ERBB2 and breast cancer: Generally, recommended treatments for luminal A and luminal B breast cancers include chemotherapeutic agents, anti-HER2 treatments, and endocrine therapy (Parise and Caggiano, 2014), and for HER2+ breast cancers, anti-HER2 agents in combination with other cytotoxic chemotherapy are the conventional options (Burnett et al., 2017; Ponde et al., 2018).