Study Shows H-RT Is Safe, Effective for Low-Risk Prostate Cancer

Deborah Watkins Bruner, PhD, RN

Study results that examined patient-reported outcomes and quality of life measures demonstrate that hypofractionated radiotherapy (H-RT) is a viable, safe, and value-added alternative to patients with low-risk prostate cancer. H-RT offers one-third less treatment time than conventional radiotherapy (C-RT) and comparable health-related quality of life outcomes, according to findings presented by Deborah Watkins Bruner, PhD, RN, during the plenary session of the 2016 ASTRO Annual Meeting.

“There is a preponderance of evidence, finally, that shows that H-RT is effective,” said Bruner, associate director for Mentorship, Education, and Training, Winship Cancer Institute of Emory University.¹The objective of her study was to assess the degree, duration, and clinical significance of the differences between men who received H-RT or C-RT, Bruner said. “In trials in which survival rates are hypothesized to be similar, it’s the secondary outcomes of toxicity, quality of life, and costs that are essential to interpreting the primary results,” said Bruner.

Bruner’s study was based on a parent study, led by Lee et al, and presented in 2015, that examined non-inferiority results in which hypofractionation outcomes were shown to be equivalent to outcomes in men who received conventional therapy.²In the Lee study, 1115 men with low-risk prostate cancer were randomized to receive 70 Gy in 28 fractions over 5.6 weeks (H-RT) and men in the C-RT arm received 73.8 Gy in 41 fractions over 8.2 weeks.

Lee reported that no differences in early gastrointestinal or genitourinary adverse events were observed. However, late grade 2/3 gastrointestinal adverse events were approximately 60% more likely to occur in men who were assigned to treatment with H-RT (relative risk 1.55 to 1.59). Similarly, late grade 2/3 genitourinary adverse events were more likely in men assigned to treatment with H-RT (relative risk, 1.31 to 1.56). No differences in more severe events were observed.

For Bruner, a total of 962 patients reported health-related quality of life data, including 478 men from the C-RT group and 448 men from the H-RT group. Baseline characteristics between the two groups were similar, and the median patient age was 67 years, said Bruner.

Quality-of-life assessments were determined using the Expanded Prostate Index Composite (EPIC), a 50-question instrument that evaluates patient-reported side effects after prostate cancer treatment. The questionnaire measured side effects in each of EPIC’s four domains—bowel, urinary, sexual, and hormonal. EPIC assesses prostate cancer-specific health-related quality of life on a Likert scale that assigns a score of 0-100 to responses, with higher scores indicating better health-related quality of life. Participant feedback was collected at baseline, 6 months after treatment began, and 1-year post-treatment, with change scores compared between the C-RT and H-RT groups. A Wilcoxon test was used to assess differences.

Compared with men without prostate cancer, most patients in both groups reported poor baseline EPIC sexual domain scores, with the C-RT group’s score averaging 47.5 and the H-RT group’s score averaging 44.2. At baseline, the groups reported only slightly lower-than-average bowel and urinary scores.

Following treatment, patients who received higher doses in fewer sessions (the H-RT group) reported similar health-related quality of life as the patients who received conventional doses (the C-RT group). There were no differences in change scores for either group on any EPIC domain at 6-months follow-up. At 12-months follow-up, hypofractionation patients reported a larger decline in the bowel domain compared to those who received C-RT, but the change was not deemed clinically significant to patients.

“In terms of urinary function, there was no significant differences between the two arms; in terms of hormonal function, there was no significant differences at any time point,” said Bruner.

Bruner noted a marked decline from baseline for sexual function, but the decline was equal in both arms. “There was a 15-point decline in the C-HT arm and about an 11-point decline in the H-RT arm. This was neither clinically nor statistically significant.”

“We conclude that EPIC domain scores, except for sexual function, exhibited a small decline of 1-year follow-up from baseline in both arms. As compared with C-HT, patients with H-RT had a larger decline in bowel reported outcomes, which was statistically significant, but not clinically significant. Patient-reported outcomes were comparable and supports the use of H-RT for low-risk prostate cancer as a value-based care approach,” said Bruner.

References:

1. Bruner WD. NRG Oncology/RTOG 0415 phase III noninferiority study comparing 2 fractionation schedules in patients with low-risk prostate cancer: prostate specific quality of life results. Presented at: 2016 ASTRO Annual Meeting; Boston, Massachusetts, September 25-28, 2016. Plenary session PL 01.
2. Lee RW, Dignam JJ, Amin MB, et al. Randomized phase III noninferiority study comparing two radiotherapy fractionation schedules in patients with low-risk prostate cancer.J Clin Oncol. 2016;34(20):2325-2332. doi: 10.1200/JCO.2016.67.0448.