Increased concentrations of α-fetoprotein (AFP) in serum are less common in patients with malignancies of the gastrointestinal tract and of other organ systems with massive hepatic metastases. Hence, AFP determination is useful for the diagnosis of certain germ line tumors that contain yolk sac structures (testicular and ovarian tumors), hepatocellular carcinoma (hepatoma), and some malignant tumors of the gastrointestinal tract. AFP serves as an important marker for certain genetic and embryonic defects. Routine screening of pregnancies with a risk of neural tube defects (spina bifida, anencephaly, and Down′s syndrome) may be facilitated by the monitoring of AFP levels.
