Aromatase inhibitors and breast cancer: time for a change?

Aromatase inhibitors bind reversibly or irreversibly to the aromatase enzyme in peripheral fat and also in the breast, leading to undetectable plasma levels of oestrogens in postmenopausal women. These agents have been shown to be more effective than tamoxifen in first-line treatment of oestrogen receptor-positive advanced and metastatic breast cancer. Additionally, they have been demonstrated to be superior as both adjuvant and neoadjuvant treatment. It is likely that they will also be useful for breast cancer prevention but the cost/benefit ratio has yet to be determined.