Acute and late toxicity and preliminary outcomes report of moderately hypofractionated helical tomotherapy for localized prostate cancer: a mono-institutional analysis.

To assess toxicity and clinical outcomes of moderately hypofractionated helical tomotherapy (HT) for the curative treatment of localized prostate cancer (PC). From December 2012 to May 2018, 170 patients were treated with definitive intent for PC. Thirty-four percent were low risk, 30% intermediate risk (IR) and 36% high risk (HR). All patients received 70 Gy in 28 fractions to the prostate; 61.6 Gy were delivered to the seminal vesicles for IR; pelvic lymph nodes irradiation for a total dose of 50.4 Gy was added in the HR subgroup. Toxicity was assessed using CTCAE V4.0, and biochemical failure was defined following Phoenix criteria. Time-to-event data were analyzed using the Kaplan-Meier method and log-rank test. The median follow-up was 36 months (range 12-78); acute toxicity was as follows: G1 and G2 in 27.6% and 19.4% for GI; 53% and 24% for GU. No G ≥ 3 event was observed. For late toxicity, G ≥ 3 GI and GU rates were, respectively, 3% and 2.4% at 3 years and 3% and 4.8% at 4 years; no G4 occurred. A statistical correlation between acute or late G3 incidence and clinical or dosimetric parameters was not found. At the time of analysis, 2- and 3-year biochemical relapse-free survival rates were 90% and 87.5% and 2- and 3-year overall survival rates were 96.4% and 90%, respectively. The log-rank test revealed no difference between the risk groups in terms of biochemical control (p = 0.16). Moderately hypofractionated RT with HT for localized prostate cancer reported excellent outcomes with mild acute and late toxicity incidence, with promising biochemical control rates.