[Antitumor effect of 5'-DFUR and PyNPase activity in colorectal cancer]

Following preoperative administration of 5'-deoxy-5-fluorouridine (5'-DFUR) in patients with colorectal cancer, histologic antitumor effects as well as pyrimidine nucleoside phosphorylase (PyNPase) activities in cancerous tissues were examined. Fifty-five patients were randomly divided into two groups: Twenty-five patients received 5'-DFUR orally at a daily dose of 800 mg for 3 weeks before operation (Group A) and twenty-nine received no medication (Group B). PyNPase activities in cancerous tissues obtained from resected specimens in Group A and B were 49.7 +/- 21.6 and 66.6 +/- 40.0 U/mg prot, respectively, which were significantly higher than 25.5 +/- 14.1 and 22.1 +/- 11.2 U/mg prot in normal colorectal tissues. No significant difference was observed in PyNPase activities in cancerous tissues between Group A and B. PyNPase activities in cancerous tissues in Group A were no different either from 59.2 +/- 40.0 U/mg prot in biopsy specimens before administration of 5'-DFUR. Histologic anti-tumor effects were as follows: Grade 2, 1 case Grade 1b, 5; Grade 1a, 10; and Grade 0, 9. Although no correlation was observed between antitumor effects and PyNPase activities in cancerous tissues, antitumor effects of 2 cases in which PyNPase activities in cancerous tissues before administration of 5'-DFUR showed more than 100 U/mg prot were Grade 2 and 1b, respectively.