Short-course Hypofractionated RT with Boost (SHoRT-B) in Women with Stage 0-IIIa Breast Cancer: A Phase II Trial
Mené sur 83 patientes atteintes d'un cancer du sein de stade 0-IIIa traité (âge médian : 53,4 ans ; durée médiane de suivi : 40 mois), cet essai de phase II évalue l'efficacité, du point de vue de la récidive locorégionale et des résultats esthétiques, et la toxicité d'une radiothérapie hypofractionnée de courte durée en combinaison avec une dose de rayonnement additionnel du lit tumoral
Purpose/Objectives : Conventionally fractionated whole breast irradiation (WBI) with a boost takes approximately 6-7 weeks. We evaluated a short course of hypofractionated, accelerated whole breast irradiation (HF) in which therapy is completed in 3 weeks inclusive of a sequential boost. Materials/Methods : We delivered a whole breast dose of 36.63 Gy in 11 fractions of 3.33 Gy over 11 days followed by a lumpectomy bed boost in 4 fractions of 3.33 Gy delivered once daily for a total of 15 treatment days. Acute toxicities were scored using CTCAE v 4. Late toxicities were scored using the RTOG/EORTC scale. Cosmesis was scored using the Harvard Cosmesis Scale. Our primary endpoint was freedom from locoregional failure; we incorporated early stopping criteria based on predefined toxicity thresholds. Cosmesis was examined as a secondary endpoint. Results : We enrolled 83 women with Stage 0-IIIa breast cancer. After a median follow up of 40 months, 2 cases of isolated ipsilateral breast tumor recurrence occurred (2/83, crude rate 2.4%). Three year estimated local recurrence-free survival is 95.9% (95% CI: 87.8% - 98.7%). The 3-year estimated distant recurrence-free survival is 97.3% (95% CI: 89.8% - 99.3%). Three year secondary malignancy free survival is 94.3% (95% CI: 85.3% - 97.8%). Twenty-nine patients (34%) had Grade 2 acute skin toxicity and 1 patient had a late grade 2 toxicity (fibrosis). One patient had acute grade 3 dermatitis while 2 patients experienced a grade 3 late skin toxicity. Ninety-four percent of evaluable patients had good/excellent cosmesis. Conclusions : Our phase II institutional study offers one of the shortest courses of HF--delivered in 15 fractions inclusive of a sequential boost. We demonstrated expected low toxicity and high local control rates with good-excellent cosmetic outcomes. This fractionation scheme is feasible and and well-tolerated and offers women WBI in a highly convenient schedule.