Abstract GS5-12: Hypofractionated Radiotherapy in patients with Breast Cancer (HRBC): Acute toxicity data of a phase III randomized study
Budhi Singh Yadav, Divya Dahiya, Manish Gupta
Abstract
Abstract Background HRBC is a phase III randomized open label study of adjuvant radiotherapy in patients with breast cancer. In this study we compared a 3 weeks radiation schedule with 2 weeks. Materials and methods Patients with breast cancer, stage I-III, post mastectomy or after breast conservative surgery who needed adjuvant locoregional radiotherapy were randomized to 34Gy in 10 fractions over 2 weeks (study arm) or 35Gy in 15 fractions over 3 weeks to the chest wall and 40Gy/15#/3wks to breast and supraclavicular fossa (control arm). Boost dose when indicated was 8Gy/2# in both the arms. Patients were planned on simulator with 2 tangential fields to breast/chest wall and incident supraclavicular fossa field. Acute toxicity was assessed using a RTOG grading system. Assessment was carried out weekly during radiotherapy and at 4 weeks after treatment by the physician. Cosmetic outcome was assessed using Harvard/NSABP/RTOG scale. The toxicity between the two arms was compared using Fisher’s exact test. The trial was approved by institutional ethics committee. This trial is registered with ClinicalTrials.gov, number NCT04075058. Results This study included 1121 patients. Median follow up was 35 months (range 6-84 months). Mean age was 48 year (range 24-80 years). The patient characteristics were comparable between the two arms except for more mastectomies in the 3 week arm and more node positive patients in the 2 week arm. There were more oestrogen receptor positive tumors in the 3 week arm. Acute skin toxicities were comparable between the two arms. Grade 2 and 3 skin toxicity was 98(17%) and 82(15%); and 16(3%) and 10(2%) in the 3 week and 2 week arm (p=0.15), respectively. Cosmetic outcome was significantly better in 2 week arm 94% as compared to 90% in the 3 week arm (p=0.016). Conclusion The two radiation schedules were comparable in terms of acute skin toxicity. Cosmetic outcome was better in the 2 week schedule. Citation Format: Budhi Singh Yadav, Divya Dahiya, Manish Gupta. Hypofractionated Radiotherapy in patients with Breast Cancer (HRBC): Acute toxicity data of a phase III randomized study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS5-12.