Guidelines from the American Society of Clinical Oncology discourage the use of CA19-9 as a screening test for cancer, particularly pancreatic cancer. The reason is that the test may be falsely normal (false negative) in many cases, or abnormally elevated in people who have no cancer at all (false positive). The main use of CA19-9 is therefore to see whether a pancreatic tumor is secreting it; if that is the case, then the levels should fall when the tumor is treated, and they may rise again if the disease recurs.
CA19-9 can be elevated in many types of gastrointestinal cancer, such as colorectal cancer, esophageal cancer and hepatocellular carcinoma. Apart from cancer, elevated levels may also occur in pancreatitis, cirrhosis, and diseases of the bile ducts. It can be elevated in people with obstruction of the bile ducts.
In patients who lack the Lewis antigen (a blood type antigen on red blood cells), which is about 10% of the Caucasian population, CA19-9 is not expressed, even in those with large tumors. This is because of a deficiency of a fucosyltransferase enzyme that is needed to produce CA19-9 as well as the Lewis antigen.
- Perkins, G.; Slater, E.; Sanders, G.; Prichard, J. (2003). "Serum tumor markers". American family physician 68 (6): 1075–1082. PMID 14524394.
- CA-19-9 Antigen at the US National Library of Medicine Medical Subject Headings (MeSH)
- Koprowski H, Herlyn M, Steplewski Z, Sears HF (1981). "Specific antigen in serum of patients with colon carcinoma". Science 212 (4490): 53–5. doi:10.1126/science.6163212. PMID 6163212.
- Locker G, Hamilton S, Harris J, Jessup J, Kemeny N, Macdonald J, Somerfield M, Hayes D, Bast R (2006). "ASCO 2006 update of recommendations for the use of tumor markers in gastrointestinal cancer". J. Clin. Oncol. 24 (33): 5313–27. doi:10.1200/JCO.2006.08.2644. PMID 17060676.
- Goonetilleke KS, Siriwardena AK (April 2007). "Systematic review of carbohydrate antigen (CA 19-9) as a biochemical marker in the diagnosis of pancreatic cancer". Eur J Surg Oncol 33 (3): 266–70. doi:10.1016/j.ejso.2006.10.004. PMID 17097848.
- CA19-9 at Lab Tests Online
- CA19-9: analyte monograph - The Association for Clinical Biochemistry and Laboratory Medicine