[Studies in vivo and in vitro on the influence of 5-fluorouracil and n'-(2'-furanidyl)-5-fluorouracil on the walker carcinosarcoma 256 in the rat (author's transl)].

We compare the effects of 5-fluorouracil and N'-(2'-furanidyl)-5-fluorouracil (Ftorafur) in vivo (tumor size) and in vitro ([6-3H]-deoxyuridine incorporation) on solid Walker carcinosarcoma of the rat. 5-Fluorouracil and Ftorafur have a dose-dependent effect on tumor size and on [6-3H]-deoxyuridine incorporation in vitro. The in vivo effects on tumor size are similar when the dose of Ftorafur calculated by its molecular weight is about 3 times higher than that of 5-fluorouracil. In vitro an about 650 times higher dose of Ftorafur is required to achieve a comparable reduction of [6-3H]-deoxyuridine incorporation in the tumor cells.