Tumour Marker Interpreter

What tumour markers are

Tumour markers are substances, mostly proteins, that some cancers release into the blood in larger amounts than normal tissue does. A blood test measures them. Only a few, such as PSA, hCG and calcitonin, are specific enough to help find a cancer; most are used after diagnosis to follow how a known cancer responds to treatment and to spot a recurrence early.

Newer tests that look for tumour DNA in the blood (circulating tumour DNA, liquid biopsy) work differently and are reported differently; this tool covers the classic protein markers found on a routine blood report.

Why a raised marker is not a diagnosis

Every marker on this page is also raised by benign conditions: smoking for CEA, endometriosis and menstruation for CA 125, blocked bile ducts for CA 19-9, acid-suppressing medicines for chromogranin A, a badly handled sample for LDH and NSE. In the other direction, many cancers never raise their marker at all, and some people cannot produce a marker for genetic reasons.

This is why guidelines from the European Group on Tumour Markers, ESMO and national bodies do not recommend tumour marker panels for screening healthy people. A marker result is one clue that your doctor reads together with your history, examination and imaging.

Reference ranges: why your laboratory’s number wins

The upper limit for a marker depends on the assay maker and the population the laboratory used to set it. CA 15-3 limits run from 25 to 32 U/mL, AFP from 7 to 20 ng/mL, LDH by a factor of two between methods. The typical values in this tool are common adult cut-offs from the sources below; the range printed on your own report is the one your team uses, so enter it when you have it.

For the same reason, results from different laboratories are not directly comparable. If you are being followed with a marker, try to have the test done at the same laboratory each time.

Trends beat single values

A marker is most useful as a series. After surgery it should fall towards normal over weeks; during treatment a falling value suggests response and a rising one may prompt a scan. The half-life matters: CEA takes about a week to halve, so a check the day after surgery is too early.

Small changes are often noise. Between two tests, differences of less than about 20 to 25 percent can come from the assay itself, hydration or the time of day. Your team looks at the direction over three or more results, and usually confirms a rise before acting on it.

Which markers your team may follow

• Colorectal cancer: CEA, sometimes CA 19-9.
• Pancreatic and biliary cancers: CA 19-9, CEA.
• Ovarian cancer: CA 125, HE4, sometimes CEA or inhibin depending on the type.
• Breast cancer (metastatic): CA 15-3, CEA.
• Liver cancer: AFP.
• Testicular and germ cell tumours: AFP, hCG and LDH, always together.
• Prostate cancer: PSA.
• Thyroid cancer: thyroglobulin (papillary and follicular), calcitonin and CEA (medullary).
• Neuroendocrine tumours: chromogranin A, sometimes NSE or urinary 5-HIAA.
• Melanoma: S100B, LDH.
• Lung cancer: CYFRA 21-1, CEA, NSE, depending on the type.

Questions to ask

Bring the result with you and ask:

• Which marker are you following in my case, and how often?
• What was my value at diagnosis, and what does the trend since then show?
• Could anything else I have, or take, be raising this value?
• At what change would you order a scan or change treatment?
• Can I have my tests done at the same laboratory each time?