Until recently, tamoxifen, a nonsteroidal antiestrogen, was the mainstay of endocrine
treatment of breast cancer. However, new aromatase inhibitors that are many times more
potent and specific than the first such agent, aminoglutethimide, are changing the
management of breast cancer in postmenopausal women. This review discusses the role of
aromatase inhibitors such as letrozole, anastrozole, and exemestane in the treatment of
breast cancer.