Three-Year Outcomes With Hypofractionated Versus Conventionally Fractionated Whole-Breast Irradiation: Results of a Randomized, Noninferiority Clinical Trial
Mené sur 286 patientes atteintes d'un cancer du sein de stade 0 à II (durée médiane de suivi : 4,1 ans), cet essai multicentrique évalue, du point de vue des événements esthétiques indésirables à 3 ans et par rapport à une radiothérapie fractionnée conventionnelle, la non infériorité d'une radiothérapie hypofractionnée de l'ensemble du sein, en combinaison ou non avec une chimiothérapie ou une dose de rayonnement additionnel du lit tumoral
Purpose : The adoption of hypofractionated whole-breast irradiation (HF-WBI) remains low, in part because of concerns regarding its safety when used with a tumor bed boost or in patients who have received chemotherapy or have large breast size. To address this, we conducted a randomized, multicenter trial to compare conventionally fractionated whole-breast irradiation (CF-WBI; 50 Gy/25 fx + 10 to 14 Gy/5 to 7 fx) with HF-WBI (42.56 Gy/16 fx + 10 to 12.5 Gy/4 to 5 fx). Patients and Methods : From 2011 to 2014, 287 women with stage 0 to II breast cancer were randomly assigned to CF-WBI or HF-WBI, stratified by chemotherapy, margin status, cosmesis, and breast size. The trial was designed to test the hypothesis that HF-WBI is not inferior to CF-WBI with regard to the proportion of patients with adverse cosmetic outcome 3 years after radiation, assessed using the Breast Cancer Treatment Outcomes Scale. Secondary outcomes included photographically assessed cosmesis scored by a three-physician panel and local recurrence-free survival. Analyses were intention to treat. Results : A total of 286 patients received the protocol-specified radiation dose, 30% received chemotherapy, and 36.9% had large breast size. Baseline characteristics were well balanced. Median follow-up was 4.1 years. Three-year adverse cosmetic outcome was 5.4% lower with HF-WBI (Pnoninferiority = .002; absolute risks were 8.2% [n = 8] with HF-WBI v 13.6% [n = 15] with CF-WBI). For those treated with chemotherapy, adverse cosmetic outcome was higher by 4.1% (90% upper confidence limit, 15.0%) with HF-WBI than with CF-WBI; for large breast size, adverse cosmetic outcome was 18.6% lower (90% upper confidence limit, −8.0%) with HF-WBI. Poor or fair photographically assessed cosmesis was noted in 28.8% of CF-WBI patients and 35.4% of HF-WBI patients (P = .31). Three-year local recurrence-free survival was 99% with both HF-WBI and CF-WBI (P = .37). Conclusion : Three years after WBI followed by a tumor bed boost, outcomes with hypofractionation and conventional fractionation are similar. Tumor bed boost, chemotherapy, and larger breast size do not seem to be strong contraindications to HF-WBI.