An overview of the use of non-steroidal aromatase inhibitors in the treatment of breast cancer

A. Buzdar

A number of potent and selective non-steroidal aromatase inhibitors are now available for the treatment of advanced breast cancer in postmenopausal women. In particular, anastrozole represents a significant advantage over earlier agents, such as aminoglutethimide and formestane, in terms of both efficacy and tolerability. These agents are now established as the second-line therapy of choice in postmenopausal women with advanced disease progressing on tamoxifen and, furthermore, data are now available on the efficacy and tolerability of anastrozole as first-line treatment of advanced breast cancer compared with tamoxifen. The full potential of the new-generation aromatase inhibitors in the treatment of breast cancer is currently being investigated in a large programme of clinical trials, including evaluation as neoadjuvant treatment in postmenopausal women with newly-diagnosed locally-advanced or large operable breast cancers, as first-line treatment of advanced breast cancer in postmenopausal women. Aromatase inhibitors have been available for over 20 years; the ability of these compounds to reduce circulating oestradiol levels has been shown to produce clinical benefit in postmenopausal women with advanced breast cancer. Early aromatase inhibitors, however, such as aminoglutethimide and formestane, were not specific for the aromatase enzyme and resulted in significant side-effects.