Gemcitabine or Combination Chemotherapy Followed by Chemoradiation for Stage IB, II, or III Pancreatic Cancer

RATIONALE: Drugs used in chemotherapy, such as gemcitabine hydrochloride, cisplatin, epirubicin hydrochloride, fluorouracil, and capecitabine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Radiation therapy uses high-energy x-rays to kill tumor cells. It is not yet known whether gemcitabine hydrochloride is more effective when given alone or together with combination chemotherapy and radiation therapy in treating patients with pancreatic cancer. PURPOSE: This randomized phase II/III trial is studying gemcitabine hydrochloride to see how well it works when given alone or together with combination chemotherapy and radiation therapy in treating patients with stage IB, stage II, or stage III pancreatic cancer.