Aim: The response to fluoropyrimidine chemotherapeutic drugs is different in individual tumors. Predictive biomarkers of antitumor effects by these drugs are unknown. 5'-Deoxy-5-fluorouridine (5'-DFUR), a fluoro-pyrimidine chemotherapeutic drug, is converted to 5-fluorouracil (5-FU) by pyrimidine nucleoside phosphorylase (PyNPase). It is suggested that 5'-DFUR will efficiently exert antitumor effects via PyNPase in tumor tissues. The change of PyNPase activity in tumor tissues following 5'-DFUR administration may reflect antitumor effects, and may be useful for detecting predictive factors of antitumor effects. The aim of this study was to search for predictive factors of antitumor effects by analyzing the relationship between clinicopathological factors and the change of PyNPase activity in colorectal tumor tissues after preoperative 5'-DFUR administration.
Patients and methods: PyNPase activity in colorectal tissues from 45 patients with colorectal tumors was measured using an ELISA method.
Results: The reduction rate of PyNPase activity in colorectal tumor tissues after preoperative 5'-DFUR administration was correlated with significant differences in lymphatic invasion, stage, and histologic classification. It is suggested that lymphatic invasion, stage (distant metastasis), and histologic classification may be predictive factors for evaluating antitumor effects and selecting 5-FU-based chemotherapeutic drugs for patients with colorectal tumors.