ERBB2 and carcinoma: Our knowledge of human epidermal growth factor receptor 2 (HER2) amplification has expanded from breast carcinoma to other human carcinomas including gastroesophageal cancer and uterine serous carcinoma because HER2‐positive cancers may benefit from anti‐HER2 monoclonal antibody therapy (trastuzumab) [13, 14, 15].