S-AFP (alpha-1-fetoprotein) is a glycoprotein and biomarker that is naturally produced by the fetal liver and yolk sac during pregnancy. During this period, the protein plays a key role in the transport of fatty acids and bilirubin, as the fetal liver has not yet developed the ability to produce albumin, a protein that later takes over this function after birth. S-AFP levels in newborns are initially high but decrease rapidly during the first year of life, remaining very low in healthy adults.
However, in adults, elevated levels of S-AFP may indicate pathological processes, including malignancies such as hepatocellular carcinoma (HCC), non-seminomatous testicular cancer, or liver metastases. Since S-AFP can rise in certain liver diseases, such as cirrhosis or chronic hepatitis, it is also used as a screening marker in high-risk populations. As a result, S-AFP has become an integral tool in modern oncology and hepatology for cancer diagnosis, risk assessment, and monitoring of treatment response.
S-AFP in Suspected Cancer and Liver Diseases
S-AFP is strongly associated with certain cancers and liver-related conditions. Since the protein is normally produced in significant amounts only during fetal development, elevated concentrations in adults can be interpreted as an indication of abnormal cellular activity, such as malignant transformation or intensive liver cell regeneration. Therefore, S-AFP is used both as a diagnostic tumor marker and as an indicator of disease progression and treatment response.
S-AFP is primarily used in cases of suspected primary liver cancer (hepatocellular carcinoma, HCC) and certain types of testicular cancer, particularly non-seminomatous tumors. Additionally, this marker is used to monitor patients at increased risk of developing primary liver cancer, such as those with chronic liver disease, including liver cirrhosis, hemochromatosis, and homozygous α1-antitrypsin deficiency. Screening high-risk groups can enable earlier detection of liver cancer and improve treatment options. Elevated levels may occur in several conditions, including:
- Hepatocellular carcinoma (HCC): One of the most specific tumor markers for HCC. Levels above 400 µg/L are strongly associated with the diagnosis.
- Testicular cancer: S-AFP is used alongside other markers, such as hCG, for diagnosing and monitoring certain types of non-seminomatous testicular cancer.
- Liver metastases: Secondary tumors that have spread to the liver can also cause elevated levels.
- Liver regeneration: In liver cirrhosis or acute liver damage, regenerative processes may lead to mildly elevated levels.
Reference Values and Interpretation of S-AFP Test Results
Elevated AFP levels in adults may indicate primary liver cancer, testicular cancer, or ovarian cancer. However, S-AFP levels can also be elevated in other situations, such as during pregnancy, in newborns during their first year of life, or during liver regeneration. This can occur in cases of acute and chronic hepatitis or liver cirrhosis.
- Adults: Values below 10 µg/L.
Common Symptoms of Elevated S-AFP
The symptoms associated with elevated S-AFP levels primarily depend on the underlying disease causing the increase rather than the S-AFP levels themselves. Since S-AFP is often linked to severe conditions such as cancer or liver disease, symptoms may vary based on the type and stage of the disease. Common symptoms include:
- In liver cancer: Jaundice (yellowing of the skin and eyes), weight loss, abdominal pain, loss of appetite, and a feeling of pressure or fullness in the abdomen. Ascites (fluid accumulation in the abdominal cavity) may also occur in advanced cases.
- In testicular cancer: Swelling, tenderness, or a noticeable lump in one or both testicles. Abdominal or back pain may occur if the tumor has metastasized.
- In ovarian cancer: Bloating, changes in bowel habits, abdominal pain, weight changes, and a feeling of heaviness in the pelvis.
- In chronic liver disease: Fatigue, weakness, nausea, dark urine, pale stools, and symptoms of liver failure may occur, which can worsen if liver cancer develops.
Symptoms can vary depending on the extent of the disease and how early it is detected. Therefore, it is important to interpret elevated S-AFP levels in conjunction with other clinical findings and diagnostic tests to determine the cause and initiate appropriate treatment.