The concentrations of
1-hexylcarbamoyl-5-fluorouracil (
HCFU), were determined in sera and in tissues of patients with gynecologic
cancers. In patients who received a single administration of 600 mg of
HCFU, the concentrations of
5FU in tissues were higher than 0.05 microgram/g, which has been appreciated as a sufficiently effective concentration to act on
cancer cells. The concentration of
5FU in tissues ranged from one-fifth to one-tenth of those in sera. In patients who received daily administrations of 600 mg of
HCFU for more than 28 days, the concentrations of
5FU in tissues were about 0.05 microgram/g, while serum concentrations were lower than 0.02 microgram/ml. The concentrations of
5FU in tissues of patients who received daily administrations of 600 mg of
HCFU for more than 28 days and a single additional administration of 200 mg of
HCFU were the same as those in patients who received a single administration of 600 mg of
HCFU immediately before the determinations. In patients who received 400 mg of
HCFU per day divided into 4 doses, the concentrations of
5FU in tissue might be higher than 0.05 microgram/g, based on the concentrations in sera.
HCFU might be effective against gynecologic
cancers when used in maintenance
therapy at a lower dosage (300--400 mg) than previously estimated.