Inhibitory effect of simultaneous intraportal administration of 5-fluorouracil, uracil and degradable starch microspheres on experimental hepatic micrometastasis, is of colon cancer

This study was designed to examine the optimal regimen of 5-fluorouracil (5-FU), uracil and degradable starch microspheres (DSM) to prevent the hepatic metastasis of colorectal cancer. BALB/C mice were used as a model of hepatic micrometastasis of mouse transplantable colorectal cancer, Colon 26. We intraportally administered to the mice 5-FU at a dose of 34.8 mg/kg body weight; uracil at the dose equal to, or 8 times higher than that of 5-FU in molar weight and DMS at a dose of 5 mg/kg body weight. We investigated the hepatic and serum concentrations of 5-FU and uracil and the inhibitory effect of various combinations of the three substances on hepatic metastasis. The study showed that concurrent use of 5-FU with uracil at a dose 8 times higher than that of 5-Fu could keep 5-FU concentration high in hepatic tissue and relatively low in serum. This tendency became more marked with the presence of DSM. These findings support the previous study results that uracil antagonizes breakdown of 5-FU in the liver and with the aid of DSM, retards excretion of 5-FU from the liver. Further investigations for clinical application of this method will lower the incidence of hepatic metastasis of colorectal cancer.