Ma WJ, et al. - In this retrospective study, researchers examined the efficacy of additional resection of invasive cancer proximal ductal margin (PM) under different levels of preoperative carbohydrate antigen 19-9 (CA19-9) by analyzing data from patients who had hepatectomy for hilar cholangiocarcinoma (HCCA) from 2000 to 2017. Results of this study suggested that survival in HCCA patients could benefit from a negative PM following additional resection. Among HCCA patients, survival could be similar to that of negative PM without additional resection. It was noted that a length of the PM >10 mm was maybe more related to better survival vs whether additional resection of the positive PM was conducted under different levels of preoperative CA19-9.