Immunological assay of pancreatic ribonuclease in serum as an indicator of pancreatic cancer.

Serum levels of RNase activity, presumed to originate in the pancreas, have been suggested to be of use in the diagnosis of pancreatic cancer. We have used a radioimmunological assay of human pancreatic-like RNase to quantitate this protein in serum from normal blood donors and patients with a variety of diseases. Serum pancreatic-like RNase rises gradually with age, and its level is usually higher in males than females. Although many patients with pancreatic cancer show elevated serum levels of immunologically cross-reactive enzyme, others are apparently normal. In several other types of cancer, a similar pattern of elevated RNase is apparent. However, in kidney or bladder carcinoma and in patients with severe kidney disease, RNase levels are almost always greater than normal. Regardless of the nature of the disease, an elevated level of pancreatic-like enzyme is usually accompanied by above-normal levels of serum urea nitrogen. Hence, elevated circulating levels of pancreatic-like RNase are best related to kidney function and do not serve as a specific marker for cancers of the pancreas or other organs.