Cancer Antigen 19-9 (CA 19-9) Test
Note: this site is for informational purposes only. To view test results or book a test, use the NHS app in England or contact your GP.
The cancer antigen 19–9 (CA 19–9) test is performed on a blood sample to measure levels of the CA 19–9 protein, which can be elevated in certain cancers. It is used to help monitor treatment response and detect recurrence of pancreatic cancer and other gastrointestinal cancers when combined with clinical assessment.
Why get tested?
To help tell the difference between cancer of the pancreas and bile ducts and other conditions; 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 is obtained by inserting a needle into a vein in the arm.
Test preparation needed?
No test preparation is needed
Common questions
CA 19–9 is used as a tumour marker:
- to help tell the difference between cancer of the pancreas and bile ducts and other non-cancerous conditions, such as pancreatitis;
- to monitor a patient’s response to pancreatic cancer treatment; and
- to look for pancreatic cancer recurrence.
CA 19–9 may be requested along with other tests, such as carcinoembryonic antigen (CEA), bilirubin, and/or liver function tests, when a patient has symptoms that may indicate pancreatic cancer, including abdominal pain, nausea, weight loss, and jaundice.
If 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 help detect recurrence of the cancer.
Small increases in CA 19–9 levels can be detected in some healthy people, and in many benign 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 a condition called 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.
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.
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.
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.
Your doctor may request 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.
Doctors still do not know what causes most cases of pancreatic cancer. Identified risk factors include smoking, age (most people diagnosed with pancreatic disease are over 50 years old), gender (males are more likely to have it than females), family history, diabetes, chronic pancreatitis, and heavy occupational exposure to certain chemicals and dyes.