ERBB2 and breast cancer: If breast cancer cases are categorized into early stages and metastatic groups, treatment of breast cancer can be managed by surgical resection, neoadjuvant/adjuvant chemotherapy, radiotherapy, endocrine therapy, and anti-HER2 therapy among early stages, and systemic therapy including endocrine therapy, target therapy, and cytotoxic chemotherapy within metastatic breast cancers [117].