[Antitumor effect of UFT against differentiated thyroid cancer].

We have determined the levels of 5-FU, tegafur and uracil in the thyroid cancer and normal thyroid tissue in the patients with differentiated carcinoma who were administered UFT 600 mg/day p.o. preoperatively for six days. 5-FU and uracil levels in the thyroid cancer tissue were significantly higher than in normal thyroid tissue. However, tegafur level did not show significant differences in any tissues. Two cases with differentiated carcinoma, which resulted in PR after prolonged administration of UFT were presented. These findings suggest that oral administration of UFT for a long term is a useful treatment for advanced differentiated thyroid cancer.