RATIONALE: Estrogen can cause the growth of breast cancer cells. Hormone therapy using anastrozole or fulvestrant may fight breast cancer by lowering the amount of estrogen the body makes or by blocking the use of estrogen by the tumor cells. Giving hormone therapy before surgery may be an effective treatment for breast cancer. It is not yet known whether anastrozole is more effective than fulvestrant when given before surgery in treating women with breast cancer.

PURPOSE: This randomized phase II trial is studying anastrozole to see how well it works compared with fulvestrant in treating postmenopausal women with stage II or stage III breast cancer that can be removed by surgery.

OBJECTIVES:

Primary

• To compare the clinical response rates (complete and partial responses) at 6 months in postmenopausal women with operable stage II or III breast cancer treated with neoadjuvant anastrozole vs fulvestrant.

Secondary

• To compare the breast surgery conservation rate in patients treated with these drugs.
• To correlate imaging findings by mammography, ultrasonography, and MRI with histological and clinical response in these patients and with sensitivity profile to these drugs.
• To compare histological response in patients treated with these drugs.
• To define criteria appropriate for neoadjuvant hormonal therapy.
• To correlate baseline molecular characteristics and modifications during treatment with response in these patients.
• To compare the tolerability of these drugs in these patients.
• To compare the serum proteomic profile of patients treated with these drugs.
• To correlate 3-year event-free and overall survival rates with clinical and histological response in these patients.

OUTLINE: This is a multicenter study. Patients are randomized to 1 of 2 treatment arms.

• Arm I: Patients receive oral anastrozole once daily for 4-6 months in the absence of clinical progression.
• Arm II: Patients receive fulvestrant intramuscularly on days 1, 15, and 29 in the first month and then every 28 days in each subsequent month. Treatment continues for 4-6 months in the absence of clinical progression.

Patients in both arms then undergo surgery and radiotherapy according to institutional guidelines. Patients then receive adjuvant hormonal therapy for at least 5 years.

After completion of study therapy, patients are followed periodically for up to 3 years.

DISEASE CHARACTERISTICS:

• Histologically confirmed infiltrating breast adenocarcinoma

  • Large, operable tumor

  • Stage T2 (≥ 3 cm) or T3-T4 (excluding inflammatory disease), N0-N3, M0 disease

    • No bilateral inflammatory breast tumors (T4d [PEV-2 or PEV-3])

  • Elston-Ellis grade I or II and mitotic index 1 or 2 (if < 65 years of age)

• At least 1 embedded and 1 frozen biopsy sample available

• No multifocal or multicentric tumors for which breast conservation cannot be envisaged

• No ErbB2-overexpressing tumors (HER2 3+ by IHC OR HER2 2+ by IHC and FISH positive)

• Hormone receptor status:

  • Estrogen receptor and/or progesterone receptor positive tumor (> 10%) as assessed by IHC

PATIENT CHARACTERISTICS:

• Female

• Postmenopausal

• ECOG performance status 0-2

• ANC ≥ 2,000/mm³

• Platelet count ≥ 100,000/mm³

• Hemoglobin ≥ 10 g/dL

• Creatinine ≤ 1.5 times upper limit of normal (ULN)

• Total bilirubin ≤ 1.25 times ULN

• AST and ALT ≤ 1.5 times ULN

• Alkaline phosphatase ≤ 2.5 times ULN

• No other cancer within the past 10 years, except basal cell skin cancer or previously treated carcinoma in situ of the cervix

• No uncontrolled cardiac pathology, including any of the following:

  • Angina pectoris
  • Congestive cardiac insufficiency
  • Myocardial infarction within the past 3 months

• No known history of hemorrhagic diathesis

• No known allergy to the study drugs or their excipients

• No congenital galactosemia, glucose malabsorption syndrome, or lactase deficiency

• No chronic somatic or psychiatric illness with pejorative prognosis

• No geographical, social, or psychiatric condition that would preclude study compliance and follow-up schedule

• No individual deprived of liberty or placed under the authority of a tutor

PRIOR CONCURRENT THERAPY:

• No prior chemotherapy, hormonal therapy, or any targeted treatment for the breast tumor
• At least 2 weeks since prior hormone replacement therapy for menopause
• No concurrent long-term anticoagulation treatment
• No concurrent participation on another therapeutic trial involving an experimental molecule