In a trial reported in JAMA Oncology, Julia S. Wong, MD, and colleagues found that hypofractionated postmastectomy radiation therapy did not improve outcomes in the physical well-being domain of the Functional Assessment of Cancer Therapy–Breast (FACT-B) assessment vs conventionally fractionated radiation therapy after implant-based reconstruction in women with breast cancer.
Julia S. Wong, MD
Study Details
The U.S. multicenter study included 400 women undergoing mastectomy and immediate expander or implant reconstruction for breast cancer (Tis, TX, or T1–3) and unilateral postmastectomy radiation therapy between March 2018 and November 2021. Patients were randomly assigned to hypofractionated radiation therapy consisting of a chest wall dose of 4,256 cGy in 16 fractions (n = 199) or conventionally fractionated radiation therapy consisting of 5,000 cGy in 25 fractions.
The primary outcome measure of the study was change in the physical well-being domain of FACT-B at 6 months after starting postmastectomy radiation therapy.
Key Findings
Median follow-up was 40.4 months (range = 15.4–63.0 months).
A total of 330 patients, including 164 in the hypofractionated group and 166 in the conventionally fractionated group, had physical well-being scores at baseline and at 6 months. Change in mean score at 6 months was 0.18 (95% confidence interval [CI] = −0.53 to 0.88) in the hypofractionated group vs 0.05 (95% CI = −0.63 to 0.74) in the conventionally fractionated group, yielding a nonsignificant difference favoring hypofractionation of 0.13 (95% CI = −0.86 to 1.11, P = .80).
Significant interaction between age group and study group was observed (P = .03 for interaction). Among patients aged 45 and younger, the 6-month absolute physical well-being score was 23.6 (95% CI = 22.7–24.6) in the hypofractionated group vs 22.0 (95% CI = 20.7–23.3) in the conventionally fractionated group (P = .047), with those in the hypofractionated group reporting less bother from adverse events (P = .02) and nausea (P = .04).
Among patients included in the as-treated analysis, 11 distant recurrences and 1 local-regional recurrence was reported in 190 patients in the hypofractionated group, and 12 distant recurrences and 1 local-regional recurrence were observed in 195 patients in the conventionally fractionated group.
Chest wall toxic effects occurred in 20 patients in the hypofractionated group and 19 patients in the conventionally fractionated group, at a median of 7.2 months. Compared with conventional fractionation, hypofractionation was not associated with an increased risk of chest wall toxic effects on multivariate analysis (hazard ratio = 1.02, 95% CI = 0.52–2.00, P = .95).
Patients in the hypofractionated group were less likely to have a treatment break (2.7% vs 7.7%, P = .03) or to require unpaid time off work (8.5% vs 16.9%, P = .02) than those in the conventionally fractionated group.
The investigators concluded: “In this randomized clinical trial, the hypofractionated regimen did not significantly improve change in physical well-being compared with the conventionally fractionated regimen. These data add to the increasing experience with hypofractionated postmastectomy radiation therapy in patients with implant-based reconstruction.”
Rinaa S. Punglia, MD, of the Department of Radiation Oncology, Dana-Farber Cancer Institute, is the corresponding author of the JAMA Oncology article.
Disclosure: The study was supported by a Patient-Centered Outcomes Research Institute (PCORI) award. For full disclosures of the study authors, visit jamanetwork.com.
