In the early 2000s, Perou et al. identified a distinctive molecular portrait of breast cancer based on variations in tumor gene expression patterns and hierarchical clustering [14,15], they described a molecular classification system for breast carcinoma consisting of five intrinsic subtypes: luminal A, luminal B, HER2-enriched, basal-like, and normal breast-like tumors. Here, ERBB2 is linked to breast cancer.