Comparison of the sensitivity and specificity of the CA19-9 and carcinoembryonic antigen assays in detecting cancer of the pancreas

Abstract

In this study, we determined the sensitivity and specificity of the new serum assay CA19-9 in detecting adenocarcinoma of the pancreas and compared the results with those of the serum assay to carcinoembryonic antigen (CEA). Thirty-seven patients with biopsy-proven adenocarcinoma (14 patients with resectable disease and 23 patients with unresectable disease) were compared with 157 controls (48 patients with benign pancreatic disease, 34 patients with nonpancreatic sources of abdominal pain, 58 patients with benign jaundice, 7 patients with nonpancreatic malabsorption, and 10 patients with renal failure on dialysis). It was determined that a cutoff of 75 U/ml enhanced the diagnostic efficiency (sensitivity + specificity) of CA19-9 over the manufacturer's recommended cutoff of 37 U/ml. The sensitivity of CA19-9 (greater than 75 U/ml) in detecting cancer was greater than that of CEA (greater than 5 ng/ml) (86.5% vs. 48.4%) (p less than 0.01, McNemar test). The sensitivity of CA19-9 was 78.6% in resectable and 91.3% in unresectable disease. The specificity of CA19-9 was also greater than CEA (92.5% vs. 87.3%), although this difference was not statistically significant. The higher the CA19-9 or CEA level, the greater the specificity of either assay; at CA19-9 levels greater than 600 U/ml and CEA levels greater than 20 ng/ml the specificity is approximately 99%. The combination of an elevated CA19-9 level (greater than 75 U/ml) and an elevated CEA level (greater than 5 ng/ml) also enhanced specificity to 99%. It is concluded that CA19-9 used alone is superior to CEA used alone in detecting cancer of the pancreas and that the combination of mild elevations of both assays improves their specificity. Although the CA19-9 marker can be elevated with other intraabdominal adenocarcinomas (e.g., gastric, biliary, or colonic), CA19-9, together with CEA, will be useful to the clinician in differentiating benign from malignant pancreatic processes and in alerting the clinician to the possible presence of an intraabdominal neoplasm in the proper clinical setting.