Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed adenocarcinoma of the breast

- Locally advanced or metastatic disease

- Incurable disease

- Tumor accessible for biopsy

- Prior breast cancer allowed

- No symptomatic or untreated brain metastases or carcinomatous meningitis

- Neurologically stable patients with inactive brain metastases are allowed if off
corticosteroids for at least 4 weeks prior to study

- Hormone receptor status:

- Not specified

PATIENT CHARACTERISTICS:

Age:

- 18 and over

Sex:

- Male or female

Menopausal status:

- Not specified

Performance status:

- ECOG 0-2

Life expectancy:

- At least 3 months

Hematopoietic:

- Granulocyte count at least 1,500/mm^3

- Platelet count at least 100,000/mm^3

Hepatic:

- Bilirubin normal

- ALT/AST no greater than 2.5 times upper limit of normal

Renal:

- Creatinine normal OR

- Creatinine clearance at least 60 mL/min

Cardiovascular:

- LVEF at least 40%

- No symptomatic congestive heart failure

- No unstable angina pectoris

- No cardiac arrhythmia

Ophthalmic:

- No prior abnormalities of the cornea, including:

- Dry eye syndrome or Sjogren's syndrome

- Congenital abnormality (e.g., Fuch's dystrophy)

- Abnormal slit-lamp examination with a vital dye (e.g., fluorescein or
Bengal-Rose)

- Abnormal corneal sensitivity test (e.g., Schirmer test or similar tear
production test)

- No concurrent use of contact lenses

Other:

- No prior allergic reactions attributed to compounds of similar chemical or biologic
composition to erlotinib (e.g., gefitinib or other anilinoquinazolines)

- No other concurrent uncontrolled illness

- No active infection

- No uncontrolled diabetes mellitus

- No psychiatric illness or social situation that would preclude study

- No untreated life-threatening disease

- No other primary malignancy within the past 5 years except carcinoma in situ of the
cervix or nonmelanoma skin cancer

- Weight less than 136 kg

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- Not specified

Chemotherapy:

- At least 3 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin)

- No concurrent chemotherapy

Endocrine therapy:

- See Disease Characteristics

- At least 2 weeks since prior hormonal therapy

- No concurrent hormonal therapy

Radiotherapy:

- At least 3 weeks since prior radiotherapy

- No concurrent radiotherapy except localized external beam radiotherapy for palliative
treatment of metastatic disease (cannot include significant cardiac muscle within the
radiotherapy field)

Surgery:

- Not specified

Other:

- No other concurrent investigational anticancer agents