Combination of chemotherapy and endocrine treatment in breast cancer — is it still a taboo?

For many years, it has been believed that a combination of endocrine therapies with chemotherapeutic agents should not be used in clinical practice as the treatment for either early or advanced breast cancer. These conclusions resulted from clinical trials conducted several decades ago, which combined a selective estrogen receptor modulator (tamoxifen) with polychemotherapy regimens in early breast cancer patients. However, recent results of clinical trials and cohort studies that evaluated combinations of novel chemotherapy regimens with aromatase inhibitors or fulvestrant demonstrated that chemoendocrine therapy is feasible, safe, and active in patients with HR+ breast cancer at various stages of the disease. This article reviews the available data on the safety, activity, and clinical utility of systemic treatment approaches based on the simultaneous administration of endocrine agents with mainly metronomic chemotherapy.