Carcinoembryonic antigen in colonic lavage.

Colonoscopic lavage was performed for assay of carcinoembryonic antigen (CEA) concentration in patients with small and large colonic adenomas, in patients with adenocarcinoma of the colon, and in normal controls. CEA concentration was considerably higher in colonoscopic lavage as compared to plasma. CEA concentration in normal controls and in patients with colonic adenomas less than 1 cm in size were not significantly different. CEA concentrations in patients with colonic adenomas greater than 1 cm in size and in patients with adenocarcinoma of the colon were significantly higher than those observed in patients with small adenomas and in the normal controls. In all except 2 patients, plasma CEA concentrations were normal. Assay of CEA concentrations in colonic lavage may have potential application in the further assessment of the mucosa at risk for colon adenomas and for colon cancer. It does not appear to be accurate enough for diagnosis of colon cancer in individual patients.