Cisplatin, Etoposide, and Cyclophosphamide in Treating Patients With Extensive-Stage Small Cell Lung Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed small cell lung cancer Extensive stage disease (i.e., disease beyond the hemithorax and cannot be encompassed safely by a tolerable radiation field) Measurable disease Concurrent CNS metastases allowed provided patient remains asymptomatic Radiotherapy or surgery for uncontrolled symptoms allowed before study entry PATIENT CHARACTERISTICS: Age 18 and over Performance status ECOG 0-2 Life expectancy Not specified Hematopoietic Absolute neutrophil count ≥ 1,500/mm^3 Platelet count ≥ 100,000/mm^3 Hemoglobin ≥ 8 g/dL (transfusion allowed) Hepatic ALT ≤ 2 times upper limit of normal (ULN) Bilirubin ≤ 2 times ULN Renal Creatinine ≤ 1.5 mg/dL OR Creatinine clearance ≥ 60 mL/min Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No other malignancy within the past year except adequately treated basal cell or squamous cell skin cancer PRIOR CONCURRENT THERAPY: Biologic therapy No prior biologic therapy Chemotherapy No prior chemotherapy Endocrine therapy Concurrent corticosteroids for brain metastases allowed Radiotherapy See Disease Characteristics Prior radiotherapy to any symptomatic site allowed provided the target site(s) was not previously irradiated No concurrent radiotherapy Surgery See Disease Characteristics