The evolution of adjuvant radiation therapy for early-stage and locally advanced breast cancer.

Adjuvant radiation therapy is often delivered after breast cancer surgery, both in the post-lumpectomy and post-mastectomy settings. Standard fractionation whole breast irradiation (SF-WBI), which is typically delivered over 5-7 weeks, was previously considered the standard of care. More recent data has helped to establish hypofractionated whole breast irradiation (HF-WBI), which consists of a 3-4 week regimen, as a new standard of care. This article provides an overview of the major randomized trials that support the routine use of HF-WBI for the majority of patients undergoing breast-conserving surgery for early-stage breast cancer. Newer data on the use of a hypofractionated approach in the post-mastectomy setting, as well as ongoing randomized trials addressing this topic, are also discussed.