The development of endocrine therapy for women with breast cancer

The development of endocrine therapies has transformed the treatment of patients with breast cancer. The shift from ablative surgery and aggressive chemotherapies to more targeted, better tolerated therapy has improved both mortality and quality of life for patients with hormone-responsive disease. During the 1970s, the selective oestrogen-receptor modulator, tamoxifen, emerged as a new treatment for women with advanced breast cancer. The subsequent development of numerous and diverse selective endocrine therapies such as luteinising hormone-releasing hormone agonists, aromatase inhibitors and oestrogen-receptor antagonists have added further treatment options. Furthermore, with well-tolerated and effective endocrine therapy, adjuvant treatment became an option for patients with early breast cancer. Tamoxifen emerged as the gold standard adjuvant therapy in the 1980s; however, later trials in postmenopausal women showed the aromatase inhibitors offer advantages over tamoxifen. In addition to AIs being indicated as adjuvant therapy, some are also being evaluated for use as a preventative measure in high-risk women. This chronological account outlines key milestones in the evolution of endocrine therapies over the last 40 years, highlighting each class of agent and the key trials that have led to changes in clinical practice. The advances in endocrine therapies outlined here, coupled with advances in breast cancer management and diagnostics, will likely lead to more patient-tailored therapy, resulting in greater clinical benefits and more cost-effective treatment strategies.