From PROMIS to PRO-MRI in primary prostate cancer

tau.amegroups.com © Translational Andrology and Urology. All rights reserved. In the emerging field of MRI in prostate cancer (PCa) diagnosis, it has become clear that targeted biopsy with MRI guidance has additional value over systematic transrectal ultrasound-guided biopsies (TRUS-Bx) alone. The targeted biopsy approach driven by a positive MRI increases the diagnostic yield of high-grade [Gleason score (GS) ≥3+4] or clinically significant (cs) PCa, while concomitantly reducing the number of biopsy cores and the detection of low-grade PCa (GS 3+3) (1-3). Consequently, the question arises what the diagnostic accuracy of MRI (with or without targeted biopsies) in current clinical practice would be? Ahmed and his co-authors have recently published a prospective multicenter-paired validation study, titled the PROstate Mri Imaging Study (PROMIS) (4) that begins to fill this void in the literature. This study, which has a very sound methodology, evaluates the MRI (index test 1) in combination with transrectal ultrasound guided biopsies (TRUS-Bx) (index test 2) in reference with template mapping prostate biopsies (TMP-Bx) in biopsy-naïve men. They started from the hypothesis that targeted biopsies would have similar diagnostic accuracy as compared to TMP-Bx. We need to be aware of that MRI targeted biopsies were not included in this study design. The authors’ main conclusion is that TRUS-Bx performs poorly as a diagnostic test for clinically significant prostate cancer. Prostate MRI, used as a triage test before first prostate biopsy, could identify a quarter of men who might safely avoid an unnecessary biopsy, can also reduce overdiagnosis of clinically insignificant prostate cancer, and might improve the detection of clinically significant cancer. And yes, we believe that the PROMIS study works in daily clinical practice as advertised if we do not expect to find all significant disease, if we accept that results depend on the current definitions of clinical significance, and if we assure the quality of the diagnostic process (including MRI scanner, MRI protocol, biopsy procedures, MRI scans, interpretation and reporting), and have robust training for radiologists and urologists.