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

BACKGROUND Dose-escalated (DE) radiation therapy (RT) and androgen deprivation therapy (ADT) improve prostate cancer outcomes over standard-dose RT. The benefit of adding ADT to DE-RT for men with intermediate-risk prostate cancer (IR-PrCa) is uncertain. PATIENTS AND METHODS We identified 636 men treated for IR-PrCa with DE-RT (>75Gy). The adult comorbidity evaluation-27 index classifed comorbidity. Kaplan-Meier and log-rank tests compared failure-free survival (FFS) with and without ADT. RESULTS Forty-five percent received DE-RT and 55% DE-RT with ADT (median 6 months). On Cox proportional hazard regression that adjusted for comorbidity and tumor characteristics, ADT improved FFS (adjusted hazard ratio 0.36; P=0.004). Recursive partitioning analysis of men without ADT classified Gleason 4+3=7 or ≥50% positive cores as unfavorable disease. The addition of ADT to DE-RT improved 5-year FFS for men with unfavorable disease (81.6% versus 92.9%; P=0.009) but did not improve FFS for men with favorable disease (96.3% versus 97.4%; P=0.874). When stratified by comorbidity, ADT improved FFS for men with unfavorable disease and no or mild comorbidity (P=0.006) but did not improve FFS for men with unfavorable disease and moderate or severe comorbidity (P=0.380). CONCLUSION The addition of ADT to DE-RT improves FFS for men with unfavorable IR-PrCa, especially those with no or minimal comorbidity.