Risk Stratification of Prostate Cancer According to PI-RADS® Version 2 Categories: Meta-Analysis for Prospective Studies

Purpose: The Prostate Imaging Reporting and Data System (PI-RADS) version 2 (v2) categorizes the likelihood of clinically significant prostate cancer on magnetic resonance imaging and determines the diagnostic pathway. We determined clinically significant prostate cancer and all prostate cancer detection rates in each PI-RADS v2 category. Materials and Methods: MEDLINE (R), EMBASE (R) and Cochrane databases were searched for prospective studies reporting the detection rates of clinically significant prostate cancer or all prostate cancer. Random effects models were used to determine pooled detection rates of clinically significant prostate cancer and all prostate cancer for each PI-RADS category. The risk of bias was assessed with the Quality Assessment of Diagnostic Accuracy Studies-2. Meta-regression analysis was performed to identify factors affecting study heterogeneity. Results: Thirteen prospective studies including 4,265 men who underwent magnetic resonance imaging targeted biopsy and/or systematic biopsy for a PI-RADS v2 category 3 or greater, or systematic biopsy for PI-RADS 1e2 were included. The pooled detection rates of clinically significant prostate cancer monotonically increased for each PI-RADS v2 category, ie 4% (95% CI 2-8) for category 1-2, 17% (95% CI 13e21) for category 3, 46% (95% CI 38-55) for category 4 and 75% (95% CI 73-78) for category 5. Substantial study heterogeneity was noted in clinically significant prostate cancer detection rates for categories 1-2 and 4, which were significantly affected by study subject selection (biopsy naive patients only or not) and studies with a high risk of bias. Conclusions: PI-RADS v2 can be useful for the stratification of the risk of clinically significant prostate cancer in patients at risk for prostate cancer but the limitations in category 4 still remain.