144 - Early Outcomes of a Phase III Randomized Controlled Trial Comparing Ultra-Hypo Fractionated 5 Fraction Treatment vs. Hypofractionated 15 Fraction Treatment for Patients Receiving Regional Nodal Irradiation
Presenter(s)
C. Vargas1, L. A. McGee1, C. A. Dodoo2, M. Halyard1, M. Truman2, J. Niska1, D. Shumway3, S. S. Park3, K. S. Corbin3, L. A. Vallow4, O. T. Oladeru1, S. E. James1, and R. W. Mutter3; 1Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, 2Mayo Clinic Department of Statistics, Scottsdale, AZ, 3Department of Radiation Oncology, Mayo Clinic, Rochester, MN, 4Department of Radiation Oncology, Mayo Clinic, Jacksonville, FL
Purpose/Objective(s): To report early provider and patient reported outcomes of 5 vs. 15 fraction breast and regional nodal irradiation treatments after breast-conserving surgery (BCS) or mastectomy with or without reconstruction.
Materials/Methods: A total of 146 patients were dynamically randomized to receive locoregional ultra-hypofractionated radiation (UHF), delivering 26 Gy over 5 treatments (n=73), or hypofractionated radiation (HF), delivering 40 Gy over 15 treatments (n=73). Patients were stratified based on radiotherapy type (protons vs x-rays). A simultaneous integrated boost was allowed. Physician-reported adverse events (AEs), patient-reported AEs, PROMIS-10, Mayo-10, and the Breast Cancer Treatment Outcome Scale (BCTOS) were collected prior to radiation, at the end of treatment (EOT), and at 3 and 6 months. All procedures, surgeries, emergency room visits, and hospital admissions were reviewed to assess their cause and relation to treatment.
Results: The median follow-up was 23 months for the UHF group and 24 months for the HF group (p=0.9). Tumor staging included cT1 (34%), cT2 (43%), and cT3 (23%), with nodal involvement classified as N0 (8.9%) and N1-3 (91.1%). BCS was performed in 36% of patients, mastectomy with reconstruction in 38%, and mastectomy alone in 38%. Pre-treatment Grade 2 or higher adverse events (AEs) were observed in 7.5% of HF patients and 11% of UHF patients (p=0.44). At the end of treatment (EOT), 25% of HF patients experienced Grade 2 or higher AEs, compared to 4.2% in the UHF group (p<0.001). At three months, Grade 2 or higher AEs were reported in 11% of HF patients and 10% of UHF patients (p=0.89). Grade 2 brachial plexopathy was present in four patients before radiation therapy (RT), persisted in one patient at EOT, and resolved in all patients by three months. Among reconstructed patients, one implant failure occurred in an HF patient due to a non-healing wound. Additionally, four implant exchanges were performed in HF patients (26%), compared to one implant exchange in a UHF patient (5%) (p=0.18). Quality-of-life (QoL) metrics suggested lower pain scores (p=0.076), better aesthetic symptoms (p=0.003), and improved breast shape (p=0.005) with UHF at EOT; however, these differences disappeared by three months. All other QoL metrics were not statistically different between UHF and HF at EOT or at three months.
Conclusion: This report highlights the safety of ultra-hypofractionated radiation following BCS or mastectomy with or without reconstruction when comprehensive regional nodal irradiation is administered.