Carcinoembryonic antigen (CEA) is a protein normally found in the tissue of a developing baby in the womb. Blood levels of this protein disappear or become very low after birth. In adults, an abnormal amount of CEA may be a sign of cancer.
A blood test can be done to measure the amount of CEA in your blood.
Carcinoembryonic antigen blood test
A blood sample is needed. For information on how this is done, see: Venipuncture
Smoking may increase CEA levels. If you smoke, your doctor may tell you to avoid doing so for a short time before the test.
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample may be more difficult from some people than from others.
This test is done to check for the return of colon and other cancers in people already diagnosed with cancer. It is not used as a screening test for cancer.
The normal range is 0 to 2.5 micrograms per liter (mcg/L). In smokers, the normal range is 0 to 5 mcg/L.
Normal value ranges may vary from lab to lab. In smokers, slightly higher values may be considered normal.
High CEA levels in a person recently treated for certain cancers may mean the cancer has returned. Higher than normal levels may be due to the following cancers:
Higher than normal CEA levels alone cannot diagnose a new cancer. Further testing is needed.
Increased CEA levels may also be due to:
Abnormal CEA levels can be found in people who do not have cancer.
Blanke CD, Faigel DO. Neoplasms of the small and large intestine. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 199.