CA19-9
{{Chembox
| Name = Sialyl-LewisA
| verifiedrevid = 409334500
| ImageFile = Sialyl lewis a.svg
| ImageSize = 200px
| SystematicName = (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
| OtherNames = sialyl LeA, SLeA, cancer antigen 19-9, CA19-9
|Section1={{Chembox Identifiers
| CASNo = 92448-22-1
| CASNo_Ref = {{cascite|correct|CAS}}
| ChEBI = 61793
| ChemSpiderID = 9160877
| PubChem = 10985677
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = ZEJ6FM4UJK
| SMILES = O=C(O)[C@@]1(O[C@H]2[C@@H](O)[C@@H](CO)O[C@@H](O[C@H]3[C@H](O[C@H]4[C@@H](O)[C@H](O)[C@H](O)[C@H](C)O4)[C@@H](CO)OC(O)[C@@H]3NC(C)=O)[C@@H]2O)C[C@H](O)[C@@H](NC(C)=O)[C@H]([C@H](O)[C@H](O)CO)O1
| MeSHName = sialyl+Lewis+A
}}
|Section2={{Chembox Properties
| C=31 | H=52 | N=2 | O=23
| Appearance =
| Density =
| MeltingPt =
| BoilingPt =
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|Section3={{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt =
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}}
Carbohydrate antigen 19-9 (CA19-9), also known as sialyl-LewisA, is a tetrasaccharide 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 a tumor marker used primarily in the management of pancreatic cancer.{{Cite journal | last1 = Perkins | first1 = G. | last2 = Slater | first2 = E. | last3 = Sanders | first3 = G. | last4 = Prichard | first4 = J. | title = Serum tumor markers | journal = American Family Physician | volume = 68 | issue = 6 | pages = 1075–1082 | year = 2003 | pmid = 14524394 | url= http://www.aafp.org/afp/2003/0915/p1075.html}}
Structure
CA19-9 is the sialylated form of Lewis antigenA. It is a tetrasaccharide with the sequence Neu5Acα2-3Galβ1-3[Fucα1-4]GlcNAcβ.
Clinical significance
=Tumor marker=
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 (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.{{cite journal |vauthors=Locker G, Hamilton S, Harris J, Jessup J, Kemeny N, Macdonald J, Somerfield M, Hayes D, Bast R |title=ASCO 2006 update of recommendations for the use of tumor markers in gastrointestinal cancer |journal=J. Clin. Oncol. |volume=24 |issue=33 |pages=5313–27 |year=2006 |pmid=17060676|url=http://jco.ascopubs.org/cgi/content/full/24/33/5313 |doi=10.1200/JCO.2006.08.2644|url-access=subscription }} Therefore it is useful as a surrogate marker for relapse.
In people with pancreatic masses, CA19-9 can be useful in distinguishing between cancer and other diseases of the gland.
==Limitations==
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 occur in pancreatitis, cirrhosis, and diseases of the bile ducts. It can also be elevated in people with obstruction of the bile ducts.
In people who lack Lewis antigenA (a blood type antigen on red blood cells), which is about 10% of the white population, CA19-9 is not produced by any cells,{{cite journal |vauthors=Goonetilleke KS, Siriwardena AK |title=Systematic review of carbohydrate antigen (CA19-9) as a biochemical marker in the diagnosis of pancreatic cancer |journal=Eur J Surg Oncol |volume=33 |issue=3 |pages=266–70 |date=April 2007 |pmid=17097848 |doi=10.1016/j.ejso.2006.10.004}} even in those with large tumors. This is because of a deficiency of a fucosyltransferase enzyme that is needed to produce Lewis antigenA.
History
CA19-9 was discovered in the serum of patients with colon cancer and pancreatic cancer in 1981.{{cite journal |vauthors=Koprowski H, Herlyn M, Steplewski Z, Sears HF |title=Specific antigen in serum of patients with colon carcinoma |journal=Science |volume=212 |issue=4490 |pages=53–5 |year=1981 |pmid=6163212 |doi=10.1126/science.6163212|bibcode=1981Sci...212...53K }} It was characterized shortly after, and it was found to be carried primarily by mucins.{{cite journal|last1=Magnani|first1=JL|title=The discovery, biology, and drug development of sialyl Lea and sialyl Lex.|journal=Archives of Biochemistry and Biophysics|date=15 June 2004|volume=426|issue=2|pages=122–31|pmid=15158662|doi=10.1016/j.abb.2004.04.008}}
See also
References
{{reflist}}
External links
- {{MeshName|CA-19-9+Antigen}}
- CA19-9 at [http://labtestsonline.org/understanding/analytes/ca19-9/tab/test Lab Tests Online]
- [http://www.acb.org.uk/docs/default-source/committees/scientific/amalc/ca19-9.pdf CA19-9: analyte monograph] - The Association for Clinical Biochemistry and Laboratory Medicine
- [https://www.ncbi.nlm.nih.gov/books/NBK453042/#_Ch14_s2_ Essentials of Glycobiology 3rd Edition, Chapter 14: "Structures Common to Different Glycans" https://www.ncbi.nlm.nih.gov/books/NBK453042/#_Ch14_s2_]
{{Tumor markers}}