AFP is very high during the neonatal period, and drops to 10 µg/L to 20 µg/L by the age of 1 year, and the AFP content in adult serum is very low. When the liver cells undergo malignant transformation, the AFP content is significantly increased, which is an important indicator for clinical diagnosis of primary liver cancer.
1. Screening
Serum AFP combined with liver ultrasonography can be used as a screening test for people at high risk of primary liver cancer. High-risk groups are mainly those infected with hepatitis B virus (HBV) and/or hepatitis C virus (HCV), long-term alcoholics, and those with a family history of primary liver cancer. The screening age is males ≥40 years old and females ≥50 Starting from the age of 6 months, it is advisable to check once every 6 months.
2. Auxiliary diagnosis
① Serum AFP is the most commonly used tumor marker for clinical auxiliary diagnosis of primary liver cancer (hepatocarcinoma for short). For serum AFP ≥400μg/L for more than 1 month, or ≥200μg/L for 2 months, after excluding pregnancy, active liver disease and germline embryogenic tumors, liver cancer should be highly suspected, and B-ultrasound examination is necessary. Do CT/MRI and biopsy from time to time to confirm the diagnosis. The positive rate of serum AFP in the diagnosis of liver cancer is generally about 70%, and about 30% of patients with liver cancer have a negative AFP test. Therefore, AFP alone cannot be used to diagnose liver cancer.
② Elevated serum AFP can also be seen in germline embryonic tumors, such as testicular non-seminoma, yolk sac tumor, and malignant teratoma. It can also be seen in other malignant tumors, such as gastric cancer, colorectal cancer and so on.
③ Serum AFP in patients with acute and chronic hepatitis and cirrhosis may increase to varying degrees, mostly between 20 and 200 µg/L, and generally decreases gradually as the condition improves within 2 months.
④ Serum AFP can be seen elevated in women after 3 months of pregnancy, mainly from the fetus. Abnormal increase in serum AFP in pregnant women can be seen in fetal neural tube defects, spina bifida, and anencephaly. AFP can enter the amniotic fluid through the open neural tube, causing its content in the amniotic fluid to increase abnormally. The abnormal decrease of AFP in the serum of pregnant women indicates that the fetus is at risk of Down's syndrome. Therefore, monitoring of AFP concentration in pregnant women's serum and amniotic fluid can be used for prenatal diagnosis of fetal neural tube defects and Down's syndrome.
3. Prognosis assessment
Serum AFP is an important marker for judging the prognosis of primary liver cancer. A high concentration of serum AFP indicates a poor prognosis.
4. Efficacy and recurrence monitoring
① The determination of serum AFP helps to monitor the response of liver cancer patients to treatment. After liver cancer surgery, the serum AFP concentration drops within the reference range, indicating that the operation is effective; if the serum AFP drops only partly, it indicates that the operation is incomplete or there have been metastatic lesions.
② Serum AFP can be used for follow-up and recurrence monitoring after liver cancer surgical resection or liver transplantation of liver cancer patients. It should be tested every 3 months within 2 years after surgery and every 6 months within 3 to 5 years.
