Associations between peripheral whole blood cell counts derived indexes and cancer prognosis: An umbrella review of meta-analyses of cohort studies

Meta-analyses have reported conflicting data on the whole blood cell count (WBCC) derived indexes (neutrophil-to-lymphocyte ratio [NLR], platelet-to-lymphocyte ratio [PLR], and lymphocyte-to-monocyte ratio [LMR]) and cancer prognosis. However, the strength and quality of this evidence has not been quantified in aggregate. To grade the evidence from published meta-analyses of cohort studies that investigated the associations between NLR, PLR, and LMR and cancer prognosis. A total of 694 associations from 224 articles were included. And 219 (97.8%) articles rated as moderate-to-high quality according to AMSTAR. There were four associations supported by convincing evidence. Meanwhile, 165 and 164 associations were supported by highly suggestive and suggestive evidence, respectively. In this umbrella review, we summarized the existing evidence on the WBCC-derived indexes and cancer prognosis. Due to the direction of effect sizes is not completely consistent between studies, further research is needed to assess causality and provide firm evidence.