This is a tumor marker for pancreas cancer that is measured through a blood test. It is useful in assisting with an initial diagnosis. However, it is more useful in measuring the effectiveness of cancer treatment by studying the patient's CA19-9 levels over time.
In general, before surgery, the higher the CA19-9 level is, the larger the tumor is and the less chance that the tumor is resectable. For the purposes of evaluating treatment, a decreasing or stable CA19-9 level generally indicates an improved prognosis and an increasing level indicates the progression of disease.
Currently, there are not sufficiently accurate diagnostic blood tests for pancreatic cancer. Very few cancers, such as prostate and liver cancers, can be confidently diagnosed solely on the basis of blood test results. Perfecting a suitable blood test for PC is an area of active research because it would enable screening for individuals considered at-risk.
CA19-9 is elevated in the blood of 50-75% of individuals with PC. Other blood tests such as CEA are not as accurate. Supplemental imaging studies and tissue samples are required with CA19-9 levels for a definitive diagnosis.
CA19-9 can be used to track treatment progress of previously diagnosed PC patients. This blood test in conjunction with periodic CT scans will show whether the cancer is in remission or is continuing to grow.
If your doctor suspects pancreatic cancer, an abnormal CA 19-9 blood level will increase the suspicion. However, there are benign diseases of the bile ducts and pancreas that occasionally result in elevated CA 19-9 levels. For this reason CA 19-9 is not considered a diagnostic test.