Monosialoganglioside/glycolipid detected in low levels in healthy persons and elevated in pancreatic, hepatocellular, gastric, colorectal and ovarian cancers.
Carbohydrate antigen 19-9 is used in pancreatic adenocarcinoma and colorectal cancers with decreasing levels and following treatment and persistence at low levels are used to assess treatment responses to resectable in metastatic disease states.
Elevated levels can be seen in conditions with extrahepatic biliary obstruction.
Most useful tumor marker in the diagnosis, prognosis, and evaluation in the management of patients with pancreatic cancer.
Confounding factors with the use of CA 19–9 is related to this Lewis blood group and change in elevation in the setting of obstructive jaundice.
Patients negative for Lewis antigen do not synthesize Ca19-9 and this group accounts for 4-15% of the population.
10% of patients with pancreatic cancer lack focosyl-transferase and up to 1/3 of patients of normal levels at presentation.
Hyperbilirubinemia elevates the Ca19-9 levels due to the inability of the liver to degrade and secrete Ca19-9.