biopsy

An elevated risk of significant PCa is established based on one or more of the primary diagnostic tools applied, such as PSA level, DRE, or primary imaging. While in the classic diagnostic algorithm the indication for biopsy was generally solely based on a PSA-threshold or abnormal DRE, different two- or three-tier sequential / conditional pathways are now available to indicate prostate biopsy, such as imaging and/or biomarkers. These can be combined and/or sequenced into two or multiple-tier conditional diagnostic pathways (e.g. PSA -> MRI, PSA -> risk calculator, PSA -> risk calculator -> MRI, etc). Age, co-morbidity, life expectancy, and therapeutic consequences should also be considered and discussed beforehand [278].

The chosen diagnostic algorithm may be elected based on availability, expertise, and resources. The different approaches impact cancer detection rates, number of (un)necessary biopsies, number of patient visits, and option of targeted biopsies. The elected strategy may also be decided based on prevalence of disease in men entering the pathway (e.g. screening versus clinical symptoms).

Different sequences and combinations of these tools, lead to different rates of biopsy indications, detection rates of insignificant PCa, and significant PCa, but also on the burden and costs of the diagnostic algorithm [279].

5.4.1.1. Risk calculators assessing the risk of csPCa

At different steps during the diagnostic process, available parameters may be combined into risk calculators to optimise risk-assessment of csPCa. Validation and adaption to the target population are important issues before use. Risk calculators, combining clinical data (age, DRE findings, PSA level, prostate volume, etc.) may be useful in helping to determine (on an individual basis) what the potential risk of cancer may be, thereby improving the balance of the cancer detection rates and number of biopsies [280].

Several tools developed from cohort studies are available including (among others) the calculator derived from the ERSPC cohort (http://www.prostatecancer-riskcalculator.com/seven-prostate-cancer-risk-calculators) that has been updated by incorporating the 2014 ISUP Pathology Gleason Grading and Cribriform growth [150], and the one derived from the Prostate Cancer Prevention Trial (PCPT) cohort (PCPTRC 2.0 https://riskcalc.org/PCPTRC/). However, calculators are limited by their dependency on disease prevalence. All calculators show miscalibration when tested in populations with a different prevalence than that of the training population of the model. Recalibrations taking into account the local prevalence are possible, but this approach is difficult in routine as the local prevalence is difficult to estimate and may change over time.

5.4.1.2. Using risk-stratification to avoid Magnetic resonance imaging scans and biopsy procedures

A retrospective analysis including 200 men from a prospective database of patients who underwent MRI and combined systematic and targeted biopsy showed that upfront use of the Rotterdam Prostate Cancer Risk Calculator would have avoided MRI and biopsy in 73 men (37%). Of these 73 men, ten had ISUP grade group 1 cancer and 4 had ISUP grade group ≥ 2 cancer [281]. A prospective multi-centre study evaluated several diagnostic pathways in 545 biopsy-naive men who underwent MRI and systematic and targeted biopsy. Using a PHI threshold of > 30 to perform MRI and biopsy would have avoided MRI and biopsy in 25% of men at the cost of missing 8% of the ISUP grade group ≥ 2 cancers [282]. Another prospective multi-centre trial including 532 men (with or without history of prostate biopsy) showed that using a threshold of ≥ 10% for the Stockholm3 test to perform MRI and biopsy would have avoided MRI and biopsy in 38% of men at the cost of missing 8% of ISUP grade group ≥ 2 cancers [207]. Finally, a risk calculator developed on 1,486 men who underwent MRI and biopsy was externally validated on a cohort of 946 men from two institutions; using a risk threshold that provided 95% sensitivity in the development cohort could have avoided 22% of the MRI scans in the validation cohort while missing 5% of csPCa [283].

5.4.2. MRI based indication for biopsy

5.4.2.1. MRI as a triage test for biopsy (‘MRI pathway’)

Owing to its high sensitivity, MRI showed an excellent NPV for ruling out the presence of csPCa not only at subsequent biopsy [284], but also after four years of follow-up [285].

The diagnostic yield and number of biopsy procedures potentially avoided by the ‘MR pathway’ (in which only patients with positive MRI undergo biopsy) depends on the Likert/PI-RADS threshold used to define a positive MRI. In pooled studies on biopsy-naive patients and patients with prior negative biopsies, a Likert/PI-RADS threshold of ≥ 3 would have avoided 30% (95% CI: 23–38) of all biopsy procedures while missing 11% (95% CI: 6–18) of all detected ISUP grade group ≥ 2 cancers (relative percentage) [186]. Increasing the threshold to ≥ 4 would have avoided 59% (95% CI: 43–78) of all biopsy procedures while missing 28% (95% CI: 14–48) of all detected ISUP grade group ≥ 2 cancers [186]. Of note, the percentages of negative MRI (Likert/PI-RADS score ≤ 2) may show substantial variability among series. In the PRECISION, MRI-FIRST and 4M trials were 21.1%, 28.9% and 49%, with related ISUP grade group ≥ 2 cancer prevalence of 27.7% (23.7–32.6), 37.5% (31.4–43.8), and 30% (ND) respectively [121,189,190].

In the MR PROPER trial, a prospective, multi-centre, non-randomised opportunistic early detection setting (PSA > 3 ng/mL), comparable rates of ISUP grade group ≥ 2 cancer detection (24% vs. 25%) were obtained by the MRI pathway and by a strategy indicating systematic biopsy based on a risk calculator. However, the MRI pathway avoided biopsy in more men as compared to the diagnostic pathway using a risk calculator (559/1015, 55% vs. 403/950, 42%; difference -13%, 95% 27 CI: -17% to -8.3%; p < 0.01); it also detected less ISUP grade group 1 cancers (84/1015, 8.3% vs. 121/950, 13%; difference 4.5%, 95% CI: 1.8–7.2%; p < 0.01) [286].

5.4.2.2. Combining MRI and PSA Density

Prostate-specific antigen density (PSA-D) may help refine the risk of csPCa in patients undergoing MRI as PSA-D and the PI-RADS score are significant independent predictors of csPCa at biopsy [287,288]. Combinations of PSA-D and MRI have been explored [289,290], showing guidance in biopsy-decisions whilst safely avoiding redundant biopsy testing and detection of insignificant PCa. In a meta-analysis of eight studies, pooled MRI NPV for ISUP grade group ≥ 2 cancer was 84% (95% CI: 81–87) in the whole cohort, 83% (95% CI: 80–84) in biopsy-naive men and 88% (95% CI: 85–91) in men with prior negative biopsies. In the subgroup of patients with PSA-D < 0.15 ng/mL/cc, NPV increased to respectively 90% (95% CI: 87–93), 89% (95% CI: 83–93) and 94% (95% CI: 91–97) [291]. In contrast, the risk of ISUP grade group ≥ 2 cancer is as high as 27–40% in patients with negative MRI and PSA-D > 0.15–0.20 ng/mL/cc [189,288,292-294].

