Phase II Trial of Pure Hypofractionated Radiotherapy in the Treatment of Localized Carcinoma of the Prostate.

Purpose To evaluate acute and late genitourinary (GU) and gastrointestinal (GI) toxicity and the biochemical control of pure hypofractionated radiotherapy (without acceleration) for the treatment of prostate cancer. Methods and materials This phase II prospective trial evaluated low-risk and intermediate-risk prostate cancer patients who received hypofractionated radiotherapy. Fifty-three patients with low-risk prostate cancer received 50 Gy in 15 fractions, 156 patients with intermediate-risk prostate cancer received 60 Gy in 20 fractions over eight weeks. Acute toxicity and late toxicity were graded per the Radiation Therapy Oncology Group (RTOG) toxicity scales and the Phoenix Definition (nadir plus two) defined biochemical failure. Results Median follow-up was 6.5 years. Acute phase grade 2/3 toxicity was 6%/0 and 8%/2% for GI and GU symptoms, respectively, and one grade 4 acute GU toxicity (0.5%). Late grade 2/3 GI and GU toxicity were 7%/0 and 8%/0.5%, respectively. There were no late grade 4 toxicities. The five-year freedom-from-biochemical-failure (FFBF) rates were 85% for low-risk patients and 80% for intermediate-risk patients. Conclusions Pure hypofractionation seems to be associated with low toxicity rates and biochemical control rates that are similar or better than those observed with accelerated hypofractionated or conventionally fractionated therapy.