Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically proven unresectable locally advanced or metastatic
adenocarcinoma of the stomach or gastroesophageal junction Limited prior immunotherapy or
chemotherapy OR Failure after no more than 1 prior regimen of immunotherapy or
chemotherapy (including chemotherapy as radiosensitizer) Primarily resistant or responsive
disease but with subsequent progression No osseous metastasis as only site of disease
Bidimensionally measurable or evaluable disease Mediastinal or hilar lymph nodes must be
at least 1.5 cm in diameter by CT or MRI scan to be considered measurable No brain
metastases

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Zubrod 0-1 OR Karnofsky
80-100% Life expectancy: At least 12 weeks Hematopoietic: Absolute granulocyte count at
least 1,500/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least 8 g/dL Hepatic:
Bilirubin no greater than 1.5 mg/dL No Gilbert's syndrome Renal: Creatinine no greater
than 1.5 mg/dL Calcium no greater than 12 mg/dL OR No symptomatic hypercalcemia under
treatment Cardiovascular: No New York Heart Association class III or IV heart disease No
angina, myocardial infarction, or congestive heart failure within the past 6 months
Gastrointestinal: No intestinal obstruction No diarrhea (greater than 4 loose stools per
day) Able to swallow Other: Not pregnant or nursing Negative pregnancy test Fertile
patients must use effective contraception No concurrent serious infection or nonmalignant
medical illness that is uncontrolled or for which control may be jeopardized by
complications of study therapy No history of seizures No psychiatric disorder that would
preclude compliance No other malignancy within the past 5 years except nonmelanomatous
skin cancer or carcinoma in situ of the cervix No pre-existing cystitis

PRIOR CONCURRENT THERAPY: Biologic therapy: See Disease Characteristics No concurrent
immunotherapy including filgrastim (G-CSF) Chemotherapy: See Disease Characteristics No
prior topoisomerase I inhibitors (e.g., irinotecan, topotecan, or aminocamptothecin) At
least 4 weeks since other prior chemotherapy and recovered No other concurrent
chemotherapy Endocrine therapy: No concurrent anticancer hormonal therapy Radiotherapy: No
prior radiotherapy to major bone marrow-containing areas (e.g., pelvis, lumbar spine) No
prior radiotherapy to sole indicator lesion At least 4 weeks since prior limited
radiotherapy and recovered No concurrent radiotherapy Surgery: At least 1 week since prior
minor surgery and recovered At least 3 weeks since prior major surgery and recovered
Other: No concurrent phenytoin, phenobarbital, or other antiepileptic prophylaxis