Irinotecan and Carboplatin in Treating Patients With Newly Diagnosed Extensive-Stage Small Cell Lung Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed small cell lung cancer Extensive stage disease Newly diagnosed, treatment-naive disease At least 1 unidimensionally measurable lesion No massive pleural or pericardial effusion by chest CT scan Manageable effusions allowed PATIENT CHARACTERISTICS: Age Over 18 Performance status ECOG 0-2 Life expectancy More than 3 months Hematopoietic WBC ≥ 3,000/mm^3 Absolute granulocyte count ≥ 1,500/mm^3 Hemoglobin ≥ 9.0 g/dL Hepatic ALT or AST ≤ 2 times upper limit of normal Bilirubin ≤ 1.5 mg/dL Renal Creatinine normal Cardiovascular No myocardial infarction within the past year No uncontrolled hypertension No unstable angina No congestive heart failure No ventricular arrhythmia requiring medical intervention No other serious cardiovascular disease Pulmonary Arterial oxygen pressure (Pa O_2) ≥ 70 mm Hg No interstitial pneumonitis or pulmonary fibrosis by chest x-ray Other Not pregnant or nursing No uncontrolled diabetes No severe infection No paralytic or obstructive ileus No serious diarrhea No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix that is in complete remission PRIOR CONCURRENT THERAPY: Biologic therapy Not specified Chemotherapy Not specified Endocrine therapy Not specified Radiotherapy No prior radiotherapy to the chest Other prior radiotherapy allowed Surgery At least 2 weeks since prior surgery and recovered