Primarily to monitor cancer treatment, including response to therapy and recurrence; as an indicator of the amount of cancer or size of tumor present (tumor burden) and to assist in cancer staging; occasionally 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 the cancer
Carcinoembryonic Antigen (CEA)
Carcinoembryonic antigen (CEA) is a protein that is present in certain tissues of a developing baby (fetus). By the time a baby is born, it drops to a very low level. In adults, CEA is normally present at very low levels in the blood but may be elevated with certain types of cancer. This test measures the amount of CEA in the blood to help evaluate individuals diagnosed with cancer.
CEA is a tumor marker. 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. CEA can also be increased in some non-cancer-related conditions, such as inflammation, cirrhosis, peptic ulcer, ulcerative colitis, rectal polyps, emphysema, and benign breast disease, and in smokers. For this reason, it is not useful as a general cancer screening tool, but it does have a role in evaluating response to cancer treatment. When an individual has been diagnosed with cancer, an initial baseline test for CEA may be performed. If this level is elevated, then subsequent serial testing of CEA may be performed to monitor the cancer as the individual undergoes treatment.
How is it used?
The carcinoembryonic antigen (CEA) test may be used:
- To monitor the treatment of people diagnosed with colon cancer. It may also be used as a marker for medullary thyroid cancer and cancers of the rectum, lung, breast, liver, pancreas, stomach, and ovaries. An initial CEA test is typically ordered prior to treatment as a "baseline" value. If the level is elevated, then the test can be used to monitor a person's response to therapy and to determine whether the cancer has progressed or recurred.
- To stage cancer—cancer staging involves evaluating the size of the tumor as well as how far it has spread.
- Testing CEA in a body fluid sample may help to determine if cancer has spread to a body cavity such as the chest or abdomen (pleural or peritoneal cavity).
A CEA test may be used in combination with other tumor markers in the evaluation of cancer.
Not all cancers produce CEA, and a positive CEA test is not always due to cancer. Therefore, CEA is not recommended for screening the general population.
When is it ordered?
A CEA test may be ordered when a person has been diagnosed with colon cancer or other specific types of cancer. It will be measured before therapy is initiated and then on a regular basis to evaluate the success of treatment and to detect recurrence.
Sometimes a CEA test may be performed when cancer is suspected but not yet diagnosed. This is not a common use for the test because CEA can be elevated with many conditions, but it may provide a healthcare practitioner with additional information.
What does the test result mean?
For treatment, recurrence monitoring:
When CEA levels are initially elevated and then decrease to normal after therapy, it means the cancer has been successfully treated. A steadily rising CEA level is often the first sign of tumor recurrence.
On initial testing, people with smaller and early-stage tumors are likely to have a normal or only slightly elevated CEA value. People with larger tumors, later-stage cancer, or tumors that have spread throughout the body are more likely to have a high CEA value.
Testing for metastasis:
If CEA is present in a body fluid other than blood, then the person's cancer is likely to have spread into that area of the body. For example, if CEA is detected in cerebrospinal fluid, this may indicate that cancer has spread to the central nervous system.
Since not all cancers produce CEA, it is possible to have cancer but also have a normal CEA. If a cancer does not produce CEA, then the test will not be useful as a monitoring tool.
Is there anything else I should know?
Laboratories may use different methods to test for CEA, so results can vary from lab to lab. If you are having a series of CEA tests done, it is advised that you have the tests done by the same method, typically by the same laboratory, so that the results can be compared and interpreted correctly. You may wish to discuss this issue with your healthcare provider.
Individuals who smoke cigarettes tend to have higher CEA levels than non-smokers.
If I am a smoker, does an elevated CEA level mean I have cancer?
Will every person with cancer have a CEA test performed?
No. CEA has a role to play in certain tumors, particularly colon cancer. However, a number of other tumor markers have been developed to monitor cancers from different areas of the body. As an example, breast cancer is usually monitored with a CA 15-3 test or a CA 27.29 test. For some cancers, testing for tumor markers is not done at all.