The clinical value of the tumor markers CA 19/9 and carcinoembryonic antigen (CEA) in colorectal carcinomas: a critical comparison.

The monoclonal antibody serum test CA 19.9 after having been described as being colon tumor specific, was advertised as being more sensitive than CEA in the detection of both early and advanced colorectal carcinomas. Furthermore, the combined estimation of the two markers, CEA and CA 19.9 was said to improve the detection rate significantly. However, our own comparative studies as well as those of several other groups recently published have shown CA 19.9 measurements to be less valuable, because being less sensitive than those of CEA. This is especially true for the early stages of intestinal carcinomas. The parallel determinations of CA 19.9 and CEA improved the positivity rate insignificantly, because in only 3.5% of all cases C 19.9 was elevated in CEA negative cancer sera. However, CA 19.9 was found to have a much lower rate of (false) positive results than CEA in benign intestinal diseases.