Sensitivity Test for 5-Fluorouracil and Its Analogues, 1-(2-Tetrahydrofuryl)-5-Fluorouracil, Uracil/1-(2-Tetrahydrofuryl)-5-Fluorouracil (4:1) and 1-Hexylcarbamoyl-5-Fluorouracil, Using the Subrenal Capsule Assay

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Abstract
The chemosensitivity of 20 human neoplastic tissues including 13 gastric and 7 colorectal cancers was tested using 5-fluorouracil (5-FU) and its analogues: 1-(2-tetrahydrofuryl)-5FU (FT), uracil/FT (UFT) and 1-hexylcarbamoyl-5-FU (HCFU), and the in vivo subrenal capsule (SRC) assay. The relative variation of tumor size (.DELTA.TS/TS0) was calculated as follows: .DELTA.TS/TS0 = (TS6-TS0/TS0) .times. 100%, where TS6 was the tumor size of day 6 and TS0 on day 0, and the chemosensitivity was considered to be sensitive when .DELTA.TS/TS0 in the treated group was decreased to below -10%. The mean tumor size was -10.9 .+-. (SD)10.9% for 5-FU, -12.3 .+-. 17.1% for FT, -18.4 .+-. 15.8% for UFT and -17.9 .+-. 15.4% for HCFU. The decrease of tumor size was marked when exposed to UFT (p < 0.01) or HCFU (p < 0.02), compared with that to 5-FU. Positive correlations were noted bewteen the tumor sizes of 5-FU and its analogues (5-FU vs. FT, r = 0.851; 5-FU vs. UFT, r = 0.746; 5-FU vs. HCFU, r = 0.685). In 9 tissues resistant to 5-FU, 2 (22%) were sensitive to FT, 4 (44%) to UFT, 5 (56%) to HCFU and 7 tissues (78%) to at least one of these analogues. These results suggest that the SRC assay is useful for predicting the effective drug among 5-FU and 5-FU analogues, for individual patients with cancer.