Aromatase inhibitors—extending the benefits of adjuvant therapy beyond tamoxifen

Adjuvant tamoxifen is still considered standard care for postmenopausal women with early stage hormone receptor-positive breast cancer. However, efficacy and safety of tamoxifen are limited by its partially estrogenic properties. Aromatase inhibitors have proven highly effective in advanced breast cancer and are currently being investigated in the adjuvant setting, either as an alternative to or in sequence with tamoxifen, or as extended adjuvant therapy following tamoxifen. Results of several adjuvant aromatase inhibitor trials have been published and strongly indicate that efficacy may be increased compared with tamoxifen alone. This review will examine the published data, discuss ongoing trials, and address the question of how to best integrate the aromatase inhibitors into adjuvant treatment.