Effect of 5‐Fluorouracil and UFT on Experimental Liver Metastasis Model of Colorectal Cancer Using Mouse Colon 26 Cells

Effects of 5‐fluorouracil (5‐FU) and UFT on an experimental liver metastasis model were compared at equi‐effective dosage levels against subcutaneous tumor of mouse colon 26. 5‐FU at the dosage level of 40 mg/kg suppressed the subcutaneous tumor growth by 70.0% and 45.0% on day 13 and day 18, respectively, and UFT at 20 mg/kg provided almost equal suppression (63.0% and 48.0%). In the liver metastasis model, 5‐FU at 40 mg/kg showed more potent prevention of the formation of metastatic foci (94.9%) than did UFT (60.4%) at 20 mg/kg. 5‐FU at 40 mg/kg produced a much higher peak serum level of 5‐FU than did UFT at 20 mg/kg and also showed a much higher AUC (area under the curve) level in the portal blood. These results suggest that oral administration of 5‐FU might be useful in prevention of liver metastasis of colorectal cancer.