Carcinoembryonic Antigen (CEA) – Serum

What Is Carcinoembryonic Antigen (CEA)?

Carcinoembryonic antigen (CEA) is a protein found in small amounts in healthy people but can rise in certain cancers, such as colorectal, pancreatic, or breast cancer. It was originally identified in fetal tissue, hence the name. In adults, elevated CEA levels often signal cancer, though they can also be influenced by smoking, chronic inflammation, or other conditions.

Why Might You Need This Test?

Doctors order CEA tests to monitor cancer progression, check treatment response, or screen for recurrence after treatment. It’s sometimes used alongside other tests, like colonoscopy or imaging, to assess risk. However, CEA alone isn’t enough to diagnose cancer—it’s part of a broader evaluation.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed for CEA levels using an immunoassay method. Results are compared to reference ranges, though individual results may vary based on health status and other factors.

What Do the Results Mean?

Results are reported in nanograms per milliliter (ng/mL). A normal range isn’t absolute—it depends on your health, age, and medical history. Elevated levels may indicate cancer, but they can also be caused by other conditions. Follow-up testing or additional evaluations are often needed for diagnosis.