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# Carcinoembryonic antigen (CEA)

CEA is a fetal gut glycoprotein; it is used to follow colorectal cancer after treatment, not to screen for it.

Updated 2026-11-01

## Key facts

- A cell-adhesion glycoprotein of fetal gut epithelium; adults make only tiny amounts.
- Main use: a baseline value before colorectal cancer surgery and follow-up to detect relapse (especially liver metastases).
- It does not work for screening: it is normal in many early cancers and rises in benign conditions.
- It rises in smokers, ulcerative colitis, pancreatitis, cirrhosis, hypothyroidism and other cancers (pancreas, stomach, lung, breast, medullary thyroid).
- Its normal value depends on the laboratory and is somewhat higher in smokers.

## In detail

- What it measures: serum CEA concentration by immunoassay; it can also be measured in fluids (pleural, ascitic, pancreatic cysts).
- Where it comes from: fetal colonic epithelium expresses it; tumour cells make it again and release it into the blood.
- Why it rises: colorectal cancer (more in advanced stages), liver metastases, other adenocarcinomas; benign inflammatory causes and tobacco.
- Pitfalls: the liver clears it, so cholestasis or cirrhosis raises it; an isolated high value is repeated before a work-up.
- After resection of a colorectal cancer it should normalise within weeks; if it rises again steadily, relapse is sought with imaging.

**Also called**
CEA

## Clinical notes

- A high preoperative CEA is linked to a worse prognosis in colorectal cancer.
- In pancreatic cysts, a high CEA in the fluid points to a mucinous cyst.
- Colorectal cancer screening uses stool tests or colonoscopy, never CEA.

## Related conditions

- [Colorectal cancer](https://durgical.com/en/conditions/colorectal-cancer/)
- [Pancreatic cancer](https://durgical.com/en/conditions/pancreatic-cancer/)
- [Lung cancer](https://durgical.com/en/conditions/lung-cancer/)
- [Ulcerative colitis](https://durgical.com/en/conditions/ulcerative-colitis/)
- [Cirrhosis](https://durgical.com/en/conditions/cirrhosis/)

## Related

- [Tumour markers: principles of use](https://durgical.com/en/biochemistry/topics/tumour-markers-principles-of-use/)

## Test yourself

Think of the answer, then tap the question to see it.

## What is CEA used for in colorectal cancer?

As a preoperative baseline and for follow-up after treatment, looking for relapse.

## Why is CEA unsuitable for colorectal cancer screening?

It is normal in many early tumours and rises in benign conditions such as smoking, colitis or cirrhosis.

## Which habit raises baseline CEA?

Smoking.

## What does a CEA rising again after curative resection suggest?

Possible relapse (often in the liver), which is sought with imaging.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: [CEA Test: MedlinePlus Medical Test](https://medlineplus.gov/lab-tests/cea-test/) (MedlinePlus, US National Library of Medicine, 2026); [CEA blood test: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003574.htm) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/topics/carcinoembryonic-antigen/