Anastrozole or Fulvestrant in Treating Postmenopausal Patients With Breast Cancer

RATIONALE: Estrogen can cause the growth of breast cancer cells. Hormone therapy using anastrozole may fight breast cancer by lowering the amount of estrogen the body makes. Fulvestrant may fight breast cancer by blocking the use of estrogen by the tumor cells. Given the lack of clinical data on fulvestrant in patients with large operable or locally advanced hormone-receptor-positive breast cancer, and the potential to identify differences in the mechanism of resistance using the neoadjuvant model,we decided to perform a multicentre randomised phase II clinical trial of anastrozole and fulvestrant. PURPOSE: The aim of this study was to assess the efficacy of neoadjuvant anastrozole and fulvestrant treatment of large operable or locally advanced hormone-receptor-positive breast cancer not eligible for initial breast-conserving surgery, and to identify genomic changes occurring after treatment.