Use of Sentinel Lymph Node Biopsy in Patients With Early-Stage, Palpable Node-Positive HR+/HER2- Breast Cancer Having Upfront Surgery and Adjuvant Radiation

Inclusion Criteria: * Patients aged ≥18 years with biopsy-proven invasive breast cancer * Patients with cTx, cT1, or cT2 tumors with palpable ipsilateral mobile adenopathy of level I/II axillary nodes with biopsy-proven (either by pre-operative biopsy or intraoperative frozen section) nodal metastasis (cN1) who are undergoing upfront surgery * Patients with tumors of the HR+/HER2- subtype, defined as: 1. HR+: Positive for estrogen receptor and/or progesterone receptor staining, indicated by ≥1% immunoreactive tumor nuclei 2. HER2-: Immunohistochemistry assay demonstrating no or faint staining in ≤10% of tumor cells (IHC 0 or 1+) or negative by dual probe in situ hybridization assay Exclusion Criteria: * Patients with prior ipsilateral breast cancer * Patients who are pregnant * Patients with stage IV disease at presentation * Patients with advanced regional disease (cN2/cN3)