What is the sensitivity of AFP for diagnosing liver cancer?

Primary liver cancer, or hepatocellular carcinoma or hepatoma, is more common in some forms of chronic liver disease. As a screening test in patients with chronic hepatitis B and C, or hemochromatosis, AFP has a sensitivity for liver cancer of about 70%. In other words, an elevated AFP blood test is seen in about 70% people with primary liver cancer. That leaves about 30% of patients in these high-risk groups who can have liver cancer but have normal AFP levels. Consequently, the test is not diagnostic but is an indicator of a potential situation. Therefore, a normal AFP does not exclude liver cancer. For example, AFP levels are normal in a patient with fibrolamellar carcinoma, a variant of hepatocellular carcinoma.

As noted above, an abnormal AFP does not mean that an individual has liver cancer. It is important to note, however, that people with cirrhosis (scarring) of the liver and an abnormal AFP, despite having no evidence of liver cancer, still are at very high risk of developing liver cancer. Thus, anyone with cirrhosis and an elevated AFP, particularly with steadily rising blood levels, will either most likely develop liver cancer or actually already have an undiscovered liver cancer.

An AFP greater than 500 ng/ml is very suggestive of liver cancer. In fact, the blood level of AFP loosely relates to (correlates with) the size of the liver cancer.

Finally, in patients with liver cancer 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 liver cancer is successfully removed surgically (resected). If AFP then increases again, liver cancer recurrence is likely.

In certain cancers of the testis as described above, the AFP is measured at diagnosis and followed as a tumor marker in a fashion similar to that described above in people with liver cancer.

AFP is not recommended as a screening tool for detection of cancer in normal, healthy people.