Correlative study on expression of CA 19-9 and DU-PAN-2 in tumor tissue and in serum of pancreatic cancer patients.

The serum levels of CA 19-9 and DU-PAN-2 antigens and their expression in tumor tissue were examined in 22 pancreatic cancer patients and the results were correlated with the Lewis (Le) blood group phenotypes of the individuals. In tumor tissue, CA 19-9 was expressed in 17 of 22 (77%) specimens. The negative cases included three patients with Lea-b-, one with Lea+b- and the other with Lea-b+ phenotypes. DU-PAN-2 antigen was expressed in 20 of 22 (91%) cancer tissues. The two DU-PAN-2-negative cases were CA 19-9-positive. The combination of two markers increased the sensitivity to 100%. In the serum, CA 19-9 level was elevated (greater than 37 U/ml) in 16 of 21 (73%) cases. All Lea-b- patients had values less than 37 U/ml. An elevated level of DU-PAN-2 (greater than 300 U/ml) was detected in 14 of 21 (67%) patients including three cases with Lea-b- type. In only one patient were both antigens below the cutoff levels so that the combination of two biomarkers elevated the sensitivity to 95%. The study indicated that the cocktail of 19-9 and DU-PAN-2 antibodies might increase the sensitivity and specificity for clinical diagnosis of pancreatic cancer. In 19 of 21 (90%) cases, the serum CA 19-9 level correlated with the expression of the antigen in the cancer tissue. Discrepancy was seen in two cases; one patient had an elevated level of CA 19-9 in the serum, but lacked this antigen in the cancer cells. In the second case, the situation was reversed. For DU-PAN-2, positive correlation was seen in 14 of 21 (67%) cases. Six of seven patients with low DU-PAN-2 levels expressed the antigen in their tumor cells, and one patient with DU-PAN-2-negative cancer tissue had an elevated level of this marker in the serum. Thus, CA 19-9 expression in serum corresponded more closely to expression in tissue than did that of DU-PAN-2 antigen. The serum levels of these antigens, however, is likely due to multiple factors, only one of which is the qualitative and quantitative expression of the antigens in tumors.