Learn About the CEA Blood Test and How Doctors Use it to Determine the Spread of Cancer

Doctors use a wide range of laboratory and diagnostic tests to monitor cancer patients. Diagnostic tests such as CT scans, MRI scans, and ultrasounds can be used to assess organ function and blood flow and identify any suspicious masses or tissue patterns. Blood tests can be used to test levels of protein or cancer antigens in the blood. One of the specific blood tests used for this purpose is the CEA blood test.

What the Test Measures

This test measures the level of carcinoembryonic antigen that is in the blood. This substance is a protein that may appear in the blood of those who have had certain types of cancer. It most commonly appears in those who have had cancer of the colon, large intestine, and rectum, but can also appear in the blood of people who have had breast, ovarian, pancreatic, or lung cancer. This protein is normally only produced while a fetus is developing and production stops before the child is born. If CEA is present in the blood of an adult, it can indicate a problem.

How the Test is Used

The carcinoembryonic antigen blood test is used for several reasons. In someone who was recently diagnosed with cancer, it can be used to see how extensively a cancer has spread. It is particularly useful for assessing the spread of colon cancer. During treatment, the test may be used to determine how well drug therapy is working to rid the body of cancer. CEA levels are obtained before treatment begins and new levels are tested during the course of therapy. These levels are compared to see if the therapy is having a positive effect. This test can also be used to determine if cancer has returned after someone has already completed cancer treatment.

Performing the Test

The CEA blood test is performed by having a blood sample drawn from a vein in your arm and then having it analyzed to determine if CEA is present. To obtain this sample, a phlebotomist or other medical professional who is trained in drawing blood will first wrap a tourniquet around your upper arm. You may notice the phlebotomist rubbing or tapping your skin. This is done to help make it easier to identify veins and take a blood sample. The area being used for the blood drawer will be cleaned with an alcohol pad and a needle will be inserted so that a blood sample can be drawn. There is no special preparation needed for the test and the blood draw is relatively painless. You may feel a quick pinch, but there should be no lasting pain once the sample has been drawn.

High CEA and Noncancerous Conditions

While high CEA levels can indicate that cancer is present, they can also point to other medical conditions. Kidney failure, inflammatory bowel disease, cirrhosis of the liver, pancreatitis, and peptic ulcer disease are all known to cause elevated CEA levels.


WebMD Cancer Health Center. “Carcinoembryonic Antigen (CEA).” Retrieved April 29, 2009.