Based on a meta-analysis of > 3,000 biopsy-naive men, a risk-adapted data table of csPCa was developed, linking PI-RADS score (1-2, 3, and 4-5) to PSA-D categories (< 0.10, 0.10–0.15, 0.15–0.20 and > 0.20 ng/mL) (Table 5.4) [289]. This risk-adapted matrix table may guide the decision to perform a biopsy.

In a multi-centre retrospective cohort of 1476 men with PIRADS 3 lesions and a prevalence of 18.5% of ISUP grade group ≥ 2 cancer, age, prior negative biopsy and PSA-D were significant independent predictors of the presence of ISUP grade group ≥ 2 cancer at subsequent systematic and targeted biopsy. Applying a PSA-D cut-off of 0.15 ng/mL/cc, 817 biopsy procedures (58.4%) would have been avoided at the cost of missing ISUP grade group ≥ 2 cancer in 91 men (6.5%); ISUP grade group 1 cancer would not have been detected in 115 men (8.2%) [295]. Two studies provided follow-up data for patients with PI-RADS scores of 1-3 and PSA-D <0.15 ng/ml/cc for whom biopsy was omitted. The cumulative incidence of ISUP grade group ≥ 2 cancer detection was 1.3% at two years [296] and 3.2% at 36 months [297].

Table 5.4: Risk data table of clinically significant prostate cancer, related to PI-RADS score and PSA-D categories in biopsy-naive men, clinically suspected of having significant disease [289]*

# Thompson IM et al. N Engl J Med. 2004 May 27;350(22):2239-46. Prevalence of prostate cancer among men with a prostate-specific antigen level < or = 4.0 ng/mL. [163].

Table adapted from: Schoots, IG and Padhani AR. BJU Int 2021 127(2):175. Risk-adapted biopsy decision based on prostate magnetic resonance imaging and prostate-specific antigen density for enhanced biopsy avoidance in first prostate cancer diagnostic evaluation, with permission from Wiley.

5.4.2.3. Risk calculators incorporating MRI finding

Several groups have developed comprehensive risk calculators which combine MRI findings with simple clinical data as a tool to predict subsequent biopsy results [298]. Some calculators underwent external validation with good results both in terms of discrimination and clinical utility and tended to outperform risk calculators not incorporating MRI findings [299-302]. However, their use is hindered by their miscalibration due to prevalence dependency (see section 5.4.1.1).

5.4.2.4. MRI in screening protocols

The inclusion of MRI may improve the diagnostic algorithm after a screening PSA, as it reduces the number of men that undergo biopsies while detecting more high-grade and less low-grade PCa [179,303,304]. The Stockholm-3 (STHLM3) screening trial randomised men with a PSA > 3 ng/mL between standard biopsies (10–12 cores) or MRI and standard plus targeted biopsies in the presence of a suspicious MRI. The percentage of men that underwent prostate biopsies in the standard group was double that of the MRI group. In this non-inferiority trial, the intention-to-treat (ITT) analysis found 18% and 21% ISUP grade group ≥2 cancer and 12% and 4% ISUP grade group 1 cancer in the standard and the MRI group, respectively [304].

In the GÖTEBORG-2 screening trial, 37,887 men between 50 and 60 years of age were invited to undergo regular PSA screening [305]. Participants with a PSA level above 3 ng/mL were randomly allocated to MRI and combined systematic- and targeted biopsy (reference group) or to MRI and targeted biopsy only in case of PI-RADS ≥ 3 lesions (experimental group). In the experimental group, the detection rate of ISUP grade group 1 cancers was reduced by half (detection ratio: 0.46, 95% CI: 0.33–0.64, p < 0.001); that of ISUP grade group ≥ 2 cancers was lower but not significantly different (detection ratio: 0.81, 95% CI: 0.60 to 1.1). In the reference group, ten of the 68 men with ISUP grade group ≥ 2 cancer were diagnosed by systematic biopsy only. All these ten patients were of intermediate risk. Thus, in a screening setting, the ‘MRI pathway’ may reduce the risk of over-diagnosis by half, at the cost of delaying detection of intermediate-risk tumours in a small percentage of patients. However, these good results were obtained at a single academic centre with double reading of the MRI, which may limit their generalisability in less experienced centres (see Sections 5.5.4).

The IP1-PROSTAGRAM study (PSA > 3 ng/mL; MRI PIRADS [Prostate Imaging – Reporting and Data System] > 2), tested MRI as the initial screening test, showed highest detection of csPCa for MRI compared to a PSA threshold followed by transrectal ultrasound-guided prostate (TRUS) biopsy in a population screening setting, with similar rates of biopsy and insignificant cancer [179]. This study proposed a pathway that combines PSA >=1 ng/ml and MRI score >=4, maintaining the detection of grade group ≥2 cancers while recommending fewer men for biopsies, as the preferred strategy to evaluate in future studies at the first screening round [306].

5.5. Biopsy strategy

Prostate biopsy can be performed using different strategies (systematic, targeted etc) and approaches (i.e. transperineal vs. transrectal).

5.5.1. Systematic biopsy strategy

For systematic biopsies, where no prior imaging is used for targeting, the sample sites should be bilateral from apex to base, as far posterior and lateral as possible in the peripheral gland regardless of the approach used. A 2006 SR showed that twelve is the minimum number of cores for systematic biopsies, with > twelve cores not increasing cancer detection rate significantly [307].

5.5.2. Targeted biopsy strategy

Where MRI has shown a suspicious lesion, MR-targeted biopsy can be obtained through cognitive guidance, US/MR fusion software or direct in-bore guidance. Current literature, including SRs and meta-analyses, does not show a clear superiority of one image-guided technique over another [308-310]. The Target Biopsy Techniques Based on Magnetic Resonance Imaging in the Diagnosis of Prostate Cancer in Patients with Prior Negative Biopsies (FUTURE) randomised trial compared three techniques (cognitive fusion, software fusion, in-bore MRI) of MRI-targeted biopsy in the repeat-biopsy setting and found no differences in cancer detection [309].

