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What is being tested?
Alpha-fetoprotein (AFP) is a protein that is normally produced by the developing fetus but is also present in small amounts in normal adults. It can also be produced by certain tumours including some types of germ cell tumours (NSGCT) and hepatocellular carcinoma. Raised levels of AFP are found in the vast majority of patients with this type of liver cancer (hepatocellular carcinoma). It is also raised in some patients with cancer of the testis.
How is the test used?
AFP is used to detect certain cancers of the liver and testis. If a patient is diagnosed with one of these types of cancer, they will then undergo periodic testing for AFP to monitor their response to treatment.
AFP has a half-life of five to seven days, meaning it can be used to evaluate treatment, as values which decline over a period of 25 to 30 days following treatment, indicate effective therapy.
AFP values may elevate immediately post treatment due to breakdown of tumour cells, but then decline thereafter.
Levels of AFP should be measured pre-orchiectomy (removal of the testis) to help establish baseline levels for treatment and are valuable for staging and prognosis.
Other markers such as beta-hCG and LD can also be measured.
If you have chronic hepatitis or cirrhosis of the liver, your doctor may request AFP tests to detect hepatocellular carcinoma (HCC, a type of liver cancer).
Raised levels of AFP may be present in patients with pre-existing liver diseases, such as cirrhosis, acute or chronic hepatitis. Any unexplained large elevation of AFP in these patients should raise concerns.
Please note that AFP is also used to in pregnant women to assess the risk of their baby having Down syndrome – in this case it is NOT being used to test for cancer (see also AFP maternal testing).
When is it requested?
Your physician will request an AFP blood test if:
What does the result mean?
Increased AFP levels can be caused by liver cancer, germ cell tumour of the testis or less commonly other cancers (for example, stomach, bowel, lung, breast, lymphoma). Slightly increased levels of AFP are common in patients who have chronic hepatitis or cirrhosis and do not necessarily indicate the presence of cancer.
Is there anything else I should know?
In general, the higher the AFP level in patients with cancer, the bigger the tumour. AFP decreases when your body responds to anti-cancer therapy. If AFP does not return to normal within about one month after cancer therapy, some of the tumour may still be present.
Common questions
This cancer usually occurs in people who have chronic scarring of the liver, called cirrhosis. Most commonly, this is caused by chronic infection from one of two viruses: hepatitis B and hepatitis C. Alcohol abuse also increases the risk of developing cirrhosis. Some inherited diseases, especially a disorder called haemochromatosis (in which the body absorbs too much iron), can cause cirrhosis and later hepatocellular carcinoma.
If you have chronic liver infection or damage, a high AFP could simply be due to the disease itself. If your AFP suddenly rises, or if it is very elevated, your doctor will usually ask for a study to look at your liver, such as an ultrasound examination, a CT scan or a MRI scan. These scans can often spot liver cancers if they are present.
Not all the AFP molecules in blood are identical, although the differences between them are small. AFP L3 is a particular type of AFP molecule that some researchers think can help doctors tell whether an increase in AFP is due to tumour or not. However, it is not yet clear that this test would provide a significant benefit in routine use and it is not available in Australia.
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