Both markers are nonspecific and insufficient for accurate diagnosis.36 Several other potential serum tumor markers have been linked to CCA (eg, CYFRA21–1, CA-195, CA-242, DU-PAN-2, IL-6, and trypsinogen-2), but their clinical utility is still unclear, and they are not in routine use.36,45. This evidence concerns the gene PAN2 and cholangiocarcinoma.