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
- Colorectal cancer
- Prostate cancer
- Ovarian cancer
- Testicular cancer
- Pancreatic cancer
Related
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.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Tumor Marker Tests: MedlinePlus Medical Test (MedlinePlus, US National Library of Medicine, 2026); CEA Test: MedlinePlus Medical Test (MedlinePlus, US National Library of Medicine, 2026); Alpha Fetoprotein (AFP) Tumor Marker Test: MedlinePlus Medical 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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