The Status of Liver Margin in Perihilar Cholangiocarcinoma: A Multicenter Study.

OBJECTIVE This study aimed to investigate the prevalence and distribution of carcinoma in the liver margin (LM) of resected perihilar cholangiocarcinoma (pCCA) and establish a method for LM examination. BACKGROUND LM is the largest margin in resected pCCA with undefined status and assessment method. METHODS 227 pCCA cases underwent major hepatectomy were divided into a discovery cohort (n=101) assessed using serial whole-mount digital large sections (WDLS) combined with small sections, and a control cohort (n=126) assessed using only small sections. RESULTS The LM R1 resection rate was 38.6% (39/101) in the discovery cohort and 5.6% (7/126) in the control cohort. WDLS identified more LM R1 cases compared to the small section in the discovery cohort (38.6% vs. 5.9%, P<0.001). R0 patients in the discovery cohort had better overall survival and recurrence-free survival than those in the control cohort (both P<0.05). Additionally, 95% of carcinoma was found within 20 mm of the proximal ductal margin (DM). A proximal DM distance of<5 mm was an independent risk factor for LM R1 resection. Patients with which are more likely to experience R1 compared to those with ≥ 5 mm (P<0.001). CONCLUSIONS Positive LM was the significant cause for R1 resection of pCCA and the utilization of WDLS improved the diagnostic accuracy of LM. An examination methodology was established, highlighting the necessity of examining LM within a 20 mm radius around the proximal DM, especially in patients with a proximal DM of<5 mm.