A comparison of fulvestrant and the third-generation aromatase inhibitors in the second-line treatment of postmenopausal women with advanced breast cancer

Fulvestrant, a new type of oestrogen receptor antagonist with no agonist effects, is now licensed in the EU and USA for the treatment of postmenopausal women with hormone-sensitive advanced breast cancer following progression on prior antioestrogen therapy. Approval was based on data from two phase III trials that demonstrated fulvestrant was at least as effective as the third-generation aromatase inhibitor (AI) anastrozole as a second-line treatment for advanced breast cancer. The third-generation AIs letrozole and exemestane also demonstrate efficacy after tamoxifen failure. To compare the performance of fulvestrant and contemporary endocrine treatments (anastrozole, letrozole and exemestane) in tamoxifen-resistant disease, we conducted a literature review using the PubMed database. These indirect comparisons suggest that fulvestrant offers similar efficacy and tolerability to other second-line treatments for postmenopausal women with advanced breast cancer. Findings from these comparisons support the use of fulvestrant as an additional second-line endocrine treatment option in this setting. New trials are assessing the efficacy of fulvestrant as a second-line treatment following AI failure. The integration of new agents such as fulvestrant into the endocrine sequence may extend the endocrine treatment window, before cytotoxic chemotherapy needs to be considered, and therefore improve patient quality of life.