ERBB2 and breast cancer: Breast cancer (BC) stands out as a prevalent malignancy affecting women’s health globally.1 According to GLOBOCAN 2020 statistics, the worldwide age-standardized incidence and mortality rates (per 100 000 women) can reach up to 47.8 and 13.6, respectively.2 Among various subtypes, human epidermal growth factor receptor 2 (HER2)-positive BC accounts for approximately 15%-20% of cases and exhibits highly aggressive biological features.3 HER2 is a proto-oncogene that encodes a transmembrane receptor tyrosine kinase, belonging to the ErbB receptor family.