UFT in the treatment of colorectal and breast cancer.

UFT and leucovorin (Orzel) is a combination of tegafur and uracil in a molar ratio of 1:4. Tegafur, a prodrug of 5-fluorouracil (5-FU), is converted to 5-FU by the hepatic cytochrome P450 pathway, whereas uracil enhances the half-life of converted 5-FU leading to prolonged exposure and higher intracellular concentration of 5-FU by inhibiting dihydropyrimidine dehydrogenase (DPD), a rate-limiting enzyme in 5-FU catabolism. UFT has broad antitumor activity against colorectal and breast cancer, and has been studied extensively worldwide. Trials conducted in the United States have mainly focused on the combination of UFT and leucovorin. Compared with an intravenous 5-FU plus leucovorin regimen in advanced colorectal cancer treatment, UFT plus leucovorin appears to have equivalent antitumor efficacy with less toxicity. UFT may also provide a more convenient protracted treatment method with fewer complications, compared to intravenous programs. The application for FDA approval of UFT with leucovorin as a first-line treatment regimen for advanced colorectal cancer is pending. Administered as a single agent or in combination with other chemotherapy agents and hormones, UFT may also be effective in treating breast cancer, either as a primary adjuvant treatment or as palliative treatment for metastatic disease.