The most widely used biochemical blood test for liver cancer -  hepatocellular carcinoma (HCC) is alpha-fetoprotein (AFP), which is a protein normally made by the immature liver cells in the fetus. At birth, infants have relatively high levels of AFP, which fall to normal adult levels by the first year of life. Also, pregnant women carrying babies with neural tube defects may have high levels of AFP. (A neural tube defect is an abnormal fetal brain or spinal cord that is caused by folic acid deficiency during pregnancy.)

In adults, high blood levels (over 500 nanograms/milliliter) of AFP are seen in only three situations:

• HCC
• Germ cell tumors (cancer of the testes and ovaries)
• Metastatic cancer in the liver (originating in other organs)

Several assays (tests) for measuring AFP are available. Generally, normal levels of AFP are below 10 ng/ml. Moderate levels of AFP (even almost up to 500 ng/ml) can be seen in patients with chronic hepatitis. Moreover, many patients with various types of acute and chronic liver diseases without documentable HCC can have mild or even moderate elevations of AFP.

The sensitivity of AFP for HCC is about 60%. In other words, an elevated AFP blood test is seen in about 60% of HCC patients. That leaves 40% of patients with HCC who have normal AFP levels. Therefore, a normal AFP does not exclude HCC. Also, as noted above, an abnormal AFP does not mean that a patient has HCC. It is important to note, however, that patients with cirrhosis and an abnormal AFP, despite having no documentable HCC, still are at very high risk of developing HCC. Thus, any patient with cirrhosis and an elevated AFP, particularly with steadily rising blood levels, will either most likely develop HCC or actually already have an undiscovered HCC.

An AFP greater than 500 ng/ml is very suggestive of HCC. In fact, the blood level of AFP loosely relates to (correlates with) the size of the HCC. Finally, in patients with HCC and abnormal AFP levels, the AFP may be used as a marker of response to treatment. For example, an elevated AFP is expected to fall to normal in a patient whose HCC is successfully removed surgically (resected).

There are a number of other HCC tumor markers that currently are research tools and not generally available. These include des-gamma-carboxyprothrombin (DCP), a variant of the gamma-glutamyltransferase enzymes, and variants of other enzymes (e.g., alpha-L-fucosidase), which are produced by normal liver cells. (Enzymes are proteins that speed up biochemical reactions.) Potentially, these blood tests, used in conjunction with AFP, could be very helpful in diagnosing more cases of HCC than with AFP alone.

To read more about Hepatocellular Carcinoma (HCC), please read the MedicineNet.com Liver Cancer (Hepatocellular Carcinoma) article.

Medical Author: Tse-Ling Fong, M.D.
Medical Editor: Leslie J. Schoenfield, M.D., Ph.D.

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