ERBB2 and breast cancer: In generally, Luminal A breast cancer has the best prognosis and is usually treated with endocrine therapy; Luminal B has a good prognosis and can be treated with endocrine therapy, cytotoxic chemotherapy or targeted therapy; HER2-enriched cancers are nowadays treated with targeted therapy in combination with cytotoxic chemotherapy, which has strongly improved the prognosis; TN breast cancer still has the worst prognosis and cytotoxic (neoadjuvant) chemotherapy is the main treatment option9–13.