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

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. 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. 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. 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.