Strategic Endocrine Therapy and Targeted Radiotherapy for Prostate Cancer

The goal of this clinical trial is to study definitive external beam radiation therapy together with drugs called androgen deprivation therapy (ADT) in patients with prostate cancer. The investigators want to find out if these drugs work the same way if they are given for 6 months or for the usual 18 months in patients who receive also definitive external beam radiotherapy. The investigators will also learn about the safety of the treatments. The main questions the study aims to answer are: Do patients who get radiation therapy plus 6 months of androgen deprivation therapy need other hormone therapy or develop castration resistance at a higher rate within 5 years, compared to patients who get radiation therapy plus 18 months of androgen deprivation therapy? Participants will: Be treated with definitive external beam radiation therapy and receive androgen deprivation therapy for 6 months or 18 months. Have visits once every 3 months for checkups and tests for at least 5 years. The visits at 3 months, 1 year, and 5 years need to be done in person; all the other visits can be done in person or remotely (telehealth). Keep a diary of the missed doses of the androgen deprivation therapy.