Endocrine therapy in clinical practice

Abstract

Endocrine therapy (ET) is the mainstay of treatment of estrogen receptor-positive (ER+) breast cancer both in the early-stage as in the advanced disease settings. ET targets the ER pathway by blocking the body’s ability to produce estrogen or by directly modulating the ER. Since the estrogens are produced by the ovaries in premenopausal women and by some other tissues such as fat and skin in both premenopausal and postmenopausal women, ET for premenopausal women is different from for postmenopausal women. Needless to say, therapeutic options for early breast cancer are different to metastatic setting where more drugs are approved. This chapter will mainly review the clinical use of ET through all stages of breast cancer, with special considerations on recent advances in this field like ovarian function suppression in premenopausal patients with higher-risk early-stage tumors and the incorporation of targeted therapies that aim to circumvent mechanisms of endocrine resistance in metastatic ER+ breast cancer.