LAUSR

INTRODUCTION AND OBJECTIVE: Prostate MRI with or without targeted biopsies (TBx) is increasingly used to enhance detection of significant PCa (sPCa) and minimize unnecessary biopsies and over-diagnoses of insignificant cancers (insPCa). Prostate MRI is now recommended in European guidelines for all biopsy-naive men under suspicion of PCa based on PSA and digital rectal examination (DRE). However, the potential value and diagnostic benefits of prebiopsy prostate MRI in detecting and ruling out significant disease compared with standard transrectal ultrasound-guided biopsies (SBx) for all men may be limited in men with high PSA levels and/or positive DRE findings. Therefore, the objective was to assess which clinical risk groups stratified by PSA and DRE benefit most from prebiopsy prostate MRI. METHODS: We retrospectively analysed data from N[1,020 biopsy-naive men with clinical suspicion of PCa, who underwent biparametric MRI followed by SBx (all men) and (TBx) in men with suspicious MRIs (modified PI-RADSv2 score 3). Men were stratified by pre-biopsy PSA and DRE findings into clinical low (PSA<10 and DRE T2a), intermediate (PSA 10e20 or DRE[T2b), and high (PSA>20 or DRE T2c) risk groups. For each clinical risk group, we compared the diagnostic performance of SBx in all men with the rate of avoided biopsies, insPCa (grade group 1) and sPCa (grade group 2) diagnoses restricting biopsies to men with suspicious MRIs. Combined biopsy results for all men were used as standard reference. RESULTS: Overall, insPCa and sPCa was detected in 18% (180/1020) and 47% (475/1020) of men with median age and PSA [inter-quartile-range] of 67 yrs. [61e71] and 8.0 ng/mL [5.7e13.0], respectively. Restricting biopsies to men with suspicious MRIs meant 30% (305/1020; p<0.001) could avoid biopsies, reduced insPCa diagnosis by 42% (115 vs 198; p<0.001) and slightly improved sPCa diagnosis by 3% (454 vs 441; p[0.105). Stratified by risk groups, the rate of avoided biopsies and the detection ratios of insPCa and sPCa were 43% (247/578; p<0.001), 0.58 (88 vs 152; p<0.001) and 1.03 (142 vs 138; p[0.608) for low, 24% (49/208; p<0.001), 0.62 (24 vs 39; p[0.001) and 1.07 (107 vs 100; p[0.143) for intermediate, and 4% (9/234; p[0.004), 0.42 (3 vs 7; p[0.125), and 1.01 (205 vs 205; p[0.625) for high clinical risk groups, respectively. CONCLUSIONS: Prostate MRI used as a pre-biopsy triage test in biopsy-naïve men can be used to avoid unnecessary biopsies and reduced insPCa diagnosis compared with SBx for all men. However, these benefits seem to be restricted to men with clinical lowand intermediate risk parameters and improvement in sPCa diagnosis is limited.