PI-RADSv2 Score < 5 Associates with a Very Low Risk of Pelvic Lymph Node Invasion in Prostate Cancer, Even Among High-Risk Population

Purpose: To evaluate the role of Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) scores for estimating the risk of lymph node invasion (LNI) in prostate cancer (PCa). Materials and Methods: We retrospectively identified 308 patients who underwent multiparametric magnetic resonance imaging (mpMRI) and RP with pelvic lymph node dissection (PLND). Univariate and multivariate logistic analyses were performed. The area under the receiver operating characteristic curves (AUC) and decision curve analysis (DCA) were generated for assessing the incremental value of PI-RADSv2 scores combined with the Briganti and Memorial Sloan Kettering Cancer Center (MSKCC) nomograms. Results: Overall, 20 (6.5%) patients had LNI. According to D'Amico classification, 22 (7.1%) patients were at low, 75 (24.4%) at intermediate, 211 (68.5%) at high risk. In the multivariate analysis, PIRADSv2 scores and percentage of positive cores were independently significant predictors of LNI (p ≤ 0.006). The AUC of PI-RADSv2 score was 80.2%. The threshold of PI-RADSv2 score was 5, which provided high sensitivity (18/20, 90.0%) and negative predictive value (203/205, 99.0%). When PI-RADSv2 scores were combined with Briganti and MSKCC nomograms, the AUC value increased from 75.1% to 86.3% and from 79.2% to 87.9%, respectively (p ≤ 0.001). The DCA also demonstrated the two nomograms plus PI-RADSv2 scores improved clinical risk prediction of LNI. Conclusion: PI-RADSv2 scores alone or combined with clinical nomograms provide significant incremental value for predicting LNI in PCa. Patients with a PI-RADSv2 score < 5 were associated with a very low risk of LNI, even among a relatively high-risk population. Funding Statement: The authors state: "none." Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: The review board at the authors institution approved this retrospective study.