The impact of positive resection margin in perihilar cholangiocarcinoma, ductal margin vs. radial margin

Background: Resection margin status is the most important prognostic factor in resected perihilar cholangiocarcinoma (pCCA).Although the impact of ductal margin (DM) was reported in many studies, the influence of radial margin (RM) is unclear.This study aims to investigate the incidence and the effect of positive RM on survival.Methods: Patients with pCCA who underwent curative resection between October 2013 to December 2018 were retrospectively reviewed.Resection margin status were divided into negative resection margin (R0) and positive resection margin (R1); positive RM alone (RM+) and positive DM with or without positive RM (DM+).Results: Of the 170 pCCA patients, 63 (37%) had R1 margin.Among 63 R1 patients; 18 (28.6%)had positive DM alone, 20 (31.7%) had positive RM alone and 25 (39.7%) had both positive DM and RM.The R1 patients had a significantly greater number of LN metastases and advanced tumor staging than R0 patients, however, there was no difference between the RM+ and DM+ patients.In contrast, the RM+ patients had more combined vascular resection than the DM+ patients.The median survival time of patients with RM+ was significantly poorer than R0 patients (13.8 vs. 24.7 months; p < 0.001, respectively) and similar to the DM+ patients (9.1 months, p = 0.561).In multivariable analysis, positive resection margin and LN metastasis were independent prognostic factors.Conclusions: Positive resection margin remains the most important prognostic factors and positive RM is common in these patients.Positive RM also had a comparable effect on survival as positive DM.As a result, in pCCA, surgical resection should target both RM and DM.