Erlotinib and Radiation Therapy in Treating Older Patients With Stage I, Stage II, Stage III, or Stage IV Esophageal Cancer

RATIONALE: Erlotinib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Radiation therapy uses high-energy x-rays to kill tumor cells. Giving erlotinib together with radiation therapy may kill more tumor cells. PURPOSE: This phase II trial is studying how well giving erlotinib together with radiation therapy works in treating older patients with stage I, stage II, stage III, or stage IV esophageal cancer.