Tumour Markers in Health Screening | What Your Results Mean

Article by: Dr Ooi Poh Siang, Family Medicine Specialist

25 May 2026

Common Tumour Markers in Health Screening: What Do They Really Mean?

When you go for a health screening, you may come across a group of blood tests called tumour markers. The results can look worrying at first glance, especially when a number appears “high”. But a tumour marker result is rarely the full story on its own.

This guide explains what the most common tumour markers are, which cancers they are linked to, and why your results always need to be read together with your doctor.

What Are Tumour Markers?

Tumour markers are substances produced by cancer cells, or by the body in response to cancer. They can be detected in blood, body fluids, or tissues.

1. The Main Types of Tests

• Blood based markers (serum tumour markers) – the most commonly used
• Imaging tests (radiology based)
• Tissue tests (biopsy based)

2. Why They Are Used in Health Screening

Blood based tumour markers are popular in screening because they are simple, minimally invasive, and can help doctors assess cancer risk alongside other clinical findings. They are useful for:

• Establishing baseline levels
• Monitoring changes over time
• Supporting further investigations when necessary

3. Why Results Need Careful Interpretation

Tumour markers work best when interpreted together with symptoms, imaging, and medical assessment, because:

• Normal results do not completely rule out cancer (low sensitivity)
• Levels may sometimes rise due to non cancerous conditions (low specificity, or false positives)

The Main Categories of Tumour Markers

Tumour markers are usually grouped by what they are made of:

• Oncofetal proteins (CEA, AFP) – normally present in the foetus
• Carbohydrate antigens (CA 125, CA 19-9, CA 15-3)
• Enzymes (PSA)
• Hormones and hormone related markers (β-hCG, calcitonin)
• Others (PIVKA-II, EBV VCA IgA, MCED)

Oncofetal Proteins

1. AFP (Alpha-fetoprotein)

• What is it? – A protein made by the foetus (yolk sac and liver during development)
• Associated cancer
  • Liver cancer (hepatocellular carcinoma, HCC)
  • Testicular cancer (non seminomatous germ cell tumour)
  • Used for monitoring treatment, checking recurrence, and prognosis
• Other cancers
  • Stomach cancer
  • Pancreatic cancer
  • Colon cancer
  • Lung cancer
• Non-cancer causes
  • Hepatitis (A, B, C)
  • Liver cirrhosis
  • Liver abscesses
  • Liver injury (drug induced hepatotoxicity)
  • Pregnancy
  • Some genetic diseases (rare)

2. CEA (Carcinoembryonic Antigen)

• What is it? – A protein involved in cell adhesion, normally seen in foetal development
• Associated cancer
  • Colorectal cancer (colon cancer)
  • Used for monitoring after surgery and detecting recurrence
• Other cancers
  • Lung cancer
  • Pancreatic cancer
  • Gastric cancer
  • Liver cancer
  • Breast cancer
  • Thyroid cancer
  • Cervical cancer
  • Lymphoma
  • Melanoma
• Non-cancer causes
  • Smoking
  • Lung diseases such as pneumonia, tuberculosis, chronic obstructive pulmonary disease, and idiopathic pulmonary fibrosis
  • Inflammatory bowel disease
  • Liver disease
  • Kidney disease, including those on dialysis
  • Hypothyroidism
  • Diabetes (poorly controlled)

Carbohydrate Antigens (CA Markers)

1. CA 125

• What is it? – A protein from tissues derived from the Müllerian ducts (female reproductive system)
• Associated cancer
  • Ovarian cancer
  • Used for monitoring treatment response
• Other cancers
  • Endometrial cancer
  • Breast cancer
  • Cervical cancer
  • Lung cancer
  • Pancreatic cancer
• Non-cancer causes
  • Menstruation
  • Ovarian cysts
  • Endometriosis
  • Fibroids
  • Liver disease and heart failure (fluid retention)
  • Kidney disease

2. CA 19-9

• What is it?
  • A carbohydrate antigen related to the Lewis blood group
  • Some people (Lewis negative) cannot produce CA 19-9, leading to falsely low results
• Associated cancer
  • Pancreatic cancer
  • Used to monitor treatment
• Other cancers
  • Colorectal cancer
  • Bile duct cancer
  • Gastric cancer
  • Lung cancer
  • Thyroid cancer
• Non-cancer causes
  • Gallstones or bile duct blockage
  • Pancreatitis
  • Liver cirrhosis
  • Lung diseases such as idiopathic pulmonary fibrosis, bronchiectasis, and tuberculosis
  • Diabetes (poorly controlled)
  • Excessive tea consumption

3. CA 15-3

• What is it? – A protein from the MUC1 gene (breast tissue)
• Associated cancer
  • Breast cancer
  • Used for detecting metastasis (spread) and monitoring treatment
• Other cancers
  • Pancreatic cancer
  • Lung cancer
  • Ovarian cancer
  • Colon cancer
  • Liver cancer
• Non-cancer causes
  • Liver disease such as hepatitis and cirrhosis
  • Autoimmune diseases
  • Lung disease
  • Kidney disease
  • Blood disorders such as thalassaemia
  • Vitamin B12 deficiency

