MP13-09 PRE-BIOPSY MULTIPARAMTRIC MR IMAGING USING PI-RADS SCORING SYSTEM SIGNIFICANTLY PREDICT UPGRADING OF RANDOM TRANSRECTAL PROSTATE BIOPSIES GRADING FOLLOWING RADICAL PROSTATECTOMY

Abstract

INTRODUCTION AND OBJECTIVE: An increase or ‘upgrade’ in Gleason Score (GS) in prostate cancer following Transrectal Ultrasound (TRUS) guided biopsies remains a significant challenge to overcome. To evaluate whether pre-biopsy magnetic resonance imaging (MRI) has the potential to narrow the discrepancy of histopathological grades between TRUS biopsy and radical prostatectomy using Prostate Imaging Reporting and Data System version 2 (PIRADS v2.0). METHODS: Three hundred and thirty men treated consecutively by laparoscopic radical prostatectomy (LRP) between July 2013 and January 2019 with localised prostate cancer were included in this study. All the participants had a pre-biopsy 3T-MRI scan followed by TRUS biopsies. An independent radiologist and pathologist assessed the PIRADS scoring of the MRI and histopathology of the biopsies and prostatectomy specimens respectively. An improved orientation between imaging and histopathology was achieved by using 3-D fabricated moulds to direct histopathological grossing. A multivariate model was constructed using logistic regression analysis to assess the ability of PIRADS v2.0 score to predict upgrading in TRUS biopsy GS in a nomogram. A decision-analysis curve was constructed assessing impact of nomogram using different thresholds for probabilities of upgrading. RESULTS: Eight men were excluded for analysis for various reasons. PIRADS scores were obtained from MRI scans in all the included cases. Of the remaining 322 patients, 101/322 (31%) experienced histopathological upgrading on LRP from TRUS biopsies. Most of the participants with upgrading had high (≥ 4) PIRADS score (91/101; 90%). In a multivariate analysis, the PIRADS score significantly improved prediction ability of pre-biopsy MRI scans for upgrading of TRUS biopsy GS (p=0.001, 95% CI [0.06-0.034]), which improved the C-index of predictive nomogram significantly (0.90 vs. 0.64, p<0.05). CONCLUSIONS: PIRADS v2.0 score is an independent predictor of postoperative GS upgrading and this should be taken into consideration while offering treatment options to men with localised prostate cancer. Source of Funding: No Funding