Incidence and risk factors of portal vein or bile duct invasion in colorectal liver metastases

Introduction: There are few reports about portal vein or bile duct invasion (PBI) in colorectal liver metastases (CRLM). We experienced a case with CRLM having positive resection margin due to portal vein invasion after non-anatomical resection. The aim of this study was to evaluate the frequency of PBI and clinico-pathological factors to predict PBI. Method: Between September 2009 and June 2017, 113 patients with CRLM underwent hepatectomy in our institution. We defined “Pathological PBI” as pathologically diagnosed portal vein or bile duct invasion. “Radiological PBI” was defined as the presence of any of following radiological findings in dynamic CT; “the presence of A-P shunt or bile duct dilation in the peripheral region of the tumor” or “tumor thrombus in the portal vein”. Clinico-pathological factors including primary tumor characteristics and CRLM characteristics were analyzed. Results: Among 113 patients, 69.9%(71 patients) was male, and median age at hepatectomy was 71 years old. Anatomical resection was performed in 76 patients (67.2%). Pathological PBI was found in 29 patients (25.7%). On univariate analysis, “Primary T status was T4b (80.0% vs 23.1%, p=0.015)” and “presence of radiological PBI (62.5% vs 15.7%, p< 0.01)” were associated with pathological PBI. We could not find any clinical implication of PBI including recurrence and overall survival. Conclusions: PBI is not rare in CRLM and the presence of PBI should be considered in whom primary T status was T4b and PBI was suspected on preoperative CT. Reconsideration of the optimal surgical procedure for those patients may be necessary.