Validation of the 2015 prostate cancer grade groups for predicting long-term oncologic outcomes in a shared equal-access health system.

Abstract

A 5-tier prognostic grade group (GG) system was enacted to simplify the risk stratification of patients with prostate cancer in which Gleason scores of ≤6, 3 + 4, 4 + 3, 8, and 9 or 10 are considered GG 1 through 5, respectively. The authors investigated the utility of biopsy GG for predicting long-term oncologic outcomes after radical prostatectomy in an equal-access health system. Men who underwent prostatectomy at 1 of 6 Veterans Affairs hospitals in the Shared Equal Access Regional Cancer Hospital database between 2005 and 2015 were reviewed. The prognostic ability of biopsy GG was examined using Cox models. Interactions between GG and race also were tested. In total, 2509 men were identified who had data available on biopsy Gleason scores, covariates, and follow-up. The cohort included men with GG 1 (909 patients; 36.2%), GG 2 (813 patients; 32.4%), GG 3 (398 patients; 15.9%), GG 4 (279 patients; 11.1%), and GG 5 (110 patients; 4.4%) prostate cancer. The cohort included 1002 African American men (41%). The median follow-up was 60 months (interquartile range, 33-90 months). Higher GG was associated with higher clinical stage, older age, more recent surgery, and surgical center (P < .001) as well as increased biochemical recurrence, secondary therapy, castration-resistant prostate cancer, metastases, and prostate cancer-specific mortality (all P < .001). There were no significant interactions with race in predicting measured outcomes. The 5-tier GG system predicted multiple long-term endpoints after radical prostatectomy in an equal-access health system. The predictive value was consistent across races. Cancer 2017;123:4122-4129. © 2017 American Cancer Society.