DISEASE CHARACTERISTICS: Diagnosis of extensive stage small cell lung cancer At least 1 bidimensionally measurable non CNS lesion At least 1 cm in one diameter and at least 2 cm in another diameter by CT or MRI scan At least 2 cm in two diameters by x-ray, ultrasound, or for palpable tumor masses by physical exam Measurable skin lesion at least 1 cm in at least one diameter by photography No symptomatic CNS and/or leptomeningeal metastases requiring corticosteroid therapy to control symptoms