Role of chemotherapy in the treatment of colorectal carcinoma.

Large bowel cancer afflicts more patients in the United States than any other malignancy excluding skin cancer. Fifty percent of patients who undergo resection of colorectal carcinoma have positive lymph nodes, and approximately 18% have liver metastases at initial presentation. To improve survival, more effective treatment than surgical resection of the primary must be developed. The most active single agent in the treatment of colorectal carcinoma is 5-fluorouracil (5-FU). To increase the response rate obtained with this agent, work has been done on the modulation of 5-FU by other agents, using drugs that are synergistic with 5-FU and manipulating the method of 5-FU administration. Combination chemotherapy has improved response rates in some situations, though generally it has not been shown to improve survival. Studies using direct hepatic infusion clearly demonstrate an increase in response rates, but again, it is too early to say whether this type of treatment increases survival. Early adjuvant chemotherapy trials used inadequate doses of chemotherapy for short periods of time and demonstrated no added efficacy to surgery alone. Later studies with more aggressive therapy suggested some benefit to treating patients with rectal carcinoma; however, there is still little evidence that adjuvant chemotherapy improves survival in patients with colon carcinoma. To compare and understand the various chemotherapy trials, more stringent reporting of baseline laboratory values, performance status, and estimation of tumor involvement are needed.