Evaluation of the effectiveness of adding androgen deprivation to modern dose-escalated radiotherapy for men with favorable intermediate-risk prostate cancer

Abstract

Background: Randomized trials have shown that androgen-deprivation therapy (ADT) improves survival for men with intermediate-risk prostate cancer treated with radiotherapy (RT). The benefit of ADT to patients with favorable intermediate-risk prostate cancer treated with modern dose-escalated RT is unknown. This study evaluated the effectiveness of ADT on survival of men with favorable intermediate-risk prostate cancer treated with dose-escalated RT.

Methods: This study was a retrospective cohort analysis of men with favorable intermediate-risk prostate cancer from 2004 to 2007 in the National Cancer Data Base. Favorable intermediate-risk disease was defined as 1 adverse risk factor (prostate-specific antigen level of 10-20 ng/mL or Gleason score of 7) and clinical T1/T2 prostate cancer. All patients were treated with primary dose-escalated RT (≥75.6 Gy or RT with a brachytherapy boost). Overall survival was analyzed with propensity score adjustment and Cox multivariate modeling.

Results: The study included 18,598 patients. The use of ADT decreased from 43.5% in 2004 to 39.5% in 2007. The propensity score-adjusted survival analysis demonstrated similar 8-year overall survival for men treated with dose-escalated RT and ADT and men treated with RT alone (77.7% vs 78.4%). ADT was not associated with improved survival in any age or comorbidity subgroup. In a sensitivity analysis using Cox multivariate modeling, the receipt of ADT was not associated with overall survival (hazard ratio, 0.99; 95% confidence interval, 0.91-1.07; P = .768).

Conclusions: Adding ADT to modern dose-escalated RT was not associated with improved survival for patients with favorable intermediate-risk prostate cancer. The applicability of the survival benefit seen in older trials to modern patients is unclear. Because of the morbidity associated with ADT, dose-escalated RT alone for patients with favorable intermediate-risk prostate cancer may be a reasonable option. Cancer 2016;122:2341-2349. © 2016 American Cancer Society.

Keywords: National Cancer Data Base (NCDB); androgen-deprivation therapy (ADT); intermediate-risk prostate cancer; radiotherapy; survival.