Prognostic prediction of the platelet-to-lymphocyte ratio in hepatocellular carcinoma: a systematic review and meta-analysis

Background: Platelet-to-lymphocyte ratio (PLR) has been used to predict the prognosis of patients with hepatocellular carcinoma (HCC) with inconsistent results. This meta-analysis aimed to clarify the prognostic value of PLR in patients with HCC.Methods: We systematically retrieved relevant literature published in the PubMed, Embase, Web of Science, and Cochrane databases up to November 20, 2021. The primary outcomes were the hazard ratios (HRs) and their 95% confidence intervals (CIs) for overall survival (OS), and secondary study outcomes were recurrence-free survival (RFS), disease-free survival (DFS), progression-free survival (PFS). All statistical analyses were conducted by Review Manager 5.4.1 and STATA 16.0 software.Results: A total of 21 studies comprising 8,779 patients were included in this meta-analysis. Pooled results suggested that a high PLR was significantly associated with poor OS (HR: 1.34, 95% CI: 1.18-1.52, P<0.00001; I2=59%, P=0.0005), RFS or DFS (HR: 1.35, 95% CI: 1.13-1.63, P=0.001; I2=69%, P=0.002), and PFS (HR: 1.55, 95% CI: 1.09-2.22, P=0.02; I2=73%, P=0.02). The subgroup analysis for OS showed, when the PLR cutoff value was greater than 150, the heterogeneity decreased to 0 (HR: 1.48, 95% CI: 1.33-1.68, P<0.00001; I2=0%, P=0.56); when the HBsAg positive population was increased to 100%, the heterogeneity decreased to 0 (HR: 1.46, 95% CI: 1.22-1.73, P<0.0001; I2=0%, P=0.45); compared with other regions in the world, it was more significant in China (HR: 1.43, 95% CI: 1.26-1.62, P<0.00001; I2=52%, P=0.01). In addition, scatter plot showed that the HR was negatively correlated with the proportion of patients with liver cirrhosis.Conclusions: This meta-analysis suggests that PLR is a negative correlation prognostic biomarker for HCC, high PLR values indicate poor OS, RFS, DFS and PFS, especially in hepatitis B virus (HBV) related patients.