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