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Biochemistry · Topic

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.

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 (MedlinePlus, US National Library of Medicine, 2026); CEA blood test: MedlinePlus Medical Encyclopedia (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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