Preoperative Single-Fraction Radiotherapy in Early Stage Breast Cancer

The study team hypothesizes that a single fraction of 21Gy can be delivered preoperatively to the intact breast tumor with acceptable cosmetic outcomes. Furthermore, the investigators anticipate that pre- and post-radiation breast tumor samples will provide an avenue for understanding breast cancer radiation response Rationale for single-fraction preoperative technique This trial is proposed to build on the favorable results of the investigators' phase I trial by extending the findings to a larger cohort of subjects. The preoperative approach has several advantages: 1. a small intact breast tumor results in significantly less uninvolved breast tissue receiving high radiation doses which likely decreases toxicity; 2. more accurate targeting of the high-risk areas of subclinical disease surrounding the tumor is possible, 3. smaller treatment volumes are amenable to dose escalation which can further accelerate treatment and improve accessibility for subjects, 4. this technical approach is widely utilized in other tumor sites and can be delivered at most radiation facilities 5. the pre-operative approach provides a novel opportunity to study breast cancer radiation response.