Hypofractionated whole breast radiation: how low can you go?

Abstract

Breast conserving therapy (BCT), consisting of breast conserving surgery (BCS) followed by whole breast radiation therapy (WBRT), is a well-established standard for the treatment of women with ductal carcinoma in situ (DCIS) and early-stage invasive breast cancer. While the original trials establishing this paradigm utilized conventionally fractionated (CF-WBRT) treatment delivered with daily fractions over 5–7 weeks, there is a significant amount of level I evidence in support of standardly using hypofractionated (HF-WBRT) regimens delivered over 3–4 weeks, and now there is data supporting even shorter courses. This article reviews the historical basis for CF-WBRT and subsequent radiobiological reasoning for attempting HF-WBRT. Summarized herein are the major clinical trials that have established the safety and efficacy of HF-WBRT as the standard of care in almost all women receiving BCT for early stage, node-negative breast cancer which form the basis of the American Society for Radiation Oncology (ASTRO) consensus statements. Completed and ongoing clinical trials that are attempting to establish the role of hypofractionated (HF) regimens for patients who require regional nodal irradiation as part of postmastectomy radiation therapy (PMRT) are presented. Recently, published data on ultra-hypofractionated courses are reviewed. Finally, there is a discussion of adoption of hypofractionation globally. The goal of this review is to provide a rationale for the routine use of HF courses to improve patient access and convenience, healthcare resource utilization, and potentially decreasing patient exposure in the setting of the ongoing