Tumour markers such as CEA, CA 19-9, CA 125 and AFP are often added to health checks. They miss most early cancers, are often raised for harmless reasons, and are not recommended for screening healthy people. Here is what works instead.
Many health screening packages include a panel of “tumour markers”. It seems like a simple way to check for cancer with one blood test. Unfortunately, it does not work well, and medical guidelines do not recommend tumour markers for screening people who feel well.
What tumour markers are
Tumour markers are substances in the blood that can be produced by some cancers, and also by normal tissues. Common ones include:
| Marker | Linked with | Also raised by |
|---|---|---|
| CEA | Colorectal and some other cancers | Smoking, inflamed bowel, liver disease, lung infection |
| CA 19-9 | Pancreas and bile duct cancers | Gallstones, blocked bile duct, pancreatitis, poorly controlled diabetes |
| CA 125 | Ovarian cancer | Menstruation, pregnancy, endometriosis, fibroids, fluid in the abdomen |
| AFP | Liver cancer | Hepatitis flares, liver inflammation, pregnancy |
| PSA | Prostate cancer | Enlarged prostate, prostate infection |
The pitfalls of using them for screening
- They miss early cancer. Most cancers caught at an early, curable stage do not raise tumour markers. A normal result does not mean there is no cancer.
- They are often raised without cancer. Smoking, gallstones, hepatitis, diabetes, periods and many other common conditions can push a marker above the normal range. Most raised results in healthy people are false alarms.
- False alarms lead to more tests. A raised marker often leads to repeat blood tests, CT or MRI scans, and scopes, with worry, cost and radiation along the way, usually to find nothing.
- False reassurance. The bigger danger is a normal panel making someone feel safe and skip the tests that really do find cancer early, or ignore symptoms that need checking.
When tumour markers are useful
- Following a cancer that has already been diagnosed, to see how it responds to treatment
- Checking for a cancer coming back after treatment
- AFP, together with an ultrasound, for people with cirrhosis or chronic hepatitis B, as part of liver cancer surveillance
- Sometimes, alongside scans, when a specialist is already investigating symptoms or an abnormal finding
What to do instead: screening that works
Good cancer screening is matched to your age, sex and personal risk. These recommendations follow Singapore’s national screening guidelines and international practice.
- Bowel (colorectal) cancer: from age 45, a yearly stool test (FIT) or a colonoscopy every 10 years. Earlier and by colonoscopy if a close relative had bowel cancer. The national Screen for Life programme offers FIT from age 50. See colorectal cancer screening.
- Breast cancer: a mammogram every 2 years for women aged 50 to 69. Women aged 40 to 49 can discuss yearly mammograms with their doctor.
- Cervical cancer: a Pap smear every 3 years from age 25 to 29, then an HPV test every 5 years from age 30 to 69.
- Liver cancer: for people with cirrhosis or chronic hepatitis B, an ultrasound and AFP every 6 months. See liver cancer surveillance.
- Stomach cancer: a gastroscopy may be worthwhile from around 50, especially for Chinese men, people with a family history, or those with H. pylori or intestinal metaplasia. See stomach cancer screening.
- Lung cancer: people aged 50 to 80 with a heavy smoking history can discuss a yearly low-dose CT scan with their doctor.
- Prostate cancer: PSA testing is not recommended for all men. Men aged 50 to 69 who are thinking about it should talk through the benefits and harms with their doctor first.
- Nose and throat (nasopharyngeal) cancer: people with a close relative who had it can ask their doctor about checks.
If you already have a raised tumour marker
- Do not panic. Most raised results in people without symptoms are not cancer.
- A doctor will look at your health and other test results for a harmless cause, and often repeat the test after a few weeks, ideally at the same laboratory.
- Further tests are guided by your symptoms, risk factors and the trend over time, not by one number on its own.
Symptoms matter more than any blood test
Whatever your test results, see a doctor promptly for blood in the stool, a lasting change in bowel habit, black stools, difficulty swallowing, persistent vomiting, unexplained weight loss, yellow eyes or skin, or anaemia.
General information only. Reviewed by Dr Chia Chung King, 2026-11-07. Book a consultation.