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Carcinoembryonic Antigen (CEA)

Published: July 27, 2026Updated: August 25, 2026

CEA is a protein that is often elevated in the blood of people with certain types of cancer, particularly colorectal cancer. It is primarily used for monitoring treatment response and detecting recurrence.

Quick summary

CEA is a tumor marker used for monitoring cancer treatment and recurrence.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
ng/mL
Clinical utility
monitoring
Result kind
quantitative
FDA-cleared
Roche CEA, Abbott CEA, Siemens CEA, Beckman CEA
interpretation: {"text":"0–3 ng/mL: CEA levels within this range are generally considered normal for non-smokers. Smokers may have slightly higher levels.","label":"Normal"}; {"text":">3 ng/mL: Levels above 3 ng/mL may indicate the presence of cancer or other conditions. Further diagnostic tests are needed for confirmation.","label":"Elevated"}

Carcinoembryonic Antigen (CEA) is a glycoprotein involved in cell adhesion, which is typically found in very low levels in the blood of healthy adults. Elevated levels can indicate the presence of various cancers, including colorectal, pancreatic, lung, breast, and medullary thyroid carcinomas.

In oncology, CEA is primarily used as a tumor marker to monitor the effectiveness of cancer treatments, such as surgery, chemotherapy, and radiation therapy. Post-treatment surveillance with CEA tests can help detect cancer recurrence early.

While CEA is a valuable tool for monitoring, it is not specific enough to be used for cancer diagnosis alone. Elevated CEA levels can also be caused by non-cancerous conditions such as inflammatory bowel disease, liver disease, and smoking.

Frequently asked questions

Can CEA levels be used to diagnose cancer?
No, CEA levels alone cannot diagnose cancer. They are used in conjunction with other clinical findings and diagnostic tests.
What factors can affect CEA levels?
Smoking, inflammatory conditions, and certain non-cancerous diseases can cause elevated CEA levels.
  1. 1
    American Cancer Society: Carcinoembryonic Antigen (CEA) TestSource
  2. 2
    National Cancer Institute: Tumor MarkersSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy