[5-FU concentration in the blood and tissue of patients with gastric and colorectal cancer after administration of UFT or tegafur].

UFT or tegafur (5, 7.5 and 15 mg/kg, respectively) were given to Donryu rats with AH-130 cancer twice a day for 3 days, and 5-FU concentrations in the blood, tumor, normal stomach and large bowel tissues were measured by chemical assay and compared. The 5-FU concentrations in the tumor were higher than those of normal tissues and still remained 12 hours after the final dosage. According to increased UFT dosage, there were significantly higher levels of 5-FU concentration in tumor tissues but blood levels of 5-FU were low. The peak of concentration occurred at one to two hours after the final dosage. However, increase in tegafur dosage volume did not correlate with 5-FU levels. Clinical cases (74 patients) of gastric and colorectal cancer were orally administered UFT or tegafur at 300 mg twice a day for 3 days preoperatively. Materials were obtained at surgery at 5.5 hours on average after the final dosage and 5-FU levels in tissues were measured by chemical assay. Concentrations of 5-FU in cancerous tissues after UFT administration were 0.177 +/- 0.131 micrograms/g in gastric cancer and 0.130 +/- 0.051 micrograms/g in colorectal cancer, while in patients to whom tegafur had been administered, the concentrations were 0.194 +/- 0.124 micrograms/g and 0.119 +/- 0.075 micrograms/g, respectively. There was no significant difference in 5-FU levels between the UFT-administered group and the tegafur group.