Radiation With or Without 6 Months of Androgen Suppression Therapy in Intermediate- and High-Risk Clinically Localized Prostate Cancer: A Postrandomization Analysis by Risk Group

Abstract

Six months of androgen suppression therapy (AST) plus radiation (RT) prolongs survival vs. RT alone in men with unfavorable risk localized prostate cancer (PCa), but it is unknown if this benefit applies to all risk subgroups and, in particular, the intermediate-risk group. Among 206 men with stages T1b to T2b PCa and either a prostate-specific antigen level of >10 or a Gleason score of > or =7 or MRI evidence of T3 disease randomized to receive 70 Gy of RT with or without 6 months of AST, Cox multivariable analysis was used to assess the impact of AST on overall survival in intermediate- and high-risk localized PCa, adjusting for age, Adult Comorbidity Evaluation 27 comorbidity score, interaction between comorbidity and treatment, and known prognostic factors. Survival estimates were compared using a two-sided log-rank test. After an 8.2-year median follow-up, 74 men died. Compared to treatment with AST plus RT, treatment with RT alone was associated with an increased risk of death in intermediate-risk (adjusted hazard ratio, 3.0 [95% confidence interval, 1.3-7.2]; p = 0.01) and high-risk PCa (adjusted hazard ratio, 3.3 [95% confidence interval, 0.94-11.3]; p = 0.06). The survival benefit of adding AST was restricted to men with no or mild comorbidity in both the intermediate-risk (90.9% vs. 85.8% survival, respectively, at 7 years for AST plus RT vs. RT alone; p = 0.009) and high-risk (88.9% vs. 51.2% survival, respectively, at 7 years for AST plus RT vs. RT alone; p = 0.007) subgroups. In men with localized PCa who have no or mild comorbidity, adding 6 months of AST to RT was associated with improved survival for those with both intermediate-risk and high-risk disease, but in men with moderate to severe comorbidity, no benefit was observed in either risk group.