Erlotinib and Gemcitabine in Treating Patients With Metastatic Breast Cancer Previously Treated With An Anthracycline and/or a Taxane

DISEASE CHARACTERISTICS:

* Histologically or cytologically confirmed breast cancer

  * Clinical evidence of metastatic disease
* Candidate for first- or second-line chemotherapy for metastatic disease
* Must have received prior anthracycline or taxane therapy (may have had both in the neoadjuvant, adjuvant, or metastatic setting)
* At least 1 measurable lesion at least 20 mm by CT scan or MRI OR at least 10 mm by spiral CT scan

  * The following are not considered measurable disease:

    * Small lesions less than 20 mm by CT scan or MRI
    * Bone lesions
    * Ascites
    * Pleural/pericardial effusion
    * Inflammatory breast disease
    * Lymphangitis cutis/pulmonis
    * Abdominal masses not confirmed and followed by imaging techniques
    * Cystic lesions
* No active CNS metastases (treated CNS metastases stable for more than 8 weeks are allowed)
* 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

* Absolute neutrophil count at least 1,500/mm\^3
* Platelet count at least 100,000/mm\^3
* Hemoglobin at least 8.5 g/dL

Hepatic

* Bilirubin no greater than 1.5 times upper limit of normal (ULN)
* AST no greater than 3 times ULN
* Alkaline phosphatase no greater than 3 times ULN

Renal

* Creatinine no greater than 1.5 times ULN

Cardiovascular

* No symptomatic congestive heart failure
* No unstable angina pectoris
* No cardiac arrhythmia

Gastrointestinal

* No inability to take oral or nasogastric medication
* No requirement for IV alimentation
* No active peptic ulcer disease

Ophthalmic

* No abnormalities of the cornea based on history (e.g., dry eye syndrome or Sjögren's syndrome)
* No congenital abnormality (e.g., Fuch's dystrophy)
* No abnormal slit-lamp examination using a vital dye (e.g., fluorescein or Bengal-Rose)
* No abnormal corneal sensitivity test (Schirmer test or similar tear production test)

Other

* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception

  * Sub-dermal implants and condoms are not considered acceptable forms of contraception
* No other invasive non-breast malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer
* No ongoing or active infection
* No psychiatric illness or social situation that would preclude study compliance
* No other concurrent uncontrolled illness

PRIOR CONCURRENT THERAPY:

Biologic therapy

* At least 2 weeks since prior immunotherapy
* No prior cetuximab

Chemotherapy

* At least 2 weeks since prior chemotherapy and recovered
* No more than 1 prior chemotherapy regimen for metastatic disease
* No more than 2 prior chemotherapy regimens total, including adjuvant therapy

Endocrine therapy

* Prior hormonal therapy allowed in metastatic and/or adjuvant setting

Radiotherapy

* At least 2 weeks since prior radiotherapy
* No prior radiotherapy to more than 25% of bone marrow
* No prior strontium chloride Sr 89

Surgery

* More than 4 weeks since prior major surgery
* No prior surgical procedures affecting absorption

Other

* No prior epidermal growth factor receptor-targeting therapies (e.g., gefitinib or EKB-569)
* No concurrent combination antiretroviral therapy for HIV-positive patients
* No other concurrent antitumor therapy