Magnetic Resonance Imaging (MRI) of prostate continues to transform the way prostate cancer is being diagnosed and risk stratified. Multiple prospective single (e.g. the Biparametric MRI for Detection of Prostate Cancer [BIDOC]  and Improved Prostate Cancer Diagnosis ‐ Combination of Magnetic Resonance Imaging and Biomarkers [IMPROD] ) and multi‐institution trials (e.g. PROstate MRI Imaging Study [PROMIS] , PRostate Evaluation for Clinically Important Disease: Sampling Using Image‐guidance Or Not? [PRECISION] , multi‐institutional IMPROD (Multi‐IMPROD) , Assessment of Prostate MRI Before Prostate Biopsies [MRI‐FIRST] ) have demonstrated the potential of prostate MRI to limit the number of unnecessary biopsies in men with suspected prostate cancer.
In this issue of the BJUI, Khoo et al.  retrospectively analysed reports from a multicentre prostate cancer pathway registry, Rapid Assessment and Prostate Imaging for Diagnosis (RAPID). Men with a clinical suspicion of prostate cancer were enrolled based on various clinical criteria such as: age, performance status, and PSA level. All men had a pre‐biopsy MRI, including dynamic contrast‐enhanced MRI, reported using a 5‐point Likert scale and Prostate Imaging Reporting and Data System version 2.0 (PI‐RADSv2.0) systems by one of four uro‐radiologists (5–9 years of experience of prostate multi‐parametric MRI). Subsequently, all Likert and PI‐RADSv2.0 scores were reviewed by a dedicated reader in a multidisciplinary team setting. Likert scores were reported with knowledge of clinical variables such as: PSA, patient age, and past medical history. Men with Likert or PI‐RADSv2.0 score ≥4 or a score of 3 with a PSA density ≥0.12 ng/mL/mL underwent transperineal targeted prostate biopsies. Additionally, some men below these thresholds deemed to be at particularly high risk of prostate cancer (usually based on presence of other risk factors such as family history, high PSA kinetics or ethnic risk) were also offered biopsy on a case‐by‐case basis. At least three targeted cores were taken from each MRI‐suspicious lesion and no systematic biopsy cores were included in this analysis.
In total, 489 men were included in the analyses, with 377 and 408 men meeting the Likert and PI‐RADSv2.0 biopsy thresholds, respectively, of whom 316 (83.8%) and 346 (84.8%) proceeded to biopsy (P = 0.704), respectively. The Likert system predicted more clinically significant prostate cancer than PI‐RADSv2.0, e.g., 58.2% (184/316) vs 53.2% (184/346) of prostate cancer (P = 0.190) with Gleason score ≥3+4. Detection rates of clinically insignificant prostate cancer were comparable. The authors concluded that the Likert system was superior to PI‐RADSv2.0.
The authors should be congratulated on their effort to improve prostate MRI as a risk‐stratification and biopsy targeting tool. However, caution should be applied when translating these results to other centres. In order to access inter‐centre variability and to allow independent external validation, research groups should provide access to their imaging and patient level data. The authors do not provide such access and do not present inter‐reader variability of Likert vs PI‐RADv2.0 for all enrolled men. Similar to other trials evaluating prostate MRI in men with a clinical suspicion of prostate cancer, true prostate cancer and significant prostate cancer prevalence in this cohort is unknown, as men did not undergo saturation biopsy or prostatectomy with whole‐mount prostatectomy sections.
Overall, this retrospective analysis by Khoo et al. , comparing Likert scores reported using clinical variables vs PIRADSv2.0, provides further evidence that good quality prostate MRI can be used as a risk‐stratification and biopsy targeting tool in men with a clinical suspicion of prostate cancer. Each centre needs to develop its own quality control process and continually review its own performance measures of prostate MRI and MRI‐targeted biopsy. Furthermore, in order to access inter‐centre variability in performance of prostate MRI and MRI‐targeted biopsy, free public access to imaging and patient level data should be provided.
by Ivan Jambor and Ugo Falagorio
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