Influence of Timing Between Androgen Deprivation Therapy and External Beam Radiation Therapy in Patients With Localized, High-Risk Prostate Cancer.

Purpose: Treatment with long-term androgen deprivation therapy (ADT) and radiation therapy (RT) is the nonsurgical standard-of-care for patients with high- or very high-risk prostate cancer (HR-PC), but the optimal timing between ADT and RT initiation is unknown. We evaluate the influence of timing between ADT and RT on outcomes in patients with HR-PC using a large national cancer database.

Methods And Materials: Data for patients with clinical T1-T4 N0, M0, National Cancer Comprehensive Network HR-PC who were treated with definitive external RT (≥60 Gy) and ADT starting either before or within 14 days after RT start were extracted from the National Cancer Database (2004-2015). Patients were grouped on the basis of ADT initiation: (1) >11 weeks before RT, (2) 8 to 11weeks before RT, and (3) <8 weeks before RT. Kaplan-Meier, propensity score matching, and multivariable Cox proportional hazards were performed to evaluate overall survival (OS).

Results: With a median follow-up of 68.9 months, 37,606 patients with HR-PC were eligible for analysis: 13,346 (35.5%) with >11 weeks of neoadjuvant ADT, 11,456 (30.5%) with 8 to 11 weeks of neoadjuvant ADT; and 12,804 (34%) patients with <8 weeks of neoadjuvant ADT. The unadjusted 10-year OS rates for >11 weeks, 8 to 11 weeks, and <8 weeks neoadjuvant ADT groups were 49.9%, 51.2%, and 46.9%, respectively ( = .002). On multivariable and inverse probability of treatment weighting analyses, there was a significant OS advantage for patients in the 8 to 11 weeks neoadjuvant ADT group (adjusted hazard ratio 0.90; 95% confidence interval, 0.86-0.95; < .001) but not the >11 weeks group.

Conclusions: Neoadjuvant ADT initiation 8 to 11 weeks before RT is associated with significantly improved OS compared with shorter neoadjuvant ADT duration. Although prospective validation is warranted, this analysis is the largest retrospective study suggesting an influence of timing between ADT and RT initiation in HR-PC.