Primary breast cancers can be categorized into four main molecular classes regarding their gene expression profiles: basal-like, HER2-enriched, luminal A and luminal B.35TP53 mutations are very frequent in the basal-like (80%) and HER2-enriched (72%) genotypes, which exhibit very aggressive phenotypes compared with the luminal A/B types. Here, ERBB2 is linked to breast cancer.