Nick Mulcahy

October 06, 2016

BOSTON — For men with low-risk prostate cancer, hypofractionated radiation therapy (RT) provided quality-of-life (QoL) outcomes similar to those of conventional RT, but with about one-third less treatment time, according to new research presented here at the American Society for Radiation Oncology (ASTRO) 2016 Annual Meeting.

The shorter, more intensive RT had previously been found to provide efficacy similar to that of the conventional approach in terms of progression-free survival, lead study author, Deborah Bruner, PhD, from Emory University in Atlanta, Georgia, told reporters here during a meeting press briefing.

Nevertheless, the hypofractionated approach is still considered to be investigational, she added.

However, Dr Bruner said that new results should be considered "for changing RT practice guidelines" for men with low-risk prostate cancer.

The new results are pivotal because there has been a concern that the more intensive hypofractionated RT might cause more adverse events, she explained.

Indeed, at last year's ASTRO meeting, safety results reported from this same NRG Oncology/RTOG 0415 trial indicated as much. In clinician-reported findings, there was a "slight increase" in late grade 2, gastrointestinal, and genitourinary adverse events in the hypofractionated group compared with the conventional fractionation group, explained Dr Bruner.

However, the new safety results are patient-reported outcomes.

QoL and toxicity outcomes are important in a noninferiority trial, such as the NRG Oncology/RTOG 0415 trial, said Dr Bruner, because they are likely to be what ultimately differentiates the treatment groups.

In the trial, investigators randomly assigned patients to receive hypofractionated RT (70 Gy in 28 fractions over 5.6 weeks) or conventional RT (73.8 Gy in 41 fractions over 8.2 weeks).

A total of 962 patients reported QoL data, which was measured by using the Expanded Prostate Index Composite questionnaire. This instrument has four domains: bowel, urinary, hormonal, and sexual. The median patient age was 67 years.

Participant feedback was collected at baseline, 6 months after treatment began, and 1 year post-treatment, with change scores compared between the two groups.

At baseline, there were no statistically significant differences between treatment groups in any of the QoL domains.

Change scores also did not differ in either group on any EPIC domain at 6 months' follow-up.

However, at 12 months' follow-up, patients receiving hypofractionation reported a larger decline in the bowel domain compared with those who received conventional RT, with an average change from baseline of –3.6 vs –1.8, respectively (P = .0037), but the change was not deemed clinically significant to patients, said Dr Bruner.

Sexual function had a large decline in both groups: 15 points in the conventional RT group and 11 points in the hypofractionated group, but these changes were not statistically significant.

Urinary scores exhibited almost "no decline" from baseline in both groups: 0 points for conventional RT and 2 points for hypofractionation. The difference was not significant, said Dr Bruner.

Hormonal scores did not change from baseline in either group.

"There is now a significant body of evidence showing that men can safely be treated with shorter-course radiation for low-risk prostate cancer," summarized Dr Bruner. The shorter treatment is similarly effective, less expensive, and more convenient, she commented.

"This study exemplifies what ASTRO is trying to achieve," she told reporters at a meeting press briefing, adding that it represents "value-based care."

Colleen Lawton, MD, from the Medical College of Wisconsin in Milwaukee, moderated the press briefing and agreed. "The shorter course is cheaper for the healthcare system, it's cheaper for the patient, and it's easier for the patient," she said.

The study was funded by the National Institutes of Health. Dr Bruner and Dr Lawton have disclosed no relevant financial relationships.

American Society for Radiation Oncology (ASTRO) 2016 Annual Meeting. Abstract 4. Presented September 26.

Follow Medscape senior journalist Nick Mulcahy on Twitter: @MulcahyNick

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