Abstract
Serum levels were determined in 434 patients with benign and malignant gastrointestinal diseases and compared with the serum concentrations of carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP). The highest proportion of elevated CA-50 levels (greater than 17 U ml-1) was found in patients with pancreatic cancer (73%). High levels were mainly associated with advanced cancer, but also half of the patients with a resectable pancreatic tumour had an increased CA-50 concentration. The CA-50 level was elevated in 37-58% of patients with colorectal, gastric, hepatocellular and biliary tract cancers. In all gastrointestinal cancers, CA-50 gave additional information compared with CEA and AFP, except in hepatocellular carcinoma where AFP was the best marker.