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Aims: To assess toxicity and clinical outcomes of moderately hypofractionated helical tomotherapy (HT) for the curative treatment of localized prostate cancer (PC). Methods: 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 70Gy in 28 fractions to the prostate; 61.6Gy were delivered to the seminal vesicles for IR; pelvic lymph nodes irradiation for a total dose of 50.4Gy 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. Results: The median follow-up was 36months (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 3years and 3% and 4.8% at 4years; 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). Conclusions: Moderately hypofractionated RT with HT for localized prostate cancer reported excellent outcomes with mild acute and late toxicity incidence, with promising biochemical control rates.

Based on radiobiology evidence, hypofractionated radiotherapy has the potential of improving treatment outcome in prostate cancer patients. In this study, we evaluated the safety, in terms of acutetoxicity, of using moderate hypofractionated radiotherapy delivered with Helical Tomotherapy (HT) to treat prostate cancer patients. Between December 2012 and April 2014, 42 consecutive patients were treated with hypofractionated radiotherapy using HT. All patients received 70 Gy in 28 fractions to PTV1, which included the prostate. In the intermediate risk group, 61.6 Gy were delivered to PTV2, which included the seminal vesicles. In high risk patients, the pelvic nodes were added (PTV3) and received 50.4 Gy. Acute toxicity was recorded prospectively with RTOG and Common Terminology Criteria for Adverse Events 3.0, retrospectively with CTCAE 4.0. Expanded Prostate Cancer Index Composite (EPIC) was measured at baseline and 3 months after end of treatment, to investigate health related quality of life with regards to bladder and gastrointestinal function. Acute toxicity was acceptable, independently from the system used to score side effects. Moderate genitourinary toxicity was more frequent than gastrointestinal toxicity. No correlation between acute side effects and patients’ characteristics or physical dose parameters was registered. EPIC evaluation showed a negligible difference in urinary and bowel function post-treatment, that did not reach statistical significance. Our experience confirms the safety of moderate hypofractionation delivered with HT in prostate cancer patients with low, intermediate and high risk.