The prognostic value of neutrophil-to-lymphocyte ratio in cholangiocarcinoma: a systematic review and meta-analysis.

The neutrophil-to-lymphocyte ratio (NLR) is used as biomarker in malignant diseases showing significant association with poor oncological outcomes. The main research question of the present study was whether NLR has also prognostic value in cholangiocarcinoma patients (CCA). A systematic review was carried out to identify studies related to NLR and clinical outcomes in CCA evaluating the literature from 01/2000 to 09/2021. A random-effects model, pooled hazard ratios (HR) and 95% confidence interval (CI) were used to investigate the statistical association between NLR and overall survival (OS) as well as disease-free survival (DFS). Subgroup analyses, evaluation of sensitivity and risk of bias were further carried out. 32 studies comprising 8572 patients were eligible for this systematic review and meta-analysis. The pooled outcomes revealed that high NLR prior to treatment is prognostic for poor OS (HR 1.28, 95% CI 1.18-1.38, p < 0.01) and DFS (HR 1.39, 95% CI 1.17-1.66, p < 0.01) with meaningful HR values. Subgroup analysis revealed that this association is not significantly affected by the treatment modality (surgical vs. non-surgical), NLR cut-off values, age and sample size of the included studies. Given the likelihood of NLR to be prognostic for reduced OS and DFS, pre-treatment NLR might serve as a useful biomarker for poor prognosis in patients with CCA and therefore facilitate clinical management.