Aromatase inhibitors as adjuvant therapy for breast cancer

Aromatase inhibitors are widely accepted for the endocrine therapy of breast carcinoma. By blocking the aromatase enzyme, aromatase inhibitors reduce the synthesis of estrogen and decrease the estrogen levels that account for the proliferation of hormone-sensitive breast cancer. There is a new generation of steroid (Exemestan) and nonsteroid (Anastrozol, Letrozol) aromatase inhibitors that show strong antitumor activity with an acceptable spectrum of side effects. This new generation of aromatase inhibitors is widely accepted as first- and second-line treatment options for advanced breast cance. Although the antiestrogen tamoxifen remains the gold standard for the adjuvant treatment of hormone-responsive breast cancer, new studies predict a likely switch towards aromatase inhibitors in the near future. However, further studies and longer follow-up times of recent studies are needed. This article describes the relevance of aromatase inhibitors for the adjuvant therapy of breast cancer.