Prevalence and clinical significance of biliary intraepithelial neoplasia (BilIN) in cholangiocarcinoma

Biliary intraepithelial neoplasia (BilIN) is the most common noninvasive precursor lesion which progresses to cholangiocarcinoma (CC) and is often found synchronously adjacent to the tumor or at the surgical resection margin. The aim of this study was to elucidate the prevalence and prognostic effect of BilIN on survival after resection for CC. We retrospectively analyzed the database of patients with CC who underwent surgery performed at our institution from 2010 to 2017. There were 142 patients who underwent surgery for CC. BilIN was detected in 42 patients (29.5%). On univariate analysis, extrahepatic CC (ExtraH CC) patients with BilIN lesions significantly showed better disease-free survival (P 5 0.05). Also, although not statistically significant, ExtraH CC patients with BilIN lesions revealed better overall survival (OS) (P 5 0.09). On multivariate analysis, presence of BilIN lesion, irrespective of location, was significantly associated with better disease-free survival (HR 5 2.059, 95% confidence interval (CI): 1.057-4.432, P 5 0.041) and OS (HR 5 1.831, 95% CI: 1.149-3.534, P 5 0.044) in ExtraH CC patients. The presence of BilIN lesions was not uncommon in CC patients and was significantly associated with better diseasefree survival and OS in ExtraH CC patients. However, larger studies with longer follow-up are needed to accurately determine its clinical significance.