Important CT Findings for Prediction of Incomplete (R1 or R2) Resection and Poor Survival of Perihilar Cholangiocarcinoma after Curative-Intent Surgery

Abstract

Purpose: To evaluate CT findings to predict incomplete (R1 or R2) resection and poor survival in patients with perihilar cholangiocarcinoma using pre-operative CT.Materials and Methods: From 2006 to 2012, a total of 139 patients with perihilar cholangiocarcinoma who underwent pre-operative multiphase CT and subsequent curative-intent surgery were included. After two radiologists independently reviewed CT findings including the likelihood of bile duct (BD) involvement from intrapancreatic common bile duct (CBD) to bilateral second-order branches and peritumoral fat stranding using a 5-point scale, vessel involvement (no, abutment, encasement), and LN involvement, imaging findings were finalized by a consensus of two radiologists. When the likelihood scale of 4 or more on preoperative CT was regarded as BD involvement, the diagnostic ability of CT was analyzed by the receiver operating curve using histopathologic results as a reference standard. Residual tumor categorized into no residual tumor (R0) and residual tumor (R+; R1 or R2). Predictive factors of R+ resection on pre-operative CT were analyzed by logistic regression. Cox proportional hazard model was used to determine the prognostic factor for overall survival by using pre-operative CT findings and laboratory results.Results: Seventy-one patients were R0 and sixty-eight patients were R+ resection. For resectability evaluation, mid-CBD involvement (score ≥ 4) in pre-operative CT was significant factor for R+ resection in multivariable analysis (<i>P</i> < 0.01) with substantial interobserver agreement. In multivariable Cox regression, intrapancreatic CBD involvement (score ≥ 4, hazard ratio [HR] = 1.81, <i>P</i> < 0.01) as well as elevated total bilirubin (HR = 1.53, <i>P</i> = 0.04) and CA 19-9 level (HR = 1.75, <i>P</i> < 0.01) were significant predictors for poor survival. Diagnostic ability to predict mid-CBD and intrapancreatic CBD involvement on pre-operative CT were 0.71 and 0.72 (AUC values).Conclusions: Distal longitudinal extent of perihilar cancer on pre-operative CT is a significant factor for margin positive resection and poor survival on curative-intent surgery.