[Comparative studies on the antitumor activity of the fluorinated pyrimidines 5'-DFUR, tegafur, UFT and FUra on various murine tumors].

Antitumor activities of fluorinated pyrimidines by oral administration were compared with various murine tumor models. 5'-Deoxy-5-fluorouridine (5'-DFUR) showed a better antitumor activity in terms of the growth inhibition and increase of the survival time than those of 5-fluorouracil(FUra), tegafur and UFT, particularly with respect to the chemotherapeutic indices. The activity of these fluorinated pyrimidines were further investigated in more detail with mice bearing colon 26 adenocarcinoma to suggest some means to optimize their treatment regimens in clinical trials. 5'-DFUR showed the activity irrespective of the size of tumor mass at the time of start of therapy. Additionally only 5'-DFUR was safely administered to the mice daily for long period up to more than 100 days, suppressing the tumor growth and increasing the survival to great extent.