Treatment with a shortened (hypofractionated) radiotherapy (HRT) schedule achieved similar efficacy as treatment with the longer, conventional RT (CRT) schedule in men with low-risk prostate cancer. The shortened treatment delivered 70 Gy of radiation in 28 fractions over 5.6 weeks, and the conventional RT delivered 73.8 Gy of radiation in 41 fractions over 8.2 weeks.1

Treatment with HRT resulted in 5-year disease-free survival (DFS) that was not worse than CRT by more than 7.65% (HRT/CRT hazard ratio [HR] <1.52).

“Given the potential to increase patient convenience and reduce treatment costs, we set out to determine if the efficacy of this approach is no worse than that of a conventional schedule in men with low-risk prostate cancer,” said W. Robert Lee, MD, MEd, MS, a radiation oncologist at Duke University, Durham, North Carolina, and first author of the study.

“The study results are directly analogous to the breast cancer story in which shorter courses of radiotherapy work as well.”

In total, 1115 men with low-grade prostate cancer were randomly assigned to HRT or CRT. From the men originally enrolled, 1092 were protocol eligible and had follow-up information available. HRT was administered to 550 men, and CRT was administered to 542 men. Median follow-up was 5.8 years.

In the HRT arm, the estimated 5-year DFS was 86.3% (95% CI, 83.1 to 89.0), and in the CRT arm, it was 85.3% (95% CI, 81.9 to 88.1). Patients in the HRT arm experienced an increase of late grade 2 and 3 gastrointestinal (GI) and genitourinary (GU) adverse events (HR, 1.31 to 1.59).

“In conclusion, the results of this trial demonstrate that in men with low-risk prostate cancer, the efficacy of 70 Gy delivered in 28 fractions over 5.5 weeks is not inferior to 73.8 Gy delivered in 41 fractions over 8.25 weeks, although an increase in late grade 2 and 3 GI and GU adverse events was observed,” concluded the authors.

Grants from the National Cancer Institute funded this research.

REFERENCE

1. Lee WR, Dignam JJ, Amin MB, et al. Randomized phase III noninferiority study comparing two radiotherapy fractionation schedules in patients with low-risk prostate cancer [published online ahead of print April 4, 2016]. J Clin Oncol. doi:10.1200/JCO.2016.67.0448.