5.5.3. Targeted biopsy versus systematic biopsy

5.5.3.1. Increased detection of cancers labelled as clinically significant

The PRECISION (Prostate Evaluation for Clinically Important Disease: Sampling Using Image Guidance or Not?) [121] and PRECISE (Prostate Evaluation for Clinically Important Disease: MRI vs. Standard Evaluation Procedures) [188] prospective trials randomized biopsy naïve patients to either ten to twelve core systematic biopsy or to MRI with subsequent MRI-targeted biopsy (up to four cores) in case of positive MRI. They found that MRI-targeted biopsy significantly out-performed [121] or was not inferior to [188] systematic biopsy for the detection of ISUP grade group ≥ 2 cancers. In pooled data of 25 reports on agreement analysis (head-to-head comparisons) between systematic biopsy (median number of cores: 8–15) and MRI-targeted biopsies (median number of cores: 2–7), the detection ratio (i.e. the ratio of the detection rates obtained by MRI-targeted biopsy alone and by systematic biopsy alone) was 1.12 (95% CI: 1.02–1.23) for ISUP grade group ≥ 2 cancers and 1.20 (95% CI: 1.06–1.36) for ISUP grade group ≥ 3 cancers, and therefore in favour of MRI-targeted biopsy [168]. Another meta-analysis of studies limited to biopsy-naive patients with a positive MRI also found that MRI-targeted biopsy detected significantly more ISUP grade group ≥ 2 cancers than systematic biopsy (risk difference, -0.11 [95% CI: -0.2 to 0.0]; p = 0.05) [311]. This data was confirmed in prospective multi-centre trials evaluated MRI-targeted biopsy in biopsy-naive patients [121,189].

In a subgroup of 152 patients from the FUTURE trial who underwent both MRI-targeted biopsy and systematic biopsy in a repeat biopsy setting, MRI-targeted biopsy detected significantly more ISUP grade group ≥ 2 cancers than systematic biopsy (34% vs. 16%; p < 0.001, detection ratio of 2.1) [191]. These findings support that MRI-targeted biopsy significantly out-performs systematic biopsy for the detection of ISUP grade ≥ 2 also in the repeat-biopsy setting.

5.5.3.2. Reduced detection of cancers labelled as ISUP grade group 1

In pooled data of 25 head-to-head comparisons between systematic biopsy and MRI-targeted biopsy, the detection ratio for ISUP grade group 1 cancers was 0.62 (95% CI: 0.44–0.88) in patients with prior negative biopsy and 0.63 (95% CI: 0.54–0.74) in biopsy-naive patients [186]. In the PRECISION and 4M trials, the detection rate of ISUP grade group 1 patients was significantly lower in the MRI-targeted biopsy group as compared to systematic biopsy (9% vs. 22%, p < 0.001, detection ratio of 0.41 for PRECISION; 14% vs. 25%, p < 0.001, detection ratio of 0.56 for 4M) [121,189]. In the MRI-FIRST trial, MRI-targeted biopsy detected significantly fewer patients with clinically insignificant PCa (defined as ISUP grade group 1 and maximum cancer core length < 6 mm) than systematic biopsy (5.6% vs. 19.5%, p < 0.0001, detection ratio of 0.29) [190]. Consequently, MRI-targeted biopsy without systematic biopsy significantly reduces over-diagnosis of low-risk disease, as compared to systematic biopsy. This seems true even when systematic biopsies are indicated after risk stratification with the Rotterdam Prostate Cancer Risk Calculator) [286].

5.5.3.3. Added value of systematic biopsy and targeted biopsy

From head-to-head comparisons between the two biopsy techniques, it is possible to compute their added value, i.e. the percentage of additional patients with csPCa they contribute to diagnose. Table 5.3 shows the added value of systematic and MRI-targeted biopsy for ISUP grade group ≥ 2 and ≥ 3 cancer detection. The absolute added values in the table refer to the percentage of patients in the entire cohort; if the cancer prevalence is considered, the ‘relative’ percentage of additional detected csPCa can be computed. Adding MRI-targeted biopsy to systematic biopsy in biopsy-naive patients increases the number of detected ISUP grade ≥ 2 and grade ≥ 3 PCa by approximately 20% and 30%, respectively. In the repeat-biopsy setting, adding MRI-targeted biopsy increases detection of ISUP grade group ≥ 2 and grade group ≥ 3 PCa by approximately 40% and 50%, respectively. Omitting systematic biopsy in biopsy-naive patients would miss approximately 16% of all detected ISUP grade group ≥ 2 PCa and 18% of all ISUP grade ≥ 3 PCa. In the repeat-biopsy setting, it would miss approximately 10% of ISUP grade group ≥ 2 PCa and 9% of ISUP grade group ≥ 3 Pca. The low added value of systematic biopsy in the repeat biopsy setting has been further confirmed by other studies that reported absolute added values of 1.2-3.9% for the detection of ISUP grade group ≥2 cancers and of 1.2-1.6% for ISUP grade group ≥ 3 cancers [191,312,313].

Table 5.5: Absolute added values of targeted and systematic biopsies for ISUP grade ≥ 2 and ≥ 3 Cancer Detection

*Intervals in parenthesis are 95% CI.
The absolute added value of a given biopsy technique is defined by the percentage of patients of the entire cohort diagnosed only by this biopsy technique.
ISUP = International Society of Urological Pathology (grade); MRI-TBx = magnetic resonance imaging-targeted biopsies; ND = not defined.

Table 5.6: Detection rates of ISUP grade group 1 cancers by targeted and systematic biopsies

* In the MRI-FIRST trial, the percentages refer to the detection rates of ISUP 1 cancers with a maximum cancer core length < 6 mm

5.5.4. Perilesional biopsy

A minimum of three to five cores is required for proper sampling of an MRI detected lesion [313,314]. Including additional peri-lesional/regional systematic biopsies, rather than standard sextant-based systematic biopsies may decrease the total number of cores taken (by avoiding systematic biopsies in MRI-negative lobes) and improve the detection of csPCa (by compensating for guiding imprecision). In addition, the MRI-targeted and regional biopsy approach could avoid detecting 12-17% of the insignificant cancers detected by the classical combined approach [315-317].

A meta-analysis of eight studies showed a non-significant difference in detection of ISUP grade group ≥2 cancer in the MRI-directed targeted and regional biopsy approach, compared to the recommended practice of MRI-directed targeted- and systematic biopsy approach (RR: 0.95, 95% CI: 0.90–1.01; p = 0.09). However, the MRI-directed targeted- and regional biopsy approach detected significantly more ISUP grade group ≥2 cancers than MRI-targeted biopsy alone (RR: 1.18, 95% CI: 1.10–1.25; p < 0.001) [255]. Other prospective [318] and retrospective [317,319] studies not included in the meta-analysis provided similar evidence
(Table 5.7).

