Carcinoembryonic antigen (CEA) is a glycoprotein

Glycoprotein

Glycoproteins are proteins that contain oligosaccharide chains covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending...

 involved in cell adhesion

Cell adhesion

Cellular adhesion is the binding of a cell to a surface, extracellular matrix or another cell using cell adhesion molecules such as selectins, integrins, and cadherins. Correct cellular adhesion is essential in maintaining multicellular structure...

. It is normally produced during fetal development, but the production of CEA stops before birth. Therefore, it is not usually present in the blood of healthy adults, although levels are raised in heavy smoker

Smoker

Smoker is a noun derived from "smoke"/"smoking" and may have the following specialized meanings:* Someone who smokes tobacco or cannabis, cigarette substitutes, or various other drugs* Smoking , smoker, an apparatus for smoking...

s. CEA is a glycosyl phosphatidyl inositol (GPI)-cell surface anchored glycoprotein whose specialized sialofucosylated glycoforms serve as functional colon carcinoma L-selectin

L-selectin

L-selectin, also known as CD62L, is a cell adhesion molecule found on leukocytes. It belongs to the selectin family of proteins, which recognize sialylated carbohydrate groups...

 and E-selectin

E-selectin

E-selectin, also known as CD62 antigen-like family member E , endothelial-leukocyte adhesion molecule 1 , or leukocyte-endothelial cell adhesion molecule 2 , is a cell adhesion molecule expressed only on endothelial cells activated by cytokines. Like other selectins, it plays an important part in...

 ligands, which may be critical to the metastatic dissemination of colon carcinoma cells.

History

CEA was first identified in 1965 by Phil Gold

Phil Gold

Phil Gold, CC, OQ, FRSC, FRCPC, MACP is a Canadian physician, scientist, and professor.Born in Montreal, Quebec, he received a B.Sc. degree in 1957, a M.Sc. degree in 1961, a M.D. degree in 1961, and a Ph.D. in 1965 from McGill University.In 1968, he co-discovered with Samuel O...

 and Samuel O. Freedman

Samuel O. Freedman

Samuel Orkin Freedman, OC, CQ, FRSC is a Canadian clinical immunologist, professor and academic administrator. In 1965, he co-discovered with Phil Gold the carcinoembryonic antigen, the basis of a blood test used in the diagnosis and management of people with colorectal cancer.Born in Montreal,...

 in human colon cancer tissue extracts.

Uses

It was found that serum

Blood plasma

Blood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...

 from individuals with colorectal carcinoma, gastric carcinoma, pancreatic carcinoma, lung carcinoma and breast carcinoma, as well as individuals with medullary thyroid carcinoma, had higher levels of CEA than healthy individuals (above 2.5 ng/ml).
Regions of high CEA levels in the body can be detected with the monoclonal antibody arcitumomab

Arcitumomab

Technetium arcitumomab is a drug used for the diagnostic imaging of colorectal cancers, marketed by Immunomedics. It consists of the Fab' fragment of a monoclonal antibody and a radionuclide, technetium-99m....

.

CEA measurement is mainly used as a tumor marker

Tumor marker

A tumor marker is a substance found in the blood, urine, or body tissues that can be elevated in cancer, among other tissue types. There are many different tumor markers, each indicative of a particular disease process, and they are used in oncology to help detect the presence of cancer...

 to identify recurrences after surgical resection, or localize cancer spread though dosage of biological fluids. The CEA blood test is not reliable for diagnosing cancer or as a screening test for early detection of cancer. Most types of cancer do not produce a high CEA. Elevated CEA levels should return to normal after successful surgical resection, or within 6 weeks of starting treatment if cancer treatment is successful.

CEA levels may also be raised in some non-neoplastic conditions like ulcerative colitis

Ulcerative colitis

Ulcerative colitis is a form of inflammatory bowel disease . Ulcerative colitis is a form of colitis, a disease of the colon , that includes characteristic ulcers, or open sores. The main symptom of active disease is usually constant diarrhea mixed with blood, of gradual onset...

, pancreatitis

Pancreatitis

Pancreatitis is inflammation of the pancreas. It occurs when pancreatic enzymes that digest food are activated in the pancreas instead of the small intestine. It may be acute – beginning suddenly and lasting a few days, or chronic – occurring over many years...

, cirrhosis

Cirrhosis

Cirrhosis is a consequence of chronic liver disease characterized by replacement of liver tissue by fibrosis, scar tissue and regenerative nodules , leading to loss of liver function...

, COPD, Crohn's disease

Crohn's disease

Crohn's disease, also known as regional enteritis, is a type of inflammatory bowel disease that may affect any part of the gastrointestinal tract from mouth to anus, causing a wide variety of symptoms...

 as well as in smokers.

Genetics

CEA and related genes

Gênes

Gênes is the name of a département of the First French Empire in present Italy, named after the city of Genoa. It was formed in 1805, when Napoleon Bonaparte occupied the Republic of Genoa. Its capital was Genoa, and it was divided in the arrondissements of Genoa, Bobbio, Novi Ligure, Tortona and...

 make up the CEA family belonging to the immunoglobulin superfamily. In humans, the carcinoembryonic antigen family consists of 29 genes, 18 of which are normally expressed.

The following is a list of human genes which encode carcinoembryonic antigen-related cell adhesion proteins:

CEACAM1

CEACAM1

Carcinoembryonic antigen-related cell adhesion molecule 1 also known as CD66a , is a human gene.-Interactions:...

,
CEACAM3

CEACAM3

Carcinoembryonic antigen-related cell adhesion molecule 3 also known as CD66d , is a human gene....

,
CEACAM4

CEACAM4

CEACAM4 is a gene which encodes carcinoembryonic antigen....

,
CEACAM5

CEACAM5

Carcinoembryonic antigen-related cell adhesion molecule 5 also known as CD66e , is a human gene.-Further reading:...

,
CEACAM6

CEACAM6

Carcinoembryonic antigen-related cell adhesion molecule 6 also known as CD66c , is a human gene.-External links:...

,
CEACAM7

CEACAM7

Carcinoembryonic antigen-related cell adhesion molecule 7 is a protein that in humans is encoded by the CEACAM7 gene.-Further reading:...

,
CEACAM8

CEACAM8

Carcinoembryonic antigen-related cell adhesion molecule 8 also known as CD66b , is a human gene.-Further reading:...

,
CEACAM16

CEACAM16

CEACAM16 is a gene which encodes carcinoembryonic antigen....

,
CEACAM18

CEACAM18

CEACAM18 is a gene which encodes carcinoembryonic antigen....

,
CEACAM19

CEACAM19

CEACAM19 is a gene which encodes carcinoembryonic antigen....

,
CEACAM20

CEACAM20

CEACAM20 is a gene which encodes carcinoembryonic antigen....

,
CEACAM21

CEACAM21

CEACAM21 is a gene which encodes carcinoembryonic antigen....