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Carcinoembryonic antigen (CEA)

Carcinoembryonic antigen (CEA) is a protein normally found in the tissue of a developing fetus. Levels of CEA in the blood decrease after birth. CEA is normally found in small amounts in the blood of most healthy people.

Why a CEA test is done

A CEA test may be done to:

  • help diagnose and monitor a person’s response to treatment for certain cancers
    • It is most commonly used for colorectal cancer.
    • CEA may also be used for the following cancers:
      • breast
      • lung
      • pancreas
      • stomach
      • ovary
  • check if a cancer has come back (recurred)

How a CEA test is done

A CEA test is usually done in a private laboratory or hospital laboratory. No special preparation is usually needed.

  • CEA is usually measured by a blood test.
  • The sample is sent to a laboratory to be analyzed by special machines.

What the results mean

An increased CEA value may be due to:

  • smoking
    • Smokers who do not have cancer can have an increased CEA value.
  • non-cancerous conditions
    • inflammatory bowel disease (such as colitis)
    • benign breast disease
    • benign ovarian disease
    • inflammation of the pancreas (pancreatitis)
    • liver disease (such as cirrhosis or hepatitis)
    • chronic lung disease
  • cancerous conditions
    • colorectal cancer
    • breast cancer
    • lung cancer
    • pancreatic cancer
    • stomach cancer
    • ovarian cancer
    • bladder cancer
    • thyroid cancer
    • liver cancer

In cancerous conditions:

  • A decrease in, or return to normal values of, CEA may mean that the cancer has responded well to treatment.
  • An increase may mean that the cancer is not responding well to treatment, is still growing or is coming back (recurring).
    • A slight increase may not be significant. Usually the doctor looks at trends in the increase over time.

What happens if a change or abnormality is found

The doctor will decide if more tests, procedures, follow-up care or additional treatment is needed.

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