Human epidermal growth factor receptor 2 (HER2) is a member of the receptor family related to tumor cell proliferation, apoptosis, adhesion, migration and differentiation, and is involved in the pathogenesis and adverse results of a variety of cancers, including advanced gastric cancer (AGC) and gastroesophageal junction cancer (GJC) [2, 3]. The gene discussed is ERBB2; the disease is cancer.