Patient Test Information

Carcinoembryonic Antigen (CEA)

  • Why Get Tested?

    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

    When To Get Tested?

    When you have been diagnosed with colon, pancreas, breast, lung, ovarian, medullary thyroid or other cancer prior to starting cancer treatment and then, if elevated, at intervals during and after therapy; occasionally when cancer is suspected but not confirmed – to aid in its detection

    Sample Required?

    A blood sample is taken by needle from a vein in the arm. Occasionally, another body fluid such as peritoneal fluid, pleural fluid, or cerebrospinal (CSF) is collected by a healthcare practitioner for testing.

    Test Preparation Needed?


  • What is being tested?

    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.

    A CEA test may sometimes be performed on a fluid other than blood when a healthcare practitioner suspects that a cancer has metastasized (e.g., spread to the pleural or peritoneal cavity).

    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.

    For staging:
    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?

    Not necessarily. Smokers can have CEA values up to twice the normal range for non-smokers and not 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.

    Increased CEA levels can indicate some non-cancer-related conditions, such as inflammation, cirrhosis, peptic ulcer, ulcerative colitis, rectal polyps, emphysema, and benign breast disease.

  • View Sources

    Sources Used in Current Review

    2020 review performed by Imad Tarhoni, MD, PhD.

    Su BB, Shi H, Wan J: Role of serum carcinoembryonic antigen in the detection of colorectal cancer before and after surgical resection. World J Gastroenterol 2012, 18:2121-6.

    Hall C, Clarke L, Pal A, Buchwald P, Eglinton T, Wakeman C, Frizelle F: A Review of the Role of Carcinoembryonic Antigen in Clinical Practice. Ann Coloproctol 2019, 35:294-305.

    © 1995–2020. Mayo Foundation for Medical Education and Research. Carcinoembryonic Antigen (CEA), Serum. Available online at Accessed May 2020.

    Sources Used in Previous Reviews

    Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry, AACC Press, Washington, DC. Pp 244-245.

    Pagana K, Pagana T. Mosby's Manual of Diagnostic and Laboratory Tests. 3rd Edition, St. Louis: Mosby Elsevier; 2006 pp 161-162.

    MedlinePlus Medical Encyclopedia: CEA. Available online at Accessed February 2009.

    (Revised 2012 January 20). How is Thyroid Cancer Diagnosed? American Cancer Society [On-line information]. Available online at Accessed October 2012.

    Dugdale, D. (Updated 2011 August 5). CEA blood test. MedlinePlus Medical Encyclopedia. [On-line information]. Available online at Accessed October 2012.

    (Revised 2012 October 1). How is colorectal cancer diagnosed? American Cancer Society. [On-line information]. Available online at Accessed October 2012.

    (© 1995-2012). Carcinoembryonic Antigen (CEA), Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at Accessed October 2012.

    (Revised 2011 March 24). Common cancers and the tumor markers linked to them. American Cancer Society [On-line information]. Available online through Accessed October 2012.

    (Reviewed 2011 December 30). Tests to Detect Colorectal Cancer and Polyps. National Cancer Institute. [On-line information]. Available online at Accessed October 2012.

    Pagana, K. D. & Pagana, T. J. (© 2011). Mosby's Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 223-224.

    Clarke, W., Editor (© 2011). Contemporary Practice in Clinical Chemistry 2nd Edition: AACC Press, Washington, DC. Pp 244-245.

    Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. 4th edition, St. Louis: Elsevier Saunders; 2006, Pg 768.

    U.S. National Library of Medicine (1 August 2015 updated). CEA Blood Test. Available online at Accessed June 28, 2016.

    Penn Medicine Oncolink® (28 April 2016 updated). Patient Guide to Tumor Markers. Available online at Accessed June 28, 2016.

    National Cancer Institute (4 November 2015 reviewed). Tumor Markers. Available online at Accessed June 28, 2016.

    American Cancer Society (6 March 2014 updated). How Is Advanced Cancer Found? Available online at Accessed June 28, 2016.