R1 vascular or parenchymal margins: what is the impact after resection of intrahepatic cholangiocarcinoma?

Background: to date, long-term outcomes of R1 vascular (R1vasc) and R1 parenchymal (R1par) resections in the setting of intrahepatic cholangiocarcinoma (iCCA) have been examined in only one study which did not find significant difference. Patients and Methods: we analyzed consecutive patients who underwent iCCA resection between 2000 and 2019 in two tertiary French medical centers. We report overall survival (OS) and disease-free-survival (DFS). Univariate and multivariate analyses were performed to determine associated factors. Results: 195 patients were analyzed. The number of R0, R1par and R1vasc patients was 128 (65.7%), 57 (29.2%) and 10 (5.1%), respectively. The 1- and 2-year OS rates in the R0, R1par and R1vasc groups were 83%, 87%, 57% and 69%, 75%, 45%, respectively (p = 0.30). The 1- and 2-year DFS rates in the R0, R1par and R1vasc groups were 58%, 50%, 30% and 43%, 28%, 10%, respectively (p = 0.019). Resection classification (HR 1.56; p = 0.003) was one of the independent predictors of DFS in multivariate analysis. Conclusions: the survival outcomes after R1par resection are intermediate to those after R0 or R1vasc resection. R1vasc resection should be avoided in patients with iCCA as it does not provide satisfactory oncological outcomes.