CA19.9

A CA19.9 test, also known as carbohydrate antigen 19.9, is a blood test used to measure the levels of CA 19.9 protein in the blood. CA 19.9 is a tumor marker that may be increased in individuals with certain types of cancer, particularly pancreatic cancer and some non-cancerous conditions. This test helps diagnose cancer, monitor cancer treatment response, and detect cancer recurrence post-treatment.

CA19.9, a carbohydrate-rich glycoprotein known as mucin, is an important biomarker associated frequently associated with pancreatic cancer. However, increased CA 19.9 levels may also be seen in other cancers, including colorectal, gastric, hepatobiliary, and ovarian cancer. Additionally, the levels of CA19.9 may be elevated in non-cancerous conditions such as pancreatitis, cirrhosis, benign gallbladder disease (cholestasis), and cystic fibrosis. Hence, it is important to note that a CA19.9 test is not a standalone test, and other confirmatory procedures, such as medical history, clinical findings, imaging studies, or biopsies, may be necessary to validate cancer diagnosis.

Single values of CA19.9 are less informative. Hence, serial measurements over time, beginning before treatment, are preferred. Changes in CA 19.9 levels over time with disease progression or therapy may reflect the effectiveness of treatment and help guide further management decisions. A persistently high CA19.9 value may indicate disease progression, poor response to treatment, or even metastasis (tumor spread). Additionally, there is no correlation between the size of the tumor and the CA19.9 assay values. Patients with confirmed cancer may have a normal range before treatment initiation.

No special preparations are required before undergoing a CA19.9 test. However, it is important to provide a brief clinical history or doctor's prescription at the time of sample collection.  

Test results may vary across laboratories, and values obtained with different test methods should not be used interchangeably. An expert should interpret results in conjunction with clinical findings and other diagnostic tests to guide appropriate patient care and optimized treatment outcomes.