ERBB2 and breast cancer: Briefly, the intrinsic subtypes are classified by hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-, Luminal A), HR+/HER2+ (Luminal B), HR-/HER2+ (HER2-enriched), HR-/HER2- (basal-like or triple negative breast cancer, TNBC), and claudin-low (TNBC-metaplastic) (8, 9). Worldwide, there were over 2 million new BC cases in 2018 (6); and global epidemiological patterns show the importance of cultural and lifestyle factors, with only 5-10% of BCs being inherited (10).