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 you have 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 during treatment.
How is the test used?
The carcinoembryonic antigen (CEA) test may be used:
- To monitor the treatment of 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, such as chemotherapy or radiation therapy, 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 returned after treatment.
- To stage cancer—cancer staging involves evaluating the size of the tumor as well as how far it has spread.
- To help determine if cancer has spread to a body cavity such as the chest or abdomen by measuring the CEA level in a body fluid (e.g., pleural or peritoneal fluid).
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 you have been diagnosed with colon cancer or other specific type of cancer. It will be measured before therapy is initiated and then on a regular basis to evaluate the success of treatment and to determine whether the cancer has come back after treatment (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 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.
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.
Are there any side effects of performing a CEA test?
A CEA blood test typically has no associated risk. Very mild pain and bruising may occur at the site where blood was collected using a needle. To assess metastasis, fluid can be collected from other sites. For example, pleural fluid may be collected from the area surrounding the lungs. This procedure has a small risk of lung injury, bleeding, or infection. When peritoneal fluid (the liquid in the abdomen filling the sacs surrounding the intestine) is collected to assess abdominal metastasis, there may be a small risk of damage to the intestine or other organs. You may also feel pain and dizziness after the procedure. To assess brain metastasis, CSF will be collected by a spinal tap (lumbar puncture) to measure the CEA. With this procedure, back pain or tenderness at the needle insertion might happen, and a post lumbar headache or dizziness might occur.
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.