A study from the Mayo group included 25 patients with unresectable cholangiocarcinoma who were treated with PDT from 1991 to 2004 showed that the time interval between diagnosis and treatment with PDT is an important predictor of survival following PDT even when adjusted for other potential factors that affect survival such as age, gender, Bismuth stage, presence of tumor mass on imaging and presence of extra biliary spread. Early treatment with PDT may lead to greater preservation of liver function. A recent study by the primary investigator has also recently reported improved survival in patients receiving PDT and stent compared to stent only (16.2 months vs 7.4 months).