Effect of adding short-term androgen deprivation therapy to dose-escalated radiation therapy on failure-free survival for select men with intermediate-risk prostate cancer.

176 Background: Independently, dose-escalated external beam radiation therapy (DE-EBRT) and short-term androgen deprivation therapy (ADT) improve outcomes for men with intermediate-risk prostate cancer; however, the incremental benefit of adding short-term ADT to DE-EBRT is uncertain. The aim of this study was to determine the effect of adding ADT to DE-EBRT and to identify men most likely to benefit from ADT. Methods: We reviewed the medical records of 636 men treated for intermediate-risk prostate cancer with DE-EBRT (>75 Gy) from 1995 to 2009. The adult comorbidity evaluation-27 index categorized severity of comorbidity. Recursive partitioning analysis defined unfavorable disease. Kaplan-Meier and log-rank tests compared failure-free survival (FFS) with and without ADT. Results: Median age was 70 years (interquartile range [IQR] 65–74). Overall, 45% received DE-EBRT alone and 55% DE-EBRT with ADT (median 6 months, IQR 6-8). Median follow up was 4.3 years. On Cox-proportional hazard regression analysis ...