DISEASE CHARACTERISTICS:

• Stratum A (less than 3 months since prior therapy) closed to accrual effective 06/20/2000)

• Histologically or cytologically confirmed recurrent or refractory small cell lung cancer

  • Only 1 prior regimen allowed (an alternating regimen with cyclophosphamide/doxorubicin/vincristine and etoposide/cisplatin is acceptable)
• No mixed histology
• Measurable or evaluable disease that has not been in the field of prior radiotherapy
• No uncontrolled CNS metastases (treated CNS metastases eligible)

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-2

Life expectancy:

• Not specified

Hematopoietic:

• Absolute neutrophil count at least 2,000/mm^3
• Platelet count at least 100,000/mm^3

Hepatic:

• Total bilirubin no greater than 1.5 times upper limit of normal (ULN) OR
• Direct bilirubin normal

Renal:

• Creatinine no greater than 1.5 times ULN

Cardiovascular:

• No unstable angina pectoris
• No uncontrolled congestive heart failure
• No myocardial infarction within the past 3 months

Other:

• No uncontrolled infections
• No other concurrent malignancy except skin cancer or localized prostate cancer
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• See Disease Characteristics
• No prior topoisomerase I inhibitor (e.g., topotecan or irinotecan) or taxane (e.g., paclitaxel or docetaxel)
• At least 3 months since other prior chemotherapy

Endocrine therapy:

• Not specified

Radiotherapy:

• See Disease Characteristics
• At least 2 weeks since prior radiotherapy
• No concurrent radiotherapy

Surgery:

• At least 3 weeks since any prior major surgery