Endocrine agents without any agonist effect could potentially be used in combination with aromatase inhibitors, under the rationale that the combination would maximally blockade estrogen receptor signaling, thus potentially improving the antitumor effect. Fulvestrant (FASLODEX) is a pure estrogen antagonist with no known agonist effect; thus, it has the potential to provide additional benefit when combined with an aromatase inhibitor. This concept provides the rationale for using the combination of anastrazole and fulvestrant in this study.