The prognostic significance of Gleason scores in metastatic prostate cancer

PurposeAlthough the majority of metastatic prostate cancer (mPCa) will arise from tumors with Gleason scores (GS) of 8 to 10 existing tumor grade analyses for mPCa have been almost uniformly limited to comparisons of≤7 vs.≥8. In this analysis, we comprehensively evaluate the GS as a prognostic factor for mPCa in the era of the updated Gleason grading system.MethodsThe Surveillance, Epidemiology, and End Results (SEER) database was queried for patients with mPCa, GS 6 to 10, diagnosed from 2006 to 2008. GS and primary-secondary Gleason pattern variations were analyzed for overall survival and prostate cancer-specific survival (PCSS).ResultsA total of 4,654 patients were evaluable. At 4 years, the overall survival rates were 51%, 45%, 34%, 25%, and 15% and PCSS rates were 69%, 57%, 44%, 33%, and 21% for GS 6, 7, 8, 9, and 10, respectively. Survival differences for GS 7 vs. 8, 8 vs. 9, and 9 vs. 10 were highly significant on both univariate and multivariate analyses accounting for age, prostate-specific antigen level, and T stage (all P<0.001). Gleason pattern 5 was an independent prognostic factor, both overall for patients with GS 6 to 10 and on primary-secondary Gleason pattern comparisons within the GS 8 (4+4 vs. 3+5 and 5+3) and GS 9 (4+5 vs. 5+4) subgroups. No survival differences were observed between 3+4 vs. 4+3. Overall, lower prostate-specific antigen level, younger age, and lower GS were associated with improved survival, with GS being the strongest prognostic factor for PCSS.ConclusionsIn this large population-based cohort, stratified survival outcomes were observed for GS 6 to 10, with sequential comparisons of GS 7 to 10, and the presence and extent of Gleason pattern 5 representing independent prognostic factors in the metastatic setting.