CA 19-9

High levels of CA 19-9 can be a sign of certain cancers of the digestive tract, including cancers of the pancreas, liver, stomach, and colon or rectum. However, high CA 19-9 levels can also be a sign of other conditions.

Because high levels of CA 19-9 can mean different things, health care providers don't use the results from a CA 19-9 test alone to screen for or diagnose cancer or other diseases. To do this, your provider will have to consider the results of a CA 19-9 test as well as the results of other tests.

If you're being treated for cancer, you may be tested several times during your treatment. Your provider will look at all your test results to see how your CA 19-9 levels have changed over time, which can help track whether the disease is responding to treatment or coming back.

Healthy people can sometimes have a slightly raised CA 19-9. Non-cancer conditions such as pancreatitis, gallstones, blocked bile ducts, hepatitis, and cirrhosis can also push it up, though the level usually stays under about 1,000 U/mL with these benign causes. Numbers above that range are more often seen with cancers like pancreatic or bile-duct cancer, but other tests are still needed before any diagnosis is made.

About 5 to 7 out of every 100 people are 'Lewis-antigen negative,' meaning their bodies do not make CA 19-9 at all. For these people the test isn't useful for tracking cancer, so your provider may pick a different marker.

Talk with your provider about what your results may mean. If your provider thinks you may have one of these conditions, you will probably need other tests to find out for sure.