Fulvestrant in the treatment of postmenopausal women with advanced breast cancer.

Fulvestrant is a new type of estrogen receptor antagonist with no agonist effects, and represents a valuable addition to the range of endocrine treatments available to treat postmenopausal women with advanced breast cancer. Fulvestrant binds, blocks and degrades the estrogen receptor, thereby retarding growth and progression of hormone-sensitive tumors. Two Phase III trials have demonstrated that fulvestrant is at least as effective as the third-generation aromatase inhibitor anastrozole in the treatment of advanced breast cancer following progression on antiestrogen therapy. In addition, a Phase III trial comparing fulvestrant with tamoxifen in postmenopausal women with advanced breast cancer showed similar efficacy and tolerability. Clinical trials are ongoing to evaluate different endocrine sequence options for postmenopausal women with breast cancer, and to evaluate the efficacy of fulvestrant in combination with anticancer agents that target other signaling pathways.