I. What Is Carcinoembryonic Antigen (CEA) Testing?

An estimated 40% of adults in the United States are diagnosed with cancer during their life. Carcinoembryonic antigens are proteins produced by cancer cells. Since CEA isn’t normally present in healthy adults, health care providers use CEA levels to assess the treatment of some cancers. It may be used with other tests, such as complete blood counts, to monitor your health during cancer therapy.

Why should you get tested

CEA testing tells your doctor how well your body is responding to treatment and if cancer is recurring. It’s also used to determine the stage of the cancer.

Who should get tested

This test is used if you’ve been diagnosed with cancer and are being treated or have completed treatment.

When to get tested

Your doctor may order CEA tests prior to starting therapy to get a baseline measurement. It’s also used during treatment to see how the cancer is responding to therapy and after treatment to see if the cancer returns.

II. How to Prepare for Carcinoembryonic Antigen Testing

CEA testing measures the levels of carcinoembryonic antigens in your body and is performed using a blood draw. You don’t need to prepare in advance for the test.

You should advise your doctor if you smoke, as smoking can affect the test results.

III. How a Carcinoembryonic Antigen Test Works

CEA testing is primarily used to monitor how cancer is responding to treatment after diagnosis. It’s important to note that it isn’t a diagnostic or screening tool for cancer. There are some cancers that don’t cause elevated CEA and some noncancerous conditions that do increase CEA levels. As well, the test doesn’t diagnose where in your body a tumor is located.

Healthy people have low levels of CEA. The levels of CEA are often elevated in cancers such as:

  • Colorectal
  • Breast
  • Pancreatic
  • Medullary thyroid
  • Stomach
  • Liver
  • Ovarian

CEA testing is performed using a blood sample that’s usually taken from your arm. You may feel a small pinch from the needle or soreness at the puncture site, but the procedure is relatively painless.

IV. Understanding Carcinoembryonic Antigen Testing Results

CEA test results are typically available to your doctor within a few days. The test can be used in several ways, according to MedlinePlus.

If you’ve been diagnosed with cancer, a CEA test prior to beginning treatment can help determine the stage of your cancer.

  • Low levels of CEA may mean the cancer tumor is small
  • Higher levels of CEA may mean the cancer tumor is large or has spread

CEA tests are usually performed during and after treatment and compared to a baseline to monitor progress. Because it’s a tumor marker, it’s most meaningful when used as a serial measurement rather than in isolation.

  • Continued high levels of CEA may mean the treatment isn’t working
  • Decreased levels of CEA may mean the cancer is responding to treatment
  • CEA levels that drop and then increase again may indicate that the cancer has come back

Your physician may order other tests in addition to CEA testing to get a better overview of your health. For example, chemotherapy can affect red blood cell and white blood cell counts. Based on your results, your doctor can recommend further tests or therapies.

V. Learn From Our Carcinoembryonic Antigen Testing Sources

Ready to learn more about CEA testing? Here are some of the sources used to create this guide.