Ajax Harwood Clinic
CEA (Carcinoembryonic Antigen)
This test is useful only in specific situations — it's not right for everyone who asks about it.
What this test is
CEA is a blood test. It follows certain cancers, most often colon or rectal cancer. This is only after the cancer is found and treated. Doctors check it on a set plan, usually every 3 to 6 months for 5 years. It is checked along with checkups, scans, and colonoscopies. This helps watch for the cancer coming back. CEA is not a screening test. It can go up from other cancers too, and from things that are not cancer at all. So a high result alone does not point to colon cancer. If you worry about colorectal cancer and have not been diagnosed, look at your symptoms first. Colonoscopy or stool testing may be the better next step.
Want to see the full clinical reasoning? The reference we use for this test is open to anyone — it is detailed and written for clinicians, and you are welcome to read it.
Open the clinician reference →Looking for other tests, or more on a condition an ND raised? Explore ask.ajaxharwoodclinic.com →
General health information for Ajax Harwood Clinic patients and the public — not medical advice, and not a substitute for seeing your own doctor. Last reviewed 2026-09-23.