Combination Chemotherapy in Treating Patients Who Have Extensive-Stage Small Cell Lung Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically proven extensive stage small cell lung cancer, not previously treated with chemotherapy or radiotherapy except for symptomatic brain metastases Measurable or evaluable disease Ascites, pleural effusions, osteolytic and osteoblastic bone metastases are not measurable or evaluable PATIENT CHARACTERISTICS: Age: Over 18 Performance status: ECOG 0-3 Life expectancy: Not specified Hematopoietic: Platelet count at least 100,000/mm^3 Absolute neutrophil count at least 2,000/mm^3 Hepatic: Bilirubin no greater than 1.25 times upper limit of normal (unless due to liver metastases) Renal: Creatinine clearance at least 60 mL/min Cardiovascular: No cardiac failure or rhythm disturbances requiring medication Other: No history of hypersensitivity to castor oil No active uncontrolled infection No nonmalignant disease presenting a poor medical risk Not pregnant Fertile patients must use effective contraception during and for 3 months after the study PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent immunotherapy Chemotherapy: See Disease Characteristics No other concurrent chemotherapy Endocrine therapy: No concurrent hormonal therapy Radiotherapy: See Disease Characteristics Palliative radiotherapy allowed (indicator lesion should be outside of irradiated field) Surgery: Not specified