Gemcitabine Plus Docetaxel or Irinotecan in Treating Patients With Stage IIIB or Stage IV Non-small Cell Lung Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed stage IIIB, IV, or recurrent non-small cell lung cancer (NSCLC) including: Squamous cell carcinoma Adenocarcinoma (including bronchoalveolar cell) Large cell anaplastic carcinoma (including giant and clear cell carcinomas) Stage IIIB eligible for other CALGB protocols consisting of combined chemotherapy and chest radiotherapy not permitted Malignant pleural effusion allowed CNS metastases allowed following completion of cranial radiotherapy Unidimensionally or bidimensionally measurable disease Solid tumor mass or hilar lesion surrounded by aerated lung Pleural based mass Mediastinal or hilar adenopathy clearly measurable No bone only disease No pleural or pericardial effusions No irradiated lesions unless progression is documented following radiotherapy PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-1 Life expectancy: Not specified Hematopoietic: Granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL SGOT no greater than 2 times upper limit of normal (ULN) Alkaline phosphatase less than 2.5 times ULN if SGOT is greater than 1.5 times ULN Renal: Creatinine no greater than 2.0 mg/dL Other: No other malignancies within the past 5 years except curatively treated basal or squamous cell skin cancer or carcinoma in situ of the cervix or breast Not pregnant or nursing Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics No prior chemotherapy for NSCLC Endocrine therapy: Not specified Radiotherapy: See Disease Characteristics At least 2 weeks since prior radiotherapy At least 2 weeks since prior whole brain radiotherapy or stereotactic radiotherapy for CNS disease Surgery: At least 2 weeks since prior surgery for CNS disease