Comparison of Combination Chemotherapy Regimens in Treating Patients With Metastatic Colorectal Cancer

DISEASE CHARACTERISTICS: Histologically confirmed colorectal carcinoma Metastatic disease Not amenable to surgery Unidimensionally measurable disease No bone metastases No brain metastases PATIENT CHARACTERISTICS: Age 18 to 75 Performance status WHO 0-2 Life expectancy At least 12 weeks Hematopoietic Neutrophil count at least 2,000/mm^3 Platelet count at least 100,000/mm^3 Hemoglobin at least 10 g/dL Hepatic Bilirubin no greater than 1.25 times upper limit of normal (ULN) (1.5 times ULN if hepatic metastases are present) SGPT and SGOT no greater than 3 times ULN (5 times ULN if hepatic metastases are present) Renal Creatinine no greater than 1.25 times ULN Cardiac No concurrent cardiac abnormalities that would preclude study therapy Pulmonary No concurrent pulmonary abnormalities that would preclude study therapy Other Not pregnant or nursing Fertile patients must use effective contraception No chronic enteropathy No other prior cancer within the past 5 years except carcinoma in situ of the cervix or curatively treated basal cell skin cancer No concurrent severe uncontrolled infection No obstruction or partial obstruction that would interfere with study therapy No psychological, social, familial, or geographical situation that would preclude study participation PRIOR CONCURRENT THERAPY: Biologic therapy No concurrent anticancer biological response modifiers Chemotherapy No prior chemotherapy (except adjuvant chemotherapy completed more than 6 months ago) No prior irinotecan No prior oxaliplatin No other concurrent chemotherapy Endocrine therapy No concurrent anticancer hormonal therapy Radiotherapy At least 4 weeks since prior pelvic radiotherapy No prior abdominopelvic radiotherapy Surgery At least 4 weeks since prior surgery No prior extensive intestinal resection (i.e., more than 1 prior hemicolectomy or extensive resection of the small intestines) Other No other concurrent experimental medication No other concurrent anticancer therapy