Two studies retrospectively used the location of biopsy cores registered by MRI/US fusion systems to assess the added value of systematic cores based on their distance from the nearest MRI lesion. The diagnostic yield of these systematic cores decreased with increasing distance. Combining the targeted and systematic cores located within a 10 mm and a 15 mm radius from the MR lesions detected 90-92% and 94-97% of the csPCa respectively [315,316]. The width of the distance from the MRI lesion which enclosed 90% of csPCa may also depend on the PI-RADS score of the lesion; in one series it was found to be 5.5 mm, 12 mm and 16 mm for lesions with PI-RADS scores of 5, 4 and 3 respectively [315]. As a consequence, in men with a PI-RADS 5 index lesion, the absolute added value of additional biopsy has been repeatedly found to be less than 4% for ISUP grade group ≥ 2 cancers and less than 2% for ISUP grade group ≥ 3 cancers [313,320-322].

5.5.5. Prostate MRI and MRI-targeted biopsy reproducibility

Despite the use of the PI-RADS scoring systems, MRI inter-reader reproducibility remains moderate at best. MRI performance is better with experienced radiologists and at high-volume centres. This currently limits its broad use by non-dedicated radiologists [314,323].

The accuracy of MRI-targeted biopsy is also substantially impacted by the experience of the biopsy operator [314]. The PRECISE trial, that reproduced the design of the PRECISION trial obtained quite different results. In both trials, the detection rate for ISUP grade group ≥2 PCa was higher for the MRI pathway than for the classical systematic biopsy pathway. Yet, the difference was much lower in the PRECISE trial (+5.2% vs. +12.1% for ISUP grade group ≥2 cancers; +2.1% vs. +5.5% for ISUP grade group ≥3 cancers). In addition, there was major intersite variability in the PRECISE trial: the centre with the highest csPCa detection rate on MRI-targeted biopsy had the lowest on systematic biopsy and vice versa.

These factors of variability give rise to concerns about the reproducibility of the good results of the MRI-directed diagnostic pathways. Efforts towards standardization of the whole diagnostic pathway (MRI acquisition and interpretation, biopsy planning and acquisition) through quality assurance and quality control are currently undertaken [314,324]. However, significant improvement in the accuracy of MRI and MRI-targeted biopsy can be observed over time through simple measures such as training and participation to MDT meeting with pathological correlation and feedback [314,325]. Whether artificial intelligence-based assistance will improve MRI interpretation accuracy remains questionable, as preliminary studies reported conflicting results on the topic [326].

5.5.6. Cancer grade shift

MRI findings are significant predictors of adverse pathology features on prostatectomy specimens, and of survival-free BCR after RP or RT [96,327,328]. In addition, tumours visible on MRI are enriched in molecular hallmarks of aggressivity, as compared to invisible lesions [329]. Thus, MRI does identify aggressive tumours.

Nonetheless, as MRI-targeted biopsy is more sensitive than systematic biopsy in detecting areas of high-grade cancer, ISUP grade group ≥ 2 cancers detected by MRI-targeted biopsy are, on average, of better prognosis than those detected by the classical diagnostic pathway (Will Rogers phenomenon [98]. This is illustrated in a retrospective series of 1,345 patients treated by RP which showed that, in all risk groups, patients diagnosed by MRI-targeted biopsy had better BCR-free survival than those diagnosed by systematic biopsy only [96]. To mitigate this grade shift, in case of targeted biopsies, the 2019 ISUP consensus conference recommended using an aggregated ISUP grade group summarizing the results of all biopsy cores from the same MR lesion, rather than using the result from the core with the highest ISUP grade group [101] (see pathology section 4.2). When long term follow-up of patients who underwent MRI-targeted biopsy is available, a revision of the risk-groups definition will become necessary. In the meantime, results of MRI-targeted biopsy must be interpreted in the context of this potential grade shift [330].

Table 5.7: Detection rates for ISUP grade group ≥2 prostate cancer achieved by targeted biopsy, combined systematic and targeted biopsy and targeted biopsy with perilesional sampling

5.5.7. Guidelines for MRI imaging in biopsy indication and strategy

5.6. Biopsy approach

Ultrasound (US)-guided prostate biopsy is now the standard of care although MRI in-bore biopsy is now possible in a few centres. Ultrasound-guided prostate biopsy can be performed by either the transperineal approach or the transrectal one. Both can be performed under local anaesthesia [333]. However, the only SR and meta-analysis comparing MRI-targeted transrectal biopsy to MRI-targeted transperineal biopsy, analysing 8 studies, showed a higher sensitivity for detection of csPCa when the transperineal approach was used (86% vs. 73%) [334]. This benefit was especially pronounced for anterior tumours. Evidence also suggests reduced infection risk with the transperineal route (see Section 5.2.8.1.1) [335,336].

5.6.1. Local anaesthesia prior to biopsy

Ultrasound-guided peri-prostatic block is recommended [337]. Ten mL of 2% lidocaine is infiltrated bilaterally along the apex to base. Intra-rectal instillation of local anaesthesia is inferior to peri-prostatic infiltration [338]. Local anaesthesia can also be used effectively for MRI-targeted and systematic transperineal biopsy [339]. Patients are placed in the lithotomy position. Twenty mL of 0.5% bupivacaine with adrenaline (1 in 200,000) is injected into the perineal skin and subcutaneous tissues anterior to the anus, followed two minutes later by a peri-prostatic block. A SR evaluating pain in 3 studies comparing transperineal vs. transrectal biopsies found that the transperineal approach significantly increased patient pain (RR: 1.83 [1.27–2.65]) [340]. In a randomised comparison a combination of peri-prostatic and pudendal block anaesthesia reduced pain during transperineal biopsies compared to peri-prostatic anaesthesia only [341]. Targeted biopsies can then be taken via a brachytherapy grid or a freehand needle-guiding device under local infiltration anaesthesia [339,342]. Perineal nerve-block was superior for the relief of pain during the biopsy procedure versus periprostatic block (2.80 vs. 3.98; on 1-10 scale) [343].

