The aim of this study was to evaluate local control, survival and toxicity profile of a consecutive cohort of early-stage breast cancer (EBC) patients treated with adjuvant hypofractionated radiotherapy (HF) with no boost delivered to the lumpectomy cavity, after breast-conserving surgery (BCS). Between 2005 and 2015, a total of 493 women affected with EBC were treated with HF (46 Gy/20 fractions or 40.05 Gy/15 fractions) to the whole breast without boost to tumor bed, because of age and/or favorable tumor characteristics. The primary endpoint was 5-year actuarial local control (LC); secondary endpoints included survival, toxicity profile and cosmesis. Median follow-up was 57 months (range 6-124). Actuarial 5-year overall, cancer-specific, disease-free survival and LC were 96.3, 98.9, 97.8 and 98.6 %, respectively. On multivariate analysis, tumor stage (T1 vs. T2) and hormonal status (positive vs. negative estrogen receptors) were significantly correlated with LC. Only 2 % of patients experienced ≥G3 acute skin toxicity. Late toxicity was mild with only 1 case of G3 fibrosis. Most of the patients (95 %) had good-excellent cosmetic results. HF to the whole breast with no boost delivered to the tumor bed is a safe and effective option for a population of low-risk breast cancer patients after BCS, with excellent 5-year LC, mild toxicity profile and promising cosmetic outcome. A subgroup of patients with larger tumors and/or with no estrogen receptor expression may potentially benefit from treatment intensification with a boost dose to the lumpectomy cavity.
Keywords: Adjuvant therapy; Boost; Breast cancer; Hypofractionated radiotherapy; Hypofractionation; Local control.