Biomarkers

Alpha Fetoprotein (AFP) Tumor Marker Test

    
What is an AFP (alpha-fetoprotein) tumor marker test?
An AFP tumor marker test is a blood test that measures the level of AFP (alpha-fetoprotein) in a sample of your blood. It's usually used to help diagnose certain types of cancer and to check how well treatment is working.
AFP is a protein that the liver makes when its cells are growing and dividing to make new cells. AFP is normally high in unborn babies. After birth, AFP levels drop very low. Healthy children and adults who aren't pregnant have very little AFP in their blood.
AFP in non-pregnant people is mainly measured as a tumor marker. Tumor markers are substances that are often made by cancer cells or by normal cells in response to cancer. High levels of AFP can be a sign of cancer of the liver, ovaries or testicles.
An AFP tumor marker test cannot be used by itself to screen for or diagnose cancer. That's because other conditions can increase AFP levels, including liver diseases that aren't cancer. And some people who do have liver, ovarian, or testicular cancer will have normal AFP levels. So, an AFP tumor marker test can't rule out cancer for sure. But when used with other tests and exams, AFP tumor marker testing can help diagnose and monitor cancers that cause high AFP levels.
Other names: total AFP, alpha-fetoprotein-L3 Percent
What is it used for?
An AFP tumor marker test may be used during the diagnosis and/or treatment of cancer of the liver, ovaries, or testicles that make high levels of AFP. It is used to:

  • Help confirm or rule out a cancer diagnosis when used with other exams and tests.
  • Predict how cancer may behave over time.
  • Monitor cancer treatment. AFP levels often go up if cancer is growing and go down when treatment is working.
  • Check whether cancer has returned after treatment.

In certain cases, results from an AFP tumor marker test may be used to guide treatment choices for specific types of cancer. The test may also be used to monitor your health if you have chronic (long lasting) hepatitis or cirrhosis of the liver. These conditions aren't cancer, but they increase your risk of developing liver cancer.
Why do I need an AFP tumor marker test?
You may need an AFP tumor marker test if:

  • A physical exam and/or other tests suggest that you may have cancer of the liver, ovaries, or testicles.
  • You are currently being treated for a cancer that causes high AFP levels. Measuring your AFP test can show how well your treatment is working.
  • You have completed treatment for a cancer that increased your AFP level. You may need an AFP tumor marker test from time to time to check whether your cancer is coming back.

If you have chronic hepatitis or cirrhosis, you have a higher risk of developing liver cancer. A very high level of AFP or a sudden increase can be an early sign of liver cancer. Most medical experts don't recommend measuring AFP levels to screen for cancer in these diseases. But, some health care providers may still use an AFP tumor marker test with other tests to watch for liver cancer.
What happens during an AFP tumor marker test?
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Will I need to do anything to prepare for the test?
You don't need any special preparations for an AFP tumor marker test.
Are there any risks to the test?
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
What do the results mean?
If you haven't been diagnosed with cancer, test results that show:

  • High levels of AFP may be a sign of cancer of the liver, ovaries, or testicles. But having a high AFP level doesn't mean you have cancer or that you will get cancer. Liver injury and liver diseases that aren't cancer can also cause high AFP levels. Less often, high levels of AFP may be a sign of other cancers, including lymphoma or lung cancer. Your provider will use your medical history and other test results to make a diagnosis.
  • Normal levels of AFP mean you're less likely to have a cancer that causes high AFP levels. But a normal test result doesn't rule out cancer because some people with these cancers have normal AFP levels.

If you're being treated for a cancer that increased your AFP levels, you may be tested several times during treatment. Your provider will look at all your AFP test results to see how your levels have changed over time. If your results show:

  • Your AFP levels are increasing, it may mean that your treatment isn't working.
  • Your AFP levels are decreasing, it may mean your treatment is working.
  • Your AFP levels have stayed the same, it may mean your disease is stable and hasn't gotten better or worse.

If you've finished treatment for cancer that caused high AFP levels and your test results are:

  • Not normal, it may mean that you still have some cancer in your body.
  • Higher now than they were shortly after treatment, it may mean your cancer is growing again.

If you have a long-lasting liver disease that's not cancer, you may need other tests to check for liver cancer if your test results show a sudden increase in AFP or your level is very high.
Ask your provider to explain what your test results mean for your health.
Learn more about laboratory tests, reference ranges, and understanding results.
Is there anything else I need to know about an AFP tumor marker test?
In the U.S., the most common AFP tumor marker test measures all forms of AFP in your blood. A less common AFP test may be used to check the risk of liver cancer in people who have chronic liver disease. It measures a form of AFP called L3.
An AFP-L3 percent test (AFP-L3%) compares the amount of L3 to the amount of total AFP in your blood. If the portion of L3 increases, it may mean you have a high risk of developing a serious form of the most common liver cancer called hepatocellular carcinoma.
You may have heard of another type of AFP test that's used during pregnancy. This test measures total AFP levels in the blood, but it's not a tumor marker test for cancer. It's used to check for the risk of certain birth defects in an unborn baby.

 

References

Testing.com [Internet]. Seattle (WA): OneCare Media; c2022. Alpha-fetoprotein (AFP) Tumor Marker; [modified 2021 Nov 9; cited 2022 Aug 23]; [about 11 screens]. Available from: https://www.testing.com/tests/alpha-fetoprotein-afp-tumor-marker/