Cancer Antigen 19-9
Cancer Antigen 19-9 (CA 19-9) is a derivative of the Lea blood group antigen present on normal mesenteric epithelium. It is not expressed in Lewis-negative individuals, who represent approximately seven percent of the total population in the U.S. It is of clinical use because it is also expressed at high levels in most patients with carcinomas of the pancreas, liver, biliary tract, stomach, colon, and breast. CA 19-9 and carcinoembryonic antigen (CEA) may be used together to help differentiate benign disease from pancreatic carcinoma. Elevations of both are suggestive of neoplasia.
