Gemcitabine With or Without Cisplatin in Treating Patients With Unresectable Locally Advanced or Metastatic Cholangiocarcinoma or Other Biliary Tract Tumors

RATIONALE: Drugs used in chemotherapy, such as gemcitabine and cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy) may kill more tumor cells. It is not yet known whether gemcitabine is more effective with or without cisplatin in treating cholangiocarcinoma or biliary tract tumors. PURPOSE: This randomized phase III trial is studying gemcitabine and cisplatin to see how well they work compared to gemcitabine alone in treating patients with unresectable locally advanced or metastatic cholangiocarcinoma or other biliary tract tumors.