Tumour markers AFP, CEA, CA-125 and PSA: what they are and who should test
What the tumour markers in health check packages can and cannot tell you, why a high value doesn't mean cancer, and who benefits from testing.
Tumour markers make a health check package look complete and reassuring, and they also cause the most unnecessary worry. A slightly raised value can come from many ordinary causes, and a normal value doesn't guarantee there is no cancer. Below is who these tests are for.
Key takeaways
- Tumour markers were designed to monitor people already diagnosed with cancer, not to screen healthy people with no symptoms.
- Values rise with hepatitis, smoking, periods, an enlarged prostate or inflammation, while many early cancers show normal values.
- Evidence-based exceptions: AFP with ultrasound every 6 months for hepatitis B carriers or people with cirrhosis, and PSA for men who have made a shared decision with their doctor.
- Cancer screening that works for the general population is cervical screening, mammography, and faecal testing or colonoscopy for bowel cancer.
What a tumour marker is
A tumour marker is a substance that some cancer cells release into the blood in larger amounts than normal cells. The problem is that many normal cells release the same substances during inflammation or other conditions, and early cancers often don't produce enough to detect. These tests therefore suit monitoring whether treatment is working or cancer has returned in someone already diagnosed, rather than finding disease in people without symptoms.
The four found in packages
| Marker | Linked cancers | Other causes of a high value | Who benefits from testing |
|---|---|---|---|
| AFP | Liver cancer, some testicular cancers | Hepatitis, cirrhosis, pregnancy | Hepatitis B or C carriers and people with cirrhosis, with liver ultrasound every 6 months |
| CEA | Bowel cancer and several others | Smoking, bowel inflammation, pancreatitis, emphysema | People treated for bowel cancer, to monitor recurrence. Not for screening |
| CA-125 | Ovarian cancer | Periods, endometriosis, fibroids, pregnancy, pelvic inflammation | Women with a pelvic mass or a high-risk family history, under a gynaecologist's care |
| PSA | Prostate cancer | Enlarged prostate, prostatitis, cycling, a rectal exam before the blood draw | Men aged 50–69 after discussing pros and cons with a doctor, or from 45 with a family history |
Does a high value mean cancer?
Not necessarily. Of men in the general population with PSA above 4 ng/mL, only about one in four turns out to have cancer on biopsy; the rest have an enlarged or inflamed prostate. CA-125 in pre-menopausal women rises with the menstrual cycle itself. A high value in someone without symptoms therefore leads to further tests that cost money, cause worry and sometimes carry procedural risk, and in most cases no cancer is found.
Conversely, a normal value guarantees nothing. Many early bowel cancers have a normal CEA. Getting a normal result and then skipping screening that actually works, such as a faecal test, is the hidden harm of these tests.
Good to know: If you've already been tested and a value is high, don't panic. Bring the result to a doctor to assess symptoms and history, and repeat or add tests as appropriate. One value is not a diagnosis.
So who should test?
- Hepatitis B carriers, chronic hepatitis C or cirrhosis: AFP with liver ultrasound every 6 months is well-supported surveillance
- Men aged 50–69: PSA after discussing the benefits (earlier detection) and harms (over-testing and over-treatment) with a doctor and choosing to test
- People with a family history of liver, bowel, ovarian or prostate cancer at a young age: individual advice, which may include certain markers or earlier endoscopy
- People with symptoms such as weight loss, chronic bloating or abnormal urination: see a doctor to find the cause, where markers may form part of the work-up, rather than a self-ordered package
Who is the clinic's Plan C for?
Plan C, 3,290 baht, includes AFP, CEA and either CA-125 or PSA by sex. We offer it for people who meet the criteria above or who want it after discussing with the doctor. If you're 30–40, healthy and have no family history, Plan B, with hepatitis and HbA1c, is the better fit. Read what to test by age, or message us on LINE with your age and history and the doctor will help you choose.
Frequently asked questions
For people without risk factors the evidence doesn't support it: sensitivity is low in early disease and false positives are common. Screening proven to reduce deaths is cervical screening, mammography and bowel cancer screening.
Related services
Related articles
Sources
- Tumor Markers National Cancer Institute, U.S. National Institutes of Health
- Prostate Cancer: Screening U.S. Preventive Services Task Force
- Thailand guideline for the management of hepatocellular carcinoma Thai Association for the Study of the Liver
This content is general information and does not replace an examination, diagnosis or personal advice from a doctor. Published 20 September 2026
Everyone's health is different
If you have a health condition, take regular medication, are pregnant or have unusual symptoms, let a doctor assess you first. Message us on LINE.
