Determination of CA 19-9 antigen in serum and pancreatic juice for differential diagnosis of pancreatic adenocarcinoma from chronic pancreatitis.

Serum CA 19-9 levels were measured in 63 patients with ductal pancreatic adenocarcinoma and in 49 patients with chronic pancreatitis. Concentrations were abnormally high (greater than 40 U/ml) in 57 (90%) patients with cancer and only in 5 (10%) patients with chronic pancreatitis. All patients with falsely normal serum values had poorly differentiated carcinomas. Median CA 19-9 concentrations were progressively higher in patients with more advanced cancer. Fifteen of 16 (93%) patients with localized cancer has abnormal serum levels but only 5 (31%) of them had values greater than 120 U/ml, which was the highest score observed in patients with chronic pancreatitis. Pure pancreatic juice was obtained endoscopically from 23 patients with pancreatic cancer and from 20 with chronic pancreatitis. CA 19-9 concentrations in pancreatic juice were significantly higher in patients with cancer than in non-neoplastic patients. All 11 patients with resectable cancer investigated had a ratio of CA 19-9 to secretory protein concentration in pancreatic juice above the range of patients with chronic pancreatitis. We conclude that serum CA 19-9 determination is highly sensitive and specific for the differential diagnosis of pancreatic cancer versus chronic pancreatitis. However, moderately increased values (less than 120 U/ml), as seen in patients with localized pancreatic adenocarcinoma, are not conclusive for malignancy. The measurement of CA 19-9 to total protein ratio in pure pancreatic juice is proposed as an adjunctive, accurate diagnostic marker for early stages of pancreatic adenocarcinoma.