Comparison of a new tumour marker CA 242 with CA 19-9, CA 50 and carcinoembryonic antigen (CEA) in digestive tract diseases.

The levels of CA 242, a new tumour marker of carbohydrate nature, were measured in sera of 185 patients with malignancies of the digestive tract and of 123 patients with benign digestive tract diseases. High percentages of elevated CA 242 levels (greater than 20 U ml-1) were recorded in patients with pancreatic and biliary cancers (68%). The sensitivity was somewhat lower than that of CA 19-9 (76%) and CA 50 (73%). On the other hand, in benign pancreatic and biliary tract diseases the CA 242 level was less frequently elevated than the CA 19-9 and CA 50 levels. The serum CA 242 concentration was increased in 55% of patients with colorectal cancer. CA 242 detected more Dukes A-B carcinomas (47%) than CEA (32%), whereas CEA was more often elevated (71% vs 59%) in Dukes C-D carcinomas. CA 242 was slightly elevated (ad 41 U ml-1) in 10% of patients with benign colorectal diseases. CA 50 and CA 19-9 had lower sensitivities than CA 242 using the recommended cut-off values. When cut-off levels based on relevant benign colorectal diseases were used, the sensitivities of these markers were similar and somewhat higher than that of CEA. Less than half of patients with gastric cancer (44%) had an elevated CA 242 serum level. CA 242 is a promising new tumour marker, that may be of additional value in the diagnosis of pancreatic and biliary, as well as colorectal cancer, and may be useful in monitoring cancer patients after radical surgery.