While traditional clinicopathological factors such as tumor size, histologic grade, lymph node status, and patient age continue to guide surgical decision-making, growing recognition of breast cancer heterogeneity has led to the adoption of intrinsic molecular subtypes (luminal A, luminal B HER2-, luminal B HER2+, HER2-enriched, and basal-like). Here, ERBB2 is linked to breast cancer.