S0226 Anastrozole With or Without Fulvestrant as First-Line Therapy in Postmenopausal Women With Metastatic Breast Cancer

RATIONALE: Estrogen can stimulate the growth of breast cancer cells. Hormone therapy using drugs such as anastrozole and fulvestrant may fight breast cancer by blocking the use of estrogen. It is not yet known whether anastrozole is more effective with or without fulvestrant in treating breast cancer. PURPOSE: This randomized phase III trial is studying giving anastrozole together with fulvestrant to see how well it works compared to anastrozole alone as first-line therapy in treating postmenopausal women with metastatic breast cancer.