At a glance

Also known as

Cancer Antigen 19-9

Why get tested?

CA 19-9 is used to help tell the difference between cancer of the pancreas or bile ducts and other conditions; CA 19-9 is used to monitor response to pancreatic cancer treatment and to watch for recurrence.

When to get tested?

When your doctor suspects that you have pancreatic cancer and during or following pancreatic cancer treatment.

Sample required?

A blood sample drawn from a vein in your arm.

Test preparation needed?


What is being tested?

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 produced by the tumour cells, making it useful as a tumour 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 and diseases such as bowel cancer, lung cancer, gall bladder cancer, gall stones, pancreatitis, cystic fibrosis and liver disease. Very small amounts of CA 19-9 may also be found in healthy patients.

How is the sample collected for testing?

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

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

How is it used?

CA 19-9 is used as a tumour marker

  • to monitor a patient's response to pancreatic cancer treatment; and
  • to watch for pancreatic cancer recurrence.

When is it requested?

CA 19-9 is initially elevated in pancreatic cancer, then it may be requested several times during cancer treatment to monitor response and, on a regular basis following treatment, to see if the cancer has come back.

What does the test result mean?

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 a temporary rise in CA 19-9.

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 in pancreatic ductal adenocarcinoma - 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 the vast majority of pancreatic cancers are found.

Repeated measurements of CA 19-9 may be useful during and following treatment because rising or falling levels may give your doctor important information about whether the treatment is working, whether all of the cancer was removed successfully during surgery, and whether the cancer is returning.

Not everyone with pancreatic cancer will develop high levels of CA 19-9. Five to ten percent of Caucasians have a particular blood type described as Lewis negative and these people test negative for CA 19-9 even if they have pancreatic cancer.

About Reference Intervals

Is there anything else I should know?

Unfortunately, early pancreatic cancer gives few warnings. By the time a patient has symptoms and elevated levels of CA 19-9, their pancreatic cancer is usually at an advanced stage.

Common Questions

Why is my doctor not screening me for CA 19-9?

CA 19-9 is not recommended as a screening test for people who do not have symptoms of pancreatic cancer because there are many other conditions that can cause CA 19-9 to rise. Researchers are searching for other markers that may help detect pancreatic cancer at an earlier stage and that may be more suitable for screening.

What other procedures will my doctor request along with my CA 19-9?

Your doctor may order a CT scan (computed tomography), an ultrasound, an ERCP (endoscopic retrograde cholangiopancreatography, a procedure in which a small lighted tube is passed through the mouth and stomach into the small intestine), and/or a biopsy to look for cancer cells under the microscope. Samples of the cancer may be tested for abnormalities (mutations) of the gene K-RAS to help the doctor decide on the best treatment.

What are the main risk factors for pancreatic cancer?

Doctors still do not know what causes most cases of pancreatic cancer. Identified risk factors include smoking, age (most are over 50 years old), gender (males are more likely to have it than females), family history, diabetes, obesity, chronic pancreatitis, and heavy occupational exposure to certain chemicals and dyes.

Last Review Date: September 17, 2022

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