Alpha Fetoprotein Tumor Marker
Alpha-Fetoprotein (AFP) is a protein that is normally found in large concentrations in body of a human fetus. After the birth, the serum level of AFP decreases and for the rest of life, it is present in very low concentrations. AFP is an important tumor marker, i.e. its concentration sharply increases in some tumors.
Note: In gynecology and obstetrics, the level of AFP in maternal blood and amniotic fluid may be used for screening purposes or diagnostics of Down syndrome, congenital defects of the neural tube and others. This article, however, is rather related to the importance of AFP as a tumor marker in adult medicine.
Alpha-fetoprotein is very important for diagnosis of the liver cancer. The serum level of AFP is evaluated in biochemical laboratory from a sample of venous blood.
Significantly elevated level of AFP is commonly found in case of liver cancer and certain elevation may (or may not) accompany liver metastases of other tumors. Therefore, AFP evaluation is indicated when we find a suspiciously-looking focal liver lesion by an imaging method such as abdominal ultrasound or computed tomography. However, when possible, it is advisable to examine such lesion by liver biopsy, which allows us to obtain a sample of tissue for histological evaluation. In addition, the AFP can be elevated in some very rare embryonic tumors.
Like other tumor markers, the AFP may be falsely positive or negative, i.e. its increased value does not always mean the presence of a cancer and on the contrary, its normal value does not completely rule out the tumor presence. Falsely positive AFP can be found in patients with liver cirrhosis, with acute or chronic liver inflammation and in pregnant women.