A study by the Korean group of National Cancer Center. Eighty-two patients with T1-3bN0M0 prostate cancer were randomized to one of five arms: Arm 1, 60 cobalt gray equivalent (CGE)/20 fractions/5 weeks; Arm 2, 54 CGE/15 fractions/5 weeks; Arm 3, 47 CGE/10 fractions/5 weeks; Arm 4, 35 CGE/5 fractions/2.5 weeks; and Arm 5, 35 CGE/5 fractions/4 weeks. In the current exploratory analysis, these ardms were categorized into the moderate hypofractionated (MHF) group (52 patients in Arms 1-3) and the extreme hypofractionated (EHF) group (30 patients in Arms 4-5).

At a median follow-up of 7.5 years, this study reported the 7-year biochemical failure-free survival (BCFFS) of 76.2% for the MHF group and 46.2% for the EHF group (p = 0.005). Acute GU toxicities were more common in the MHF than the EHF group (85 vs. 57%, p = 0.009), but late GI and GU toxicities did not differ between groups. The authors concluded that the efficacy of EHF is potentially inferior to that of MHF and that further studies are warranted, therefore, to confirm these findings.