Fulvestrant: expanding the endocrine treatment options for patients with hormone receptor-positive advanced breast cancer.

With the aromatase inhibitors (AIs) replacing tamoxifen as the first-line treatment for postmenopausal women with hormone receptor-positive early and advanced breast cancer, there is a need to evaluate appropriate endocrine treatment options following AI failure. However, until recently, there were no Phase III trial data in this area. Fulvestrant (Faslodex) is an oestrogen receptor antagonist utilised for the treatment of postmenopausal women with locally advanced or metastatic breast cancer following progression or recurrence on anti-oestrogen therapy. Fulvestrant has a mode of action that is distinct from the AIs and the selective oestrogen receptor modulators, and thus may offer an effective treatment option in the post-AI setting. The Evaluation of Faslodex and Exemestane Clinical Trial (EFECT) is the first Phase III trial to evaluate the efficacy and tolerability of fulvestrant and the steroidal AI, exemestane, in patients with locally advanced or metastatic breast cancer who have progressed or recurred while receiving a non-steroidal AI. EFECT confirmed that fulvestrant and exemestane offer effective treatment options in this setting. Similar efficacy was seen in both treatment groups and there were no significant differences in reported adverse events between fulvestrant and exemestane. The EFECT data provide further evidence for the activity of fulvestrant in the treatment of advanced breast cancer. Other ongoing fulvestrant trials will further define its full role, including the potential for a high-dose regimen, combination of fulvestrant with an AI, and identification of clinical and biological markers to help in targeting those patients who are most likely to respond to treatment.