[Aromatase inhibitors: therapeutic outlook]

Hormone therapy of breast cancer has been dominated for a very long time by a single class of drugs, the antiestrogens, and especially tamoxifen. Tamoxifen has been the standard treatment in the adjuvant, neoadjuvant, and metastatic contexts. Ten years ago a new generation of aromatase inhibitors became available that was more selective than previous generations. They form two groups that are quite distinct from a pharmacological standpoint: type II non-steroid inhibitors and type I steroid inhibitors or rather steroid "aromatase inactivators". Aromatase inhibitors are prescribed to menopausal women. They are active in patients with tamoxifen-resistant metastatic cancer. They are a potential alternative to tamoxifen in first-line therapy of women with metastatic cancer. They have been proven useful as neoadjuvant therapy. They are under study in several trials in an adjuvant context. Many issues still remain outstanding.