CA 19.9 represents the most important and basic carbohydrate tumor marker. Usually very little of CA19.9 is detectable in the blood of normal individuals. The immunohistologic distribution of CA 19.9 in tissues is consistent with the quantitative determination of higher CA 19.9 concentrations in cancer than in normal or inflamed tissues. Recently reports indicates that the serum CA 19. 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 CA 19.9 is suggestive of gallbladder neoplasm in the setting of inflammatory gallbladder disease. This tumor-associated antigen may also be elevated in some non-malignant conditions. Research studies demonstrate that serum CA19.9 values may have utility in monitoring subjects with the above-mentioned diagnosed malignancies.
It has been shown that a persistent elevation in serum CA19.9 value following treatment may be indicative of occult metastatic and/or residual disease.A persistently rising serum CA 19.9 value may be associated with progressive malignant disease and poor therapeutic response. A declining CA 19.9 value may be indicative of a favourable prognosis and good response to treatment. A group of mucin type glycoprotien Sialosyl Lewis Antigens (SLA), such as CA 19.9 and CA 19.5, has come to be recognized as circulating cancer-associated antigens for gastrointestinal cancer.
Clinical Application
To diagnose pancreatic cancer (in conjunction with other diagnostic modalities like CT, USG).
- To monitor therapy and recurrences.
- Levels correlate well with pancreatic cancer staging. With the cut off of 37 U/ml, 67% of patients with respectable and 87 % of those with unrespectable pancreatic cancer have elevated levels. With 1000 U/ml as cut off, 35 % of patients with unrespectable and 5% of respectable pancreatic cancer have elevated values.
- Pancreatic cancer in the non-jaundiced patients can be difficult to diagnose, even with the aid of modern scanning techniques. The detection and quantification of CA 19.9 can be used in serological diagnosis of disease.
- As an aid in serological diagnosis of cystic fibrosis patients.
- May indicate development of cholangiocarcinoma in patients with primary sclerosing cholangitis.
Decreased levels
Low amounts of CA 19.9 can be detected in a certain percentage of healthy people, and many conditions that affect the liver or pancreas can cause temporary elevations.
Increased levels
- Moderate to high levels are found in pancreatic cancer, other cancers, and in several other diseases and conditions.
- The highest levels of CA 19.9 are seen excretory ductal pancreatic cancer- cancer that is found in the pancreas tissues that produce food- digesting enzymes and in the ducts that carry those enzymes into the small intestine. This tissue is where 95% of pancreatic cancers are found.
- Hepatobiliary cancer.
- Colon cancer.