PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior chemotherapy for small cell lung cancer No other concurrent chemotherapy Endocrine therapy: No concurrent steroids except for adrenal failure No concurrent hormones except for nondisease related conditions (e.g., insulin for diabetes) No concurrent dexamethasone except for intermittent use as an antiemetic or as an adjunct to prophylactic cranial irradiation Radiotherapy: No prior mediastinal radiotherapy Surgery: Not specified