Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically proven metastatic or unresectable high grade neuroendocrine tumor
including:

- Small cell carcinoma

- Large cell neuroendocrine carcinoma

- Other high grade neuroendocrine carcinomas without specification to cell size

- No lung only involvement without any other primary site

- No primary small cell lung cancer with or without metastases

- Bidimensionally measurable disease with at least one lesion measuring at least 1 cm
by 1 cm

- High grade tumor indicated by at least one of the following:

- Growth pattern suggestive of neuroendocrine differentiation

- Mitotic rate greater than 15 mitoses per 10 hpf

- Presence of abundant necrosis

- Immunohistochemical evidence of neuroendocrine differentiation by positive staining
for chromogranin, synaptophysin, or neuron specific enolase if no classic microscopic
appearance of small cell carcinoma

- No low grade neuroendocrine tumors (e.g., carcinoid tumors, pancreatic endocrine
tumors) and atypical tumors

PATIENT CHARACTERISTICS:

Age:

- 18 and over

Performance status:

- Karnofsky 70-100%

Life expectancy:

- Not specified

Hematopoietic:

- WBC at least 3,500/mm^3

- Granulocyte count at least 1,500/mm^3

- Platelet count at least 75,000/mm^3

Hepatic:

- Bilirubin no greater than upper limit of normal (ULN)

- SGOT no greater than 5 times ULN

Renal:

- Creatinine no greater than 2.0 mg/dL

Cardiovascular:

- No myocardial infarction within the past 6 months

- No uncontrolled congestive heart failure requiring therapy

Other:

- No active or uncontrolled infection

- HIV negative

- No psychiatric or other disorder that would preclude study

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy

- Not specified

Chemotherapy

- No more than 2 prior chemotherapy regimens

- No prior camptothecins

Endocrine therapy

- Not specified

Radiotherapy

- Not specified

Surgery

- Not specified