CEA Test

What is a CEA test?

A CEA test measures how much of a specific protein called carcinoembryonic antigen (CEA) you have. Healthy fetuses have high levels of this protein because CEA helps cells divide quickly, leading to more rapid growth. After birth, however, levels decrease quickly. Adults have very little if any CEA in their body.

If CEA is present, however, it may be a tumor marker. Tumor markers are substances that are often made by cancer cells or by normal cells in response to certain types of cancer. The types of cancer that may cause high levels of CEA include those of the:

• Colon and rectum (colorectal or bowel cancer)
• Prostate
• Ovary
• Lung
• Thyroid
• Liver
• Pancreas
• Breast

However, other noncancerous conditions may also cause high CEA levels. These include:

• Gastritis and stomach ulcers
• Chronic obstructive pulmonary disease (COPD)
• Liver diseases like cirrhosis, gallstones, or steatotic liver disease
• Diverticulitis
• Diabetes
• Autoimmune or inflammation diseases such as Crohn's disease

Most CEA tests use a sample of your blood to measure your CEA level. Sometimes the test uses a sample of fluid from your spine, chest, or abdomen (belly), but this is less common.

Other names: CEA assay, CEA blood test, carcinoembryonic antigen test

What is it used for?

A health care provider may order a CEA test along with other tests to:

• Learn more about a cancer that causes high CEA levels. Soon after your cancer has been diagnosed, your provider may use your CEA levels, along with other factors such as your cancer's stage (how advanced it is), to make a prognosis. A prognosis is a health care professional's prediction for how an illness will behave over time.
• Check if your CEA levels are going down during treatment. If they are, it may mean that your cancer treatment is working.
• See if cancer has returned after treatment. If your CEA levels start to rise again after treatment, it could mean the cancer has returned.

CEA tests are not used to screen for or diagnose cancer. That's because:

• You can have normal CEA test results even though you have a type of cancer that can cause high CEA levels
• Many other health problems that aren't cancer can make CEA levels rise

Why do I need a CEA test?

A CEA test is mostly used in people who have been diagnosed with cancers that often increase CEA levels. The most common of these is colorectal cancer.

If you've been diagnosed with a cancer that may increase your CEA level, you may need CEA testing:

• Before treatment to help you and your provider understand how serious your cancer is and what treatment would be helpful. Your provider may also want to get a measurement of your CEA level before treatment so that they can compare it to your CEA level after treatment.
• During cancer treatment to see if the treatment is working.
• After treatment to check whether cancer has come back. You may need to have tests on a regular schedule. Depending on your cancer's type and stage (how advanced it is), you may need to have follow-up tests every 3-6 months during the first 5 years after treatment.

What happens during a CEA test?

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. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

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. For these tests, your provider will remove a small sample of fluid using a thin needle. They may also give you a numbing medicine (anesthesia) so that you won't feel any pain.

Will I need to do anything to prepare for the test?

If you smoke, you may need to stop for a while before your test. That's because smoking increases CEA levels. Depending on what type of test you're getting, your provider will let you know if there are any special instructions to follow.

For a CEA blood test, you usually don't need to do anything to prepare.

If your provider wants to collect peritoneal fluid (from your belly) or cerebrospinal fluid from your spine, they may ask you to empty your bladder (pee) and bowels (poop) before the test.

Are there any risks to the test?

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 your provider collected cerebrospinal fluid, there is very little risk. You may feel a little pinch or pressure when the needle is inserted. After the test, you may feel some pain or tenderness in your back, or have some bleeding where the needle was inserted. You may also get a headache. The headache may last for several hours or up to a week or more. Your provider may suggest treatment to relieve the pain.

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.

What do the results mean?

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.

If you had a test before starting cancer treatment, in general:

• A low level of CEA may mean your tumor is small and the cancer has not spread to other parts of your body. 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.
• A high level of CEA may mean you have a larger tumor and/or your cancer has spread. You'll need other tests to confirm how serious your cancer is.

If you had a test to monitor your cancer during or after treatment, your provider will compare your current CEA test results with your past test results. In general:

• Decreases in CEA over time often mean that treatment is working.
• Increases in CEA or high levels that stay high may mean that treatment isn't working. For example, if you had surgery for colorectal cancer, high levels may mean that the entire tumor wasn't removed or the cancer is growing back.
• Decreases in CEA after treatment followed by increases may mean cancer has come back.

CEA levels that remain high or increase after treatment don't always mean that treatment isn't working, or cancer is growing. So, if your CEA levels don't come down, your provider will likely order other tests to find out why.

Labs use different methods to measure CEA, which can affect your results. So, it's best to have your tests done the same way, and usually in the same lab. This allows your provider to compare your results over time.

If you have questions about your results, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results.