Antitumor effect of intermittent oral administration of UFT against human rectal cancer xenografted in nude mice

Effect and toxicities of oral administration of UFT were examined with tumor xenografts (COK-7LiM) in nude mice. Special attention was paid to the differences between daily (Q1D X 9) and intermittent (Q4D X 3) treatments with this agent. The optimal doses of UFT were determined on the basis of the maximal tolerated dose of the agent in nude mice. It was remarkable that the chemotherapeutic effect by intermittent administration of UFT showed a significantly better result than that by daily administration. No difference was seen in the toxicities between the two methods of administration of UFT. Moreover, the concentration of 5-FU in the tumor tissue treated with UFT intermittently was significantly higher than that by daily administration method.