Post-operative hypofractionated radiotherapy for prostate cancer: a mono-institutional analysis of toxicity and clinical outcomes.

Background As the use of hypofractionation has spread in the setting of curative prostate radiotherapy, few data are available in the post-operative scenario. This study reports a mono-institutional experience of moderate post-operative hypofractionated radiotherapy for prostate cancer. Methods In February 2021, we retrospectively assessed the outcomes of 129 patients who received between April 2013 and May 2020 hypofractionated post-operative radiotherapy using Helical Tomotherapy. Toxicity was assessed using CTCAE criteria v4.0. Survival endpoints were calculated with Kaplan-Meier method. Results Median age and follow-up were, respectively, 67 years and 43 months. Adjuvant and salvage treatment were delivered to 63.5% and 36.4% of patients to a median total dose of 63.8 Gy (61.6-65.25 Gy) in 29 fractions (2.12-2.25 Gy/fraction). Pelvic lymph-nodes irradiation was performed in 67.4% of cases. ADT was added in 50%. Acute toxicity was: G1 and G2 GU events in 36% and 9.3% of cases; G1 and G2 GI events in 29.4% and 13.9%. Late GU toxicity occurred in 12.4% of cases: 3.1% G1, 7.7% G2 and 1.5% G3 events; GI toxicity consisted of 1.5% G1 and 7.7% G2 events. Biochemical relapse occurred in 26.3% of cases, recording no significant differences between adjuvant and salvage (p = 0.67), with 4- and 5-years bRFS rates of 78.7% and 75.6%. Two patients died of progressive disease and eight for non-oncological causes resulting in 3-years overall survival and cancer-specific survival rates of 98% and 98.4%. Conclusions Our experience supports the use of moderate hypofractionation for prostate bed radiotherapy, with minimal toxicity and promising results in terms of clinical outcomes.