Ultra-hypofractionated radiotherapy combined with HDR brachytherapy: An optimized treatment.

Abstract

To evaluate safety and efficacy of ultra hypofractionated radiotherapy (UHF) combined with high dose rate brachytherapy boost (HDR-BB) in comparison to a moderately hypo-fractionated (MHF) regimen, in patients treated for intermediate risk prostate cancer. 199 patients with intermediate risk prostate cancer were recruited in the experimental UHF treatment cohort of 25 Gy in 5 fractions plus a 15 Gy HDR-BB. They were compared to two historical control groups, treated with either 36 Gy in 12 fractions (152 patients) or 37.5 Gy in 15 fractions (311 patients) with an identical HDR-BB. The study reported the biochemical cure rate (BCR) defined as PSA < 0.2 ng/ml at 4 years, as well as biochemical relapse-free survival (BRFS) and overall survival (OS). Additionally, genitourinary (GU), gastrointestinal (GI), and sexual toxicities were evaluated. At the time of analysis, median follow up was respectively 36, 90 and 102 months for the UHF, 36 Gy and 37.5 Gy group. The BCR was 81.8 %, 78.4 % and 66.7 % in the UHF and both MHF groups (p = 0.11). There was no statistical difference in BRFS and OS between the three groups. There was no grade 3 toxicity in UHF group compared to 0.7 % in 36 Gy and 5.1 % in 37.5 Gy groups. No difference was found in late GU and GI toxicities between groups. Our study confirms UHF with HDR-BB is safe for intermediate-risk prostate cancer, reducing treatment time and patient burden. Longer follow-up is needed to confirm results.