Carcino Embryonic Antigen
What is CEA?
Carcinoembryonic antigen (CEA) is a tumor marker protein that is normally present at very low levels in the blood in adults. However, in certain cases like cancer, the levels may get elevated. This test measures the amount of CEA in the blood to help evaluate individuals diagnosed with cancer. Originally, it was thought that CEA was a specific marker for colon cancer, but further study has shown that an increase in CEA may be seen in a wide variety of other cancers and some non-cancer-related conditions, such as inflammation, cirrhosis, peptic ulcer, ulcerative colitis, rectal polyps, emphysema, and benign breast disease, and in smokers.
Why is CEA done?
The carcinoembryonic antigen test is done:
- To monitor cancer treatment (colon, pancreas, breast, lung, ovarian, medullary thyroid, or other cancer) including response to therapy and recurrence
- As an indicator of the amount of cancer or size of tumor present (tumor burden)
- To assist in cancer staging
- As follow-up to a positive screening test for cancer: to compare whether the level falls to normal (indicating that the cancer was all likely removed) after treatment for cancer
What does CEA Measure?
Carcinoembryonic antigen (CEA) is a protein that is present in certain tissues of a developing baby (fetus). By the time a baby is born, the levels of this protein drop very low, while in adults CEA is normally present at very low levels in the blood but may get elevated with certain types of cancer.
CEA is a tumor marker for colon cancer and a variety of other cancers like pancreas, breast, lung, ovarian, medullary thyroid, or other cancer. CEA can also be increased in some non-cancer-related conditions, such as inflammation, cirrhosis, peptic ulcer, ulcerative colitis, rectal polyps, emphysema, benign breast disease, and in smokers. Since it is non-specific and can increase in a variety of other conditions, it is not useful as a general cancer screening tool. However, it does help to evaluate and monitor response to cancer treatment. It also acts as an initial baseline test for CEA and then subsequent serial testing of CEA may be performed.
Interpreting CEA results
Following is the normal range:
Non-smoker adult: less than 2.5 ng/mL
Smoker adult: less than 5.0 ng/ml (in case of smokers, slightly higher levels of CEA can be considered as normal)
CEA levels can increase in both cancerous and non-cancerous conditions.
· The most frequent cancer which causes an increased CEA is cancer of the colon and rectum. Others include cancers of the pancreas, stomach, breast, lung, and medullary carcinoma of the thyroid, and ovarian cancer.
· Non-cancerous conditions that can show elevated CEA include smoking, infections, inflammatory bowel disease, pancreatitis, cirrhosis of the liver, and some benign tumors in the same organs in which an elevated CEA indicates cancer.
· Chemotherapy and radiation therapy can cause a temporary rise in CEA due to the death of tumor cells and the release of CEA into the bloodstream.