Adjuvant treatment of colorectal cancer.

Surgical operation remains the most effective method of treatment for patients with cancer of the large bowel. However, innovative surgical techniques have not improved survival rates for colorectal cancer in 25 years. Attempts at increasing survival with chemotherapy as an adjunct to surgical procedures remain inconclusive and controversial. Many adjuvant chemotherapy trials have failed to recognize those prognostic factors-such as nodal involvement, serosal penetration, vascular or perineural invasion, and microscopic invasion at margins of resection-that characterize certain patients at high risk for recurrent cancer. Failure to include only high risk patients in adjuvant chemotherapy is, in part, responsible for the lackluster performance to date. For rectal cancer, preoperative irradiation increases the chances of cure with surgical operation by reduction of pathologic staging, but it has not increased survival in patients with persistent nodal involvement. Immunotherapy is a possibly valuable method of treatment; however, it is clinically untested. An adjuvant immunotherapy protocol for high risk patients is described.