Panitumumab, Chemotherapy, and External-Beam Radiation Therapy in Treating Patients With Locally Advanced Pancreatic Cancer That Cannot be Removed by Surgery

RATIONALE: Monoclonal antibodies, such as panitumumab, can block tumor growth in different ways. Some block the ability of tumor cells to grow and spread. Others find tumor cells and help kill them or carry tumor-killing substances to them. Drugs used in chemotherapy, such as fluorouracil, capecitabine, and gemcitabine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. External-beam radiation therapy uses high-energy x-rays to kill tumor cells. Panitumumab may also stop the growth of pancreatic cancer by blocking blood flow to the tumor and make tumor cells more sensitive to radiation therapy. Giving panitumumab together with chemotherapy and radiation therapy may kill more tumor cells. PURPOSE: This phase II trial is studying how well giving panitumumab together with chemotherapy and external-beam radiation therapy works in treating patients with locally advanced pancreatic cancer that cannot be removed by surgery.