Preoperative Stereotactic Ablative Body Radiotherapy (SABR) for Early-Stage Breast Cancer

This study involves a course of radiation to the tumor that is delivered BEFORE surgery. The type of radiation is called stereotactic ablative body radiation therapy (SABR). The purpose of this study is to evaluate the effects, good and/or bad, of pre-operative SABR specifically focusing on its ability to reduce the chances that additional breast surgery will be needed, reducing the amount of breast/heart/lung tissue that is irradiated, and to study the tumor-tissue effects of SABR. The usual treatment for patients with early-stage breast cancer who have breast-conserving treatment (BCT) is to receive radiotherapy AFTER surgery, targeting either the whole breast or part of the breast.