Potential Risk of Other-Cause Mortality Due to Long-Term Androgen Deprivation Therapy in Elderly Patients with Clinically Localized Prostate Cancer Treated with Radiotherapy—A Confirmation Study

Androgen deprivation therapy (ADT) is used to improve overall survival (OS) in prostate cancer treatment; however, we encountered that long-term ADT in elderly patients may be related to high other-cause mortality (OCM). This study aimed to confirm the potential risk associated with long-term ADT in elderly patients using a different large cohort. A comparison analysis was conducted between the ≥2- and <2-year ADT groups using open, large data from 1840 patients with clinically localized prostate cancer treated with radiotherapy (1172 treated with high-dose-rate brachytherapy (HDR) + external beam radiotherapy (EBRT) and 668 treated with external beam radiotherapy). The OCM-free survival (OCMFS), overall survival, and prostate cancer-specific survival rates were measured. The 10-year OCMFS rates in patients aged ≥75 years were 94.6% and 86% in the <2- and ≥2-year ADT groups, respectively, but were 96.3% and 93.5% (p = 0.0006) in their younger counterparts. If dividing into HDR and EBRT groups. This inclination was found in brachytherapy group but not in EBRT group. The overall survival rate was also lower in the elderly patients in the ≥2-year ADT group than in the <2-year ADT group; however, the 10-year prostate cancer-specific survival rate was the same in both groups. Long-term ADT in elderly patients resulted in not only higher OCM rates but also poorer OS rates; therefore, longer-term ADT in elderly patients should be performed with meticulous care.