In 2017, an estimated 8,500 men in Ontario were diagnosed with prostate cancer. Approximately half of these patients will be treated with radical prostatectomy(surgery)and many of these men will be cured. However, a substantial proportion of men will develop cancer recurrence after radical prostatectomy and most of these patients will be treated with pelvic radiation. Pelvic radiation improves cancer control, but radiation can have considerable permanent adverse effects on patient health and quality of life. Specifically, radiation can worsen patient’s urinary, bowel, and sexual function. Rarely, but importantly, radiation is also associated with development of secondary cancers that may be fatal. Androgen deprivation therapy(also called hormone therapy)has been proven to benefit patients with metastases(cancer that has spread throughout the body)and in patients treated with radiation. The use of short-term androgen deprivation as an alternative to radiation has not been well studied following radical prostatectomy. We believe androgen deprivation may improve cancer control after surgery and may allow some patients to delay or avoid radiation altogether. In this proposal we will comprehensively evaluate the evidence on this topic with the aim of leading a clinical trial of androgen deprivation following radical prostatectomy.