Dihydropyrimidine dehydrogenase activity during long-term adjuvant treatment with oral uracil and tegafur for colorectal cancer

Abstract

Background: Dihydropyrimidine dehydrogenase (DPD) is a rate-limiting enzyme for the degradation of 5-fluorouracil. The effect of long-term treatment with oral fluoropyrimidines on DPD activity has not been investigated. This study was conducted to examine changes in DPD activity in peripheral mononuclear cells (PMNC) during long-term treatment with oral uracil and tegafur (UFT) for colorectal cancer.

Methods: UFT was administered for 5 consecutive days and not administered the next 2 days for 6 months after surgery. PMNC-DPD activity was measured before and 1, 2, 4 and 6 months after starting UFT administration.

Results: In 70 eligible patients, there were no significant variations of PMNC-DPD activity during postoperative administration of UFT for 6 months. Grade 2 or higher adverse events were observed in significantly more patients with low DPD than with high DPD activity (p = 0.018).

Conclusion: There were no significant variations of PMNC-DPD activity during the postoperative administration of UFT for 6 months. Low PMNC-DPD activity before UFT treatment was considered to be a predicting factor for toxicity.