Alpha1‑fetoprotein (AFP), an albumin‑like glycoprotein with a molecular weight of approximately 70 kDa, is formed in the yolk sac during fetal life, in non‑differentiated liver cells, and the fetal gastro‑intestinal tract.1,2
Tumors that synthesize AFP are mainly testicular non-seminomatous germ cell tumors (NSGCT), yolk sac tumors of the ovary and hepatocellular carcinoma (HCC). Moreover AFP is an important part in the risk assessment for trisomy 21 in the second trimester of pregnancy together with hCG+β and other parameters.3
The assay is inteded for the use as
- An aid in the diagnosis of hepatocellular carcinoma (HCC).
- An aid in the management of patients with non-seminomatous germ cell tumors.
- One component in combination with other parameters to evaluate the risk of trisomy 21 (Down syndrome). Further testing is required for diagnosis of chromosomal aberrations.4,5
Careful monitoring of the serum tumor markers AFP and human chorionic gonadotropin (hCG) is essential in the management of patients with germ cell tumors (GCT), as these markers are important for diagnosis, as prognostic indicators, in monitoring treatment response, and in the detection of early relapse.6 In addition, hCG and AFP are important parameters for estimating the survival rate of patients with advanced NSGCTs and are also recommended by the National Academy of Clinical Biochemistry for the management of such patients.7
Hepatocellular carcinoma (HCC) is frequently the result of advanced liver disease and can develop in patients with and without cirrhosis.8 AFP has long been recognized as a biomarker for HCC, and has played a prominent role in the diagnosis of HCC. Substantially elevated AFP values can indicate primary liver cell carcinoma and it has been shown that AFP levels increase with tumor size.9 Diagnosis of HCC has primarily relied on the presence of typical features seen on contrast-enhanced imaging studies, histopathological assessment, and serum AFP levels.10 While AFP is elevated during hepato‑carcinogenesis, it can also be found in other tumors such as testicular, embryonic or gastric cancer.11,12 AFP has reported sensitivities ranging from 39 to 65 %, and specificities from 76 to 94 % in HCC patients.13 The divergence in sensitivity and specificity of AFP in these studies is probably due to a variety of factors including different etiologies, variable study designs, and different cutoff values. As the AFP values can also rise during regeneration of the liver, moderately elevated values are found in alcohol‑mediated liver cirrhosis and acute viral hepatitis.14 Surveillance of patients at risk for developing HCC by abdominal ultrasonography in combination with AFP is recommended by several clinical practice guidelines.15,16, 17
Measurement of AFP makes a contribution to the risk assessment for trisomy 21 (Down syndrome) in the second trimester of pregnancy together with hCG+β and other parameters, such as exact gestational age and maternal weight.3 In a trisomy 21 affected pregnancy the maternal serum concentration of AFP is decreased whereas the maternal serum hCG+β concentration is approximately twice the normal median.18 The risk for a trisomy 21 affected pregnancy in the second trimester can be calculated by a suitable software (see “Materials required, but not provided” section6,7) using the algorithm as described by Cuckle et al.19 and the respective assay specific parameters.20,21,22,23,24