Clinical implications of dihydropyrimidine dehydrogenase expression in patients with pancreatic cancer who undergo curative resection with S-1 adjuvant chemotherapy

The predictive roles of dihydropyrimidine dehydrogenase (DPD) in patients who undergo curative resection and adjuvant chemotherapy with S-1, which is the oral 5-fluorouracil prodrug tegafur combined with oteracil and gimeracil, remain unclear. In the present study, the clinical data from 66 consecutive patients who underwent curative resection and received adjuvant chemotherapy with S-1 for the treatment of pancreatic cancer at Kanagawa Cancer Center (Yokohama City, Japan) from April 2005 to March 2014 were retrospectively analyzed. The association between the DPD status and the survival and clinicopathological features were investigated. Of the 66 patients, 34 patients exhibited positive DPD expression (51.5%). Although a significant increase in DPD expression in male patients was observed, no significant differences were identified for other clinicopathological parameters, including tumor factor or node factor, between the DPD-positive expression group and the DPD-negative expression group. The median follow-up period of the present study was 29.2 months. There was no significant difference in the 3-year overall survival (OS) rates following surgery, which were 12.6 and 14.5% in the DPD-positive and DPD-negative expression groups, respectively (P=0.352). However, in a subgroup analysis, a significant difference in the 3-year OS rates following surgery was noted, which were 58.9 and 14.5% in the DPD-high and DPD-low expression groups, respectively (P=0.019). The intratumoral DPD expression in curatively resected pancreatic cancer patients treated with S-1 adjuvant chemotherapy was identified to not be useful as a predictive marker, whereas the level of DPD expression is a potential predictive marker. The results of the present study require confirmation in another cohort or in a prospective multicenter study.