RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Combining more than one drug may kill more tumor cells.

PURPOSE: Phase II trial to compare the effectiveness of gemcitabine plus either docetaxel or irinotecan in treating patients who have stage IIIB or stage IV non-small cell lung cancer.

OBJECTIVES: I. Compare the complete and overall response rate to gemcitabine and docetaxel versus gemcitabine and irinotecan in chemotherapy naive patients with stage IIIB or IV non-small cell lung cancer. II. Compare the overall and failure free survival, duration of response, and toxicity associated with these combination regimens in this patient population.

OUTLINE: This is a randomized study. Patients are stratified according to disease stage (stage IIIB vs stage IV without CNS involvement vs stage IV with CNS involvement vs recurrent/progressive disease post surgery and/or radiotherapy). Patients are randomized to one of two treatment arms. Arm I: Patients receive gemcitabine IV over 30 minutes immediately followed by irinotecan IV over 90 minutes on days 1 and 8. Arm II: Patients receive gemcitabine IV over 30 minutes immediately followed by docetaxel IV over 60 minutes on days 1 and 8. Treatment repeats every 3 weeks in the absence of disease progression or unacceptable toxicity. Patients achieving partial or complete response or stable disease receive treatment for least 6 courses and for 2 additional courses beyond the maximum response, and then at the investigator's discretion. Patients are followed every 3 months for 1 year, every 6 months for 2 years, and then annually thereafter until disease progression or death.

PROJECTED ACCRUAL: A total of 72 patients (36 per treatment arm) will be accrued for this study within 12 months.

• Drug: docetaxel
• Drug: gemcitabine hydrochloride
• Drug: irinotecan hydrochloride

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 Unidimesionally 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