Anastrozole.

Recent trials have indicated that the aromatase inhibitors (anastrozole, letrozole, exemestane) are more effective than tamoxifen, the standard adjuvant treatment for estrogen receptor-positive breast cancer, both in adjuvant and first-line advanced settings. This paper reviews the mode of action and the main clinical trials done with anastrozole, the only aromatase inhibitor currently licensed for use in the adjuvant setting in estrogen receptor-positive tumors. Results from studies using anastrozole as a first-line treatment in advanced disease strongly suggest that this drug should now be considered as an alternative first-line therapy to tamoxifen in postmenopausal women with estrogen receptor-positive advanced breast cancer. As a second-line treatment in tamoxifen failures, anastrozole has shown a better survival rate and a better side-effect profile than megestrol acetate. Similarly, the use of anastrozole in the adjuvant setting has shown a significantly prolonged disease-free survival time and improved tolerability compared to tamoxifen in postmenopausal breast cancer survivors.