Role of anastrozole across the breast cancer continuum: from advanced to early disease and prevention.

Breast tumorigenesis is a continuum from preinvasive lesions to early breast cancer and advanced disease. In this article the data supporting the use of the aromatase inhibitor anastrozole in postmenopausal women across this continuum are reviewed. In advanced disease, anastrozole has a significant survival benefit and tolerability advantage compared with megestrol acetate when used as second-line treatment. As first-line therapy, anastrozole significantly prolongs time to progression compared with tamoxifen in women with hormone receptor-positive (HR+) disease. In the adjuvant setting, anastrozole has superior efficacy and tolerability compared with tamoxifen in newly diagnosed patients and those who have already received 2-3 years' prior adjuvant tamoxifen. Therefore, anastrozole should be considered a preferred treatment option for postmenopausal women with HR+ early breast cancer. Furthermore, anastrozole has preoperative efficacy in HR+ large or locally advanced tumors. Finally, anastrozole substantially reduces the incidence of contralateral breast cancer compared with tamoxifen in women with HR+ early breast cancer and, therefore, is a potential chemopreventive agent. Anastrozole is thus positioned to become the standard care for postmenopausal women with HR+ disease across the whole breast cancer continuum. Additional data from ongoing studies will further clarify the role of anastrozole across the continuum and answer outstanding questions regarding the optimal timing and duration of treatment.