Intratumoural expression of dihydropyrimidine dehydrogenase is an independent prognostic factor in resected pancreatic ductal adenocarcinoma treated with adjuvant gemcitabine

Pancreatic ductal adenocarcinoma (PDAC) is associated with a poor prognosis, and biomarkers to guide treatment decisions in PDAC are generally lacking. Intratumoural expression of dihydropyrimidine dehydrogenase (DPD) is a potential prognostic parameter in patients with PDAC undergoing surgical resection and postoperative chemotherapy. In the present study, DPD was analysed by immunohistochemistry of a tissue microarray platform including a real-world cohort of 495 patients with PDAC who had undergone resection with curative intent at any of three tertiary centres, including Northern, Western and Southeastern regions of Sweden, between 1993 and 2019. DPD level (high/low) was analysed and overall survival associations were assessed in treatment subgroups using a multivariate Cox regression model accounting for potential confounders. In patients who had not received adjuvant chemotherapy (n=182), the median overall survival time was 11.6 months (95% CI 9.6-13.5), compared with 28.8 months (25.0-32.6) among those who had (n=313; log-rank P<0.001). The most common type of chemotherapy was gemcitabine single agent (Gem, n=239) followed by gemcitabine plus capecitabine (GemCape, n=39). Tumour-Node-Metastasis (TNM) stage and DPD expression were statistically significant prognostic parameters in the Gem group (HR 1.19, 95% CI 1.01-1.41, P=0.036), with high expression of DPD linked with worse survival. In addition, tumour grade and TNM stage were statistically significant prognostic factors in the group that did not receive any chemotherapy (P≤0.001). No statistically significant parameters were identified in the GemCape group. Taken together, intratumoural expression of DPD may be considered a prognostic marker for patients with PDAC treated with adjuvant gemcitabine following surgical resection, with low expression levels predicting better survival. Further studies in larger cohorts of patients receiving multi-drug or non-gemcitabine based regimens are warranted.