The role of aromatase inactivators in the treatment of breast cancer.

Abstract

Third-generation aromatase inhibitors and inactivators have earned their place in the treatment of metastatic breast cancer. The third-generation aromatase inactivator exemestane was found to be superior to megestrol acetate as second-line endocrine therapy in postmenopausal women, with respect to time to progression as well as overall survival, and the results from an ongoing study comparing exemestane with tamoxifen in first-line treatment are promising. The finding that exemestane may also work in patients previously exposed to nonsteroidal aromatase inhibitors reveals lack of complete cross-resistance between the compounds. Currently, exemestane given as monotherapy, or in sequence with tamoxifen (2-3 + 3-2 years of tamoxifen-exemestane or 5 years of tamoxifen followed by 2 years of exemestane) is being compared with tamoxifen 5 years monotherapy in the adjuvant setting. In addition, we are currently addressing the toxicity of exemestane in a placebo-controlled trial in low-risk breast-cancer patients. The results from these studies will outline the potential role of exemestane in adjuvant treatment and, potentially, for breast-cancer prevention in postmenopausal women.