Role of anti-aromatase agents in postmenopausal advanced breast cancer

Endocrine therapy is a well-recognized approach to the treatment of postmenopausal patients with advanced breast cancer, particularly those with estrogen receptor-positive tumors. The availability of anti-aromatase agents, both reversible (nonsteroidal) and irreversible (steroidal), provides clinicians with additional hormonal treatment options.

A MEDLINE search was conducted to identify studies that evaluated anti-aromatase therapy in the treatment of postmenopausal women with advanced breast cancer. In selecting studies, priority was given to randomized, controlled trials.

Tamoxifen is the standard first-line therapy for advanced breast cancer. However, recent results have demonstrated the efficacy of newer anti-aromatase agents in this setting. Among patients who have progressed after tamoxifen therapy, anti-aromatase agents have emerged as first choice therapy based on their better tolerability and improved efficacy compared with megestrol acetate. Exemestane and anastrozole (irreversible and reversible anti-aromatase agents, respectively) have demonstrated survival benefits over megestrol acetate in second-line therapy. Anti-aromatase agents have also demonstrated efficacy in patients who have failed multiple hormonal therapies. Based on these data, an algorithm for the treatment of postmenopausal women with advanced breast cancer is proposed.

The enhanced tolerability and superior efficacy of anti-aromatase inhibitors compared with megestrol acetate has resulted in these agents becoming the endocrine treatment of choice for women with advanced breast cancer who have progressed after tamoxifen treatment. The increased use of tamoxifen in the adjuvant setting and the demonstrated activity of aromatase inhibitors in first-line therapy will further increase the role of these agents.