OBJECTIVES: I. Determine the objective response rate in women with progressive or recurrent, locally advanced or metastatic breast cancer treated with erlotinib. II. Determine the safety of this drug in these patients. III. Determine the duration of objective response, time to disease progression, and duration of survival in patients treated with this drug. IV. Determine the proportion of patients with stable disease for at least 4 months after treatment with this drug. V. Determine potential factors that contribute to inter-patient variability in pharmacokinetic behavior in patients treated with this drug. VI. Determine exposure-effect relationships in patients treated with this drug.

OUTLINE: This is a multicenter study. Patients are stratified according to disease progression on or after prior therapy (anthracycline, taxane, and capecitabine vs at least 1 chemotherapy regimen for metastatic disease). Patients receive oral erlotinib once daily. Treatment continues in the absence of disease progression or unacceptable toxicity. Patients are followed every 2 months.

PROJECTED ACCRUAL: A total of 42-200 patients (21-150 in stratum 1 and 21-50 in stratum 2) will be accrued for this study.

DISEASE CHARACTERISTICS: Histologically confirmed incurable locally advanced or metastatic breast cancer Measurable disease At least 2 cm in diameter At least 1 cm by spiral CT scan Disease at previously irradiated sites considered measurable if there is clear disease progression after radiotherapy Disease progression during or after prior therapy with at least 1 chemotherapy regimen for metastatic disease (stratum 2) OR with an anthracycline, taxane, and capecitabine (stratum 1) Therapy in combination or in sequence for locally advanced or metastatic disease and/or as adjuvant therapy allowed Disease recurrence in stratum 1 must have occurred during or within 12 months after completion of adjuvant therapy HER2 negative, unknown, or positive with disease progression after prior trastuzumab (Herceptin) therapy No pleural effusions or blastic bone lesions as only manifestations of metastatic disease No symptomatic or untreated brain metastases Brain metastases allowed if neurologically stable and at least 4 weeks since prior corticosteroid therapy Hormone receptor status: Not specified

PATIENT CHARACTERISTICS: Age: 18 and over Sex: Female Menopausal status: Not specified Performance status: ECOG 0-2 Life expectancy: At least 3 months Hematopoietic: Granulocyte count greater than 1,500/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least 9 g/dL (transfusion allowed) Hepatic: Bilirubin less than 1.5 times upper limit of normal (ULN) ALT and AST less than 2.5 times ULN (no greater than 5 times ULN if liver metastases present) Alkaline phosphatase less than 2.5 times ULN (no greater than 4 times ULN if liver or bone metastases present) Albumin greater than 3.0 g/dL Renal: Creatinine less than 1.5 times ULN OR Creatinine clearance greater than 60 mL/min Calcium no greater than 11.5 mg/dL Cardiovascular: Ejection fraction at least lower limit of normal by MUGA scan or echocardiogram No uncontrolled hypertension No unstable angina No congestive heart failure No myocardial infarction within the past 6 months No cardiac arrhythmia requiring medication Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No other unstable systemic disease No active infection No significant traumatic injury within the past 21 days No history of abnormalities of the cornea (e.g., dry eye syndrome or Sjogren's syndrome), congenital abnormality (e.g., Fuch's dystrophy), abnormal slit-lamp examination using vital dye (e.g., fluorescein or Bengal-Rose), and/or abnormal corneal sensitivity test (e.g., Schirmer test or similar tear production test) No gastrointestinal disease resulting in an inability to take oral medication or requiring IV alimentation No active peptic ulcer disease No other prior malignancy within the past 5 years except adequately treated carcinoma in situ of the cervix or basal or squamous cell skin cancer No history of other diseases, metabolic dysfunction, or physical or laboratory finding indicative of a disease or condition that would preclude study

PRIOR CONCURRENT THERAPY: Biologic therapy: See Disease Characteristics At least 21 days since prior immunotherapy No prior therapy with an agent designed to target epidermal growth factor receptor (EGFR) or EGFR-specific tyrosine kinase activity Chemotherapy: See Disease Characteristics At least 21 days since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) No prior cumulative dose of doxorubicin greater than 450 mg/m2 No concurrent chemotherapy for breast cancer Endocrine therapy: See Disease Characteristics At least 21 days since prior hormonal therapy No concurrent hormonal therapy for breast cancer Radiotherapy: See Disease Characteristics At least 21 days since prior radiotherapy No concurrent radiotherapy for breast cancer Surgery: At least 21 days since prior major surgery or biopsy of parenchymal organ No prior surgical procedure that would affect absorption No concurrent significant surgical procedure Other: No other concurrent experimental anticancer medications No other concurrent antitumor therapy