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Dr. Mohammadreza Dabiriفارسی
Questions and answers

What is a tumour marker and when is it useful?

CEA, CA-125, CA 19-9, PSA and AFP: the real uses of tumour markers and their limitations

Updated: 28 October 20261 min read8 references
Short answer

A tumour marker is a substance made by cancer cells, or by other body cells in response to cancer — and sometimes in benign conditions — that gives information about cancer; these substances are measured in the blood, urine, stool or tissue [1]. The main value of most blood markers is in following the response to treatment and detecting recurrence of a cancer that has already been diagnosed, not in first diagnosis or check-ups in healthy people [2, 6]. A high marker does not mean cancer, and not everyone with cancer has a high marker [1].

Key points

  • Tumour markers help to diagnose cancer (with a biopsy and imaging, not on their own), to determine the stage and outlook, to choose treatment, to measure how well treatment is working and to find recurrence early [1].
  • Only a few are used in healthy people: a PSA test after discussion with a doctor [3], and AFP with an ultrasound every 6 months in people with cirrhosis [4].
  • Markers tested on a tumour sample, such as hormone receptors and HER2 in breast cancer, are needed to choose treatment [5].

Common tumour markers and their main use

MarkerRelated cancerMain use
CEABowel and some other cancersChecking the effect of treatment and finding recurrence [6]
CA 19-9Pancreas, gallbladder, bile ducts and stomachChecking the effect of treatment [6]
CA-125OvaryHelping with diagnosis, checking response to treatment and recurrence [6]
PSAProstateHelping with diagnosis, checking response to treatment and recurrence [6]
AFPLiver, ovary and germ cell tumoursHelping with diagnosis and following treatment [6]
Beta-hCGChoriocarcinoma and germ cell tumoursStaging, prognosis and response to treatment [6]
CA 15-3 / CA 27.29BreastChecking the effect of treatment or recurrence [6]
CalcitoninMedullary thyroid cancerHelping with diagnosis, checking treatment and recurrence [6]
ThyroglobulinThyroidChecking response to treatment and recurrence [6]
LDHGerm cell tumours, lymphoma, leukaemia, melanomaStaging, prognosis and response to treatment [6]

None of these tests on its own diagnoses or rules out cancer.

Where in the treatment journey is a tumour marker useful?

  1. 1

    Before treatment

    In some cancers, the starting level of the marker helps with staging; for example CEA before surgery for bowel cancer [8].

  2. 2

    During treatment

    Repeated measurements show whether treatment is working [1]; for example CEA in bowel cancer that has spread [8].

  3. 3

    After treatment

    To find recurrence early; for example CEA every 3 months for at least 3 years in stage 2 and 3 bowel cancer, if treatment would be suitable for you should the cancer come back [8]. Read more: What does a high CEA mean?

When should I call my doctor?

Do not panic; show the result to your doctor together with your history and symptoms; the doctor interprets all the findings together, and no single test confirms cancer [7]. If you have symptoms such as unexplained weight loss, bleeding or a new lump, do not delay seeing a doctor.

If you have had cancer and are in follow-up, discuss a rise in a marker with your treatment team; for example, in pancreatic cancer, a steady rise in CA 19-9 suggests progression but must be confirmed with other tests [8].

Related questions

Is a tumour marker panel a good idea at an annual check-up?

Usually not. The available blood markers are not sensitive or specific enough to find early cancer [2]; a high result may come from a non-cancerous condition and lead to unnecessary tests and worry [1]. For screening, discuss proven methods such as mammography or a stool test with your doctor.

My tumour marker is normal; does that mean I don't have cancer?

Not necessarily. A person may have cancer and still have normal test results [7].

What is the difference between a tumour marker and a "liquid biopsy" (ctDNA)?

ctDNA looks for fragments of tumour DNA in the blood and is a newer type of marker. Read more: Liquid biopsy and circulating tumour DNA

Related cancer types

Colorectal cancerProstate cancerThyroid cancerLiver cancerPancreatic cancerOvarian cancer

Related questions

Can cancer be prevented?My faecal occult blood test was positive. What should I do?At what age is a screening colonoscopy needed?Can I exercise during cancer treatment?Do red meat and processed meat cause cancer?Does a biopsy make cancer spread?Does a high PSA mean prostate cancer?Does alcohol cause cancer?

References

8 references
Show all references, 5 with a study cardClose the reference list

Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.

  1. 1
    Tumor MarkersNational Cancer Institute · cancer.gov
    Source Back to text: 1 2 3 4 5
  2. 2
    Tumor Markers in Clinical Practice: A Review Focusing on Common Solid CancersDuffy MJ · Med Princ Pract · 2012;22:4-11
    Study cardDOI Back to text: 1 2
  3. 3
    Screening for Prostate Cancer: US Preventive Services Task Force Recommendation StatementUS Preventive Services Task Force; Grossman DC, Curry SJ, Owens DK, Bibbins-Domingo K, Caughey AB, et al · JAMA · 2018;319:1901-1913
    Study cardDOIPubMed Back to text
  4. 4
    EASL Clinical Practice Guidelines on the management of hepatocellular carcinomaEuropean Association for the Study of the Liver · J Hepatol · 2025;82:315-374
    Study cardDOIPubMed Back to text
  5. 5
    National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for Use of Tumor Markers in Testicular, Prostate, Colorectal, Breast, and Ovarian CancersSturgeon CM, Duffy MJ, Stenman UH, Lilja H, Brünner N, Chan DW, et al · Clinical Chemistry · 2008;54:e11-e79
    Study cardDOI Back to text
  6. 6
    Tumor Markers in Common UseNational Cancer Institute · cancer.gov
    Source Back to text: 1 2 3 4 5 6 7 8 9 10 11
  7. 7
    Tests and Procedures Used to Diagnose CancerNational Cancer Institute · cancer.gov
    Source Back to text: 1 2
  8. 8
    ASCO 2006 Update of Recommendations for the Use of Tumor Markers in Gastrointestinal CancerLocker GY, Hamilton S, Harris J, Jessup JM, Kemeny N, Macdonald JS, et al · JCO · 2006;24:5313-5327
    Study cardDOI Back to text: 1 2 3 4

This page is based on reputable scientific sources and was last updated on 28 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.

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Related pages

19 October 2026 What does a high CEA in a blood test mean? A high CEA can be a sign of bowel or other cancers, but it is also raised in smokers and in benign conditions; it is not suitable for screening. 19 October 2026 Does a high PSA mean prostate cancer? Not necessarily. Benign enlargement and inflammation of the prostate also raise PSA, and only about 1 in 4 men who have a biopsy because of a high PSA have cancer. 19 October 2026 What are the symptoms of ovarian cancer? The symptoms of ovarian cancer are vague: bloating and a swollen abdomen, pelvic pain or pressure, feeling full quickly and passing urine often. If they are new and happen almost every day, they need checking.