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The expression CA195 in serum, defined by monoclonal antibody CC3C195 (IgM), was studied in 67 patients with pancreatic cancer and in 138 patients with biliary or pancreatic benign disease. The results were compared with carcinoembryonic antigen (CEA) expression. The overall sensitivity of the CA195 assay (> 12 U/ml) was higher than that for CEA (89.5% vs. 53.7%) (p < 0.001). Sensitivity was increased to 92.5% with the simultaneous use of the two antigens, but the difference was statistically significant only with CEA (p < 0.001). The specificity of CA195 calculated from all patients with benign diseases was lower than that of CEA (73.1% vs. 89.8%). However, using a cutoff value of 100 U/ml for CA195, the specificity of this antigen (82%) was higher than that of CEA. These results demonstrate that marked elevations of tumor antigen CA195 are relatively specific for pancreatic carcinoma, and that this antigen is superior to CEA for diagnosing pancreatic cancer by virtue of its higher sensitivity.

We evaluated in 214 patients with primary colorectal cancer the prognostic value of the preoperative serum levels of CEA and CA195. For CEA these levels were above the cutoff of 6 ng/ml in 31.3% of patients, whereas for CA195 they were higher than 12 U/ml in 35.9% of patients. The simultaneous use of both antigens increased the sensitivity to 49%, which was significantly higher than that of CEA (p < 0.001) and CA195 (p < 0.01) taken singly. The mean preoperative CEA levels were significantly (p < 0.001) correlated with Dukes' stage only, while there was a significant correlation between preoperative serum levels of CA195 and Dukes' stage (p < 0.001), grade of differentiation (p < 0.01) and tumor location (p < 0.05). The results indicated that high preoperative serum levels of CEA and CA195 were associated with a shorter overall survival (p < 0.0001). In addition, separate Cox multivariate analysis showed that preoperative CA195 was, after Dukes' stage, the strongest factor to predict overall survival (p < 0.0001).