The Value of Platelet-to-Lymphocyte Ratio as a Prognostic Marker in Cholangiocarcinoma: A Systematic Review and Meta-Analysis

SIMPLE SUMMARY: Platelet-to-lymphocyte ratio has shown prognostic value in several malignancies; however, its role in cholangiocarcinoma remains to be determined. Therefore, we conducted a systematic review and meta-analysis of the currently available literature. Overall, our analysis revealed that a high platelet-to-lymphocyte ratio before treatment is associated with an impaired long-term oncological outcome. Further, our results indicate that this assumption was not influenced by the used treatment modality (surgical vs. non-surgical), PLR cut-off values, study population age, or sample size of the included studies. Thus, an elevated pretreatment platelet-to-lymphocyte ratio has valid prognostic value for cholangiocarcinoma patients. ABSTRACT: The platelet-to-lymphocyte ratio (PLR), an inflammatory parameter, has shown prognostic value in several malignancies. The aim of this meta-analysis was to determine the impact of pretreatment PLR on the oncological outcome in patients with cholangiocarcinoma (CCA). A systematic literature search has been carried out in the PubMed and Google Scholar databases for pertinent papers published between January 2000 and August 2021. Within a random-effects model, the pooled hazard ratio (HR) and 95% confidence interval (CI) were calculated to investigate the relationships among the PLR, overall survival (OS), and disease-free survival (DFS). Subgroup analysis, sensitivity analysis, and publication bias were also conducted to further evaluate the relationship. A total of 20 articles comprising 5429 patients were included in this meta-analysis. Overall, the pooled outcomes revealed that a high PLR before treatment is associated with impaired OS (HR = 1.14; 95% CI = 1.06–1.24; p < 0.01) and DFS (HR = 1.57; 95% CI = 1.19–2.07; p < 0.01). Subgroup analysis revealed that this association is not influenced by the treatment modality (surgical vs. non-surgical), PLR cut-off values, or sample size of the included studies. An elevated pretreatment PLR is prognostic for the OS and DFS of CCA patients. More high-quality studies are required to investigate the pathophysiological basis of the observation and the prognostic value of the PLR in clinical management as well as for patient selection.