Enzyme Markers

1. PSA (Prostate-specific Antigen)

• What is it?
  • An enzyme produced by the prostate gland
  • PSA naturally increases with age and prostate size
• Associated cancer
  • Prostate cancer
  • Useful for screening, monitoring treatment, and follow up
• Non-cancer causes
  • Benign prostate hyperplasia (BPH)
  • Prostatitis (infection of the prostate)
  • Recent procedures (biopsy, catheter)

Hormone-Related Markers

1. β-hCG (Beta Human Chorionic Gonadotropin)

• What is it? – A hormone produced during pregnancy
• Associated cancer
  • Testicular cancer
  • Gestational trophoblastic disease
  • Helpful in establishing diagnosis
• Other cancers – Lung cancer
• Non-cancer causes
  • Pregnancy
  • Hyperthyroidism
  • Kidney disease
  • Certain weight loss supplements or performance enhancing drugs

2. Calcitonin

• What is it? – A hormone produced by the thyroid C cells
• Associated cancer – Medullary thyroid cancer
• Other cancers
  • Neuroendocrine tumours
  • Lung cancer
  • Prostate cancer
  • Breast cancer
  • Kidney cancer
  • Liver cancer
• Non-cancer causes
  • Kidney disease
  • Autoimmune thyroid disease
  • Pancreatitis

Other Tumour Markers

1. PIVKA-II (Protein Induced by Vitamin K Absence-II)

• What is it?
  • A protein produced when the body cannot properly use vitamin K
  • It is an abnormal form of a clotting protein
• Associated cancer – Liver cancer (hepatocellular carcinoma, HCC)
• Other cancers
  • Gallbladder cancer
  • Pancreatic cancer
• Non-cancer causes
  • Vitamin K deficiency
  • Liver disorders such as liver abscess and haemangioma
  • Kidney disease

2. EBV VCA IgA (Epstein-Barr Virus Viral Capsid Antigen IgA Antibody)

• What is it? – A blood test that measures antibodies against the Epstein-Barr virus (EBV)
• Associated cancer – Nasopharyngeal carcinoma (NPC)
• Other cancers
  • Burkitt lymphoma
  • Hodgkin lymphoma
  • Gastric cancer
• Non-cancer causes
  • Previous EBV infection
  • Reactivation of a dormant EBV infection

3. MCED (Multi-Cancer Early Detection)

• What is it?
  • A newer blood test designed to detect signals from multiple cancers using circulating tumour DNA (ctDNA) found in the bloodstream
  • The test looks for abnormal cancer related DNA changes and may also predict where the cancer started
  • Particularly useful because some of these cancers do not have routine screening programmes
  • Still an emerging technology, and should be interpreted together with clinical assessment and conventional screening methods
• Cancers it may help detect
  • Lung, colorectal, liver, breast, uterine, ovarian, cervical, blood, gastric, skin, pancreatic, prostate, bladder, kidney, and brain
• Advantages
  • Can screen for multiple cancers with a single blood test
  • May detect cancer at earlier stages
  • Can help identify cancers that are difficult to detect early
• Limitations
  • A positive result does not confirm cancer
  • Additional tests are still required for confirmation
  • A negative result does not completely rule out cancer
  • Does not replace standard screening methods such as mammogram, Pap smear, or colonoscopy
• Who may benefit?
  • Individuals with a family history of cancer
  • Higher risk individuals seeking more extensive screening options

Key Takeaway

Screening for cancer using tumour markers is a proactive step toward taking charge of your health, but the results should never be read in isolation. An elevated marker is not a diagnosis. It is an invitation to look closer.

The most effective approach combines these blood tests with a comprehensive clinical assessment, a review of your family history, and confirmatory imaging such as ultrasounds or CT scans. By using tumour markers as a baseline, you and your doctor can monitor changes over time, so that if a genuine issue arises, it is caught at the earliest and most treatable stage.

Always discuss your results with a healthcare professional to ensure they are interpreted correctly within the context of your overall health.

References

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• Trapé J, Fernández-Galán E, Auge JM, et al. Factors influencing blood tumor marker concentrations in the absence of neoplasia. Tumor Biology. 2024;46(s1):S35-S63.
• Vaidyanathan K, Vasudevan DM. Organ Specific Tumor Markers: What’s New? Indian Journal of Clinical Biochemistry. 2012;27(2):110-120.
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• Zhang X, Wang R, Niu B, Zhang L. Protein Induced by Vitamin K Absence or Antagonist II in Primary Liver Cancer: Basic Research Insights and Clinical Applications. Journal of Clinical and Translational Hepatology. 2025;13(12):1067-1079.
• Lam WKJ, King AD, Miller JA, et al. Recommendations for Epstein-Barr virus-based screening for nasopharyngeal cancer in high and intermediate risk regions. Journal of the National Cancer Institute. 2023;115(4):355-364.
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