Clinical pattern of primary systemic therapy and outcomes of estrogen receptor-positive, HER2-negative metastatic breast cancer: a review of a single institution

Purpose In the management of estrogen receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer (ER+HER2−MBC) patients, endocrine therapy (ET) is preferred to chemotherapy (CT) as a primary systemic therapy (PST) when tumor burden is not high. However, there are no definite criteria for choosing a PST, transitioning from ET to CT or using maintenance ET subsequent to CT.