PRELIMINARY RESULTS OF A RANDOMIZED STUDY ON POSTMENOPAUSAL WOMEN WITH EARLY STAGE BREAST CANCER: ADJUVANT HYPOFRACTIONATED WHOLE BREST IRRADIATON VERSUS ACCELERATED PARTIAL BREAST IRRADIATION (HYPAB TRIAL)

Abstract Purpose to report preliminary data of a randomized phase III trial comparing hypofractionated whole breast irradiation (HWBI) and accelerated partial breast irradiation (APBI) using a volumetric modulated arc therapy (VMAT) Material and methods the HYPAB trial enrolled postmenopausal women with biopsy-proven infiltrating breast cancer, clinically negative axilla, single T1-2 tumors, treated with breast-conserving surgery. Patients were randomized 1:1 after surgery to HWBI (40.5 Gy whole breast, 48.0 Gy to surgical bed, 15 fractions over 3 weeks) or APBI (30 Gy delivered in five fractions of 6 Gy given on alternate days on the surgical bed). Cosmetic outcome was the primary end point of the study Results 172 patients were enrolled. After a median follow-up of 36 months 5 local failures and 3 locoregional failures were recorded, with no difference between the two treatment arms. Use of WBI as compared to APBI was significantly correlated to increased incidence of overall (62% versus 14%, p Conclusion APBI with VMAT technique is safe and feasible, with lower acute toxicity when compared to HWBI.