CEA Test (Carcinoembryonic Antigen)
A carcinoembryonic antigen (CEA) test measures CEA, a specific blood protein. Usually, people are born with high CEA levels that decrease as they get older. But some types of cancer can increase this protein. Your healthcare provider may use a CEA test to guide cancer treatment or to see if treatment is working.
What is a CEA test?
A carcinoembryonic antigen (CEA) test measures a specific blood protein called CEA. Everyone is born with high levels of this protein. CEA decreases as you get older. But some conditions, including certain types of cancer, can increase your blood CEA levels.
Healthcare providers use a CEA test to:
- Evaluate how well cancer treatments like chemotherapy, immunotherapy or radiation therapy are working
- Detect if cancer comes back (cancer recurrence) after you’re in remission
- See if cancer is growing/spreading (metastatic cancer)
CEA doesn’t tell you whether you have cancer, and providers don’t use it to screen for cancer. Your healthcare provider will order a CEA test regularly, depending on your diagnosis and treatment plan.
How does a CEA test work?
A CEA test is usually a blood test. During a blood test, your healthcare provider takes a small blood sample from one of your veins. Specialists in a laboratory analyze the blood to check for CEA.
Less commonly, your provider may test fluid from your:
- Abdominal wall
- Chest
- Spinal cord
In these cases, your provider takes a small fluid sample using a needle or syringe. They insert the needle or syringe into your chest or lower back.
Your healthcare provider will recommend CEA tests regularly so they can compare results over time. For example, you may need a CEA test every month during cancer treatment. But once you’re in remission, your provider may order a test every three to six months.
How do I prepare?
Your healthcare provider will tell you how to prepare. You may temporarily stop certain medicines or supplements that increase bleeding, like aspirin.
What can I expect during a CEA test?
During a CEA blood test, your healthcare provider:
- Inserts a small needle into one of your veins, usually in your arm
- Attaches a vial or test tube to the needle
- Collects a small blood sample
If your healthcare provider needs to take samples of your body fluid, they:
- Inject your lower back or chest with numbing medicine (local anesthesia)
- Insert a needle or syringe into the area
- Use an X-ray image to guide the needle to the correct position
- Collect a sample of fluid from your chest, abdomen or spine
A CEA blood test usually takes less than five minutes. CEA tests of other body fluids usually take 30 minutes or less. You can return home the same day.
What are the risks of a CEA test?
CEA tests are generally safe. Chest fluid tests have a small risk of:
- Blood loss
- Infection
- Lung damage
Possible side effects may include:
- Dizziness
- Headaches
- Lightheadedness
If you have a blood test, you may have mild pain or bruising where your provider inserted the needle.
Most people don’t experience complications. Your healthcare provider will help you understand the risks of the test beforehand.
What do levels on a CEA test mean?
Your healthcare provider uses CEA test results to see if cancer treatment is working, if cancer is spreading or if it’s come back. They compare results over time to see patterns and changes.
If your CEA levels decrease throughout treatment, it usually means your treatment is working. If levels rise, it could mean cancer is progressing or not responding to treatment.
CEA is typically measured in nanograms per milliliter (ng/mL):
- Normal CEA levels: Generally, healthcare providers consider typical CEA levels to be between 0 and 3 ng/mL. If you smoke cigarettes, a normal CEA level may be up to 5 ng/mL.
- Slightly elevated CEA levels: CEA levels greater than 3 ng/mL but less than 10 ng/mL typically suggest a small (localized) tumor and a low likelihood of cancer recurrence. Slightly elevated CEA levels could also be due to health conditions that aren’t cancer.
- High CEA levels: CEA levels greater than 10 ng/mL but less than 20 ng/mL could be a sign of early-stage cancer. CEA levels that are higher than 20 ng/mL are usually a sign that cancer is spreading.
Different labs may give different results, so it’s always a good idea to talk to your provider about your unique results.
What other conditions can cause high CEA levels?
Noncancerous conditions that can increase CEA levels include:
- Gastritis and stomach ulcers
- Chronic obstructive pulmonary disease (COPD)
- Liver diseases like cirrhosis, fatty liver or gallstones
- Diverticulitis
- Diabetes
- Any autoimmune or inflammatory disease
- Inflammatory bowel diseases (Crohn’s disease and ulcerative colitis)
- Hemorrhoids
- Pneumonias
- Smoking cigarettes
References
- Canadian Cancer Society. Carcinoembryonic antigen (CEA) (https://cancer.ca/en/treatments/tests-and-procedures/carcinoembryonic-antigen-cea). Accessed 6/4/2025.
- Kankanala VL, Zubair M, Mukkamalla SKR. Carcinoembryonic Antigen (https://www.ncbi.nlm.nih.gov/books/NBK578172/). 2024 Dec 11. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan. Accessed 6/4/2025.
- Lee TH, Kim JS, Baek SJ, Kwak JM, Kim J. Diagnostic Accuracy of Carcinoembryonic Antigen (CEA) in Detecting Colorectal Cancer Recurrence Depending on Its Preoperative Level (https://pubmed.ncbi.nlm.nih.gov/37407895/). J Gastrointest Surg. 2023 Aug;27(8):1694-1701. Accessed 6/4/2025.
- Shinkins B, Nicholson BD, Primrose J, Perera R, James T, et al. The diagnostic accuracy of a single CEA blood test in detecting colorectal cancer recurrence: Results from the FACS trial (https://pubmed.ncbi.nlm.nih.gov/28282381/). PLoS One. 2017 Mar 10;12(3):e0171810. Accessed 6/4/2025.
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