S0124: Cisplatin Combined With Irinotecan or Etoposide For Extensive-Stage Small Cell Lung Cancer

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed extensive stage small cell lung cancer (SCLC) * Measurable or evaluable disease by CT scan, MRI, x-ray, physical exam, or nuclear exam * Brain metastases allowed if previously treated with radiotherapy and/or surgery and are neurologically stable (i.e., no progressing symptoms and off steroids and anticonvulsants) PATIENT CHARACTERISTICS: Age * 18 and over Performance status * Zubrod 0-1 Life expectancy * Not specified Hematopoietic * WBC at least 3,000/mm\^3 * Absolute granulocyte count at least 1,500/mm\^3 * Platelet count at least 100,000/mm\^3 Hepatic * Bilirubin no greater than 1.5 times upper limit of normal (ULN) * AST or ALT no greater than 2.5 times ULN Renal * Creatinine normal * Creatinine clearance at least 50 mL/min Other * Not pregnant or nursing * Fertile patients must use effective contraception * 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 * HIV negative * No concurrent AIDS-related illness PRIOR CONCURRENT THERAPY: Biologic therapy * No prior biologic therapy for SCLC * No filgrastim (G-CSF) within 24 hours of chemotherapy Chemotherapy * No prior systemic chemotherapy for SCLC Endocrine therapy * See Disease Characteristics Radiotherapy * See Disease Characteristics * At least 21 days since prior brain radiotherapy and recovered * No other prior radiotherapy for SCLC Surgery * See Disease Characteristics * At least 21 days since prior thoracic or other major surgery and recovered Other * No concurrent enzyme inducing antiepileptic drugs (phenytoin, phenobarbital, oxcarboxepine, or carbamazepine)