Impact of testosterone replacement therapy after radiation therapy on prostate cancer outcomes.

99Background: Currently there is little data to guide the use of testosterone replacement therapy in prostate cancer patients who have received radiation therapy (RT). We sought to evaluate the impact of post-RT testosterone replacement on prostate cancer outcomes in a large national cohort. Methods: We conducted a population-based cohort study using the Veterans Affairs Informatics and Computing Infrastructure. We identified node-negative and non-metastatic prostate cancer patients diagnosed between 2001-2015 treated with RT. We excluded patients for missing covariate and follow-up data. Receipt of testosterone was coded as a time-dependent covariate. Other covariates included: age, Charlson Comorbidity index, diagnosis year, body mass index, race, PSA, clinical T/N/M stage, Gleason score, and receipt of hormone therapy. We evaluated prostate cancer-specific survival, overall survival, and biochemical recurrence free survival using multivariable Cox regression. Results: Our cohort included 41,544 patient...