It is well known that UFT has significant
therapeutic effects against experimental and clinical
cancers at the primary sites. In this experiment, we studied the inhibitory effect of UFT on the lung
metastasis of spontaneously developed rat mammary
carcinoma (SST-2) after surgical excision of the primary site. In comparison of UFT-treated (15 or 30 mg/kg/day) with 5-FU-treated (9.7 or 19.5 mg/kg/day) groups, UFT was more effective than
5-FU in the antitumor activity and the inhibitory effect of lung
metastasis with/without surgical excision of the primary sites. Rats (5-10 rats per group) were inoculated s.c. with 1 x 10(6) SST-2 cells and administered with UFT orally (15, 30 or 60 mg/kg/day) starting the day after
tumor inoculation for 30 days. The
therapeutic effect of UFT was studied by the growth rate of primary
tumor and the numbers of metastatic colonies in the lung 35 days after
tumor inoculation, comparing the UFT-treated with control groups. UFT administration at the doses of 30 or 60 mg/kg/day markedly inhibited the growth of the primary
tumors and the number of metastatic lung colonies decreased, compared with that of the control group. However, in the group of rats treated at the dose of 60 mg/kg/day, 60% of rats died from the side effects of UFT such as
weight loss,
hemorrhage etc. In all groups in which the primary
tumors were surgically excised 20 days after
tumor inoculation and then treated with UFT (15, 20 or 30 mg/kg/day), we observed marked prolongation of survival period and inhibition of lung
metastasis as well. Furthermore, we studied the effect of combination
therapy of UFT and
lentinan (1 mg/kg/day i.p.) on the
metastasis of SST-2 cells after surgical excision of the primary sites. It was more effective than UFT alone. Thus, it is clear that UFT is an effective anticancer
drug to inhibit
metastasis of
tumors in the lung after surgical excision of primary
tumor.