[Correlation between pyrimidine nucleoside phosphorylase (PyNPase) and clinicopathological factors in patients with...

Pyrimidine nucleoside phosphorylase (PyNPase) is a general term for enzymes which phosphorolyse pyrimidine class nucleosides; convert 5'-deoxy-5-fluorouridine (5'-DFUR), a fluoropyrimidine class anticancer drug, to an active type of 5-fluorouracil (5-FU); and demonstrate higher concentrations in tumor tissue. These findings have attracted attention from the standpoint of drug delivery systems. With regard to immunohistochemical staining studies, PyNPase expression correlated with cancer proliferation and metastasis. However, few have shown a relation between PyNPase assay and prognosis. We measured PyNPase value in tumor tissue of operative specimens from 60 gastric cancer patients. The results showed that the PyNPase value in tumor tissue was significantly higher (1.9 times) than in normal mucosa. There was no correlation between the PyNPase level in tumor tissue and clinicopathologic factors. However, many patients with relatively early gastric cancer had high enzyme levels, indicating that PyNPase may influence cancer proliferation and metastasis as well as prognosis. By detecting such a factor as PyNPase, and clinically applying the results, 5'-DFUR is promising for the treatment of patients with respect to prognosis.