A new study has failed to demonstrate hypofractionated radiotherapy as a non-inferior option to fractionated radiotherapy for patients with intermediate- or high-risk prostate cancer.
In patients with genitourinary and gastrointestinal cancers, cancer treatment can often lead to high toxicity and morbidity. To address this, several studies of prostate cancer have suggested that hypofractionation might be used to enhance biological tumor dose without increasing genitourinary and gastrointestinal toxicity.
Researchers led by Shafak Aluwini, MD, Erasmus MC Cancer Institute (Rotterdam, The Netherlands) set out to test this approach in a study, published in Lancet Oncology. For the phase 3 HYPRO (Hypofractionated irradiation for prostate cancer) study, 820 patients were randomly assigned to receive radiation therapy with standard fractionation (39 fractions of 2 Gy for 8 weeks) or with hypofractionation (19 fractions of 3.4 Gy for 6.5 weeks). Researchers looked at the cumulative incidence of grade 2 or worse acute and late genitourinary and gastrointestinal toxicity to determine whether hypofractionation was inferior to standard fractionation.
After a median follow-up of 60 months, data on late toxicity was available for 387 patients in the standard fractionation group and 395 patients in the hypofractionation group. Grade 2 or worse genitourinary effects were observed in 41.3% of patients assigned to hypofractionation and in 39% of patients assigned to standard fractionation. For gastrointestinal toxicity, the percentage of patients with grade 2 or higher toxicity at 3 years was 21.9% with hypofractionation, compared with 17.7% with standard fractionation.
Deeper analysis also revealed that a significantly greater percentage of patients assigned to receive hypofractionation had cumulative grade 3 genitourinary toxicity than patients assigned to receive standard fractionation (19% vs 12.9%), although this trend was not found for grade 3 or higher gastrointestinal toxicity, for which there was no significant difference between the two groups.
From these results, researchers stated that they could not confirm hypofractionation as non-inferior for cumulative genitourinary and gastrointestinal toxicity compared with standard fractionation. However, efficacy outcomes will need to be reported before a definitive determination can be made about the potential utility of hypofractionation for reducing radiation-related toxicity.
