RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. It is not yet known which regimen of chemotherapy is more effective for metastatic colorectal cancer.

PURPOSE: Phase III trial to compare the effectiveness of three chemotherapy regimens in treating patients who have metastatic colorectal cancer.

OBJECTIVES: I. Compare the overall survival of patients with metastatic colorectal carcinoma treated with fluorouracil and leucovorin calcium with vs without oxaliplatin vs oxaliplatin alone. II. Compare the response rate, time to tumor-related symptomatic worsening, time to disease progression, onset and duration of complete and partial responses, and duration of disease stabilization in patients treated with these regimens. III. Determine the safety profile of these regimens in these patients.

OUTLINE: This is a randomized, open-label, multicenter study. Patients are stratified according to Karnofsky performance status (50-60% vs 70-100%), number of metastatic organs (1 vs 2 or more), and LDH value (up to 1.5 times upper limit of normal (ULN) vs greater than 1.5 times ULN). Patients are randomized to one of three treatment arms. Arm I: Patients receive leucovorin calcium IV over 2 hours followed by fluorouracil IV continuously over 22 hours on days 1 and 2. Arm II: Patients receive oxaliplatin IV over 2 hours on day 1. Arm III: Patients receive oxaliplatin IV concurrently with leucovorin calcium IV over 2 hours followed by fluorouracil IV continuously over 22 hours on day 1. Leucovorin calcium and fluorouracil are administered alone on day 2 on the same schedule as on day 1. Treatment repeats every 2 weeks for up to 1 year in the absence of disease progression or unacceptable toxicity. Patients are followed for 30 days, every 2 weeks for up to 3 months, and then every 3 months thereafter.

PROJECTED ACCRUAL: A total of 786 patients (262 per arm) will be accrued for this study within 12 months.

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed metastatic adenocarcinoma of the colon or rectum that is not amenable to potentially curative therapy (e.g., inoperable metastatic disease) At least 1 unidimensionally measurable lesion at least 20 mm in diameter by conventional CT or MRI scan or at least 10 mm in diameter by spiral CT scan Progressive disease by CT or MRI scan during or no more than 6 months after the last dose of prior first-line irinotecan, fluorouracil, and leucovorin calcium (Saltz regimen) for metastatic disease

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 50-100% Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) AST and ALT no greater than 2 times ULN (no greater than 5 times ULN if liver metastases present) Alkaline phosphatase no greater than 2 times ULN (no greater than 3 times ULN if liver metastases present) Renal: Creatinine no greater than 1.5 times ULN Cardiovascular: No uncontrolled high blood pressure No unstable angina, symptomatic congestive heart failure, or serious cardiac arrhythmia No New York Heart Association class III or IV heart disease No history of cardiac toxicities with prior fluorouracil and leucovorin calcium No myocardial infarction within the past 6 months Pulmonary: No interstitial pneumonia or extensive and symptomatic fibrosis of the lung Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 6 months after study No known dihydropyrimidine dehydrogenase deficiency No allergy to platinum-containing drugs No history of intolerance to study anti-emetics (e.g., 5-HT3 antagonists) No known peripheral neuropathy (absence of deep tendon reflexes as sole deficiency allowed) No uncontrolled diabetes No active infection No other active malignancy originating from primary site other than colon or rectum

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics One and only 1 prior chemotherapy regimen for metastatic disease consisting of first-line irinotecan, fluorouracil, and leucovorin calcium (Saltz regimen) Prior adjuvant fluorouracil with leucovorin calcium allowed At least 3 weeks since prior chemotherapy for metastatic disease and recovered No prior adjuvant irinotecan No prior oxaliplatin Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy to study lesions unless evidence of progressive disease within the radiotherapy port At least 3 weeks since prior radiotherapy Surgery: See Disease Characteristics At least 4 weeks since prior major surgery and recovered Prior surgical resection of primary tumor or metastases allowed Other: At least 30 days since prior investigational drugs No other concurrent investigational agents No other concurrent anti-cancer therapy No concurrent participation in other investigational trials