Effects of Relugolix vs Leuprolide on Cardiac Function in Patients With Prostate Cancer

This phase II trial compares the effect of relugolix to leuprolide on cardiac function and performance in patients with prostate cancer. Androgen deprivation therapy (ADT) has been a key component for the treatment of advanced prostate cancer for decades. The term androgen deprivation therapy means lowering a man's testosterone. Long-term studies show that ADT may contribute to a detriment to cardiac health and predisposes men to developing cardiac diseases. Recent studies suggest that men taking relugolix for treatment of prostate cancer may have a lower risk of developing cardiovascular problems, but more studies are needed to understand this observation, and there are currently no studies reporting the direct impact of ADT (relugolix, versus the more-commonly used leuprolide) on cardiac function and outcomes. Participants will receive definitive radiotherapy for unfavorable intermediate risk prostate cancer and 6-month ADT (either relugolix or leuprolide). In addition, participants will undergo the following: 1. Comprehensive cardiac and exercise testing before and after starting ADT 2. Completion of quality-of-life questionnaires at specific intervals during the study period 3. Provide blood samples at specific intervals during the study period to test for changes in steroid levels and certain biomarkers