DISEASE CHARACTERISTICS:

• Histologically confirmed breast cancer
• Radiological and/or clinical evidence of metastatic disease
• Progressive disease after prior therapy with an antiestrogen (e.g., tamoxifen or faslodex) and a nonsteroidal aromatase inhibitor (e.g., anastrozole or letrozole) in the adjuvant and/or metastatic setting* NOTE: *Endocrine therapy must be the last treatment before study entry
• Unidimensionally measurable disease
• No rapidly progressive visceral metastases
• No uncontrolled CNS metastases

• Hormone receptor status:

  • Estrogen receptor and/or progesterone receptor positive

PATIENT CHARACTERISTICS:

Age

• 18 and over

Sex

• Not specified

Menopausal status

• Postmenopausal, defined as any of the following:

  • Natural menopause with at least 1 year since last menses
  • Radiation-induced oophorectomy with last menses more than 1 year ago
  • Chemotherapy-induced menopause with 1 year since last menses and serum follicle-stimulating hormone, luteinizing hormone, and plasma estradiol levels in the postmenopausal range
  • Surgical castration

Performance status

• ECOG 0-2

Life expectancy

• Not specified

Hematopoietic

• Not specified

Hepatic

• Bilirubin no greater than 1.5 times upper limit of normal (ULN)
• Transaminases no greater than 2.5 times ULN
• No severe or uncontrolled hepatic disease

Renal

• No severe or uncontrolled renal disease

Cardiovascular

• No severe or uncontrolled cardiac disease

Pulmonary

• No severe or uncontrolled respiratory disease

• No evidence of clinically active interstitial lung disease

  • Asymptomatic chronic stable radiographic changes allowed

Other

• No other malignancy within the past 5 years except adequately treated carcinoma in situ of the cervix, contralateral breast cancer, or nonmelanoma skin cancer
• No psychological, familial, sociological, or geographical condition that would preclude study compliance and follow-up
• No other severe or uncontrolled systemic disease
• No known hypersensitivity to any excipients of gefitinib
• No unresolved chronic toxicity greater than grade 2

PRIOR CONCURRENT THERAPY:

Biologic therapy

• No concurrent biologic agents

Chemotherapy

• No more than 1 prior chemotherapy regimen for metastatic breast cancer
• No concurrent chemotherapy

Endocrine therapy

• See Disease Characteristics
• No concurrent hormonal therapy

Radiotherapy

• Prior radiotherapy allowed
• No concurrent radiotherapy to any metastatic site

Surgery

• No surgery within 4 days after study drug administration

Other

• No prior epidermal growth factor receptor inhibitor therapy
• More than 30 days since prior investigational drugs

• No concurrent use of any of the following:

  • Phenytoin
  • Carbamazepine
  • Rifampin
  • Phenobarbital
  • Hypericum perforatum (St. John's Wort)
• No concurrent systemic retinoids
• No other concurrent investigational drugs or treatments
• No other concurrent anticancer treatments
• Concurrent bisphosphonates for the treatment and prevention of bony metastases are allowed provided therapy was initiated before study enrollment* NOTE: *Bisphosphonates may be initiated during study participation for the treatment of hypercalcemia only