Adjuvant treatment of colorectal cancer. Current status and concepts.

Colorectal cancer is the second leading cause of cancer mortality in the United States, causing approximately 50,000 deaths per year. The overall prognosis and results of treatment have not changed impressively over the last three decades. Half of all the patients who undergo curative surgery finally succumb to locoregional or metastatic recurrence of their disease. Recent clinical research has been aimed at adjuvant therapeutic measures to improve survival after curative surgical resection. For rectal cancer, combined postoperative chemotherapy and radiation therapy have been shown to reduce the overall relapse rate and improve disease-free survival. Further studies of adjuvant treatment for rectal cancer are needed to evaluate the optimal radiation schedule and limit the side-effects of the treatment. Adjuvant treatment of colon cancer must still be regarded as unsettled. Since liver metastases are the most common unfavorable outcome of colon cancer, ongoing trials using liver-directed treatment (perfusion, irradiation) should be followed with interest. The lack of proven efficacy and the side-effects of these treatments strongly favor the inclusion of an observation-only control group in trials for adjuvant treatment of colon cancer. Unfortunately, there is as yet no proven significant benefit from immunotherapy as an adjuvant therapy for colorectal cancer, but further basic and clinical studies will be of great interest in this field.