RATIONALE: Biliary stenting is the placement of a tube in the bile ducts to keep a blocked area open. Photodynamic therapy uses a drug, such as porfimer sodium, that is absorbed by tumor cells. The drug becomes active when it is exposed to light. When the drug is active, tumor cells are killed. It is not yet known whether biliary stenting is more effective with or without photodynamic therapy in treating patients with biliary tract tumors.