This heterogeneity spans multiple levels, including molecular subtypes (e.g., Luminal, HER2-positive, and triple-negative breast cancer), genomic alterations (such as PIK3CA mutations and BRCA1/2 deletions), and features of the tumor microenvironment (e.g., immune cell infiltration and stromal fibrosis). This evidence concerns the gene ERBB2 and triple-negative breast carcinoma.