Endocrine Therapy for Hormone Receptor‐Positive Breast Cancer

Abstract

Overview The importance of the reproductive endocrine system in breast cancer treatment began to be appreciated at the turn of nineteenth century. It was around this time that it was realized that approximately one‐third of premenopausal women with advanced breast cancer would respond to oophorectomy. However, it was only when the estrogen receptor (ER) was discovered that it was possible to fully appreciate the mechanisms underlying the activity of ovarian ablation and other associated treatments for breast cancer such as ovarian irradiation, adrenalectomy, and hypophysectomy. Research into both the estrogen and progesterone pathways not only provided a deeper understanding of the underlying mechanism of the carcinogenic pathway involved in the development of breast cancer but also allowed identification of potential targets for therapeutic intervention. This chapter discusses recent advances in the molecular biology and physiology underlying the estrogen and progesterone receptor (PR) pathways and potential targets for intervention. In addition it examines and compares the pharmacology and efficacy of the different endocrine agents used in the management of both early and advanced stage breast cancer.