Grade Group Underestimation in Prostate Biopsy: Predictive Factors and Outcomes in Candidates for Active Surveillance.

OBJECTIVE: We intended to analyze the outcomes and predictive factors for underestimating the prostate cancer (PCa) grade group (GG) from prostate biopsies in a large monocentric cohort of patients treated by minimally invasive radical prostatectomy (RP). MATERIALS AND METHODS: Using a monocentric prospectively maintained database, we included 3062 patients who underwent minimally invasive RP between 2006 and 2013. We explored clinicopathologic features and outcomes associated with a GG upgrade from biopsy to RP. Multivariate logistic regression was used to develop and validate a nomogram to predict upgrading for GG1. RESULTS: Biopsy GG was upgraded after RP in 51.5% of cases. Patients upgraded from GG1 to GG2 or GG3 after RP had a longer time to biochemical recurrence than those with GG2 or GG3 respectively, on both biopsy and RP, but a shorter time to biochemical recurrence than those who remained GG1 after RP (P < .0001). In multivariate analyses, variables predicting upgrading for GG1 PCa were age (P = .0014), abnormal digital rectal examination (P < .0001), prostate-specific antigen density (P < .0001), percentage of positive cores (P < .0001), and body mass index (P = .037). A nomogram was generated and validated internally. CONCLUSIONS: Biopsy grading system is misleading in approximately 50% of cases. Upgrading GG from biopsy to RP may have consequences on clinical outcomes. A nomogram using clinicopathologic features could aid the probability of needing to upgrade GG1 patients at their initial evaluation.