Usefulness of carcinoembryonic antigen measurement in feces of patients with colorectal cancer.

Anticarcinoembryonic antigen (CEA) antisera which showed no reactions with normal adult feces were prepared in guinea pigs. Using these, levels of CEA in feces from patients with colorectal carcinoma were measured by gel diffusion and rocket immunoelectrophoresis. Sixteen of 22 (73 percent) patients with carcinoma of the colon or rectum (Dukes' A4/6, B6/8, C6/7, D0/1) had detectable CEA in their feces, while none was detected in the feces of four patients with gastric ulcers or in those of 22 normal volunteers. Five of the 16 fecal CEA-positive patients showed no elevation of plasma CEA levels. Measurements using a commercial CEA kit (Abbott Laboratories) could not detect the differences between fecal CEA values of patients with colorectal carcinoma and benign diseases, or those of normal volunteers. These results suggest that measurement of fecal CEA by specific anti-CEA antisera will be valuable in screening and diagnosis of colorectal carcinoma.