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

Introduction: Resection margin status is the 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 effect of positive RM on survival.

Methods: Patients with pCCA underwent curative resection between 2013 and 2018 were retrospectively reviewed. Resection margin status was 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 167 pCCA patients, 62 (37.1%) had R1 margin. Among 62 R1 patients; 17 (27.4%) had positive DM alone, 20 (32.3%) had positive RM alone and 25 (40.3%) had both positive DM and RM. The R1 patients had a significantly greater number of lymph node metastasis (LNM) and advanced tumor staging than R0 patients, however there was no difference between the RM + and DM + patients. The median survival time of patients with RM + was significantly poorer than R0 patients (13.8 vs. 24.5 months; p < 0.001, respectively) and similar to the DM + patients (9.1 months, p = 0.556). However, in patients with LNM, those who underwent R0 resection had no statistically significant difference in survival outcomes compared to those with R1 resection.

Conclusion: Positive resection margin remains the important prognostic factor, 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.