Late results of a randomized trial on the role of mild hypofractionated radiotherapy for the treatment of localized prostate cancer

Background: Prostate cancer is considered to be highly sensitive to changes in radiation therapy dose per fraction, specifically to hypofractionation. An increase in the fractionation dose could cause a higher increase to the prostate than to the normal tissues leading to better disease control with less toxicity. Here we present the results of a randomized trial comparing mild hypofractionation to conventional fractionation after a median of 3,6 years follow up. Patients and Methods: 139 patients were randomized to receive either hypofractionated radiotherapy with 2,25 Gy/fr to a total of 72 Gy (arm 1) or conventionally fractionated treatment with 2Gy/fr to a total of 74 Gy (arm 2). 72 patients were assigned to arm 1 and 67 to arm 2. Results: After a median follow up of 3,6 years, 23 patients (31,9%) from arm 1 developed grade≥ 2 acute genitourinary toxicity and 21 (31,3%) from arm 2 (p=0,79). The corresponding values from gastrointestinal were 15 (20,8%) and 12 (17,9%) (p=0,6). For late toxicity from GU, 8 patients (11,1%) developed grade≥ 2 symptoms in arm 1 and 7 (10,4%) in arm 2 (p=0,92). late GI toxicity grade≥ 2 was observed in 8 (11,1%) patients in arm 1 and 8 (11,9%) in arm 2 (p=0,88). In multivariate analysis, hormone therapy was significantly associated with late GI events, while acute toxicity from both GU and GI was a prognostic factor of late adverse reaction. Conclusion: No difference in the toxicity profile could be identified between hypofractionation and conventional fractionation. Our schedule of 2,25Gy/fr seems safe and tolerable by the patients with acceptable rates of acute and late toxicity.