Prognostic value of peripheral blood lymphocyte-to-monocyte ratio in patients with solid tumors: a meta-analysis

BACKGROUND Although accumulating evidence suggests peripheral blood lymphocyte-to-monocyte ratio (LMR) could act as a prognosis predictor in various tumors, the prognostic value of LMR still remains controversial. We carried out this meta-analysis to evaluate the association of pretreatment LMR with survival outcomes in patients with solid tumors. METHODS Eligible studies were collected and extracted by searching PubMed and Embase databases up to June 3, 2015. The pooled hazard ratios (HRs) and their 95% confidence intervals (CIs) were computed to assess the prognostic value of LMR quantitatively. RESULTS Eighteen studies with a total of 8,377 participants were enrolled in this meta-analysis. Our findings indicated that elevated pre-treatment LMR predicted a significantly favorable overall survival (HR=0.59, 95% CI: 0.53-0.67) and disease-free survival (HR=0.74, 95% CI: 0.68-0.80) in solid tumor patients. Subgroup analyses revealed that enhanced LMR was significantly associated with favorable overall survival in patients with digestive system cancers (HR=0.63, 95% CI: 0.49-0.81), urinary tract tumors (HR=0.66, 95% CI: 0.52-0.84), lung cancer (HR=0.62, 95% CI: 0.54-0.72), and nasopharyngeal carcinoma (HR=0.50, 95% CI: 0.43-0.57). CONCLUSION This meta-analysis showed that enhanced LMR may indicate a favorable prognosis in patients with solid tumors.