Carcinoembryonic Antigen (CEA) Test
Reviewed
Also called: CEA assay, CEA blood test, Carcinoembryonic antigen test
A CEA test measures how much of a specific protein called carcinoembryonic antigen (CEA) you have.
Specimen: Blood (most common); sometimes fluid from spine, chest, or abdomen
Why this test may be ordered
- To help understand the seriousness of a diagnosed cancer and guide treatment decisions
- To get a baseline CEA level before starting treatment
- To monitor whether cancer treatment is working
- To check if cancer has returned after treatment
Preparation and collection
If you smoke, you may need to stop for a while before your test. That's because smoking increases CEA levels. For a CEA blood test, you usually don't need to do anything to prepare.
CEA is usually measured with a blood sample. During a CEA blood test, a health care professional will take a blood sample from a vein in your arm, using a small needle. Sometimes, a health care professional will use other body fluids, such as cerebrospinal fluid (CSF) from your spine or peritoneal fluid (from your belly), to test your CEA levels.
A CEA blood test has very little risk. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. If you have a peritoneal fluid test, you may feel a little dizzy after the procedure. There is a small risk that the needle could damage your bowel or bladder, which may lead to bleeding or infection.
Understanding results
To understand your CEA test results, your provider will consider the results of other tests and exams. Ask your provider to explain what your test results mean for your health and treatment.
- Low CEA level before treatment: A low level of CEA may mean your tumor is small and the cancer has not spread to other parts of your body. Limitation: But because some cancers don't make much CEA, your provider may use other tests to learn more about how much cancer you have and if it's spread. Next step: Ask your provider to explain what your test results mean for your health and treatment.
- High CEA level before treatment: A high level of CEA may mean you have a larger tumor and/or your cancer has spread. Limitation: However, other noncancerous conditions may also cause high CEA levels. Next step: You'll need other tests to confirm how serious your cancer is.
- CEA decreasing during or after treatment: Decreases in CEA over time often mean that treatment is working. Limitation: Labs use different methods to measure CEA, which can affect your results. Next step: So, it's best to have your tests done the same way, and usually in the same lab.
- CEA increasing or staying high during or after treatment: Increases in CEA or high levels that stay high may mean that treatment isn't working. Limitation: CEA levels that remain high or increase after treatment don't always mean that treatment isn't working, or cancer is growing. Next step: So, if your CEA levels don't come down, your provider will likely order other tests to find out why.
- CEA decreased after treatment, then increased: Decreases in CEA after treatment followed by increases may mean cancer has come back. Limitation: CEA levels that remain high or increase after treatment don't always mean that treatment isn't working, or cancer is growing. Next step: If you have questions about your results, talk with your provider.
- CEA tests are not used to screen for or diagnose cancer because some cancers that cause high CEA do not always raise levels, and many non-cancer conditions can also increase CEA.
- Different labs may use different methods, which can affect results; it is best to have tests done the same way and usually in the same lab for comparison over time.
- Smoking can increase CEA levels and may affect test interpretation.
What to do next
If you have questions about your results, talk with your provider.
- What do my CEA test results mean for my specific cancer and treatment plan?
- How often should I have CEA testing to monitor my condition?
- Are there any other tests I need along with the CEA test?
- Could any non-cancer conditions or medications affect my CEA levels?
- Should I stop smoking before my next CEA test?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.
U.S. National Library of Medicine: Carcinoembryonic Antigen (CEA) Test