Set against the backdrop of evolving therapeutic options for HER2-positive MBC, the Systematic Therapies for HER2-Positive Metastatic Breast Cancer Study (SystHERs) has been established to address gaps in our knowledge about which treatments are chosen and administered to patients with HER2-positive MBC, the corresponding outcomes, and the patients’ perspectives on their experience over the course of their disease. Here, ERBB2 is linked to breast cancer.