Finding the right tests…
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Finding the right tests…
Hormonal
CEA is a protein your body makes in large amounts before birth, and healthy adults normally carry only a trace of it. Doctors don't use this test to look for a new cancer — it's ordered only after a cancer diagnosis already exists, most often colorectal cancer, to see how treatment is working or to catch a recurrence early. After colorectal cancer treatment, it's typically rechecked every few months for at least two years alongside imaging, since a rising CEA can appear before a recurrence is visible on a scan. Smoking on its own raises CEA independent of cancer, which is why smokers get a higher normal cutoff. Liver problems and some non-cancerous gut conditions can also push CEA up.
This test measures carcinoembryonic antigen in a blood sample, reported in nanograms per millilitre, from a standard venous draw that needs no fasting. Smoking raises baseline CEA independent of any cancer, which is why smokers and non-smokers are read against slightly different reference ranges. After a cancer diagnosis, this is usually repeated on a schedule — often every few months for the first couple of years — so your doctor can compare a trend over time rather than relying on any single result.
Carcinoembryonic antigen is a protein made in large amounts by a developing fetus, and in healthy adults, production drops to a trace amount that barely registers on this test. Certain cancers, most notably colorectal cancer, can switch that production back on, which is the basis for using CEA as a marker.
Because CEA isn't reliably elevated in every person with cancer, and because ordinary things like smoking, liver problems, and some non-cancerous gut conditions can raise it on their own, MedlinePlus is direct about this test not being used to look for a new, undiagnosed cancer. It's ordered only once a cancer diagnosis already exists.
Once colorectal cancer is diagnosed and treated, CEA is checked on a regular schedule, commonly every few months for at least a couple of years, alongside imaging. A level that falls after surgery and stays low is reassuring; one that starts climbing again can be an early clue to recurrence, sometimes before it's visible on a scan, which is what makes ongoing tracking genuinely useful.
- Not a screening test for undiagnosed cancer - Smoking raises baseline levels independent of cancer - Used mainly to track treatment response and recurrence
No. MedlinePlus is explicit that CEA isn't used as a screening test and shouldn't be done unless a cancer diagnosis has already been made, since people with cancer don't always have high CEA and plenty of non-cancer conditions can raise it.
Smoking raises baseline CEA independent of any cancer, so smokers are given a slightly higher upper limit for what counts as normal compared with non-smokers, according to NCBI-reviewed research.
MedlinePlus and NCBI-reviewed sources place normal generally under about 2.5 to 3 ng/mL in non-smokers and up to about 5 ng/mL in smokers, though this varies by lab. Ranges vary by lab, so always check your own report's reference range.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
NCBI-reviewed guidance describes checking it roughly every three months for at least the first two years after surgery or treatment, usually alongside periodic imaging, though your doctor will confirm the schedule that applies to you.
Liver or bile duct problems, some benign gut conditions, recent chemotherapy, and heavy smoking can all raise CEA without a cancer recurrence being present, according to MedlinePlus and NCBI-reviewed sources.
A rising trend is concerning and typically triggers further testing, but it isn't a diagnosis by itself — your doctor will usually confirm with imaging before concluding the cancer has returned.
No fasting is required for a CEA blood test, according to MedlinePlus.