Alpha-fetoprotein Blood Test (cont.)
Tse-Ling Fong, MD
Dr. Fong is the Medical Director of the USC Liver Transplant Program and Associate Professor of Medicine at the USC Keck School of Medicine. He obtained his medical degree from the University of Southern California and completed his residency in Internal Medicine at Los Angeles County-USC Medical Center. He is board certified in Internal Medicine and the subspecialty of Gastroenterology.
Charles Patrick Davis, MD, PhD
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
In this Article
- What is alpha-fetoprotein (AFP) blood test?
- In which situations are high blood levels of AFP seen in adults?
- What tests are available for measuring AFP?
- What is the sensitivity of AFP for diagnosing liver cancer?
What tests are available for measuring AFP?
Several assays (tests) for measuring AFP are available. Generally, normal levels of AFP are below 10 ng/ml. Patients with various types of acute and chronic liver diseases without documentable liver cancer can have mild or even moderate elevations of AFP, though usually less than 500 ng/ml.
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 60%. In other words, an elevated AFP blood test is seen in about 60% of liver cancer patients. That leaves 40% 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 fibrolamellar carcinoma, a variant of hepatocellular carcinoma. Also, as noted above, an abnormal AFP does not mean that a patient has liver cancer. It is important to note, however, that patients with cirrhosis and an abnormal AFP, despite having no documentable liver cancer, still are at very high risk of developing liver cancer. Thus, any patient 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 non-seminomatous germ cell cancers of the testis, the AFP is assayed at diagnosis, and followed as a tumor marker in a fashion similar to that described above in resected hepatocellular carcinoma patients.
Medically reviewed by Jay B. Zatzkin, MD; Board Certified Internal Medicine with subspecialty in Medical Oncology
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University of Rochester Medical Center. "Alpha-Fetoprotein Tumor Marker (Blood)." <http://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=167&ContentID=alpha_fetoprotein_tumor_marker>.
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