This test measures the amount of a protein called CA 19-9 (cancer antigen 19-9) in the blood.

CA 19-9 is a type of tumor marker. Tumor markers are substances made by cancer cells or by

normal cells in response to cancer in the body.

Healthy people can have small amounts of CA 19-9 in their blood. High levels of CA 19-9

are often a sign of pancreatic cancer. But sometimes, high levels can indicate other types of

cancer or certain noncancerous disorders, including cirrhosis and gallstones. Because high

levels of CA 19-9 can mean different things, the test is not used by itself to screen for or

diagnose cancer. It can help monitor the progress of your cancer and the effectiveness of

cancer treatment.