ERBB2 and breast cancer: The primary aim is to analyze the concordance/discordance in risk stratification by CAB when performed on CNB versus SS from hormone receptor-positive, Her2-negative early BC patients. The secondary aim is to establish the sensitivity, specificity, positive predictive values (PPV), and negative predictive value (NPV) of CNB as a sample. Additionally, we seek to identify potential patients who may need retesting with FFPE samples of SS.