Gemcitabine-Based Chemoradiotherapy Followed by Surgery for Borderline Resectable and Locally Unresectable Pancreatic Ductal Adenocarcinoma: Significance of the CA19-9 Reduction Rate and Intratumoral Human Equilibrative Nucleoside Transporter 1 Expression

OBJECTIVES: This study aimed to evaluate the efficacy of gemcitabine-based chemoradiotherapy followed by surgery (gem-CRTS) for pancreatic ductal adenocarcinoma (PDAC) for borderline resectable (BR) and locally unresectable (UR) tumors. METHODS: One hundred patients with PDAC who underwent the gem-CRTS protocol were classified into 3 groups, namely, resectable (R; 14), BR (44), and UR (42). After chemoradiotherapy, the patients were reassessed for curative-intent resection. RESULTS: At reassessment, distant metastases became apparent in 27% of R patients, in 12% of BR patients, and in 18% of UR patients. The multivariate analysis of preoperative factors indicated that the CA19-9 reduction rate was an independent prognostic factor in the BR group. Among reassessed patients, the resection rate was 63.6% in R, 83.7% in BR, and 50.0% in UR patients. In 63 patients that underwent curative-intent resection, the 3-year survival rate was 83.3% in R, 33.0% in BR, and 7.8% in UR patients. Using multivariate analysis, the independent prognostic factor was found to be the surgical margin in BR patients and human equilibrative nucleoside transporter 1 expression in UR patients. CONCLUSIONS: We consider that our gem-CRTS protocol, even for locally UR PDAC, allows for the identification of candidates for aggressive resection at the time of reassessment and improved prognosis in the patients with positive human equilibrative nucleoside transporter 1 expression.