Abstracts
1998 Digestive Disease Week

#1011

CARBOXYPEPTIDASE A ACTIVITY IN PANCREATIC CANCER AND ACUTE PANCREATITIS. P. Shamamian*, S. Marcus*, E. Deutsch*, T. Maldonado*, A. Liu_, J. Stewart_, K. Eng*, C. Gilvarg_. *Department of Surgery, NYU School of Medicine, NY, NY; _Department of Molecular Biology, Princeton University, Princeton, NJ.

Introduction: Diseases of the exocrine pancreas are often insidious in their presentation and devastating in their clinical consequences. Carboxypeptidase A (CPA) is an ideal marker of pancreatic disease since it is produced exclusively by the pancreas as the inactive zymogen pro-CPA, and normal serum activity is low. We have developed an assay to determine serum CPA activity in its active form, A-CPA and also the total serum CPA activity (T-CPA = pro-CPA + A-CPA). We hypothesize that elevations in the level of CPA should be reflective of pancreatic pathology. In this study we investigated the utility of measuring A-CPA and T-CPA activity in patients with acute pancreatitis (AP) and pancreatic cancer (P-Ca). Methods: Serum was collected from the following patients: Group 1) patients with hyperamylasemia not due to AP (n=48); Group 2) patients with AP documented by CT scanning (n=12); Group 3) patients with adenocarcinoma arising in the head of the pancreas, presenting with jaundice, prior to surgical exploration (n=12). Serum samples were analyzed for A-CPA using the specific substrate N-acetly-phenylalanyl-3-thiaphenylalanine. T-CPA activity was measured by conversion of pro-CPA to A-CPA by the addition of clostripan to the group 3 samples. Results: Group 1 patients had amylase elevations ranging from 112-1303 U/L but did not demonstrate elevations in A-CPA activity (range 0.01-0.30 U/L; normal A-CPA 0.21+/-0.08 U/L). Patients with AP (Group 2) had elevated A-CPA activities ranging from 3.10 to 174.1 U/L. There was no correlation between severity of AP and A-CPA. Patients with P-Ca did not have significant elevations in A-CPA activity (range 0.008-0.084 U/L). Eight of 12 P-Ca patients had high T-CPA activity (range 4.2-43.9 U/L; normal = 1.5+/- 0.92 U/L). The remaining four P-Ca patients had low T-CPA activity (<0.8 U/L), and demonstrated clinical signs of pancreatic insufficiency (diarrhea and diabetes mellitus). There was no difference in TNM stage between P-Ca patients with high or low T-CPA. Conclusion: These data demonstrate that CPA may be useful in the diagnosis of pancreatic disease. A-CPA is increased in patients with AP and may help distinguish patients with AP from those with non-pancreatic hyperamyl-asemia. T-CPA may be a marker for P-Ca, as T-CPA activity was found to be elevated in 8/12 patients with P-Ca. Increased T-CPA activity may be due to increased production of T-CPA by P-Ca or arise secondary to injury of normal pancreatic tissue during the growth of the primary tumor. This would explain the low levels of T-CPA found in pateints with pancreatic insufficiency.

Copyright 1996 - 1998, SSAT, Inc. Revised 29 June 1998.