Ultrahypofractionation in Larger Breast size, a single institute feasibility study

Abstract

Background: After the standardization of adjuvant moderately hypofractionated whole reast radiotherapy (HF-WBRT) over 15-16 fractions, with the favorable long-term results of the K-FAST trial and with the uncertainty about the safety in large breast sizes. We tested the easibility of using once-weekly HF-WBRT over 5-weeks in patients with larger breast sizes. Patients and Methods: In this prospective phase-II study, patients with early breast cancer with breast size>500cc, after breast conservative surgery (BCS), received radiotherapy at a dose of 28.5Gy in 5 once-weekly fractions. Patients were categorized according to the breast size to medium and large. The primary endpoints were assessment of acute skin-toxicity and patients` quality of life (QoL); secondary endpoints were late skin and subcutaneous-tissue toxicity and cosmetic score. Results: Twenty-nine patients were recruited. The median duration of follow-up was 24-months. The mean tumor size was 2.1cm and 96.5% were node negative. Following radiotherapy, 96.5% had G0-2 acute skin-toxicity, all patients had G0-1 late skin-toxicity. Regarding cosmesis 91.7% of patients had Excellent-Good cosmetic score. No significant correlation was found between the breast size and the acute and late toxicities. The QoL was maintained during follow-up. Conclusion: The protocol showed acceptable toxicity profile regardless of the breast size.