Tumor 5-FU-related mRNA Expression and Efficacy of Oral Fluoropyrimidines in Adjuvant Chemotherapy of Colorectal Cancer.

It has not been elucidated whether the clinical efficacy of oral fluoropyrimidines for adjuvant chemotherapy of colorectal cancer varies with tumor biological characteristics. A multicenter randomized trial was performed comparing oral tegafur/gimeracil/oteracil (S-1) and uracil-tegafur/ leucovorin (UFT/LV) as adjuvant therapy for stage III colorectal cancer. Postoperative survival was compared based on the 5-FU-related mRNA levels in cancer tissues. Among patients with tumor expressing dihydropyrimidine dehydrogenase (DPD) mRNA within the 66.7th percentile (lower 2/3) of all cases, overall survival (OS) was significantly better in the S-1 than in the UFT/LV group. In the S-1 group, patients with low DPD-expressing tumors had significantly better OS than those with highly expressing tumors. Patients with low thymidine synthase (TS)-expressing tumors had significantly better OS than those with highly expressing tumors. The efficacy of oral fluoropyrimidines as adjuvant chemotherapy for colorectal cancer may be influenced by the level of 5-FU-related mRNA in cancer tissues.