Clinical application of immunoreactivity of dihydropyrimidine dehydrogenase (DPD) in gastric scirrhous carcinoma treated with S-1, a new DPD inhibitory fluoropyrimidine.

BACKGROUND A highly specific antibody against recombinant human dihydropyrimidine dehydrogenase (DPD) has been developed to immunohistochemically assess DPD expression in tumors. A new oral DPD inhibitory fluoropyrimidine (DIF), S-1, is reportedly effective against gastric scirrhous carcinoma. PATIENTS AND METHODS In this study, the relationship between immunoreactivity to DPD in biopsy specimens and the effects of chemotherapy were investigated in 61 patients treated with first-line fluoropyrimidine-based chemotherapy (S-1:DIF, 5-FU:non-DIF) for gastric scirrhous carcinoma. RESULTS The response rate was significantly higher in patients with DPD-positive tumors than in those with DPD-negative tumors in the S-1 group (45.5%, 10.0%: p < 0.05), as compared to the 5-FU group (0%, 5.6%: p = 0.398). According to the median survival time, there was no significant difference between patients with DPD-positive tumors (364 days) and those with DPD-negative tumors (406 days; p = 0.626) in either the S-1 group or the 5-FU group (181 days and 256 days, respectively; p = 0.543). CONCLUSION This study indicates that S-1 may be effective even in gastric scirrhous carcinoma with a high level of DPD activity.