External Beam Radiation Therapy (EBRT) is a primary treatment for locally advanced prostate cancer (T3–T4), often combined with long-term androgen deprivation therapy (ADT) for 18–36 months to maximize cancer control. EBRT targets the prostate, seminal vesicles, and surrounding tissues—and may include pelvic lymph nodes due to the higher risk of microscopic spread.

This approach offers strong evidence-based outcomes for reducing recurrence and improving survival. It is typically recommended for patients who are not surgical candidates or prefer non-surgical treatment. Side effects can include urinary frequency, bowel changes, and erectile dysfunction, but these are generally manageable and considered acceptable given the high risk of disease progression.