Prognostic role of lymphocyte to monocyte ratio for patients with cancer: evidence from a systematic review and meta-analysis

Inflammation influences cancer development and progression, and a low lymphocyte to monocyte ratio (LMR) has been reported to be a poor prognostic indicator in several malignancies. Here we quantify the prognostic impact of this biomarker and assess its consistency in various cancers. Eligible studies were retrieved from PubMed, Embase and Web of Science databases. Overall survival (OS) was the primary outcome, cancer-specific survival (CSS), disease-free survival (DFS), recurrence-free survival (RFS), and progression-free survival (PFS) were secondary outcomes. Pooled hazard ratios (HRs), odds ratios (ORs), and 95% confidence intervals (CIs) were calculated. Fifty-six studies comprising 20,248 patients were included in the analysis. Overall, decreased LMR was significantly associated with shorter OS in non-hematological malignancy (HR: 0.59, 95% CI: 0.53-0.66; P < 0.001) and hematological malignancy (HR: 0.44, 95% CI: 0.34-0.56; P < 0.001). Similar results were found in CSS, DFS, RFS and PFS. Moreover, low LMR was significantly associated with some clinicopathological characteristics that are indicative of poor prognosis and disease aggressiveness. By these results, we conclude that a decreased LMR implied poor prognosis in patients with cancer and could serve as a readily available and inexpensive biomarker for clinical decision.