Description
Cancer Antigen 19-9 is a tumor marker elevated in blood of patients with carcinoma of the gastro-intestinal tract. Primarily used distinguishing pancreatic cancer from pancreatitis, CA 19-9 is not sufficiently specific for use as a cancer screening test. The specificity for pancreatic cancer increases with increasing levels, high levels showing a specificity of >97% for tumor presence. CA 19-9 can be elevated in many types of gastrointestinal cancer, such as colorectal cancer, esophageal cancer and hepatocellular carcinoma. A group of mucin type glycoprotein Sialosyl Lewis Antigens (SLA), such as CA19-9 and CA19-5, have come to be recognized as circulating cancer associated antigens for gastrointestinal cancer. CA19-9 represents the most important and basic carbohydrate tumor marker. The immunohistologic distribution of CA19-9 in tissues is consistent with the quantitative determination of higher CA19-9 concentrations in cancer than in normal or inflamed tissues. Recently reports indicates that the serum CA19-9 level is frequently elevated in the serum of subjects with various gastrointestinal malignancies, such as pancreatic, colorectal, gastric and hepatic carcinomas. Together with CEA, elevated CA19-9 is suggestive of gallbladder neoplasm in the setting of inflammatory gallbladder disease.