As reported in The Lancet by Rivera et al, 5-year results of a French phase III trial (UNICANCER HypoG-01) showed noninferiority of hypofractionated locoregional radiotherapy (RT) vs standard 5-week RT in reducing risk of postsurgery lymphedema in patients with early breast cancer.
Study Details
In the open-label multicenter trial, 1,221 women (per-protocol population) requiring nodal irradiation after complete tumor resection were randomly assigned between September 2016 and March 2020 to receive hypofractionated RT at 40 Gy in 15 fractions over 3 weeks (n = 614) or 5-week RT at 50 Gy in 25 fractions (n = 607). The primary outcome measure was ipsilateral arm lymphedema, defined as 10% or greater increase in arm circumference at 15 cm proximal, 10 cm distal, or both, to the ipsilateral olecranon relative to baseline and contralateral arm, with a noninferiority margin for the hazard ratio (HR) of 1.545.
Key Findings
Median follow-up was 4.8 years (interquartile range = 4.01–5.02 years).
Ipsilateral arm lymphedema occurred in 275 patients (25%) overall, including 143 in the 3-week RT group and 132 in the 5-week RT group; noninferiority of the hypofractionated RT group was demonstrated (HR = 1.02, 95% confidence interval [CI] = 0.79–1.31, P < .001 for noninferiority). The 3-year cumulative incidence of ipsilateral arm lymphedema was 23.4% (95% CI = 19.7%–27.6%) in the 3-week RT group vs 22.2% (95% CI = 19.5%–26.3%) in the 5-week RT group.
Grade 3 or higher adverse events were observed in 8% of patients in the 3-week RT group vs 13% of the 5-week RT group. Apart from radiodermatitis, the most common adverse events of any grade among all patients were pain (69%), fatigue (65%), and fibrosis (47%). Serious adverse events were reported in 17 patients in the 3-week RT group vs 15 in the 5-week RT group.
The investigators concluded: “Three-week radiotherapy (40 Gy in 15 fractions) was found to be noninferior to 5-week radiotherapy (50 Gy in 25 fractions) for arm lymphedema risk and was comparably safe regarding other late normal tissue effects for patients prescribed locoregional radiotherapy for early breast cancer.”
Sofia Rivera, MD, PhD, of the Radiotherapy Department, Institut Gustave Roussy, Villejuif, France, is the corresponding author for The Lancet article.
DISCLOSURE: The study was funded by the French National Cancer Institute. For full disclosures of the study authors, visit thelancet.com.
