Capecitabine as Second-Line Therapy in Treating Patients With Stage IV Pancreatic Cancer Who Have the Thymidylate Synthase Gene

RATIONALE: Drugs used in chemotherapy, such as capecitabine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. PURPOSE: This phase II trial is studying how well capecitabine works as second-line therapy in treating patients with stage IV pancreatic cancer who have the thymidylate synthase gene.