The purpose of this study is to identify and evaluate changes in blood and bile that may give specific indications of malignant cell metabolism in cancer. Recently, a lot of research has been done to test for certain markers in the bile to detect cancer in a stricture. In addition to the bile, a lot of research has been done to test for certain markers like blood peptide markers of patients who have had cancer in the bile duct. Testing for these markers may help doctors in the future to better determine whether the narrowing or stricture in a bile duct is cancer or not.