Cancer antigen (CA) 19-9 is a tumor marker first described in 1979. An elevated serum level is most closely associated with adenocarcinoma of pancreatic exocrine ducts, which comprise about 95% of all pancreatic cancers.
Although the sensitivity and specificity of an elevated CA 19-9 is 90% and 98% respectively, it can not be used as a screening test for pancreatic cancer as it can be elevated in other gastrointestinal cancers, cirrhosis, and in benign conditions that cause obstructive jaundice.
CA 19-9 is not elevated in pancreatic cancer in patients that have the Lewis antigen blood type. The gene for Lewis antigen causes a deficiency in fucosyltransferase that is required for production of CA 19-9. These patients will have a normal CA 19-9 even in the setting of a large and advanced tumor.
Copyright 2007 InsideSurgery.com