Hypofractionated volumetric‐modulated arc therapy for breast cancer: A propensity‐score‐weighted comparison of radiation‐related toxicity

We assessed the clinical benefit of combining volumetric-modulated arc therapy (VMAT) and hypofractionated radiotherapy (HF-RT) considering the incidence of radiation-related toxicities. After a retrospective review for breast cancer patients treated with adjuvant RT between 2005 and 2017, a total of 4,209 patients treated with three-dimensional conventional fractionation (CF-3D, 50.4 Gy/28 fractions) and 1,540 patients treated with HF-RT (768 received HF-3D; 772, HF-VMAT; 40 Gy/15 fractions) were included. A total of 2,229 patients (38.8%) received regional node irradiation (RNI): 1,642 (39.0%), 167 (21.7%), and 420 (54.4%) received RNI via CF-3D, HF-3D, and HF-VMAT, respectively. Acute/subacute and late toxicities were evaluated. Propensity scores were calculated via logistic regression. Grade 2+ acute/subacute toxicities was the highest in CF-3D group (15.0%, 2.6%, and 1.6% in CF-3D, HF-3D, and HF-VMAT, respectively; p<0.001). HF-VMAT reduced grade 2+ acute/subacute toxicities significantly compared to CF-3D (odds ratio [OR] 0.11, p<0.001) and HF-3D (OR 0.45, p=0.010). The 3-year cumulative rate of late toxicities was 18.0% (20.1%, 10.9%, and 13.4% in CF-3D, HF-3D, and HF-VMAT, respectively; p<0.001). On sensitivity analysis, the benefit of HF-VMAT was high in RNI group. Acute and late toxicities were fewer after HF-VMAT than after HF-3D or CF-3D, especially in women who underwent RNI. This article is protected by copyright. All rights reserved.