Aim: We aimed to assess the prognostic value of pretreatment hematological biomarkers in patients with metastatic renal cell carcinoma (mRCC) treated with immune checkpoint inhibitors (ICIs). Methods: PubMed, Web of Science and Scopus databases were searched for articles according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Results: Fifteen studies comprising 1530 patients were eligible for meta-analysis. High levels of neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), C-reactive protein and lactate dehydrogenase were significantly associated with worse progression-free survival. High NLR and PLR were significantly associated with worse overall survival. Conclusion: High pretreatment NLR and PLR appear to be hematological prognostic factors of progression and overall mortality in mRCC patients treated with ICIs. These findings might help in the design of correlative biomarker studies to guide the clinical decision-making in the immune checkpoint inhibitor era.