5.6.2. Transperineal prostate biopsy

A total of eight randomised studies including 1,596 patients compared the impact of biopsy route on infectious complications. Infectious complications were significantly higher following transrectal biopsy (48 events among 789 men) compared to transperineal biopsy (22 events among 807 men) (RR: 95% CI: 2.48 [1.47–4.2]) [344,345]. In addition, a SR including 165 studies with 162,577 patients described sepsis rates of 0.1% and 0.9% for transperineal and transrectal biopsies, respectively [346]. Finally, a population-based study from the UK (n = 73,630) showed lower re-admission rates for sepsis in patients who had transperineal vs. transrectal biopsies (1.0% vs. 1.4%, respectively) [347]. The available evidence demonstrates that the transrectal approach should be abandoned in favour of the transperineal approach despite any possible logistical challenges. A SR and meta-analysis of eight non-RCTs reported no significant differences between patients receiving or not receiving antibiotic prophylaxis in terms of post-biopsy infection (0,11% vs. 0.31%) and sepsis (0.13% vs. 0,09%), for the transperineal approach [348]. This is in line with another SR and meta-analysis of 112 individual patient cohorts which also showed no significant difference in the number of patients experiencing post-transperineal-biopsy infection 1.35% of 29,880 patients receiving antibiotic prophylaxis and 1.22% of 4,772 men not receiving antibiotic prophylaxis (p = 0.8) [349]. In addition, two published RCTs have reported comparably low post-biopsy infection rates for transperineal biopsy regardless of whether antibiotic prophylaxis was administered or not [350,351]. A SR and meta-analysis comparing transperineal with and without antibiotic prophylaxis showed very low percentages of septic complications (0.05% vs. 0.08%; p=0.2) and overall infections (1.35% vs. 1.22%; p=0.8)

Thus, there is a growing body of evidence to suggest that antibiotic prophylaxis may not be required for transperineal biopsy; however, the Panel has chosen to wait until a number of ongoing RCTs report their study findings before making a recommendation on this.

5.6.3. Transrectal prostate biopsy

An updated meta-analysis of eleven RCTs including 2,237 men showed that use of a rectal povidone-iodine preparation before biopsy, in addition to antimicrobial prophylaxis, resulted in a significantly lower rate of infectious complications (RR: 95% CI: 0.47 [0.36–0.61]) [345,352,353]. Single RCTs showed no evidence of benefit for perineal skin disinfection [354], but reported an advantage for rectal povidone-iodine preparation before biopsy compared to after biopsy [355].

A meta-analysis of four RCTs including 671 men evaluated the use of rectal preparation by enema before transrectal biopsy. No significant advantage was found regarding infectious complications (RR: 95% CI: 0.96 [0.64–1.54]) [345].

An updated meta-analysis of 28 RCTs with 4,027 patients found no evidence that use of periprostatic injection of local anaesthesia resulted in more infectious complications than no injection (RR: 95% CI: 1.08 [0.79–1.48]) [344,345,353]. A meta-analysis of nine RCTs including 2,230 patients found that extended biopsy templates showed comparable infectious complications to standard templates (RR: 95% CI: 0.80 [0.53–1.22]) [345]. Additional meta-analyses found no difference in infectious complications regarding needle guide type (disposable vs. reusable), needle type (coaxial vs. non-coaxial), needle size (large vs. small), and number of injections for peri-prostatic nerve block (standard vs. extended) [345].

A meta-analysis of eleven studies with 1,753 patients showed significantly reduced infections after transrectal prostate biopsy when using antimicrobial prophylaxis as compared to placebo/control (RR: 95% CI: 0.56 [0.40–0.77]) [356].

Fluoroquinolones have been traditionally used for antibiotic prophylaxis in this setting; however, in recent years there has been an increase in fluoroquinolone resistance. In addition, the European Commission has implemented stringent regulatory conditions regarding the use of fluoroquinolones resulting in the suspension of the indication for peri-operative antibiotic prophylaxis including prostate biopsy [357].

A SR and meta-analysis on antibiotic prophylaxis for the prevention of infectious complications following prostate biopsy concluded that in countries where fluoroquinolones are allowed as antibiotic prophylaxis, a minimum of a full one-day administration, as well as targeted therapy in case of fluoroquinolone resistance, or augmented prophylaxis (combination of two or more different classes of antibiotics) is recommended [356]. In countries where use of fluoroquinolones are suspended, cephalosporins or aminoglycosides can be used as individual agents with comparable infectious complications based on meta-analysis of two RCTs [356]. A meta-analysis of three RCTs reported that fosfomycin trometamol was superior to fluoroquinolones (RR: 95% CI: 0.49 [0.27–0.87]) [356], but routine general use should be critically assessed due to the relevant infectious complications reported in non-randomised studies [358]. Of note the indication of fosfomycin trometamol for prostate biopsy has been withdrawn in Germany as the manufacturers did not submit the necessary pharmacokinetic data in support of this indication. Urologists are advised to check their local guidance in relation to the use of fosfomycin trometamol for prostate biopsy. Another possibility is the use of augmented prophylaxis without fluoroquinolones, although no standard combination has been established to date. Finally, targeted prophylaxis based on rectal swap/stool culture is plausible, but no RCTs are available on non-fluoroquinolones. See figure 5.1 for prostate biopsy workflow to reduce infections complications.

5.6.4. Summary of evidence and recommendations for performing prostate biopsy (in line with the EAU Urological Infections Guidelines Panel)

* Note on strength ratings:
The above strength ratings are explained here due to the major clinical implications of these recommendations. Although data showing the lower risk of infection via the transperineal approach is low in certainty, its statistical and clinical significance warrants its strong rating. Strong ratings are also given for routine surgical disinfection of skin in transperineal biopsy and povidone-iodine rectal cleansing in transrectal biopsy as, although quality of data is low, the clinical benefit is high and practical application simple. A ‘Strong’ rating is given for avoiding fluoroquinolones in prostate biopsy due to its legal implications in Europe.
** The indication of fosfomycin trometamol for prostate biopsy has been withdrawn in Germany as the manufacturers did not submit the necessary pharmacokinetic data in support of this indication. Urologists are advised to check their local guidance in relation to the use of fosfomycin trometamol for prostate biopsy.

Figure 5.2: Prostate biopsy workflow to reduce infectious complications*Suggested workflow on how to reduce post biopsy infections.
1. Two systematic reviews including non-RCTs and two RCTs describe comparable rates of post-transperineal biopsy infection in patients with and without antibiotic prophylaxis.
2. Be informed about local antimicrobial resistance.
3. Banned by European Commission due to side effects.
4. Contradicts principles of Antimicrobial Stewardship.
5. Only one RCT comparing targeted and augmented prophylaxis.
6. Originally introduced to use alternative antibiotics in case of fluoroquinolone resistance.
7. Various schemes: fluoroquinolone plus aminoglycoside (3 RCTs); and fluoroquinolone plus cephalosporin(1 RCT).

