BOSTON – Shortening the radiation dosing schedule by 3 weeks in men with early-stage, low-risk prostate cancer does not appear to result in worse outcomes or diminished quality of life, according to investigators in the NRG Oncology/RTOG 0415 trial.
Efficacy results from the trial, reported at the annual meeting of the American Society for Radiation Oncology, showed that a radiation schedule of 70 Gy in 28 fractions delivered over 5.6 weeks was not inferior to 73.8 Gy delivered in 41 fractions over 8.2 weeks in terms of disease-free, progression-free, or overall survival.
Courtesy ASTRO
Dr. Deborah W. Bruner
“The International Atomic Energy [Agency] in its prostate cancer guidelines still lists hypofractionated radiation therapy as investigational, but I think we are at the stage where there is a ton of evidence, and this is really no leap of faith anymore that this can become the standard of care,” said Deborah W. Bruner, PhD, of Emory University and the Winship Cancer Institute in Atlanta.
In the treatment of patients with low-risk prostate cancer who opt for therapy over active surveillance, it is essential that “we treat them with the absolute minimum amount of treatment, with minimum side effects, and with minimum cost,” she said at a plenary session.
As reported by the investigators in 2015, there were small but significant increases in clinician-reported adverse gastrointestinal and genitourinary adverse events in the hypofractionation arm compared with the conventional fractionation arm in the trial, prompting the researchers to see whether patients were actually experiencing what clinicians thought they were seeing.
The investigators examined health-related quality of life and symptoms using the Expanded Prostate Index Composite (EPIC instrument).
They used a 50-item patient-reported outcomes questionnaire using a scale of 0 (no problem) to 4 (big problem), with responses transferred to a 0-100 scale. The questionnaire asked about symptoms in four domains: bowel, urinary, sexual, and hormonal. Patients filled out the questionnaire at baseline and at 6 and 12 months of follow-up.
At 1 year, there were no changes from baseline in hormonal scores in either study arm, but sexual function scores declined by approximately 15 points among patients treated with conventional fractionation and by 11 points among patients treated with hypofractionation (between-group difference nonsignificant).
There was a small decline in urinary scores in both arms, but this difference was not significant.
Patients treated with hypofractionation had a statistically larger decline in bowel scores compared with patients treated with conventional fractionation, a 1.8-point difference, but this difference did not translate into a clinically significant difference; that is, patients themselves could not detect a significant decline in bowel function, Dr. Bruner said.
The invited discussant, Ronald Chen, MD, MPH, director of the comparative effectiveness research program at the University of North Carolina Lineberger Comprehensive Cancer Center in Chapel Hill, agreed that a difference of only 1.8 points on a 0-100 scale, while technically significant, is clinically meaningless.
“So now we have the complete story and a better understanding of perhaps the value of hypofractionation versus standard fractionation from the patient’s perspective,” he said.
He also emphasized that “quality of life is a central component of any value framework in cancer care, and we must hear the patient’s voice. For clinical trials to truly inform patient decision making and allow patients to assess the value of their treatment options, quality of life must be studied.”