DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed small cell lung cancer (SCLC)

  • Extensive stage disease

• Must have ≥ 1 unidimensionally measurable lesion (longest diameter to be recorded) ≥ 20 mm by conventional techniques or ≥ 10 mm by spiral CT scan

  • Lesion cannot be from a previously irradiated area

  • Lesions that are considered nonmeasurable include the following:

    • Bone lesions
    • Leptomeningeal disease
    • Ascites
    • Pleural/pericardial effusion
    • Lymphangitis cutis/pulmonis
    • Abdominal masses not confirmed and followed by imaging techniques
    • Cystic lesions
    • Tumor lesions in a previously irradiated area
• No brain metastasis or carcinomatous meningitis unless stable and asymptomatic

PATIENT CHARACTERISTICS:

• ECOG performance status 0-2
• Life expectancy ≥ 3 months
• ANC ≥ 1,500/mm³
• Platelet count > 100,000/mm³
• Bilirubin ≤ 1.5 mg/dL
• AST and ALT ≤ 2.5 times upper limit of normal (ULN) (5 times ULN if liver metastases present)
• Creatinine ≤ 2.0 mg/dL
• Hemoglobin ≥ 9.0 g/dL
• No coexisting medical condition that would preclude study compliance
• No known Gilbert's disease
• No uncontrolled diabetes mellitus, defined as random blood sugar > 300 mg/dL or > 16.6 mmol/L
• Not pregnant or nursing
• Negative pregnancy test
• No secondary active malignancy except for any in situ cancer, adequately treated basal cell or squamous cell skin cancer, or any cancer from which the patient has been disease-free for ≥ 2 years

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• Prior radiotherapy therapy allowed

• At least 7 days since prior phenytoin, phenobarbital, carbamazepine, or other enzyme-inducing anticonvulsant drugs

  • Concurrent gabapentin allowed
• No prior systemic anticancer therapy for extensive stage SCLC, including chemotherapy, antibody therapy, immunotherapy, gene therapy, cytokine therapy, vaccine therapy, or experimental agents
• At least 7 days since prior and no concurrent Hypericum perforatum extract (St. John's wort)
• No concurrent inhibitors of vascular endothelial or epidermal growth factor pathways
• No concurrent CNS radiotherapy