GRADE Working Group grades of evidence. High certainty: (⊕⊕⊕⊕) very confident that the true effect lies closeto that of the estimate of the effect. Moderate certainty: (⊕⊕⊕⊖) moderately confident in the effect estimate:the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: (⊕⊕⊖⊖) confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: (⊕⊖⊖⊖) very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect. Figure adapted from Pilatz et al., with permission from Elsevier.[356]

* Of note: local guidance in relation to the use of fosfomycin trometamol for prostate biopsy needs to be checked.

5.6.5. Complications

Complications of TRUS biopsy are listed in Table 5.5 [359]. Mortality after prostate biopsy is extremely rare and most are consequences of sepsis [360]. Low-dose aspirin is not an absolute contra-indication [361]. A SR found favourable infection rates for transperineal compared to TRUS biopsies with similar rates of haematuria, haematospermia and urinary retention [362]. A meta-analysis of 4,280 men randomised between transperineal vs. TRUS biopsies in thirteen studies found no significant differences in complication rates, however, data on sepsis compared only 497 men undergoing TRUS biopsy to 474 having transperineal biopsy. The transperineal approach required more (local) anaesthesia [363].

Table 5.8: Adverse events of three groups of targeted biopsy [359]*

COG-TB = cognitive registration TRUS targeted biopsy; FUS-TB = MRI-TRUS fusion targeted biopsy; MRI = magnetic resonance imaging; MRI-TB = in-bore MRI targeted biopsy; TB = targeted biopsy; TRUS = transrectal ultrasound; UTI = urinary tract infection. Data are presented as % (n).
*With permission by Elsevier.

5.7. What diagnostic pathway in clinical practice?

The ‘combined pathway’, in which patients with a positive MRI undergo combined systematic and targeted biopsy, and patients with a negative MRI undergo systematic biopsy, maximises the detection of ISUP grade group ≥2 cancers. However, it has the disadvantage of leading to a greater detection of ISUP grade group 1 cancers and of referring all patients with a clinical suspicion of cancer to biopsy. Given the growing concerns about over-detection of insignificant PCa, the development of AS protocols in patients with ISUP grade group 2 cancers (see section 6.2.1.2.1) and the grade shift induced by MRI-targeted biopsy (see section 5.5.5) the clinical relevance of a diagnostic strategy aimed only at maximising the detection of ISUP grade group ≥ 2 cancers is questionable [364,365].

The ‘MRI pathway’ in which patients with a positive MRI undergo only MRI-targeted biopsy and patients with a negative MRI are not biopsied at all could avoid biopsy in 21-49% of the patients if a PI-RADS threshold of ≥3 is used to trigger biopsy [121,186,189,190], at the cost of missing some significant cancers, especially in biopsy-naïve patients or in highly selected populations with high prevalence of csPCa (in which the MRI NPV decreases) [284,366].

Several alternative MRI-directed diagnostic pathways can be envisaged to correct these limitations, for example by selecting patients for biopsy based on a combination of MRI findings and clinical data or by adding perilesional sampling to MRI-targeted biopsy.

The best pathway remains unclear as prospective evaluations are lacking. Interestingly, in a study different MRI-directed pathways were compared to the classical combined pathway in a retrospective cohort of 499 men. The highest clinical utility above a risk threshold of 6.25% was obtained by a risk-based pathway in which patients with a PI-RADS score of 1-3 and a low-risk profile (PSA-D<0.15 ng/ml/cc, negative DRE, no family history, no ASAP or ISUP1 cancer at prior biopsy) could forgo biopsy while the others underwent combined systematic and MRI-targeted biopsy. In this pathway, biopsy could have been avoided in 99 men (19%) while missing ISUP grade group ≥ 2 cancers in only 6 men (1.2%) [367].

5.7.1. Repeat biopsy after negative biopsy

During follow-up after negative systematic biopsy, the incidence of PCa is higher, but the risk of PCa death is lower than the population average [368]. Men with prior negative systematic biopsy and persistent suspicion of PCa should have an MRI if not already performed.

Significant PCa may still be present in men with abnormal MRI and negative targeted biopsy [369]. Follow-up or direct repeat biopsy should be considered dependent on risk factors (e.g. PSA density, PIRADS).

In a contemporary series of biopsies the likelihood of finding a csPCa after follow-up biopsy after a diagnosis of atypical small acinar proliferation and high-grade prostatic intraepithelial neoplasia (PIN) was only 6-8%, not significantly different from follow-up biopsies after a negative biopsy [370,371].

The added value of other biomarkers remains unclear (see Sections 5.2.5.1 and 5.2.5.2).

5.7.2. Saturation biopsy

The incidence of PCa detected by saturation repeat biopsy (> 20 cores) is 30–43% and depends on the number of cores sampled during earlier biopsies [372]. Saturation biopsy may be performed with the transperineal technique, which detects an additional 38% of PCa. The rate of urinary retention varies substantially from 1.2% to 10% [235,373].

However, given the very low risk of subsequent csPCa after a negative biopsy and/or in case of negative MRI, the clinical utility of saturation biopsy in the repeat biopsy setting remains uncertain in the current MRI-driven diagnostic pathway and such schemes should not be routinely used [374].

5.7.3. Seminal vesicle biopsy

Indications for SV (staging) biopsies are poorly defined. At a PSA of > 15 ng/mL, the odds of tumour involvement are 20–25% [375]. A SV staging biopsy is only useful if it has a decisive impact on treatment, such as ruling out radical tumour resection or for potential subsequent RT. Its added value compared with MRI is questionable.

5.7.4. Transition zone biopsy

Transition zone sampling during baseline biopsies has a low detection rate and should be limited to MRI detected lesions or repeat template biopsies [376].

5.8. Diagnosis - Clinical Staging

5.8.1. T-staging

The cT category listed in Table 4.1 (TNM Classification) only relies on DRE findings. Imaging parameters and biopsy results for local staging are, so far, not part of the T staging (within TNM) and the EAU risk category stratification [377].

5.8.1.1. Ultrasound-based techniques and Computed Tomography

Transrectal US has limited accuracy for PCa local staging [378]. More advanced US-based techniques have not yet been tested in large-scale studies. In case of locally-advanced cancers, abdominopelvic US or CT may show rectal or bladder invasion and dilatation of the upper collecting systems [378].

5.8.1.2. Magnetic Resonance Imaging

T2-weighted imaging remains the most useful method for local staging on MRI. Pooled data from a meta-analysis showed a sensitivity and specificity of 0.57 (95% CI: 0.49–0.64) and 0.91 (95% CI: 0.88–0.93), 0.58 (95% CI: 0.47–0.68) and 0.96 (95% CI: 0.95–0.97), and 0.61 (95% CI: 0.54–0.67) and 0.88 (95% CI: 0.85–0.91), for EPE, SVI, and overall stage T3 assessment, respectively [379]. Detection of EPE and SVI seems more accurate at high field strength (3 Tesla) [379], while the added value of functional imaging remains debated [379,380].

