Background & aims: Primary sclerosing cholangitis (PSC) is associated with increased risk of cholangiocarcinoma (CCA). Early and accurate CCA detection represents an unmet clinical need, as the majority of PSC patients are diagnosed at advanced stage of malignancy. In the present study, we aimed at establishing robust DNA methylation biomarkers in bile for early and accurate diagnosis of CCA in PSC.
Approach & results: Droplet digital PCR (ddPCR) was used to analyze 344 bile samples from 273 patients with sporadic- and PSC-associated CCA, PSC, and other non-malignant liver diseases for promoter methylation of CDO1, CNRIP1, SEPT9 and VIM. Receiver operating characteristics (ROC) curve analyses revealed high area under the ROC curves (AUCs) for all four markers (0.77-0.87) for CCA detection among patients with PSC. Including only samples from PSC patients diagnosed with CCA ≤12 months following bile collection increased the accuracy for cancer detection, with a combined sensitivity of 100% (28/28) and a specificity of 90% (20/203). The specificity increased to 93% when only including PSC patients with long time follow-up (>36 months) as controls, and remained high (83%) when only including PSC patients with dysplasia as controls (n=23). Importantly, the bile samples from the CCA-PSC ≤12 patients, all positive for the biomarkers, included both early- and late stage CCA, different tumor growth patterns, anatomical locations, and CA 19-9 levels.
Conclusions: By using highly sensitive ddPCR to analyze robust epigenetic biomarkers, CCA in PSC was accurately detected in bile, irrespective of clinical and molecular features, up to 12 months before CCA diagnosis. The findings suggest a potential for these biomarkers to complement current detection and screening methods for CCA in patients with PSC.
Keywords: Biliary tract cancer; PCR; biomarkers; epigenetics; surveillance.
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