Ten-year outcomes of a multicenter phase 3 noninferiority trial of ultra-hypofractionated versus conventionally fractionated radiotherapy for localized prostate cancer

The phase 3 HYPO-RT-PC noninferiority trial, at ten centers in Sweden and two in Denmark, compared ultrahypofractionated radiotherapy (UHF RT; 42.7 Gy in seven fractions, 3 days per week for 2.5 weeks) versus conventionally fractionated radiotherapy (CF RT; 78.0 Gy in 39 fractions, 5 days per week for 8 weeks) for patients with intermediate-to-high-risk localized prostate cancer. Ten-year results have now been published. Between 2005 and 2015, 1200 patients (aged 75 years or younger; WHO performance status 0-2) were randomized to CF RT (n=602) or UHF RT (n=598). Primary endpoint was failure-free survival (FFS). At a median follow-up of 10.6 years in the CF RT group and 10.7 years in the UHF RT group, 205 and 178 primary events had occurred, respectively. The ten—year FFS rate was 65% in the CF RT group and 71% in the UHF RT group (HR 0.84; 95% CI 0.69-1.03) confirming noninferiority of UHF RT. The ten-year cumulative incidence of late grade 2 or worse GU and GI events was 30% and 14% in the CF RT group, respectively, and 28% and 14%, respectively, in the UHF RT group. The authors conclude that this ten-year follow-up confirms the noninferiority of UHF RT compared with CF RT, with similar toxicity profiles.