Gemcitabine Hydrochloride, Oxaliplatin, and Erlotinib Hydrochloride in Treating Patients With Advanced Biliary Tract Cancer, Pancreatic Cancer, Duodenal Cancer, or Ampullary Cancer

RATIONALE: Drugs used in chemotherapy, such as gemcitabine hydrochloride and oxaliplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Erlotinib hydrochloride may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Giving gemcitabine hydrochloride and oxaliplatin together with erlotinib hydrochloride may kill more tumor cells. PURPOSE: This phase I trial is studying the side effects and best dose of erlotinib hydrochloride when given together with gemcitabine hydrochloride and oxaliplatin in treating patients with advanced biliary tract cancer, pancreatic cancer, duodenal cancer, or ampullary cancer.