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. It is not yet known whether anastrozole is more effective than fulvestrant before surgery and radiation therapy in treating patients with breast cancer.

PURPOSE: This randomized phase II trial is studying anastrozole to see how well it works compared with fulvestrant in treating postmenopausal patients with breast cancer.

OBJECTIVES:

Primary

• Evaluate clinical tumor response at 6 months in patients with hormone-sensitive nonmetastatic breast cancer treated with neoadjuvant anastrozole vs fulvestrant.

Secondary

• Evaluate tumor regression by mammography and ultrasound in these patients.
• Evaluate the rate of breast conservation at 6 months of treatment in these patients.
• Evaluate the tolerability of these regimens.
• Estimate the progression-free survival at 5 years of these patients.
• Identify molecular signatures predictive of response in these patients.
• Identify genes implicated in response in these patients.
• Identify changes in mRNA splicing of genes involved in breast tumorigenesis.

OUTLINE: This is a multicenter study.

All patients undergo biopsy at baseline. Patients are randomized to 1 of 2 treatment arms.

• Arm I: Patients receive oral anastrozole once daily for 6 months.
• Arm II: Patients receive fulvestrant intramuscularly on days 1, 14, and 28 and then once a month at 2-6 months.

Within 8 days after completion of hormone therapy, all patients undergo surgical resection of the residual lesion followed by radiotherapy. Patients then receive oral anastrozole once daily for 5 years.

Tissue samples from biopsy and surgery are analyzed to assess molecular signatures and sensitivity to treatment, and to compare gene expression variation with response.

• Drug: anastrozole
  Given orally
• Drug: fulvestrant
  Given intramuscularly

• Active Comparator: Arm I
  Patients receive oral anastrozole once daily for 6 months.
  Intervention: Drug: anastrozole
• Experimental: Arm II
  Patients receive fulvestrant intramuscularly on days 1, 14, and 28 and then once a month at 2-6 months.
  Intervention: Drug: fulvestrant

DISEASE CHARACTERISTICS:

• Histologically confirmed invasive breast cancer, meeting 1 of the following criteria:

  • SBR grade I-II disease (patients < 65 years of age)
  • SBR grade I-III disease (patients > 65 years of age)
• T2 (2-5 cm), T3, or T4B, and N0-1 disease
• No metastatic disease
• Breast lesion not amenable to breast-conserving resection
• No inflammatory breast cancer
• No prior breast cancer

• Hormone receptor status:

  • Estrogen receptor- and/or progesterone receptor-positive

PATIENT CHARACTERISTICS:

• Postmenopausal
• No other cancer within the past 5 years except for adequately treated skin carcinoma or carcinoma in situ of the cervix
• No contraindication to anti-hormonal treatment
• No psychological, familial, social, or geographical reasons that would preclude follow up

PRIOR CONCURRENT THERAPY:

• At least 8 days since prior hormone replacement therapy
• No concurrent anti-vitamin K treatment