HER2 scoring was performed according to two criteria: the 2023 American Society of Clinical Oncology/College of American Pathologists HER2 Testing Guidelines in Breast Cancer and the HER2 Immunohistochemistry Scoring System for Endometrial Serous Carcinoma proposed by the International Society of Gynecological Pathologists (ISGyP). The gene discussed is ERBB2; the disease is breast cancer.