Feasibility and early toxicity in hypofractionated adjuvant breast radiotherapy with simultaneous integrated boost: A prospective study

Background: Breast-conserving surgery (BCS) followed by whole breast irradiation (WBI) is the standard of care for early-stage breast carcinoma. Hypofractionated radiotherapy with simultaneous integrated boost (SIB) offers potential advantages in treatment duration and efficacy. This study evaluates the feasibility and early toxicity profile of hypofractionated adjuvant breast radiotherapy with SIB. Methods: A prospective study was conducted on 30 patients with invasive breast cancer post-BCS between 2022-2023. Patients received 40.05 Gy in 15 fractions to the whole breast with a concomitant boost of 48.0 Gy in 15 fractions to the lumpectomy cavity over 3 weeks. Treatment was delivered using volumetric modulated arc therapy (VMAT). Dosimetric parameters and acute toxicity profiles were assessed. Results: The treatment regimen achieved satisfactory dosimetric parameters with mean ipsilateral lung dose of 9.84±1.49 Gy, V20 of 14.9±3.67%, and mean heart dose of 3.45±1.0 Gy. Acute skin toxicity was acceptable, with 36.67% of patients experiencing no change from baseline, 53.33% experiencing Grade 1 toxicity, and 10% experiencing Grade 2 toxicity. No Grade 3 or 4 toxicities were observed. No cardiac or pulmonary toxicities were noted during the follow-up period. Conclusion: Hypofractionated whole breast irradiation with simultaneous integrated boost delivering 40.05 Gy/48.0 Gy in 15 fractions is feasible with acceptable dosimetry and favorable early toxicity profile. This regimen reduces overall treatment time while maintaining safety standards.