Predictive factors associated with Gleason score underestimation on prostate biopsy in a monocentric cohort of 3,062 patients treated by mini-invasive radical prostatectomy.

Abstract

113 Background: Gleason score (GS) on prostate biopsy is a critical factor in the initial evaluation of patients with prostate cancer (PC), and can lead to different therapeutic options. However, it may differ from the final pathologic result on radical prostatectomy (RP) specimen in up to 30 to 50% of cases. The aim of this study was to explore the clinicopathological features and outcomes associated with Gleason upgrading from biopsy to RP in a contemporary cohort and to develop an upgrading risk tool available preoperatively. Methods: Using a monocentric prospectively maintained database, we included 3,062 patients who underwent minimally invasive RP between 2005 and 2012. All biopsies and surgical specimens were analyzed by dedicated pathologists. We explored clinicopathological features and outcomes associated with Gleason upgrading from biopsy to RP. A multivariate logistic regression was used to develop a nomogram predicting upgrading for Gleason 6 PC. Results: The median number of biopsy cores was 12 (10 to 13). The GS on biopsy was respectively 6, 7, and more than 7 in 58.5%, 37.4%, and 4.1%. The GS on biopsy was consistent with the specimen in 42.7%. The GS was upgraded in 37.8% and the primary pattern was upgraded in 14.1%. Patients upgraded from biopsy Gleason 6 to Gleason 7 on RP had a longer time to biochemical recurrence than those with Gleason 7 on both biopsy and RP, but a shorter time to BCR than those who remained Gleason 6 on RP (p<0,0001). On multivariate analysis, variables predicting upgrading for Gleason 6 PC were: age (p=0.0014), abnormal digital rectal examination (p<0.0001), prostate-specific antigen density (p<0.0001), percentage of positive cores (p<0.0001) and body-mass index (p=0.037). A nomogram was generated and validated internally. Conclusions: Biopsy GS is misleading in one third of cases. Gleason upgrading from biopsy to PR seems to have consequences on the clinical outcomes. A nomogram using clinicopathological features can be useful to recognize the probability of upgrading in patients with Gleason 6 PC at initial evaluation. This could help to better choose therapeutic options in low-risk PC.