Endocrine therapy for breast cancer

An understanding of the mechanism of action, pharmacology and clinical indications for various classes of endocrine agent is critical for the management of breast cancer.Three major classes of therapeutic intervention are classically considered: agents that directly target estrogen receptor through molecules that bind ER and alter ER function; estrogen deprivation through aromatase inhibition or ovarian ablation or suppression; and sex steroid therapies, including estrogen, progestins and androgens. In both the advanced disease and the adjuvant setting these differing mechanisms of action allow these approaches to be used in sequence, recapturing tumor control with each class switch. In addition the side effects of each approach are very distinct, with very important consequences for women's health when considering long-term adjuvant therapy. In this review we have attempted to accurately summarize the latest information on these approaches, with an emphasis on evidence-based approaches to management.