ERBB2 and breast cancer: It is clinically divided into three main subtypes, each with distinct risk profiles and treatment strategies (2,3); hormone receptor positive/ human epidermal growth factor receptor type 2 (ERBB2; formerly HER2) negative breast cancer (70% of patients), ERBB2-positive breast cancer (15%-20% of patients), and triple-negative breast cancer (15% of patients) [1].