Inclusion Criteria

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