Oxaliplatin, Irinotecan, and Capecitabine in Treating Patients With Advanced or Metastatic Colorectal Cancer That Cannot Be Removed By Surgery

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed unresectable advanced or metastatic colorectal cancer Measurable disease (phase II only) At least 1 unidimensionally measurable lesion ≥ 20 mm by conventional techniques OR ≥ 10 mm by spiral CT scan or MRI No presence or history of CNS metastases PATIENT CHARACTERISTICS: Age 18 to 70 Performance status WHO 0-1 Life expectancy Not specified Hematopoietic Absolute neutrophil count ≥ 1,500/mm^3 Platelet count ≥ 100,000/mm^3 Hepatic Bilirubin ≤ 1.25 times upper limit of normal (ULN) (1.5 times ULN if liver metastases are present) AST and ALT ≤ 3 times ULN (5 times ULN if liver metastases are present) Renal Creatinine clearance > 60 mL/min Cardiovascular No New York Heart Association class III-IV congestive heart failure No symptomatic coronary artery disease No uncontrolled cardiac arrhythmia No myocardial infarction within the past year No other clinically significant cardiac disease Immunologic No active autoimmune disease No uncontrolled infection No prior severe reaction to fluoropyrimidine therapy or known hypersensitivity to fluorouracil No known hypersensitivity to any component of study drugs Other Not pregnant or nursing Negative pregnancy test Patients must use effective contraception during and for 1 year after study participation No other malignancy within the past 5 years except adequately treated carcinoma in situ of the cervix or localized nonmelanoma skin cancer No peripheral neuropathy > grade 1 of any origin (e.g., alcohol or diabetes) No nausea, vomiting, or malabsorption syndrome that would preclude ingestion or absorption of oral medication No psychiatric disability that would preclude study compliance No uncontrolled diabetes No other serious underlying medical condition that would preclude study participation No known dihydropyrimidine dehydrogenase deficiency PRIOR CONCURRENT THERAPY: Biologic therapy No concurrent prophylactic hematopoietic growth factors Chemotherapy More than 6 months since prior adjuvant fluoropyrimidine chemotherapy No other prior chemotherapy Endocrine therapy Not specified Radiotherapy No concurrent radiotherapy Concurrent radiotherapy of a single painful lesion allowed Surgery Not specified Other More than 30 days since prior clinical trial participation No other concurrent experimental drugs No other concurrent anticancer therapy No concurrent sorivudine or its chemically-related analogues (e.g., lamivudine)