Irinotecan in Treating Patients With Metastatic or Recurrent Colorectal Cancer

DISEASE CHARACTERISTICS: Histologically confirmed metastatic or recurrent adenocarcinoma of the colon or rectum that is incurable by surgery or radiation therapy A metastatic lesion in the liver or lung should be evaluated for definitive surgical treatment before being considered for this study Measurable disease required Elevated CEA, hepatomegaly ascites, pleural effusion, positive nuclear scan or bone scan, or poorly defined pelvic or abdominal mass are NOT considered measurable disease Must have measurable disease outside the radiation port or progression of disease within a previously radiated area Must be eligible for a biopsy of a malignant lesion No ascites that are detectable on physical exam No brain metastasis PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Greater than 12 weeks Hematopoietic: WBC at least 4,000/mm3 Granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.2 mg/dL SGOT less than 4 times upper limit of normal Renal: Creatinine no greater than 1.5 mg/dL or Creatinine clearance at least 60 mL/min Other: No history of any other malignancy except curatively treated nonmelanoma skin cancer and carcinoma in situ of the cervix No active infection or other serious medical conditions deemed unacceptable Negative pregnancy test Effective contraception required of all fertile patients PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior chemotherapy for advanced disease Endocrine therapy: Not specified Radiotherapy: See Disease Characteristics At least 3 weeks since prior radiotherapy Surgery: At least 3 weeks since any surgical procedure