oncology Oncology is a branch of medicine that deals with the study, treatment, diagnosis and prevention of cancer. A medical professional who practices oncology is an ''oncologist''. The name's etymological origin is the Greek word ὄγκος (''ó ...

, AFP-L3 is an isoform of

alpha-fetoprotein Alpha-fetoprotein (AFP, α-fetoprotein; also sometimes called alpha-1-fetoprotein, alpha-fetoglobulin, or alpha fetal protein) is a protein that in humans is encoded by the ''AFP'' gene. The ''AFP'' gene is located on the ''q'' arm of chromosome 4 ...

(AFP), a substance typically used in the

triple test The triple test, also called triple screen, the Kettering test or the Bart's test, is an investigation performed during pregnancy in the second trimester to classify a patient as either high-risk or low-risk for chromosomal abnormalities (and neu ...

during pregnancy and for screening chronic liver disease patients for

hepatocellular carcinoma Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer in adults and is currently the most common cause of death in people with cirrhosis. HCC is the third leading cause of cancer-related deaths worldwide. It occurs in t ...

(HCC). AFP can be fractionated by affinity electrophoresis into three glycoforms: L1, L2, and L3 based on the reactivity with the

lectin Lectins are carbohydrate-binding proteins that are highly specific for sugar groups that are part of other molecules, so cause agglutination of particular cells or precipitation of glycoconjugates and polysaccharides. Lectins have a role in rec ...

''Lens culinaris'' agglutinin (LCA). AFP-L3 binds strongly to LCA via an additional α 1-6 fucose residue attached at the reducing terminus of N-acetylglucosamine; this is in contrast to the L1 isoform. It is the L1 isoform which is typically associated with non-HCC inflammation of liver disease condition. The L3 isoform is specific to malignant tumors and its detected presence can serve to identify patients whom need increased monitoring for the development of HCC in high risk populations (i.e. chronic

hepatitis Hepatitis is inflammation of the liver tissue. Some people or animals with hepatitis have no symptoms, whereas others develop yellow discoloration of the skin and whites of the eyes (jaundice), poor appetite, vomiting, tiredness, abdominal pa ...

B and C and/or liver

cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue repai ...

). AFP-L3% is now being considered as a

tumor marker A tumor marker is a biomarker found in blood, urine, or body tissues that can be elevated by the presence of one or more types of cancer. There are many different tumor markers, each indicative of a particular disease process, and they are used in ...

for the North American demographic.

AFP-L3% assay

AFP-L3 is isolated via an immunoassay and quantified using chemiluminesence on an automated platform. Results for AFP-L3 are represented as a ratio of LCA-reactive AFP to total AFP (AFP-L3%). The AFP-L3% assay, a liquid-phase binding assay, will help to identify at-risk subjects earlier, allowing for more intense evaluation for evidence of HCC according to existing practice guidelines in oncology. AFP-L3% is the standard for quantifying the L3 isoform of AFP in serum of high risk chronic liver disease (CLD) patients. Studies have shown that AFP-L3% test results of more than 10% can be indicative of early HCC or early nonseminomatous germ cell tumor. Early testimonials from hepatologists indicate that there is a target patient population for the AFP-L3% assay. This target population are those CLD patients who have AFP concentrations in the indeterminate range of 20-200+ ng/mL and a small or indeterminate mass on imaging. It is in this range that doctors experience trouble differentiating non-HCC fluctuations in AFP vs indication of HCC. In such patients these hepatologists recommend utilizing AFP-L3% to clarify the disease state. Some hepatologists also use a positive result to urge insurance companies to pay for more frequent and intensive imaging. Ultimately AFP-L3% may be used as a rule-in or rule-out assay for transplantation consideration and/or an intermediate step in surveillance precluding costly imaging on patients with fluctuating AFP results but negative for HCC.

References

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