Serum RNase in the diagnosis of pancreatic carcinoma

Serum RNase (RNase I; ribonuclease 3'-pyrimidino-oligonucleotidohydrolase, EC 3.1.4.22) activity (mean +/- SD) with polycytidine as substrate was determined in normal individuals (24.9 +/- 3.0 units/ml) and in patients with pancreatic cancer (37.3 +/- 14.8), pancreatitis (38.5 +/- 12.6), nonpancreatic diseases (48.7 +/- 14.8), or renal failure (175.8 +/- 92.8). Patients with pancreatic cancer could not be distinguished from those with pancreatitis or with nonpancreatic disease, although the RNase activities in all of these differed from the activity in normal individuals. The serum RNase activities of four patients with resectable "curable") pancreatic carcinoma and two others with advanced pancreatic cancer without obstructive jaundice were normal. After total pancreatectomy, serum RNase activity remained in the high-normal range. The data presented here and data in the literature show that serum RNase cannot be of primarily pancreatic origin. The present study also demonstrates that measurement of its activity is not useful in early detection of pancreatic cancer.