This landmark study randomized 431 men who had a diagnosis of T3N0M0 prostate cancer after undergoing a radical prostatectomy to either adjuvant radiotherapy of 60-64 Gy to the prostatic fossa and peri-prostatic tissue or to observation. In the radiotherapy group the radiotherapy had to be given within 18 weeks of surgery, and even though most men had an undetectable PSA prior to radiotherapy, some men had a PSA >0.2 ng/mL. T3N0MO pathological disease implied one of – extracapsular extension, positive surgical margin or seminal vesicle invasion. In the treatment group the benefits were significant and included improved metastasis free survival, improved overall survival, freedom from ongoing hormonal therapy and PSA biochemical improved survival. In the observation group, many men ended up needing salvage radiotherapy and high levels of hormone therapy to control disease progression. The median increase in survival was 1.7 years. In addition in men who received adjuvant radiotherapy with a PSA <0.2 ng/mL the delay to PSA recurrence was an average of 7 years. This study presents results with 12.5 years follow up data.