OUTLINE: This is a multicenter, prospective, randomized study. Patients are stratified according to surgical center, disease site (hilar/extrahepatic cholangiocarcinoma vs intrahepatic cholangiocarcinoma vs gallbladder vs intrapancreatic/common bile duct), type of resection (R0 vs R1), and ECOG performance status (0 vs 1 vs 2). Patients are randomized to 1 of 2 treatment arms.