Key points
- Markers are mainly for monitoring response and recurrence, not for screening.
- A raised marker does not prove cancer; a normal one does not exclude it.
- Obstructive jaundice raises CA 19-9 even without cancer.
- Measure a baseline before treatment so later values mean something.
A tumour marker (US spelling: tumor marker) is a substance, usually measured in the blood, that is made by a cancer or by the body in response to it.
Tumour markers list and their significance
| Marker | Main use | Also raised by |
|---|---|---|
| CEA | Colorectal cancer: follow-up after resection | Smoking, inflammation, liver disease, other GI cancers |
| CA 19-9 | Pancreatic and biliary cancer | Obstructive jaundice, cholangitis, pancreatitis. Not made at all by people who lack the Lewis antigen (about 5–10%) |
| AFP | Hepatocellular carcinoma; non-seminomatous germ cell tumours | Pregnancy, hepatitis, cirrhosis |
| β-hCG | Germ cell tumours; gestational trophoblastic disease | Pregnancy |
| CA 15-3 | Breast cancer: monitoring metastatic disease (not for early diagnosis) | Liver disease, benign breast disease |
| CA 125 | Ovarian cancer | Endometriosis, menstruation, ascites, any peritoneal irritation |
| PSA | Prostate cancer | Benign prostatic enlargement, prostatitis, catheterisation, urinary infection |
| Calcitonin | Medullary thyroid cancer | Kidney failure, PPIs |
| Thyroglobulin | Follow-up of differentiated thyroid cancer after total thyroidectomy | Any remaining thyroid tissue |
| LDH | Lymphoma, germ cell tumours, melanoma (prognosis) | Haemolysis, tissue damage |
| Chromogranin A | Neuroendocrine tumours | PPIs, kidney failure |
How to use them well
- Baseline before treatment, then trend over time: a rising CEA after colorectal surgery prompts imaging for recurrence.
- Not for screening the general population: false positives are common and most early cancers do not raise markers.
- Interpret in context: a CA 19-9 of 400 in a jaundiced patient may fall to normal once the obstruction is relieved.
- Markers support, but never replace, tissue diagnosis. The exception is that very high AFP with typical imaging in a cirrhotic liver can diagnose HCC without biopsy.
Exam trap
A patient with painless jaundice and a CA 19-9 of 1,000: the marker supports pancreatic cancer, but the diagnosis and staging come from the CT and tissue.
Frequently asked questions
What are tumour markers?
Substances, usually measured in the blood, that are made by a cancer or by the body in response to it. They are used mainly to monitor treatment and detect recurrence.
Can tumour markers be used to screen for cancer?
Generally no. False positives are common and many early cancers do not raise markers, so a normal result does not exclude cancer.
Which tumour marker is used in colorectal cancer?
CEA, measured before treatment and then followed over time; a rising CEA after surgery prompts imaging for recurrence.
Which tumour markers are used in breast cancer?
CA 15-3 (and sometimes CEA), mainly to monitor metastatic disease. They are not used to diagnose early breast cancer.
Further reading
- Duffy MJ. Tumor markers in clinical practice: a review focusing on common solid cancers. Med Princ Pract 2013;22:4–11.
- Sturgeon CM, et al. National Academy of Clinical Biochemistry guidelines for the use of tumor markers. Clin Chem 2008;54:e11–79.