Carcinoembryonic Antigen (CEA) Test
Reviewed
Also called: CEA assay, CEA blood test, Carcinoembryonic antigen test
CEA (carcinoembryonic antigen) is a protein tumor marker. Healthy adults normally have little or no CEA. High levels can occur in certain cancers (e.g., colorectal, prostate, ovarian, lung, thyroid, liver, pancreatic, breast) and in some non-cancer conditions. This test is used to help assess cancer prognosis, monitor treatment, and check for recurrence, but it is not used for screening or diagnosis.
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
Usually no preparation is needed. If you smoke, you may need to stop for a while before the test because smoking increases CEA levels.
A blood sample is taken from a vein in your arm using a small needle. The procedure usually takes less than five minutes.
A CEA blood test has very little risk. You may have slight pain or bruising at the needle site, but most symptoms go away quickly.
Understanding results
Your CEA test results must be interpreted by your healthcare provider along with other tests and exams. The following patterns describe general trends; your provider will explain what your specific results mean for your health and treatment.
- Low CEA level before treatment: May indicate a small tumor that has not spread to other parts of the body. However, some cancers do not produce much CEA, so other tests are needed. Limitation: A low level does not rule out cancer spread; some cancers produce little CEA. Next step: Your provider will use other tests to learn more about the cancer and whether it has spread.
- High CEA level before treatment: May indicate a larger tumor and/or that the cancer has spread. Limitation: High CEA can also be caused by non-cancer conditions (e.g., liver, digestive, or breathing problems) and smoking. Next step: Additional tests are needed to confirm the extent of the cancer.
- Decrease in CEA over time during or after treatment: Often means that treatment is working. Limitation: CEA levels can fluctuate; a decrease does not guarantee complete response. Next step: Your provider will continue to monitor CEA and other tests to assess treatment effectiveness.
- Increase in CEA or persistently high levels during or after treatment: May mean that treatment is not working, or that cancer has returned (e.g., after surgery for colorectal cancer, it may indicate incomplete removal or regrowth). Limitation: High or rising CEA does not always mean treatment failure or cancer growth; other conditions can cause elevations. Next step: Your provider will likely order other tests to determine the cause.
- 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
Discuss your CEA results with your healthcare provider, who will consider them along with other tests and exams to guide your care. If you have questions about how your tests are done, ask 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
U.S. National Library of Medicine: Carcinoembryonic Antigen (CEA) Test