DISEASE CHARACTERISTICS:

• Histologically* or cytologically confirmed breast cancer, meeting 1 of the following stage criteria:

  • Stage III (locally advanced) disease not considered amenable to curative therapy
  • Stage IV (primary or metastatic) disease NOTE: *Histological documentation of recurrent/metastatic disease is not required if there is clinical evidence of recurrence

• Measurable disease, defined as ≥ 1 unidimensionally measurable lesion ≥ 2.0 cm by conventional techniques or ≥ 1.0 cm by spiral CT scan

  • Lytic or blastic bone metastases as only site of disease allowed

  • The following are not considered measurable disease:

    • Bone lesions (except as above)
    • Leptomeningeal disease
    • Ascites
    • Pleural/pericardial effusion
    • Inflammatory breast cancer
    • Lymphangitis cutis/pulmonitis
    • Abdominal masses that are not confirmed and followed by imaging techniques
    • Cystic lesions

• Must have received prior therapy with 1 or 2 endocrine treatments for breast cancer in either the adjuvant or metastatic setting (not including treatment for ovarian suppression or amenorrhea)

  • Tumor must be potentially sensitive to endocrine therapy, defined as ≥ 3 months of prior endocrine therapy without disease progression in the adjuvant or metastatic setting
  • Treatments must have been commercially-available third-generation aromatase inhibitors (e.g., anastrozole, exemestane, or letrozole)* NOTE: *Sequential use of 2 different third-generation aromatase inhibitors is considered 1 prior treatment; it is not required that tumors be resistant to this treatment

• No symptomatic brain or other CNS metastases

  • Previously treated brain metastases allowed provided patient is free of symptoms AND > 3 months since prior treatment for brain metastases

• Hormone receptor status:

  • Estrogen receptor- and/or progesterone receptor-positive tumor by IHC methods (≥ 1% cells considered positive)

PATIENT CHARACTERISTICS:

• Female

• Postmenopausal, meeting 1 of the following criteria:

  • Age ≥ 60 years
  • Age ≥ 45 years with an intact uterus and amenorrhea for ≥ 12 months
  • History of bilateral oophorectomy
  • Follicle-stimulating hormone levels within postmenopausal range
  • Undergoing treatment with a gonadotropin-releasing hormone agonist for ovarian suppression for ≥ 3 consecutive months prior to study entry, and remains on such therapy throughout study treatment
• Life expectancy > 3 months
• ECOG performance status 0-2
• Granulocyte count ≥ 1,000/mm³
• Platelet count ≥ 100,000/mm³
• Total bilirubin ≤ 1.5 times upper limit of normal (ULN) (unless due to Gilbert's syndrome)
• Creatinine ≤ 2.0 mg/dL
• AST and ALT ≤ 2.5 times ULN (5 times ULN for patients with liver metastases)
• INR ≤ 1.6
• LVEF normal
• Not pregnant or nursing
• Negative pregnancy test
• No pending visceral crisis
• No acquired or inherited bleeding disorder

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics

• At least 2 weeks since prior chemotherapy and recovered

  • Prior chemotherapy in the adjuvant and/or neoadjuvant setting allowed
  • No more than 1 prior chemotherapy regimen for stage IV breast cancer

• At least 3 weeks since prior trastuzumab (Herceptin®) and recovered

  • Prior trastuzumab in the adjuvant and/or neoadjuvant setting allowed
  • No prior trastuzumab for stage IV breast cancer
• No prior fulvestrant
• No prior epidermal growth factor receptor (EGFR) inhibitors (e.g., gefitinib, erlotinib hydrochloride, lapatinib ditosylate, or cetuximab)
• No other prior or concurrent experimental EGFR inhibitors
• No other concurrent chemotherapy
• No concurrent radiotherapy, including palliative radiotherapy

• No other concurrent hormonal therapy* except for the following:

  • Steroids for adrenal failure
  • Hormones for nondisease-related conditions (e.g., insulin for diabetes or synthroid for hypothyroidism)
  • Intermittent dexamethasone as an antiemetic

• No concurrent therapeutic systemic anticoagulation (defined as maintaining INR > 1.6)

  • Low-dose warfarin or acetylsalicylic acid (or equivalent) for maintenance of central venous catheter patency allowed
• No other concurrent endocrine therapy, including systemic hormone-replacement therapy or intravaginal estrogen
• Prior initiation of and concurrent bisphosphonate therapy allowed NOTE: *Patients receiving a gonadotropin-releasing hormone agonist for ovarian suppression must remain on therapy throughout the course of study treatment