Hypofractionated Radiation Found Equivalent to Conventionally Fractionated Regimen in Early-Stage Breast Cancer
Early-stage breast cancer patients receiving a shorter course of whole-breast irradiation with higher radiation doses per fraction reported equivalent cosmetic, functional, and pain outcomes over time as those receiving a longer, lower-dose per fraction course of treatment, according to researchers from The University of Texas MD Anderson Cancer Center.
Their study, published by Swanick et al in Cancer, found patient-reported functional status and breast pain improved significantly following both radiation schedules, and there were no significant differences in physician-reported cosmetic evaluations. With a more convenient treatment schedule and equivalent outcomes, the authors suggested the shorter course as the preferred option for patients.
Conventionally Fractionated vs Hypofractionated Regimens
In the United States, women historically have been treated with conventionally fractionated whole-breast irradiation, given in smaller doses over a longer period of time, rather than hypofractionated whole-breast irradiation, which consists of higher doses for a shorter treatment period.
Large randomized trials from Canada and the United Kingdom have established hypofractionated whole-breast irradiation as a safe and effective treatment for nearly all patients with early-stage breast cancer. In previous research by published by Shaitleman et al in JAMA Oncology, the authors showed patients receiving hypofractionated whole-breast irradiation experienced less acute toxicity and postradiation fatigue compared to those treated with conventionally fractionated whole-breast irradiation. However, the adoption of hypofractionated radiotherapy has been limited in the United States. In fact, researchers note only one-third of patients for whom hypofractionated whole-breast irradiation is currently recommended by the American Society of Radiation Oncology (ASTRO) actually receive the shorter course of therapy.
“This trial is particularly important because there is still some hesitation among clinicians in the United States about adopting the hypofractionated schedule,” said lead author Cameron Swanick, MD, resident in the Department of Radiation Oncology at MD Anderson. “Because American patients tend to have a higher prevalence of obesity, and because prior trials excluded certain patients with high body mass index, there has been this concern that the shorter radiation treatment course may not be as safe for American patients.”
Study Background
For the prospective, unblinded trial, 287 women with stage 0–II breast cancer were randomized to receive either conventionally fractionated whole-breast irradiation (149 patients) or hypofractionated whole-breast irradiation (138 patients). All women also received a “boost dose,” an additional treatment targeting the tumor bed with a higher dose, which has not been systematically analyzed in previous hypofractionated radiotherapy studies.
All participants were at least 40 years of age and previously had been treated with breast-conserving surgery. Seventy-six percent were overweight or obese according to their body mass index. The researchers used validated tools to gather patient-reported outcomes on cosmetic, functional and other quality-of-life measures; physicians rated cosmetic results following treatment. Assessments were performed at baseline, 6 months, and at 1, 2, and 3 years following treatment.
Study Findings
“There were no significant differences between the treatment arms for any [patient-reported outcomes] at baseline, 6 months, 1 year or 3 years,” said Dr. Swanick. “At 2 years, outcomes from the Functional Assessment of Cancer Therapy Breast trial outcome index were modestly higher in the hypofractionated group.”
There were no significant differences in physician-reported cosmetic scores at any time point. Additionally, both patient groups reported similar improvements in breast pain and functional assessments over time.
The researchers continue to follow tumor control outcomes, though no meaningful difference in survival has been found, to date. The study has several limitations, including a lack of complete data through 3 years for all patients at the time of last follow-up. (All outcomes will be reported once all patients have completed 3-year follow-up.) Further, patients and physicians were not blinded to treatment arms, which has the potential to bias the reporting outcomes.
This work was supported by a Career Development Award from the American Society of Clinical Oncology Conquer Cancer Foundation, funded by the Breast Cancer Research Foundation.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
