Prevalence and Clinical Significance of Biliary Intraepithelial Neoplasia (BilIN) in Cholangiocarcinoma

Biliary intraepithelial neoplasia (BilIN) is a noninvasive precursor lesion which progresses to cholangiocarcinoma (CC). BilIN is often found synchronously adjacent to the tumor or at the surgical resection margin of resection CC. However, irrespective of its location, its prognostic significance on outcome after CC resection is unknown. The aim of this study was to elucidate the prevalence of BilIN in CC and to determine if the presence of BilIN has a prognostic or predictive effect on survival after resection for CC with curative intent. We retrospectively analyzed the database of patients with CC who underwent curative surgery performed at our institution from 2010 to 2017. There were 142 patients who underwent curative surgery for CC. BilIN was detected in 42 patients (29.5%) and showed a significantly higher prevalence in extrahepatic CC (90.5%) than in intrahepatic CC (9.5%; p = 0.003). On univariate analysis, extrahepatic hepatic CC patients with BilIN lesions significantly showed better disease-free survival ( p = 0.05). Also, although not statistically significant, extrahepatic CC patients with BilIN lesions revealed better overall survival ( p = 0.09). On multivariate analysis, presence of BilIN lesion, irrespective of location, was significantly associated with better disease-free (HR = 1.959, 95% CI 1.026–3.743, p = 0.042) and overall survival (HR = 2.140, 95% CI 1.006–4.552, p = 0.048) in extrahepatic CC patients. In conclusion, the presence of BilIN lesions was not uncommon in CC patients and was significantly associated with better disease-free and overall survival in extrahepatic CC patients. However, larger studies with longer follow-up are needed to accurately determine its clinical significance.