This test measures a protein called carcinoembryonic antigen (CEA) in your blood. This protein is present on some types of cancer cells.
CEA is called a tumor marker because it gives information about cancer in your body. This test may help your doctor find out if your cancer treatment is working or if the cancer is returning after treatment. The test can be used with cancers of the colon and rectum, lung, breast, pancreas, ovary, prostate, liver, and thyroid.
CEA can't tell your doctor what type of cancer you have. Because CEA can be present in conditions that aren't cancer and may not be present for all cancers, this test isn't usually used for cancer screening.
You may need this test if you have already been diagnosed with cancer and your doctor is planning treatment. CEA can help your doctor know more about the extent of your cancer before treatment begins.
You may have this test during cancer treatment to help your doctor know how well the treatment is working.
If you have already been treated for cancer, you may need this test to help find out whether your cancer has come back.
Your doctor may order other tests to find out more about your cancer. These may include X-rays, CT scans, and biopsies.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
CEA is measured in nanograms per milliliter (ng/mL). Normal results are 3.0 ng/mL or lower.
Having a normal CEA level doesn't rule out cancer, however. Some people with cancer have a normal CEA.
And higher levels of CEA don't mean you have cancer. Many conditions other than cancer can cause CEA to go up. These include:
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
Being pregnant or being a smoker can raise your CEA levels. A CEA of up to 5.0 ng/mL can be considered normal in smokers.
You don't need to prepare for this test. But be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.