AFP is a protein, during the prenatal development of the fetus, initially synthesized by the yolk sac cells, then from the 5th week it is synthesized in the liver. After giving birth, serum AFP levels gradually decrease and reach adult levels by the end of the first year of life. In adults, the normal level is low, so any increase in the level is considered as the possible presence of cancer. Levels during pregnancy gradually increase due to the fetal production of AFP and are used as a marker of defects in the development of the neural tube, anterior abdominal wall, urinary system in the fetus as part of prenatal biochemical screening.
Very high levels of AFP are found in patients with germinal tumors of the testes, ovaries, or extragonadal neoplasms. Most adequately assess not only the levels of AFP, but also hCG in this category of patients. In testicular cancer, these markers must be evaluated before orchiectomy, and then determined after surgery with a certain frequency. The rate of decline in serum should be compared with the rate of disappearance of AFP in normal conditions (half-life is 7 days) and total hCG (half-life is 3 days). The monitoring program includes monthly determinations of AFP, total hCG and LDH during the first year and in the 2nd month over the next 2 years.
The level of AFP is significantly increased in hepatocellular carcinoma, metastasis of tumors of other localization in the liver: in combination with CEA, it is used for the differential diagnosis of the primacy of the tumor process in the liver. When interpreting elevated levels, it is necessary to take into account a possible transient increase in benign liver diseases and regeneration processes.