[Human colorectal carcinoma is more sensitive to HCFU than 5-FU and tegafur in in vitro and in vivo drug sensitivity tests].

The sensitivity of human colorectal cancer to 5-fluorouracil (5-FU) and its derivatives: 1-(tetrahydro-2-furyl)-5-FU (tegafur) and 1-hexylcarbamoyl-5-FU (HCFU) was determined by in vitro succinate dehydrogenase inhibition (SDI) test and in vivo subrenal capsule (SRC) assay. Using the SDI test with 25 colorectal cancer specimens, the succinate dehydrogenase (SD) activity decreased to 73.6 +/- 17.8% for 5-FU-treated cells and 37.2 +/- 17.0% for HCFU-treated cells, compared to that of control cells. The chemosensitivity-positive rates were 16% for 5-FU and 68% for HCFU. Using the SRC assay with 7 colorectal cancer specimens, the relative variation of tumor size, which was calculated by delta TS/TS0 = (TS6-TS0)/TS0 X 100 (%), decreased to -12.6 +/- 10.1% for 5-FU, -14.9 +/- 12.4% for tegafur and -23.9 +/- 14.2% for HCFU, and the inhibition of tumor growth following exposure to HCFU was evident. The chemosensitivity-positive rates were 49% for 5-FU, 57% for tegafur and 71% for HCFU. Our results show that HCFU is more effective to colorectal cancer than 5-FU and FT-207, and the chemosensitivity test of HCFU will be useful in determining the effective drug for the treatment of colorectal cancer.