Ultra-Hypofractionated (UHF) Compared to Moderate-Hypofractionated (MHF) Prostate IGRT With HDR Brachytherapy Boost (BB): Four-Year Toxicities and Local Control

Abstract

To analyze the long term efficacity and safety of an UHF IGRT prostate treatment regimen with HDR BB.In this single arm, prospective monocentric study, 28 patients with median age 69 years and D'Amico's intermediate risk prostate cancer (T1c, T2a-b), were recruited between the years 2015 and 2016 to an experimental treatment arm of 25 Gy IGRT in 5 fractions with a 15 Gy HDR BB. They were then compared to two control groups, treated with either 36 Gy in 12 fractions or 37,5 Gy in 15 fractions with a similar HDR BB. The control groups included 151 and 311 patients respectively.Patient characteristics were similar between the three groups for age, Gleason score, stage and initial PSA. Patients outcomes were reported using the IPSS questionnaire at baseline and at each follow-up visit until 48 months. The three groups showed a significant decrease in average IPSS over time as compared to one-month post treatment. At 12 months, the average IPSS scores were 7, 9 and 9 and drop to 5, 7 and 7 at 48 months for the 25/5, 36/12 and 37,5/15 regimens respectively. A greater reduction was observed in the experimental arm while being non-significant. The median treatment time to deliver IGRT was 6 days in the UHF group compared to 16 and 21 days in the control groups. Median follow-up for all groups combined was 55 months. Local control rates for each group were 100%, 95% and 91% respectively. No biochemical recurrence occurred in the UHF arm as defined by the Phoenix criterion. There was no significant difference in overall survival.The UHF treatment scheme with HDR BB seems equivalent to standard treatment arms in terms of long-term toxicities and local control. The adoption of the UHF regimen would not only reduce the socioeconomic burden, it would also offer the shortest treatment time for intermediate risk prostate cancer known to date, of interest in the actual pandemic situation. Randomized control trials with larger cohorts are needed to further confirm our findings.