Platelet-to-lymphocyte ratio in advanced Cancer: Review and meta-analysis

Background: Inflammation biomarkers have been introduced into clinical practice for risk-rating in treatment of patients with cancer. We aimed to confirm the prognostic role of platelet-to-lymphocyte ratio (PLR) as a powerful biomarker for patients with advanced cancer. Method: A systematic literature search was conducted through PubMed, Embase and Web of Science databases for studies on advanced tumors. Research articles that analyzed the PLR and hazard ratios (HR) in patients with overall survival (OS) or progression-free survival (PFS) data were involved. Two authors assessed the eligibility of trials and extracted data independently. Meta-analyses were performed with random-effect models. Data heterogeneity was calculated with the I-2 method. Results: Thirty-three eligible cohort studies including 8215 patients were further analyzed. Elevated PLR was associated with reduced OS (HR = 1.45, 95% CI, 1.31-1.61, p < 0.001) and PFS (HR = 1.73, 95% CI, 1.31-2.29, p < 0.001) in patients with advanced cancer. A extreme result was observed in a subgroup analysis in metastatic renal cancer with the worst OS (HR = 2.47, 95% CI, 1.32-4.62, p = .005) and PFS (HR = 3.89, 95% CI, 1.23-12.28, p = 0.021). Conclusions: Patients with high pretreatment blood PLR level have poor OS and PFS. Further investigations are needed to explore the underlying mechanisms.