Platelet to lymphocyte ratio in biliary tract cancer: Review and meta-analysis

Background: The platelet to lymphocyte ratio (PLR) has been found to predict clinical outcomes in multiple malignancies. The aim of this study was to assess the prognostic value of pretreatment PLR in biliary tract cancer (BTC). Methods: We searched the MEDLINE, EMBASE, and Cochrane databases to identify studies evaluating the prognostic significance of pretreatment PLR in BTC. The end points were overall survival (OS), recurrence-free survival (RFS). Pooled hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using fixed-effects/random-effects models. Results: A total of eleven studies comprising 2392 patients were included in the study. Pooled results showed that elevated PLR was significantly associated with decreased overall survival (HR: 1.59, 95% confidence interval [CI]: 1.42-1.78, p < 0.001) and recurrence-free survival (HR: 1.53, 95% CI: 1.16-2.00, p = 0.002). Subgroup analyses suggested that a high PLR predicted decreased OS in patient with BTC, regardless of sample size ( < 200 or 200), treatment methods (surgery, mixed, or chemotherapy), tumor stage (mixed or metastatic), analysis methods (univariate or multivariate), cut-off values ( < 150 or 150), and NOS score (< 7 or >= 7). Conclusions: Elevated pretreatment PLR may be an unfavorable prognostic factor for clinical outcomes in patients with biliary tract cancer.