Background: Exemestane represents the only steroidal third-generation aromatase inactivator implemented for breast cancer therapy.
Objective: Present clinical and translational data defining the role of exemestane as an aromatase inhibitor.
Methods: Literature search including PubMed and ISI Web of Science.
Results/conclusion: Exemestane potently inhibits in vivo aromatization resembling anastrozole and letrozole. Randomized trials have revealed superiority for exemestane compared to conventional therapy in metastatic breast cancer. In addition sequential treatment with tamoxifen (for 2 - 3 years) followed by exemestane (for 3 - 2 years) has revealed superiority with respect not only to relapse-free but also borderline improvement in overall survival in adjuvant therapy. Several studies now confirm lack of cross-resistance between non-steroidal aromatase inhibitors and exemestane, which could be due to exemestane's low androgen-agonistic activity through its 17-hydro metabolite.