Inclusion Criteria:

• Cytologic or histologic proof of pancreatic ductal carcinoma is required prior to treatment. Tumor must be located in the head or neck to the right of the spleno-portal confluence such that the appropriated surgical procedure is a pancreaticoduodenectomy
• No evidence of metastatic disease as determined by chest CT scan, abdominal CT scan (or MRI with gadolinium and/or manganese), and all patients must be staged with a physical exam, chest CT, and abdominal CT with intravenous contrast. Only potentially resectable patients are eligible.

Potentially resectable is defined as: a)no extrapancreatic disease, b)no evidence (on CT) of involvement of the celiac axis or superior mesenteric artery, and c)no evidence (on CT or MRI) of occlusion of the superior mesenteric vein or superior mesenteric-portal venous confluence.

• 18 years of age or older
• ECOG Performance status of 0 or 1
• Women of child bearing potential must practice adequate contraception and to refrain from breast feeding. Female patients must have a negative pregnancy test within 7 days of treatment
• Lab values as specified in the protocol

Exclusion Criteria:

• Patients cannot have hepatic or peritoneal metastases detected by imaging or laparoscopy prior to chemoradiation
• Serious concomitant systemic disorders incompatible with the study, such as significant cardiac or pulmonary morbidity, or ongoing infection as manifested by fever
• Pregnant or lactating women
• Life expectancy < 3 months
• Serious, uncontrolled, concurrent infection(s)
• Any prior chemotherapy or radiation for treatment of the patient's pancreatic tumor
• Treatment for other cancers within the last five years, except cured non-melanoma skin cancer and treated in situ cervical cancer
• Clinically significant cardiac disease or myocardial infarction within the last 12 months
• Other serious uncontrolled medical conditions that the investigator feels might compromise study participation
• Lack of physical integrity of the upper gastrointestinal tract or malabsorption syndrome
• Known, existing uncontrolled coagulopathy
• Unwillingness to participate or inability to comply with the protocol for the duration of the study
• Any prior fluoropyrimidine therapy (unless given in an adjuvant setting and completed at least 6 months earlier)
• Prior unanticipated severe reaction to fluoropyrimidine therapy, or known hypersensitivity to 5-fluorouracil or known DPD deficiency
• Participation in any investigational drug study within 4 weeks preceding the start of study treatment
• History of uncontrolled seizures, central nervous system disorders or psychiatric disability judged by the investigator to be clinically significant, precluding informed consent, or interfering with compliance or oral drug intake
• Major surgery, excluding laparoscopy, within 4 weeks of the start of study treatment, without complete recovery
• Patients should not be on cimetidine as it can decrease the clearance of 5-FU. Another H2-blocker or proton pump inhibitor may be substituted before study entry