In 552 men treated by RP at seven different Dutch centres, MRI showed significantly higher sensitivity (51% vs. 12%; p < 0.001), and lower specificity (82% vs. 97%; p < 0.001) than DRE for non-organ confined disease. All risk groups redefined using MRI findings rather than DRE findings showed better BCR-free survival due to improved discrimination and the Will Roger’s phenomenon [381].

Traditionally, EPE/SVI is assessed visually using qualitative signs (e.g., capsular disruption, visible tumour within peri-prostatic fat). Inter-reader agreement with such subjective reading is moderate, with kappa (k) values ranging from 0.41 to 0.68 [382]. The length of tumour capsule contact (LCC) is also a significant predictor of EPE; it has the advantage of being quantitative, although the ideal cut-off value remains debated [383,384].

Several grading systems combining subjective qualitative signs and/or LCC into a score have shown good sensitivity (0.64–0.82) and specificity (0.64-0.93) for EPE, with substantial inter-reader agreement
(κ = 0.56–0.74). None of these scores has shown definitive superiority over the others [385,386].

Magnetic resonance imaging findings can improve the prediction of the pathological stage when combined with clinical and biopsy data. As a result, several groups developed multivariate risk calculators for predicting EPE/SVI or positive surgical margins [387]. In external validation cohorts, these risk calculators showed significantly better discrimination than nomograms without MRI-based features [388-390]. However, their results must be interpreted with care given potential miscalibration due to varying prevalence of EPE/SVI.

Given its low sensitivity for focal (microscopic) EPE, MRI is not recommended for local staging in low-risk patients. However, MRI can still be useful for treatment planning.

5.8.2. N-staging

5.8.2.1. Computed tomography and MRI

Abdominal CT and T1-T2-weighted MRI indirectly assess nodal invasion by using LN diameter and morphology. However, the size of non-metastatic LNs varies widely and may overlap the size of LN metastases. Usually, LNs with a short axis > 8 mm in the pelvis and > 10 mm outside the pelvis are considered malignant. Decreasing these thresholds improves sensitivity but decreases specificity. As a result, the ideal size threshold remains unclear [391,392]. Computed tomography and MRI sensitivity is less than 40% [393,394]. Detection of microscopic LN invasion by CT is < 1% in patients with ISUP grade group < 4 cancer, PSA < 20 ng/mL, or localised disease [391,395].

Diffusion-weighted MRI (DW-MRI) may detect metastases in normal-sized nodes, but a negative DW-MRI cannot rule out the presence of LN metastases, and DW-MRI provides only modest improvement for LN staging over conventional imaging [396].

5.8.2.2. Risk calculators incorporating MRI findings and clinical data

Because CT and MRI lack sensitivity for direct detection of positive LNs, nomograms combining clinical and biopsy findings have been used to estimate the risk of patients harbouring positive LNs [397-399]. Although these nomograms are associated with good performance, they have been developed using systematic biopsy findings and may therefore not be appropriate for patients diagnosed with combined MRI-targeted biopsy and systematic biopsy.

Two models incorporating MRI-targeted biopsy findings and MRI-derived findings recently underwent external validation [256,400]. One model was tested on an external cohort of 187 patients with a prevalence of LN invasion of 13.9% (vs. 16.9% in the development cohort). The C-index was 0.73 (vs. 0.81 in the development cohort); at calibration analysis, the model tended to overpredict the actual risk [400]. The Briganti 2019 model was validated in an external multi-centre cohort of 487 patients with a prevalence of 8% of LN invasion (vs. 12.5% in the development cohort). The AUC was 0.79 (vs. 0.81 in the development cohort). Using a risk cut-off of 7% would have avoided LN dissection in 273 (56% of the cohort), while missing LN invasion in seven patients (2.6% of the patients below the 7% threshold; 18% of the 38 patients with LN invasion) [401]. Another cohort of 150 high-risk patients with a LN invasion prevalence of 26% was retrospectively used to externally assess four different nomograms. All showed high sensitivity (>0.95) and low specificity (<0.19) at the tested thresholds. Using the 7% threshold, the Briganti 2019 nomogram had a sensitivity of 0.96 and a specificity of 0.18 [402]. The calibration of the nomogram will be affected by the prevalence of LN involvement in your population.

5.8.2.3. Choline PET/CT

In a meta-analysis of 609 patients, pooled sensitivity and specificity of choline PET/CT for pelvic LN metastases were 62% (95% CI: 51–66%) and 92% (95% CI: 89–94%), respectively [403]. In a prospective trial of 75 patients at intermediate risk of nodal involvement (10–35%), the sensitivity was only 8.2% at region-based analysis and 18.9% at patient-based analysis, which is too low to be of clinical value [404]. The sensitivity of choline PET/CT increases to 50% in patients at high risk and to 71% in patients at very high risk [405].

5.8.2.4. Prostate-specific membrane antigen-based PET/CT

Prostate-specific membrane antigen PET/CT uses several different radiopharmaceuticals; most published studies used 68Ga-labelling for PSMA PET imaging, but some used 18F-labelling (e.g., 18F-DCFPyL, 18F-PSMA-1007, 18F-PSMA-JK-7). PSMA is also an attractive target because of its specificity for prostate tissue, even if the expression in other non-prostatic malignancies or benign conditions may cause incidental false-positive findings [406,407].

A multi-centre prospective phase III imaging trial, investigating men with intermediate- and high-risk PCa who underwent RP and PLND, showed a sensitivity and specificity of 68Ga-PSMA-11 PET of 0.40 (95% CI: 0.34-0.46), and 0.95 (95% CI: 0.92-0.97), respectively [408]. This is line with previous results from prospective, multi-centre studies addressing the accuracy of 68Ga-PSMA and 18F-DCFPyL PET/CT for LN staging in patients with newly diagnosed PCa [409,410]. Comparable results were also demonstrated in a phase II/III prospective, multi-centre study (OSPREY) with a median specificity of 97.9% (95% CI: 94.5–99.4%) and median sensitivity of 40.3%(28.1–52.5%) for pelvic nodal involvement [411]. Prostate-specific antigen may be a predictor of a positive PSMA PET/CT. In the primary staging cohort from a meta-analysis, however, no robust estimates of positivity were found [412].

Comparison between PSMA PET/CT and MRI was performed in a SR and meta-analysis including 13 studies (n = 1,597) [413]. 68Ga-PSMA was found to have a higher sensitivity and a comparable specificity for staging pre-operative LN metastases in intermediate- and high-risk PCa [414].

