Clinical utility of PSAD combined with PI-RADS category for the detection of clinically significant prostate cancer

•Magnetic Resonance Imaging is accurate for detection of clinically significant prostate cancer•Addition of prostate-specific antigen density to Magnetic Resonance Imaging improves accuracy in patients without a previous diagnosis of prostate cancer•Patients with prostate-specific antigen density < 0.15 and Prostate Imaging Reporting and Data System score ≤ 3 have low risk of harboring clinically significant prostate cancer The goal of this study was to determine the predictive value of prostate-specific antigen density (PSAD) plus Prostate Imaging Reporting and Data System (PI-RADS) category for the detection of clinically significant prostate cancer. This retrospective study included 526 men without known prostate cancer (initial diagnosis group) and 133 men with prostate cancer grade group 1 (active surveillance group) who underwent magnetic resonance imaging–guided and/or systematic prostate biopsy procedures between August 2014 and October 2018. Prostate specific antigen (PSA), PSAD, and PI-RADS category were entered into logistic regression models for predicting clinically significant prostate cancer (grade group ≥2) at biopsy. Receiver operating characteristic curve analysis was performed to assess model accuracy. The area under the curve (AUC) increased when PSAD was combined with PI-RADS in the initial diagnosis group (difference in AUC = 0.031; 95% confidence interval: 0.012, 0.050; P = 0.002) but not in the active surveillance group (difference in AUC = 0.016; 95% confidence interval: –0.040, 0.071; P = 0.579). When a PSAD threshold of 0.15 was applied, the frequency of clinically significant prostate cancer in patients with a PI-RADS score of 3 or lower decreased from 9.8% to 5.6% in the initial diagnosis group and from 10.7% to 2.7% in the active surveillance group. The addition of PSAD improves the predictive performance of PI-RADS in men without known prostate cancer. A PSAD threshold of 0.15 can help to minimize the number of missed clinically significant prostate cancer cases in men with a PI-RADS score of 3 or lower who decide to defer biopsy.