Clinical application of biochemical modulation in cancer chemotherapy: biochemical modulation for 5-FU.

The addition of Uracil to Tegafur, a prodrug of 5-fluorouracil (5-FU), has been shown to enhance the antineoplastic effect of 5-FU while reducing the side effects attributed to 5-FU catabolism. Studies of 5-FU levels have shown that the 5-FU concentration in the tumor tissues of patients with head and neck cancer was 16.9 times greater than that in serum and approximately 2-6 times greater than in normal tissue. Similar observations have been made in tumor tissues of patients with breast cancer. The clinical efficacy of UFT, the combination of Uracil and Tegafur in a molar ratio of 4:1, has been studied in a variety of tumor types. An overall response rate of about 23% was obtained, with responses exceeding 30% in patients with head and neck, breast, and bladder cancer. Side effects are predominantly that of gastrointestinal toxicity. Hematologic toxicity is minimal and hepatotoxicity is rare. The UFT combination produces a good clinical effect in a variety of tumor types and is well tolerated.