CEA Protein

CEA was first identified in 1965 by Phil Gold and Samuel O. Freedman in human colon cancer tissue extracts . This discovery marked a significant milestone in cancer research, as it provided a potential marker for certain types of cancer.

CEA glycoproteins are characterized as members of the CD66 cluster of differentiation, which includes proteins such as CD66a, CD66b, CD66c, CD66d, CD66e, and CD66f . These proteins are glycosyl phosphatidyl inositol (GPI) cell-surface-anchored glycoproteins. Their specialized sialo fucosylated glycoforms serve as functional colon carcinoma L-selectin and E-selectin ligands, which may be critical to the metastatic dissemination of colon carcinoma cells .

CEA levels are used as a tumor marker in clinical tests. Elevated serum levels of CEA can indicate the presence of certain types of cancer, such as colorectal carcinoma, gastric carcinoma, pancreatic carcinoma, lung carcinoma, breast carcinoma, and medullary thyroid carcinoma . However, it is important to note that CEA levels can also be raised in non-cancerous conditions, such as liver disease, inflammatory bowel disease, pancreatitis, cirrhosis, chronic obstructive pulmonary disease (COPD), Crohn’s disease, and hypothyroidism . Additionally, heavy smokers may also exhibit elevated CEA levels .

The CEA blood test is primarily used to monitor colorectal carcinoma treatment, identify recurrences after surgical resection, and stage or localize cancer spread through the measurement of biological fluids . Elevated CEA levels should return to normal after successful surgical removal of the tumor, making it a useful marker for follow-up, especially in colorectal cancers .

It is important to understand that 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 result in a high CEA level . Therefore, while CEA can be a valuable tool in monitoring certain cancers, it should not be solely relied upon for diagnosis.