Alpha-fetoprotein (AFP)
A protein normally made by the developing fetus and largely switched off after birth. In adults its main use is as a tumour marker for liver cancer and certain testicular and ovarian (germ-cell) cancers, and to monitor treatment.
What it measures
Alpha-fetoprotein is a protein produced in large amounts by the fetal liver and yolk sac, which falls to very low levels after infancy. When it reappears in an adult, it can signal that certain cells have started making it again. Its principal clinical uses are as a tumour marker: for hepatocellular carcinoma (the main type of liver cancer), where it is used alongside ultrasound to monitor high-risk people such as those with cirrhosis or chronic hepatitis; and for germ-cell tumours of the testis and ovary, where it helps diagnose, stage and follow treatment. It is important to know that AFP is not specific to cancer — it also rises in pregnancy (where it is used differently, in prenatal screening) and when the liver is regenerating, as in hepatitis or cirrhosis, so a mildly raised value often has a benign explanation. It is always interpreted with imaging and the clinical picture.
What a high value can mean
- Hepatocellular carcinoma (liver cancer) — a key use; a rising AFP in someone with cirrhosis is a warning sign.
- Germ-cell tumours — certain testicular and ovarian cancers; used for diagnosis and monitoring.
- Liver regeneration — hepatitis, cirrhosis; a mild-to-moderate benign rise.
- Pregnancy — physiologically raised (used separately in prenatal screening).
- Other cancers — occasionally, less commonly.
What a low value can mean
- Normal in non-pregnant adults — a low AFP is the expected, reassuring result.
- After successful treatment of an AFP-producing tumour — a fall toward normal indicates response.
When to discuss with a doctor
AFP is a monitoring and work-up tool used in specific settings, not a general screening test for healthy people. In someone with cirrhosis or chronic hepatitis, it is checked periodically with liver ultrasound, and a rising level prompts imaging to look for liver cancer. In a young man with a testicular lump, or a woman with an ovarian mass, AFP (with other markers) helps characterise a possible germ-cell tumour. Because it also rises benignly in pregnancy and liver regeneration, a raised value is interpreted in context, not taken alone as meaning cancer. Mediora.AI shows AFP alongside liver enzymes and the other tumour markers so it is read in context; the interpretation and any imaging belong with your doctor.