Human equilibrative nucleoside transporter 1 expression is a strong independent prognostic factor in UICC T3-T4 pancreatic cancer patients treated with preoperative gemcitabine-based chemoradiotherapy

We aimed to determine the relationship between the intratumoral expression of human equilibrative nucleoside transporter (hENT1), the main gemcitabine transporter into cells, and the outcome of gemcitabine-based chemoradiotherapy (Gem-CRT) in patients with International Union Against Cancer (UICC) T3-T4 pancreatic adenocarcinoma. The expressions of hENT1, thymidylate synthase (TS), and dihydropyrimidine dehydrogenase were immunohistochemically analyzed using the resected specimens from 55 patients (T3, 38 and T4, 17) who had received curative-intent resection after Gem-CRT. The status of hENT1 expression (positive in 39 and negative in 16) was significantly associated with "clinical efficacy" (defined as more than 50% reduction of the serum carbohydrate antigen [CA] 19-9 level with stable disease [SD] or partial response [PR] according to the Response Evaluation Criteria in Solid Tumors [RECIST]) for Gem-CRT. The 1- and 3-year overall survival (OS) rates were significantly higher in the positive hENT1 expression group (82.9, 39.5%) than in the negative expression group (42.9, 14.3%) (p = 0.0037). According to combination analysis of hENT1 and TS expressions, the 1- and 3-year OS rates were significantly higher in the positive-low combination (89.1, 51.0%) group than in the negative-high group (66.7, 0%) (p = 0.023). Multivariate analysis revealed that positive hENT1 expression and R0 resection were significant prognostic factors for OS. The hENT1 expression in pancreatic adenocarcinoma strongly influences the outcome of preoperative Gem-CRT treatment. This biomarker could become a useful predictor of therapeutic effect for gemcitabine-based therapy in pancreatic cancer patients.