CA 19-9 (Cancer Antigen 19-9)

This is a test to help differentiate between cancer of the pancreas and bile ducts and other conditions. It is also used to monitor response to pancreatic cancer treatment and to watch for recurrence. Cancer antigen 19-9 (CA 19-9) is a protein that exists on the surface of certain cells. CA 19-9 does not cause cancer; rather, it is a protein that is shed by the tumor cells, making it useful as a tumor marker to follow the course of the cancer.

CA 19-9 is elevated in most patients with advanced pancreatic cancer, but it may also be elevated in other cancers, conditions, and diseases such as colorectal cancer, lung cancer, gallbladder cancer, gall stones, pancreatitis, cystic fibrosis, and liver disease. Very small amounts of CA 19-9 may also be found in healthy patients. It is not useful as a screening test for cancer because it is not sensitive or specific enough. to be used as a screen for people who do not have symptoms. There are too many false positives and false negatives associated with it. Early pancreatic cancer gives few warnings. By the time a patient has symptoms and significantly elevated levels of CA 19-9, their pancreatic cancer is usually at an advanced stage.


A blood sample is obtained by inserting a needle into a vein in the arm.


Adults: 0-37 units/mL (0-37 kunits/L)

Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.


Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.


It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.