Chemotherapy and Radiation Therapy in Treating Patients With Locally Advanced Pancreatic Cancer

OBJECTIVES: * Compare the percentage of margin-free resections in patients with locally advanced, potentially resectable adenocarcinoma of the pancreas treated with gemcitabine and radiotherapy vs gemcitabine, fluorouracil, and cisplatin followed by radiotherapy and fluorouracil. * Compare the efficacy of these regimens, as measured by CT scan response, in these patients. * Compare the posttreatment fibrosis in resected specimens of patients treated with these regimens. * Compare the toxicity of these regimens in these patients. * Compare the duration of objective response in patients treated with these regimens. * Compare the disease-free and overall survival of patients treated with these regimens. * Compare the effect of these regimens and disease recurrence on CA 19-9 values in these patients. OUTLINE: This is a randomized, multicenter study. Patients are stratified according to superior mesenteric vein (SMV)/portal vein (PV) occlusion (yes vs no), SMV/PV/superior mesenteric artery/hepatic artery abutment or narrowing (yes vs no), prior exploration (yes vs no), and whether deemed to require preoperative therapy due to other factors (yes vs no). Patients are randomized to 1 of 2 treatment arms. * Arm I: Patients undergo radiotherapy once daily 5 days a week for 6 weeks. Patients receive gemcitabine IV over 50 minutes once weekly for 6 weeks during radiotherapy. Patients undergo surgical resection 4-6 weeks after completion of chemoradiotherapy. Maintenance therapy (4-8 weeks after completion of surgery): Patients receive gemcitabine IV over 100 minutes once weekly for 2 weeks. Treatment repeats every 3 weeks for 5 courses in the absence of disease progression or unacceptable toxicity. * Arm II: Patients receive gemcitabine IV over 30 minutes on days 1, 5, 29, and 33; cisplatin IV over 60 minutes on days 1-5 and 29-33; and fluorouracil IV continuously on days 1-4 and 29-32. Patients also receive filgrastim (G-CSF) subcutaneously (SC) daily on days 6-15 and 34-43 and epoetin alfa SC weekly on weeks 1-9. After completion of chemotherapy, patients undergo radiotherapy once daily 5 days a week for 6 weeks. Patients receive fluorouracil IV continuously daily during radiotherapy. Patients undergo surgical resection 4-6 weeks after completion of chemoradiotherapy. Maintenance therapy (4-8 weeks after completion of surgery): Patients receive gemcitabine IV over 100 minutes once weekly for 2 weeks. Treatment repeats every 3 weeks for 3 courses in the absence of disease progression or unacceptable toxicity. Patients are followed every 3 months for 2 years and then every 6 months for 2 years. PROJECTED ACCRUAL: A total of 80-160 patients (40-80 per treatment arm) will be accrued for this study.