OUTLINE: This is a randomized, multicenter study. Patients are stratified according to superior mesenteric vein (SMV)/portal vein (PV) occlusion (yes vs no), SMV/PV/superior mesenteric artery/hepatic artery abutment or narrowing (yes vs no), prior exploration (yes vs no), and whether deemed to require preoperative therapy due to other factors (yes vs no). Patients are randomized to 1 of 2 treatment arms.