RATIONALE: Drugs used in chemotherapy, such as 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. Radiation therapy uses high-energy x-rays to kill tumor cells. Specialized radiation therapy that delivers a high dose of radiation directly to the tumor may kill more tumor cells and cause less damage to normal tissue. Giving more than one drug (combination chemotherapy) together with radiation therapy may kill more tumor cells.