About 30% of breast cancer is human epidermal growth factor receptor-2 (HER2) amplification or overexpression (i.e. HER2 positive). HER2 positive breast cancer is one of the indicators of poor prognosis because of its high risk of invasion and metastasis. Anti HER2 therapy can improve the survival of HER2 positive patients and reduce mortality. The aim of the open-label, real-world study is to assess efficacy and safety of Anti-HER2 treatment drugs including antibody drugs such as trastuzumab and pertuzumab, small-molecule tyrosine kinase inhibitors (TKIs) such as lapatinib, neratinib, and pyrotinib, and antibody-drug conjugates such as trastuzumab deruxtecan (DS-8201) and trastuzumab emtansine (T-DM1).
