Alpha-fetoprotein (AFP)

What is being analysed?
Alpha-fetoprotein is a glycoprotein normally produced by the developing foetus. However, it can also be produced by some types of cancer.
Raised AFP values are found in most people with a particular type of liver cancer called hepatocellular carcinoma. High levels are also seen in patients with testicular cancer.
There are many different variants of AFP.
The alpha-fetoprotein test is generally requested to measure the total concentration of all the possible variants of AFP.

One of the AFP variants is called L3 because of its ability to bind, in vitro, to a particular protein called Lens culinaris agglutinin. AFP-L3 expressed as a percentage (%) has been proposed as an innovative test that relates the amount of the L3 variant to the total amount of AFP.
A rise in the percentage of the L3 variant compared with total AFP is associated with an increased risk of developing hepatocellular carcinoma in the short term and a worse prognosis, as tumours associated with L3 are much more aggressive. However, the technique is poorly standardised and the test is not performed routinely.

How is the sample collected?
The sample is collected by taking blood from a vein.

How is it used?
When is it ordered?
What does the test result mean?
Is there anything else I should know?

How is it used?
Alpha-fetoprotein is a biochemical marker of liver and testicular cancers.
When one of these cancers has been diagnosed, regular AFP checks are used to follow the patient’s response to treatment.
In patients with chronic liver disease (cirrhosis, chronic hepatitis), regular AFP checks are used to detect the onset of hepatocellular carcinoma.

(Alpha-fetoprotein is also useful in pregnancy to assess the foetal risk of Down syndrome – in these cases the test is NOT used as a tumour marker (see also AFP/pregnancy test).

When is it ordered?
The alpha-fetoprotein test is requested:
· if liver or testicular cancer is suspected.
· during and after treatment for this type of cancer.
· to detect the onset of hepatocellular carcinoma in chronic liver disease (chronic hepatitis, cirrhosis).

What does the test result mean?
High AFP levels can be due to liver cancer, testicular germ cell tumours or, less often, other types of cancer (for example of the stomach, bowel, lung or breast, and lymphoma).
Slightly raised AFP values are found in people with chronic hepatitis or liver cirrhosis. In these patients a rise in AFP is much more significant than the actual numerical value.

Is there anything else I should know?
In general, the higher the AFP level in patients with cancer, the larger the tumour.

Alpha-fetoprotein falls if cancer treatment is effective. If AFP values do not return to normal within about a month of the end of cancer treatment, this may indicate residual tumour.

1. What are the risk factors for hepatocellular carcinoma?
2. If my AFP is normal/abnormal, do I need other tests?

1. What are the risk factors for hepatocellular carcinoma?
Hepatocellular carcinoma generally affects people with cirrhosis.
The main cause of this disease is chronic infection with the hepatitis B or C virus.
Alcohol abuse also increases the risk of developing cirrhosis.
Some inherited diseases, in particular a disorder called haemochromatosis (a condition in which too much iron builds up in the body), can contribute to the development of cirrhosis and, later, hepatocellular carcinoma.

2. If my AFP is normal/abnormal, do I need other tests?
Raised AFP levels are found in chronic liver infection or liver disease.
Very high levels or sudden rises in AFP require further investigation with ultrasound, CT or MRI. These imaging tests can often detect even very small liver tumours.