The primary curative therapy of colorectal cancer is surgical resection. However, within the last 15 years, prospectively randomized appropriately powered clinical trials have convincingly demonstrated that adjunctive postoperative adjuvant chemotherapy is of benefit to all patients with node-positive disease (stage III) and arguably to high-risk node-negative (stage II) cases. In the United States, the clinical trials encompassing greater than 5,000 cases have demonstrated that fluorouracil (5-FU)/leucovorin used in a variety of doses and schedules improves disease-free and overall survival in resected node-positive (stage III) colorectal cancer. The postoperative use of 5-FU/leucovorin for approximately 6 months represents standard of care for such patients. Current clinical trials are evaluating the role of nonfluorinated pyrimidine chemotherapeutic agents in adjuvant chemotherapy for resected large bowel cancer. 5-FU/leucovorin combined with irinotecan (CPT-11) versus 5-FU/leucovorin are being tested in a national intergroup clinical trial. Another trial is evaluating 5-FU/leucovorin plus oxaliplatin versus 5-FU/leucovorin alone. These clinical trials will be important in defining the appropriate standard of care for patients with resected colorectal cancer, since recent studies in advanced colorectal cancer in the United States and in Western Europe have demonstrated that combinations of 5-FU/leucovorin and CPT-11 or 5-FU/ leucovorin and oxaliplatin are superior to 5-FU/leucovorin alone.
