PRIMARY OBJECTIVES:
I. To evaluate the change in percent tumor-infiltrating lymphocytes (TIL) as a continuous variable before and after preoperative boost radiotherapy (RT) in hormone receptor (HR)+/human epidermal growth factor receptor2 (HER2)- breast cancers.
SECONDARY OBJECTIVES:
I. To evaluate the safety of preoperative boost RT administered to patients with HR+/HER2- breast cancer.
EXPLORATORY OBJECTIVES:
* I. To assess the mechanisms of cell death induced by preoperative boost RT.
* II. To assess immunologic and molecular responses to preoperative boost RT.
* III. To assess the correlations between immune markers, cell death markers, and their changes during treatment.
* IV. To determine if magnetic resonance imaging (MRI) can be used to predict breast tumor response to neoadjuvant radiation.
OUTLINE:
Patients undergo boost radiation therapy 6-8 days before breast surgery. After surgery, patients continue to receive standard of care radiation therapy.
After completion of study treatment, patients are followed up at 6 months.
