Perioperative Chemotherapy in Treating Patients With Colon Cancer That Can Be Surgically Removed

Eligibility Criteria for Randomization: Inclusion Criteria: * Adenocarcinoma of the colon documented by colonoscopy or barium enema * Tumor either considered resectable or totally resected within 24 hours prior to study * Randomization within 2 weeks prior to surgery or within 24 hours after surgery required * Patients randomized after surgery must meet the following criteria: * Complete resection performed with no evidence of residual disease or distant metastases * Distal margin of tumor above the peritoneal reflection in area of rectum * No free perforation Intestinal obstruction allowed * Preliminary or complementary colostomy allowed * Concurrent registration for E3293 strongly recommended * Age 18 and over * Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 * Adequate organ function based on the following tests within 2 weeks prior to randomization * White Blood Cell (WBC) at least 3,000/mm\^3 * Platelet count at least 100,000/mm\^3 * Bilirubin no greater than 2.0 mg/dL * Creatinine no greater than 2.0 mg/dL * No second malignancy within 5 years except: superficial non-melanomatous skin cancer and carcinoma in situ of the cervix * Fertile patients must use adequate contraception Exclusion Criteria: * Dual primary tumors * Prior nonmalignant systemic disease that would preclude use of chemotherapy * Pregnant or nursing * Prior fluorouracil * Other prior or concurrent chemotherapy for this malignancy * Prior or concurrent radiotherapy for this malignancy Eligibility Criteria for Re-registration for Patients Randomized Pre-operatively: * Must have pathologic classification of Dukes' B2, B3, or C disease by the contributing institution. * Must be re-registered \< 35 days after surgery. * ECOG performance status of 0-2. * Complete resection must have been performed with no evidence of residual disease or distant metastasis. * Distal margin of the tumor must not extend below the peritoneal reflection in the area of the rectum. * Single primary colon carcinoma without free perforation demonstrated. Patients with intestinal obstruction are eligible. Preliminary or complementary colostomy dose not preclude entry of a patient. * Have WBC \> 3000/mm\^3, platelets \> 100,000/mm\^3, adequate renal (serum creatinine \<= 2.0mg/dL) and hepatic function (bilirubin \<= 2.0mg/dL), within one week prior to beginning adjuvant chemotherapy (For Dukes' B3 and C patients only). Eligibility Criteria for Re-registration for Patients Randomized Post-operatively: * Must have pathologic classification of Dukes' B2, B3, or C disease by the contributing institution. * Patient must be re-registered \< 35 days after surgery. * ECOG performance status of 0-2. * Started perioperative 5-FU, if assigned, within 24 hours of surgery. * Have WBC \> 3000/mm\^3, platelets \> 100,000/mm\^3, adequate renal (serum creatinine \<= 2.0mg/dL) and hepatic function (bilirubin \< =2.0mg/dL), within one week prior to beginning adjuvant chemotherapy (For Dukes' B3 and C patients only).