 | |
| Names | |
|---|---|
| Systematic IUPAC name (12S,14S,15R,16R,32R,33R,34S,35S,36R,52R,53S,54R,55R,56Ξ,72S,73S,74R,75S,76S)-15,55-Diacetamido-14,33,35,56,73,74,75-heptahydroxy-36,52-bis(hydroxymethyl)-76-methyl-16-[(1R,2R)-1,2,3-trihydroxypropyl]-2,4,6-trioxa-1,7(2),3(4,2),5(4,3)-tetraoxanaheptaphane-12-carboxylic acid | |
| Other names sialyl LeA, SLeA, cancer antigen 19-9, CA19-9 | |
| Identifiers | |
3D model (JSmol) | |
| ChEBI | |
| ChemSpider | |
| KEGG | |
| MeSH | sialyl+Lewis+A |
| UNII | |
| |
| |
| Properties | |
| C31H52N2O23 | |
| Molar mass | 820.748 g·mol−1 |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Carbohydrate antigen 19-9 (CA19-9), also known assialyl-LewisA, is atetrasaccharide which is usually attached to O-glycans on the surface of cells. It is known to play a role in cell-to-cell recognition processes. It is also atumor marker used primarily in the management ofpancreatic cancer.[1]
CA19-9 is thesialylated form ofLewis antigenA. It is atetrasaccharide with the sequence Neu5Acα2-3Galβ1-3[Fucα1-4]GlcNAcβ.
Guidelines from theAmerican Society of Clinical Oncology discourage the use of CA19-9 as a screening test for cancer, particularlypancreatic 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 (false positive) in others. 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.[2] Therefore it is useful as a surrogate marker forrelapse.
In people withpancreatic masses, CA19-9 can be useful in distinguishing between cancer and other diseases of the gland.[1][3]
CA19-9 can be elevated in many types of gastrointestinal cancer, such ascolorectal cancer,esophageal cancer andhepatocellular carcinoma.[1] Apart from cancer, elevated levels may occur inpancreatitis,cirrhosis,[1] and diseases of the bile ducts.[1][3] It can also be elevated in people with obstruction of thebile ducts.[3]
In people who lack Lewis antigenA (a blood type antigen onred blood cells), which is about 10% of the white population, CA19-9 is not produced by any cells,[3] even in those with large tumors.[2] This is because of a deficiency of afucosyltransferase enzyme that is needed to produce Lewis antigenA.[2]
CA19-9 was discovered in the serum of patients withcolon cancer andpancreatic cancer in 1981.[4] It was characterized shortly after, and it was found to be carried primarily bymucins.[5]
