Biochemical Recurrence Risk Reduced With Hypofractionated Radiotherapy for Prostate Cancer

New research presented at the American Society for Radiation Oncology 2023 Annual Meeting has compared the efficacy of a hypofractionated radiation schedule with a conventional schedule in patients with low-risk prostate cancer (PCa).

Accrual for the study occurred from April 2006 to December 2009. The cohort included 1115 patients with favorable-risk PCa who were randomly assigned 1:1 to undergo either a conventional schedule consisting of 73.8 Gy in 41 fractions over 8.2 weeks, or a hypofractionated schedule of 70 Gy in 28 fractions over 5.6 weeks.

The trial’s primary end point was to establish with 90% power and an alpha of .05 that hypofractionated radiation results in 5-year disease-free survival (DFS) that is not lower than conventional radiation by more than 7% (hazard ratio [HR]<1.52). Secondary end points included biochemical recurrence (BR), local progression, disease-specific survival, and overall survival.

A total of 1092 patients were analyzed, with 542 receiving conventional radiation and 550 undergoing hypofractionated radiation. The median follow-up was 12.75 years. The estimated 12-year DFS was 56.1% (95% CI, 51.5-60.5) in the conventional arm and 61.8% (95% CI, 57.2-66.0) in the hypofractionated arm. The DFS hazard ratio was 0.85 (0.71-1.03), confirming noninferiority (P<.001).

The 12-year cumulative incidence of BR was 17.0% (95% CI, 13.8-20.5) in the conventional arm and 9.9% (95% CI, 7.5-12.6) in the hypofractionated arm (HR, 0.56; 0.40-0.78), suggesting improved efficacy with hypofractionated radiotherapy.

Long-term DFS was noninferior in hypofractionated radiotherapy compared with conventional radiotherapy. The risk of BR was reduced with moderate hypofractionation. No differences in late grade 3 gastrointestinal or genitourinary toxicity were observed between the arms.