Prostate specific membrane antigen PET/CT has a good sensitivity and specificity for LN involvement, possibly impacting clinical decision-making. In a review and meta-analysis including 37 articles, a subgroup analysis was performed in patients undergoing PSMA PET/CT for primary staging. On a per-patient-based analysis, the sensitivity and specificity of 68Ga-PSMA PET were 77% and 97%, respectively, after eLND at the time of RP. On a per-lesion based analysis, sensitivity and specificity were 75% and 99%, respectively [412].

In summary, PSMA PET/CT is more sensitive in N-staging as compared to MRI, abdominal contrast-enhanced CT or choline PET/CT. However, small LN metastases, under the spatial resolution of PET, may still be missed.

5.8.2.5. Risk calculators incorporating MRI and PSMA findings

An international, multi-centre study incorporated PSMA PET into existing nomograms in order to predict pelvic LN metastatic disease in PCa patients. Performance of three nomograms was assessed in 757 patients undergoing RARP and ePLND. Addition of PSMA PET to the nomograms substantially improved the discriminative ability of the models yielding cross-validated AUCs of 0.76 (95% CI: 0.70–0.82), 0.77 (95% CI: 0.72–0.83), and 0.82 (95% CI: 0.76–0.87), respectively [415].

5.8.3. M-staging

5.8.3.1. Bone scan

^99mTc-Bone scan is a highly sensitive conventional imaging technique, evaluating the distribution of active bone formation in the skeleton related to malignant and benign disease. A meta-analysis showed combined sensitivity and specificity of 79% (95% CI: 73–83%) and 82% (95% CI: 78–85%) at patient level [416]. Bone scan diagnostic yield is significantly influenced by the PSA level, the clinical stage and the tumour ISUP grade group [391,417]. A retrospective study investigated the association between age, PSA and GS in 703 newly diagnosed PCa patients who were referred for bone scintigraphy. The incidence of bone metastases increased substantially with rising PSA and upgrading GS [418]. In two studies, a dominant Gleason pattern of 4 was found to be a significant predictor of positive bone scan [419,420]. Bone scanning should be performed in symptomatic patients, independent of PSA level, ISUP grade group or clinical stage [391].

5.8.3.2. Fluoride PET/CT, choline PET/CT and MRI

¹⁸F-sodium fluoride (¹⁸F-NaF) PET or PET/CT, similarly to bone scintigraphy, only assesses the presence of bone metastases. The tracer was reported to have similar specificity and superior sensitivity to bone scintigraphy for detecting bone metastases in patients with newly diagnosed high-risk PCa [421,422]. Interobserver agreement for the detection of bone metastases was excellent, demonstrating that 18F-NaF PET/CT is a robust tool for the detection of osteoblastic lesions in patients with PCa [423].

It remains unclear whether choline PET/CT is more sensitive than bone scan but it has higher specificity with fewer indeterminate bone lesions [424-426]. Choline PET/CT has also the advantage of detecting visceral and nodal metastases.

Diffusion-weighted whole-body and axial skeleton MRI are more sensitive than bone scan and targeted conventional radiography in detecting bone metastases in high-risk PCa. Whole-body MRI can also detect visceral and nodal metastases; it was shown to be more sensitive and specific than combined bone scan, targeted radiography and abdominopelvic CT [427]. A meta-analysis found that whole-body MRI is more sensitive than choline PET/CT and bone scan for detecting bone metastases on a per-patient basis, although choline PET/CT had the highest specificity [416].

5.8.3.3. PSMA PET/CT

A SR including twelve studies (n = 322) reported high variation in ⁶⁸Ga-PSMA PET/CT sensitivity for initial staging (range 33–99%; median sensitivity on per-lesion analysis 33–92%, and on per-patient analysis 66–91%), with good specificity (per-lesion 82–100%, and per-patient 67–99%), with most studies demonstrating increased detection rates with respect to conventional imaging modalities (bone scan and CT) [428].

In a prospective multi-centre study in patients with high-risk PCa before curative surgery or RT (proPSMA), 302 patients were randomly assigned to conventional imaging or ⁶⁸Ga-PSMA-11 PET/CT [429]. The primary outcome focused on the accuracy of first-line imaging for the identification of pelvic LN or distant metastases. Accuracy of ⁶⁸Ga-PSMA PET/CT was 27% (95% CI: 23–31) higher than that of CT and bone scintigraphy (92% [95% CI: 88–95] vs. 65% [95% CI: 60–69]; p < 0.0001). Conventional imaging had a lower sensitivity (38% [95% CI: 24–52] vs. 85% [95% CI: 74–96]) and specificity (91% [95% CI: 85–97] vs. 98% [95% CI: 95–100]) than PSMA PET/CT. Furthermore, ⁶⁸Ga-PSMA PET/CT scan prompted management change more frequently as compared to conventional imaging (41 [28%] men [95% CI: 21–36] vs. 23 [15%] men [95% CI: 10–22], p = 0.08), with less equivocal findings (7% [95% CI: 4–13] vs. 23% [95% CI: 17–31]) and lower radiation exposure (8.4 mSv vs. 19.2 mSv; p < 0.001) [429].The comparison of whole body MRI and PSMA PET/CT in detecting bone metastases has led to inconclusive opposite results in two small cohorts [414,430].

5.8.4. Summary of evidence and practical considerations on initial N/M staging

The field of non-invasive N- and M-staging of PCa patients is evolving very rapidly. Evidence shows that choline PET/CT, PSMA PET/CT and whole-body MRI provide a more sensitive detection of LN- and bone metastases than the classical work-up with bone scan and abdominopelvic CT. In view of the evidence offered by the randomised, multi-centre proPSMA trial [429], replacing bone scan and abdominopelvic CT by more sensitive imaging modalities may be a consideration in patients with high-risk PCa undergoing initial staging. However, in absence of prospective studies demonstrating survival benefit, caution must be used when taking therapeutic decisions [431]. The prognosis and ideal management of patients diagnosed as metastatic by these more sensitive tests is unknown. In particular, it is unclear whether patients with metastases detectable only with PET/CT or whole-body MRI should be managed using systemic therapies only, or whether they should be subjected to aggressive local and metastases-directed therapies [432].

Results from RCTs evaluating the management and outcome of patients with (and without) metastases detected by choline PET/CT, PSMA PET/CT and MRI are awaited before a recommendation can be made to treat patients based on the results of these tests.

5.8.5. Summary of evidence and guidelines for staging of prostate cancer