BackgroundSeveral inflammatory indicators have been reported to have predictive value in many types of malignant cancer. This research was aimed to explore the ability of the monocyte-to-lymphocyte ratio (MLR) to predict prognosis in patients with intrahepatic cholangiocarcinoma (ICC) who subjected to curative hepatectomy.MethodsThis retrospective analysis included 196 patients with ICC who underwent curative hepatectomy between May 2018 and April 2023. The predictive abilities of the preoperative MLR in assessing overall survival (OS) and disease-free survival (DFS) in those patients were compared with other inflammation-based scores, including monocyte-to-white ratio, neutrophil-to-lymphocyte ratio, neutrophil-to-white ratio, platelet-to-lymphocyte ratio, platelet-to-white ratio, and systemic immune-inflammation index, as well as tumor markers, like carcinoembryonic antigen (CEA) and carbohydrate antigen 19 − 9 (CA19-9).ResultsThe area under the time-dependent receiver operating characteristic curve indicated that the preoperative MLR had higher predictive efficiency in contrast with other inflammation-based scores and tumor markers in assessing OS and DFS. Stratifying patients according to the optimal cut-off value for the preoperative MLR, the data showed that both OS and DFS in the high MLR group were significantly worse than those in the low MLR group (p < 0.05 for all). Univariable and multivariable Cox analyses revealed that the preoperative MLR was an independent risk factor for OS and DFS in patients with ICC. In addition to predicting OS in patients with high CEA levels and predicting DFS in patients with high CA19-9 levels, patients with different CEA and CA19-9 levels were divided into completely different OS and DFS subgroups based on the risk stratification of the preoperative MLR.ConclusionsOur results demonstrated that the preoperative MLR was a good prognosis indicator to predict DFS and OS following curative hepatectomy in patients with ICC.