Aromatase inhibitors in breast cancer therapy.

Recent advances have been made in the hormonal treatment of breast cancer with the advent of third-generation aromatase inhibitors (anastrozole, letrozole, and exemestane). These newer agents have substantial antitumor activity and appear to be as effective as tamoxifen, with fewer adverse effects. Recent reports indicate that anastrozole is more effective than tamoxifen as adjuvant endocrine therapy in postmenopausal women with breast cancer. This report provides an overview of the clinical trials conducted to date with the aromatase inhibitors as first- and second-line therapies, with an emphasis on recently updated analyses comparing anastrozole with tamoxifen in the adjuvant setting.