Exemestane: a potent irreversible aromatase inactivator and a promising advance in breast cancer treatment.

With the introduction of orally-active, potent and selective third-generation aromatase inhibitors and inactivators--anastrozole, letrozole and exemestane--approaches to the treatment of advanced breast cancer are undergoing re-evaluation. In advanced breast cancer, aromatase inhibitors and inactivators are likely to become established as the primary choice over tamoxifen in postmenopausal female breast cancer patients when hormonal therapy is indicated in the first-line setting. The current evaluation of exemestane, an oral steroidal irreversible aromatase inactivator, for primary and adjuvant therapy and the potential role of potent estrogen-deprivation therapy in prevention of postmenopausal breast cancer may extend the use of antiaromatase therapy as an increasingly valuable palliative treatment option, conferring survival benefit and possible preventive outcomes across several treatment settings in the management of breast cancer.