Physician- and Patient-Reported Outcomes of the MC1635 Phase 3 Trial of Ultrahypofractionated Versus Moderately Hypofractionated Adjuvant Radiation Therapy After Breast-Conserving Surgery

• DOI: 10.1016/j.ijrobp.2023.10.018
• Publication Date: 2023-10-31T23:15:24Z
• Authors: Brady S. Laughlin; Kimberly S. Corbin; Diego Augusto San...; Cameron S. Thorpe; Michael A. Golafshar; Barbara Pockaj; Patricia Cronin; Lisa A. McGee; Michele Y. Halyard; Robert W. Mutter; Sameer R. Keole; Sean S. Park; Dean A. Shumway; Tamara Z. Vern-Gross; Laura Vallow; William W. Wong; Todd A. DeWees; Carlos E. Vargas
• Keywords: Quality of Life; Humans; Female; Radiotherapy, Adjuvant; Breast Neoplasms; Patient Reported Outcome Measures; Mastectomy, Segmental; 3. Good health

Our aim was to report physician- and patient-reported outcomes of patients with localized breast cancer treated with moderate versus ultrahypofractionated whole breast irradiation (WBI) after breast-conserving surgery (BCS).Between February 2018 and February 2020, patients with localized breast cancer (pT0-3 pN0-1 M0) were offered participation in a phase 3 randomized clinical trial assessing adjuvant moderate hypofractionation (MHF) to 40 Gy in 15 fractions versus ultrahypofractionation (UHF) to 25 Gy in 5 fractions after BCS, with an optional simultaneously integrated boost. Toxicities, cosmesis, and quality of life were assessed at baseline, end of treatment (EOT), and 3 months, 1 year, 2 years, and 3 years from irradiation using validated metric tools.One hundred seven patients were randomized to MHF (n = 54) or UHF (n = 53) adjuvant WBI. The median follow-up was 42.8 months. Grade 2 radiation dermatitis was experienced by 4 patients (7.4%) in the MHF arm and 2 patients (3.7%) in the UHF arm at EOT (P = .726). No grade 3 or higher toxicities were observed. Deterioration of cosmesis by physician assessment was observed in 2 (6.7%) patients treated in the UHF arm and 1 (1.9%) patient treated in the MHF arm at EOT (P = .534), whereas at 3 months, only 1 (1.8%) patient treated in the MHF arm demonstrated deterioration of cosmesis (P = .315). At EOT, 91% and 94% of patients reported excellent/good cosmesis among those treated with MHF and UHF regimens, respectively (P = .550). At 3 months, more patients within the MHF arm reported excellent/good cosmesis compared with those in the UHF arm (100% vs 91%; P = .030). However, the difference in patient-reported cosmesis disappeared at the 1-, 2-, and 3-year time points.UHF WBI showed similar treatment-related late toxicities and similar provider-scored cosmesis compared with MHF radiation in patients treated adjuvantly after BCS.