DISEASE CHARACTERISTICS: Histologically proven metastatic non-small cell lung cancer Eligible subtypes: Adenocarcinoma Squamous cell carcinoma Large cell carcinoma At least 1 bidimensionally measurable lesion, at least 2 cm by 2 cm in perpendicular diameter on radiologic study Previously irradiated bony lesions are not considered measurable unless there is evidence of disease progression at that site prior to study No brain metastases