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 study the effectiveness of combination chemotherapy in treating patients who have extensive-stage small cell lung cancer.

OBJECTIVES:

• Determine the survival of patients with extensive stage small cell lung cancer treated with gemcitabine and irinotecan.
• Determine the response rates (confirmed and unconfirmed, complete and partial) of patients treated with this regimen.
• Determine the overall toxic effects of this regimen in these patients.

OUTLINE: This is a multicenter study.

Patients receive gemcitabine IV over 30 minutes followed by irinotecan IV over 90 minutes on days 1 and 8. Treatment repeats every 21 days for a total of 6 courses in the absence of disease progression or unacceptable toxicity.

Patients are followed every 6 months for 3 years.

PROJECTED ACCRUAL: A total of 75 patients will be accrued for this study within 12 months.

• Drug: gemcitabine hydrochloride
• Drug: irinotecan hydrochloride

DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed extensive stage small cell lung cancer (SCLC)

  • Malignant pleural effusion constitutes extensive stage disease
• Must have disease outside area of prior surgical resection or a new lesion must be present

• Controlled brain metastases allowed (asymptomatic and previously treated with surgery and/or radiotherapy)

  • Brain metastases must be re-evaluated by CT scan or MRI after completion of radiotherapy or surgery

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• Zubrod 0-2

Life expectancy:

• Not specified

Hematopoietic:

• Absolute granulocyte count at least 1,500/mm^3
• WBC at least 3,000/mm^3
• Platelet count at least 100,000/mm^3

Hepatic:

• Bilirubin no greater than 1.25 times upper limit of normal (ULN)
• SGOT or SGPT no greater than 2.5 times ULN

Renal:

• Not specified

Other:

• Not pregnant or nursing
• Fertile patients must use effective contraception
• No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or other adequately treated stage I or II cancer in complete remission

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No prior biologic therapy for SCLC

Chemotherapy:

• No prior systemic chemotherapy for SCLC

Endocrine therapy:

• Not specified

Radiotherapy:

• See Disease Characteristics
• No prior radiotherapy for SCLC except for brain metastases

Surgery:

• See Disease Characteristics
• At least 2 weeks since prior surgery (thoracic or other major surgery) and recovered