Immunohistochemical Analysis of Human Equilibrative Nucleoside Transporter-1 (hENT1) Predicts Survival in Resected Pancreatic Cancer Patients Treated with Adjuvant Gemcitabine Monotherapy

Background. Gemcitabine is a promising adjuvant treatment for patients with resected pancreatic cancer. Human equilibrative nucleoside transporter-1 (hENT1) is the major transporter responsible for gemcitabine uptake into cells. The aim of this study was to retrospectively determine the relationship between the outcome of pancreatic cancer after surgery followed by postoperative gemcitabine monotherapy and the expression of hENT1. Methods. A total of 27 resected pancreatic cancer patients treated with adjuvant gemcitabine were analyzed for tumor hENT1 expression via an immunohistochemical analysis. The staining intensity and the percentage of positive tumor cells were scored, and the composite score (hENT1 score) was obtained by obtaining the sum of these two scores. Results. There were 11 patients assigned to the low hENT1 expression group, and 16 patients to the high hENT1 group. The patients with tumors that had higher hENT1 expression had a significantly longer disease-free survival (DFS) (log rank, P = 0.022) and overall survival (OS) (P = 0.024). The hENT1 expression was indicated to be a significant and independent prognostic factor for OS by the univariate (P = 0.030) and multivariate analyses (P = 0.019). Conclusions. A high expression of hENT1 in pancreatic cancer was found to be significantly associated with a longer survival in patients who received adjuvant gemcitabine monotherapy after curative resection, and hENT1 immunohistochemistry may well serve as a significant prognostic factor for these patients.