Hypofractionated postoperative helical tomotherapy in prostate cancer: a mono-institutional report of toxicity and clinical outcomes

Francesco Cuccia,1,2 Gianluca Mortellaro,2 Vincenzo Serretta,3 Vito Valenti,1,2 Antonella Tripoli,1,2 Marina Gueci,1,2 Nicoletta Luca,1,2 Antonio Lo Casto,4 Giuseppe Ferrera2 1Radiation Oncology School, University of Palermo, Palermo, Italy; 2Radiation Oncology, ARNAS-Civico Hospital, Palermo, Italy;3Section of Urology, Department of Surgical Oncological and Oral Science, University of Palermo, Palermo, Italy; 4Radiation Oncology School, Section of Radiological Sciences, DIBIMED, Università degli Studi di Palermo, Palermo, Italy Purpose: This is a mono-institutional study of acute and late toxicities and early biochemical control of a retrospective series of 75 prostate cancer patients treated with moderate postoperative hypofractionation delivered by helical tomotherapy (HT). Patients and methods: From April 2013 to June 2017, 75 patients received adjuvant (n=37) or salvage (n=38) treatment, delivering to prostate bed a total dose of 63.8 Gy (equivalent dose in 2-Gy fractions=67.4 Gy) using 2.2 Gy fractions. Whole-pelvis irradiation was performed in 63% of cases (median dose, 49.3 Gy; range, 48–55.1 Gy). Concurrent hormonal therapy was administered in 46% of cases. Common Terminology Criteria for Adverse Events (version 4.0) was adopted for acute and lategenitourinary (GU) and gastrointestinal (GI) toxicity evaluations. Biochemical progression was defined as PSA level increase of ≥0.2 or more above the postoperative radiotherapy (RT) nadir. Results: Acute GU toxicities were as follows: G1 in 46% and G2 in 4%, detecting no G≥3 events. For GI toxicity, we recorded G1 in 36% and G2 in 18%. With a median follow-up of 30 months (range, 12–58 months), we found late toxicity G2 GI in 6.6% and G≥2 GU in 5.3%, including two patients who underwent surgical incontinence correction. Acute GI≥2 toxicity and diabetes were found to be predictive of late GI≥2 toxicity (P=0.04 and P=0.0019). Actuarial 2- and 3-year biochemical recurrence-free survivals were 88% and 73%, respectively, for the entire population. Conclusion: In our experience, moderate hypofractionated postoperative RT with HT was feasible and safe, with reports of low incidence of toxicity and promising biochemical control rates. Keywords: prostate neoplasm, radiotherapy, hypofractionation, adjuvant, salvage