Cancer Antigen 19-9 (CA 19-9)

General Information

Carbohydrate Antigen CA 19-9 is a high molecular weight mucin containing a sialylated Lewis pentasaccharide epitope which is elevated in most pancreatic adenocarcinomas, approximately 50% of gastric carcinomas and approximately 30% of colorectal carcinomas.

Several benign diseases including chronic and acute pancreatitis, liver cirrhosis, cystic fibrosis and cholecystitis may give rise to selevated CA 19-9 levels. Very high values (>5,000 kU/L) have been seen in patients with obstructive jaundice due to cholelithiasis.

CA 19-9 is primarily used for monitoring patients with pancreatic cancer. Serial measurements of CA 19-9 every 1 – 3 months, together with imaging, should be used to monitor patients with pancreatic cancer with locally advanced or metastatic disease who are receiving therapy. Increases suggest progressive disease but confirmation from other investigations should be sought.

CA 19-9 should not be used to screen for pancreatic or any other GI Cancer.