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[Biochemistry](https://durgical.com/en/biochemistry/) · Topic

# Tumour markers: principles of use

Tumour markers help follow a cancer already diagnosed; almost none can diagnose or screen for it on its own.

Updated 2026-11-01

## Key facts

- Their main use is follow-up: response to treatment and detection of relapse, compared with the patient's own value.
- Almost none is sensitive and specific enough to screen the general population (PSA is used with shared decision-making).
- Classic pairs: AFP–hepatocellular carcinoma and yolk sac tumour; CEA–colorectal; PSA–prostate; CA-125–epithelial ovarian; CA 19-9–pancreas and bile ducts; β-hCG–choriocarcinoma and germ cell tumours.
- All also rise in benign conditions: inflammation, liver disease, smoking, pregnancy.
- Ranges depend on the method: follow-up should use the same laboratory and technique.

## In detail

- A tumour marker is a substance (protein, glycoprotein, oncofetal antigen, hormone) that a tumour makes in excess or that the body makes in response to it.
- Accepted uses: supporting diagnosis together with imaging and biopsy, estimating prognosis (germ cell tumour staging with AFP, β-hCG and LDH), monitoring response and detecting recurrence.
- Each marker's half-life shows whether it falls as expected after surgery; if it does not fall, residual disease is suspected.
- False positives: inflammation (CA-125 in endometriosis, CEA in colitis), liver disease (AFP in hepatitis), smoking (CEA), prostate manipulation (PSA), biliary obstruction (CA 19-9).
- False negatives: tumours that do not express the marker (some pancreatic cancers in Lewis-negative people make no CA 19-9).
- The hook effect at extremely high concentrations and heterophile antibodies can distort immunoassays.

**Also called**
Serum tumour markers, AFP, CEA, PSA, CA-125, CA 19-9, β-hCG

## Clinical notes

- An isolated high marker without clinical or imaging findings does not diagnose cancer and is usually repeated before further work-up.
- In testicular cancer, AFP, β-hCG and LDH are part of staging.
- Surveillance for hepatocellular carcinoma in cirrhosis combines ultrasound every 6 months with or without AFP.

## Related conditions

- [Hepatocellular carcinoma](https://durgical.com/en/conditions/hepatocellular-carcinoma/)
- [Colorectal cancer](https://durgical.com/en/conditions/colorectal-cancer/)
- [Prostate cancer](https://durgical.com/en/conditions/prostate-cancer/)
- [Ovarian cancer](https://durgical.com/en/conditions/ovarian-cancer/)
- [Testicular cancer](https://durgical.com/en/conditions/testicular-cancer/)
- [Pancreatic cancer](https://durgical.com/en/conditions/pancreatic-cancer/)

## Related

- [Alpha-fetoprotein (AFP)](https://durgical.com/en/biochemistry/topics/alpha-fetoprotein/)
- [Carcinoembryonic antigen (CEA)](https://durgical.com/en/biochemistry/topics/carcinoembryonic-antigen/)
- [Prostate-specific antigen (PSA)](https://durgical.com/en/biochemistry/topics/prostate-specific-antigen/)
- [CA-125](https://durgical.com/en/biochemistry/topics/ca-125/)

## Test yourself

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

## What is the main use of tumour markers?

Following a cancer already diagnosed: response to treatment and detection of relapse compared with the patient's previous value.

## Why are most unsuitable for screening the general population?

They are not sensitive or specific enough: they rise in benign disease and may be normal in early cancers.

## Which marker is linked to colorectal carcinoma?

Carcinoembryonic antigen (CEA).

## Why should a marker be followed in the same laboratory?

Because results depend on the method and assay; switching technique can mimic a rise or a fall.

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

Sources: [Tumor Marker Tests: MedlinePlus Medical Test](https://medlineplus.gov/lab-tests/tumor-marker-tests/) (MedlinePlus, US National Library of Medicine, 2026); [CEA Test: MedlinePlus Medical Test](https://medlineplus.gov/lab-tests/cea-test/) (MedlinePlus, US National Library of Medicine, 2026); [Alpha Fetoprotein (AFP) Tumor Marker Test: MedlinePlus Medical Test](https://medlineplus.gov/lab-tests/alpha-fetoprotein-afp-tumor-marker-test/) (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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