ERBB2 and breast cancer: Overexpression of human epidermal growth factor receptor-2 (HER2) occurs in approximately 20–30% of patients with BC and is associated with aggressive behavior, resistance to traditional treatment, and a poor prognosis before the introduction of anti-HER2 agents (Jiang et al. 2018; Martinez-Saez and Prat 2021; Miles and White 2018; Xu et al. 2017).