Clinical Outcomes of Hypofractionated Whole Breast Irradiation in Early Stage, Biologically High-Risk Breast Cancer.
Practical Radiation Oncology
PURPOSE: Adoption of hypofractionated whole breast irradiation (HWBI) for patients with early-stage, biologically high-risk breast cancer remains relatively low. We compared clinical outcomes of conventionally fractionated whole breast irradiation (CWBI) versus moderate HWBI in this patient population.
METHODS AND MATERIALS: We queried a prospectively maintained database for patients with early-stage (T1-2, N0, M0) breast cancer who received whole breast irradiation with either CWBI or moderate HWBI at a single institution. We included only patients with biologically high-risk tumors (defined as either estrogen receptor/progesterone receptor/human epidermal growth factor receptor 2 negative, human epidermal growth factor receptor 2 amplified, and/or patients with a high-risk multigene assay) who received systemic chemotherapy. Inverse probability of treatment weighting was used to compare treatment cohorts and to estimate 5-year time to event endpoints. Hazard ratios (HR) and 95% confidence interval (CI) were determined based on Cox proportional hazards model.
RESULTS: We identified 300 patients, of whom 171 received CWBI and 129 received HWBI. There was a statistically significant difference in median age at diagnosis, 59 years for CWBI versus 63 years for HWBI (P = .004), and in median follow-up time, 97 months for CWBI versus 55 months for HWBI (P < .001). After accounting for differences in patient and tumor characteristics with inverse probability of treatment weighting, we found similar 5-year freedom from local recurrence (HR, 0.76; 95% CI, 0.14-4.1), freedom from regional recurrence (HR, 3.395% CI 0.15-69), freedom from distant metastasis (HR 3.9, 95% CI 0.86-17), and disease-free survival (HR 0.84; 95% CI, 0.3-2.4), between those treated with CWBI and those treated with HWBI. Results were similar among each of the 3 high-risk subtypes.
CONCLUSIONS: Our data support the use of moderate HWBI in patients with early-stage, biologically high-risk breast cancer.
Online ahead of print.
Willen BD, Quinn TJ, Almahariq MF, Chen PY, Jawad MS, Gustafson GS, et al. [Leung E, Wu MKY, Dilworth JT] Clinical outcomes of hypofractionated whole breast irradiation in early stage, biologically high-risk breast cancer. Pract Radiat Oncol. 2022 Jun 18:S1879-8500(22)00203-X. doi: 10.1016/j.prro.2022.06.008. Epub ahead of print. PMID: 35724921.