PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics No prior doxorubicin or vincristine as first line treatment for small cell lung cancer Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy to greater than 50% of bone marrow At least 30 days since prior radiotherapy Surgery: Not specified Other: No concurrent experimental drugs or anticancer therapies Concurrent medication for chronic medical conditions allowed (e.g., hypertension) No concurrent cimetidine, phenothiazines, phenobarbital, carbamazepine, troleandomycin, sulfinpyrazone, rifampin, Dilantin, and cyclosporine-A (or other P-gp inhibitors)