Abstract
We examined the antitumor effect of 5-fluorouracil (5-FU) by daily oral (p. o.) administration of 20 mg/kg compared with that by daily intraperitoneal (i. p.) administration of 10 mg/kg. A 5-FU-sensitive human stomach cancer xenograft (SC-1-NU) was used for the experiment. We also measured the binding capacity of thymidylate synthase (TS) and 5-FU incorporated into RNA (F-RNA) for the effect on DNA and RNA, respectively. Antitumor effects of 5-FU by 20 mg/kg p. o. were significantly stronger than those by 10 mg/kg i. p., throughout the experimental period (P<0.05). The minimum TIC ratios were 9.97% for 20 mg/kg p. o. and 48.1% for 10 mg/kg i. p. The effects of a single dose of 5-FU on TS and F-RNA were transient, whereas the TS inhibition rate and F-RNA content were gradually increased after successive doses of 5-FU. In both cases, no differences were seen between the effects of 20 mg/kg p. o. and 10 mg/kg i. p. It was considered that the effect of a large dose of 5-FU given orally could be equivalent to that given intraperitoneally.
