AFP Tumor Markers

AFP is used to help detect and diagnose cancers of the liver, testes, and ovaries. It is often ordered to monitor people with chronic liver diseases such as cirrhosis or chronic hepatitis B because they have an increased lifetime risk of developing liver cancer. A doctor may order an AFP test, along with imaging studies, to try to detect liver cancer when it is in its earliest, and most treatable, stages.

If a patient has been diagnosed with hepatocellular carcinoma or another form of AFP-producing cancer, an AFP test may be ordered periodically to help monitor a patient's response to therapy and to monitor for cancer recurrence.

A relatively new test, called AFP-L3%, is sometimes also ordered to compare the amount of total AFP to the amount of one of the AFP variants called AFP-L3. The AFP-L3% test is not yet widely used in the U.S. but has gained wider acceptance in other countries such as Japan. The test is used to help evaluate the risk of developing hepatocellular carcinoma, especially in those with chronic liver disease. An increase in the percentage of L3 to total AFP indicates an increased risk of rapidly developing this disease and also of having less chance of survival.

A physician may order an AFP blood test when he:

• suspects that someone has liver cancer or certain cancers of the testes or ovaries. Cancer may be suspected when, for example, lumps are felt in the abdominal area during a physical exam or when imaging tests detect possible tumors.
• is monitoring a patient with chronic liver disease for the emergence of hepatocellular carcinoma or another type of liver cancer.
• is monitoring the effectiveness of treatment in a patient who has been diagnosed with and treated for a cancer of the liver, testes, or ovaries.
• is monitoring for cancer recurrence.

An AFP-L3% is sometimes ordered to help evaluate the risk of hepatocellular carcinoma when a patient has chronic liver disease. This new test, however, is not widely used and its ultimate clinical utility has yet to be established.

Increased AFP levels may indicate the presence of cancer, most commonly liver cancer, cancer of the ovary, and germ cell tumor of the testes. However, not every liver, ovary, or testes cancer will produce significant quantities of AFP. Elevated levels may be sometimes seen with other cancers such as stomach, colon, lung, breast, and lymphoma, although it is rarely ordered to evaluate these conditions. Other diseases such as cirrhosis and hepatitis can also cause increased levels.

When AFP is used as a monitoring tool, decreasing levels indicate a response to treatment. If concentrations after cancer treatment do not significantly decrease, usually to normal or near normal levels, then some of the tumor tissue may still be present. If concentrations begin to increase, then it is likely that the cancer is recurring. If AFP levels are not elevated prior to treatment, then the test will not generally be useful to monitor the effectiveness of treatment or to monitor for recurrence.

When the AFP concentrations of people with chronic liver disease go from moderately elevated to greatly elevated, their risk of developing liver cancer increases. When total AFP and AFP-L3% are significantly elevated, then the affected person has an increased risk of having or developing hepatocellular carcinoma in the next year or two. However, both AFP and AFP-L3% concentrations can be elevated, and fluctuate, in people with chronic hepatitis and cirrhosis. In these cases, a sharp increase in AFP is more important than the actual numerical value of the test result.

Not every person with increased AFP and AFP-L3% test results has cancer or will develop liver cancer. The AFP and AFP-L3% tests are not diagnostic; they are indicators. They must be used in conjunction with information from a history and physical examination as well as imaging studies to look for the development of tumors. Although these tests can provide useful information, they are not as specific or sensitive as doctors would wish. AFP can temporarily increase whenever the liver is injured and regenerating, and moderate elevations can be seen with a variety of conditions. Because of this, AFP testing can give some false positives. In addition, not every cancer will produce AFP, so a person could still have cancer even when the AFP is normal. For these reasons, the AFP test should not be used to screen the general population for cancer.

AFP is not always a tumor marker. Because AFP is produced by the fetus, levels are normally higher in pregnant women and in their newborns. For more information on AFP testing during pregnancy, see Triple or Quad Screen.