Gemcitabine and Radiation Therapy in Treating Patients With Locally Advanced Upper Gastrointestinal Cancer

RATIONALE: Drugs used in chemotherapy, such as 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. Giving chemotherapy together with radiation therapy may kill more tumor cells. PURPOSE: This phase I trial is studying the side effects and best dose of gemcitabine when given together with radiation therapy in treating patients with locally advanced upper gastrointestinal cancer.