Chemoradiation in Locally Advanced Pancreatic Cancer

RATIONALE: Drugs used in chemotherapy, such as fluorouracil and cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy) may kill more tumor cells. Radiation therapy uses high-energy x-rays to kill tumor cells. Interferon alfa may interfere with the growth of tumor cells. Giving combination chemotherapy and radiation therapy together with interferon alfa before surgery may shrink the tumor so it can be removed. Giving chemotherapy after surgery may kill any tumor cells that remain after surgery. PURPOSE: This phase II trial is studying how well giving combination chemotherapy and radiation therapy together with interferon alfa works in treating patients with locally advanced pancreatic cancer that cannot be removed by surgery.