Human equilibrative nucleoside transporter 1 (hENT1) is a membrane transporter which is a predicting marker for gemcitabine chemotherapy. However, there is a limited evidence of it as an indicator for adjuvant gemcitabine chemotherapy. In this study, investigators try to investigate the role of hENT1 as a indicator of selection of adjuvant chemotherapy regimen between gemcitabine and 5-fluorouracil (5-FU).

After surgical resection of pancreatic cancer, the tissue is immunostained by hENT1 antibody. The grades of immunostaining are categorized as 0 (0%), 1 (<50%), and 2 (>=50%). According to the grade, patients with grade 0 or 1 will be treated with 5-FU and those with grade 2 will be treated with gemcitabine. After the study, investigators will calculate the overall survival and recurrence free survival of the patients and investigate the role of hENT1 as a predictive biomarker for adjuvant gemcitabine chemotherapy.

Inclusion Criteria:

• Patients with curatively resected pancreatic cancer
• Age between 18 and 75
• Eastern Cooperative Oncology Group performance score 0 or 1
• Patients with compliance
• Patients with informed consent

Exclusion Criteria:

• Patients refuse to enroll this study
• Patients with concomitant chemoradiation therapy
• Previous chemotherapy
• Pregnant or preparing a pregnancy
• Uncontrolled infection, diabetes, hypertension, ischemic heart disease, myocardial infarction within 6 months
• Enrolled another clinical trial within 30 days
• Patients will be expected to be risk because of enrollment
• Patients without informed consent