Serum elastase 1 appears specific for cancer of the pancreatic head.

Molecular size distribution of serum elastase 1 was investigated, by means of Sephadex G-200 gel filtration, in 10 patients with acute pancreatitis and in 19 patients with pancreatic cancer associated with high values of serum elastase 1. The elution profile of immunoreactive elastase 1 (IRE1) showed a single peak in the molecular position of the alpha 1-antitrypsin-elastase 1 (alpha 1-AT-E1) complex in all 10 patients with acute pancreatitis, six of seven patients with cancer of the pancreatic body-tail, and in the two patients with cancer of the pancreatic uncinate without poststenotic dilatation of the main pancreatic duct. The elution profile of all patients with pancreatic head cancer and one of seven patients with pancreatic body-tail cancer with a poststenotic dilatation of the main pancreatic duct showed two peaks: the first was eluted in the position of the alpha 1-AT-E1 complex, and the second was eluted between alpha 1-AT-E1 and elastase 1. The molecular weight of the IRE1 appearing specifically in patients with cancer of the pancreatic head was about 46,000 to 48,000, which was different from the 30,500 molecular weight of (pro)elastase 1. It is possible that proelastase 1 binding with an unknown substance exists in patients with pancreatic cancer. These data suggest that the stenosis or obstruction of the pancreatic duct by cancer probably liberates proelastase 1 from the normal pancreatic acinal cells into the blood. Therefore, the determination of the molecular size distribution of elastase 1 in the serum appears useful in the differential diagnosis of acute pancreatitis and pancreatic head cancer accompanied by pancreatitis.