Prognostic value of lymphocyte-to-monocyte ratio for breast cancer: a systematic review and meta-analysis.

BACKGROUND: The incidence of breast cancer has been ascending. The lymphocyte-to-monocyte ratio (LMR) has been reported as a prognostic factor for breast cancer. This meta-analysis aimed to assess the predictive significance of LMR in breast cancer. METHOD: PubMed, Embase, Cochrane, and Web of Science were searched for relevant articles on the predictive significance of LMR in breast cancer up to May 2024. The hazard ratio (HR) of overall survival (OS), disease-free survival (DFS), recurrence-free survival (RFS), and distant metastasis-free survival (DMFS) was calculated using fixed-effects or random-effects models. The LMR threshold and follow-up information were extracted, and subgroup analyses were performed. RESULT: Twenty-two studies were included in the meta-analysis. LMR accurately predicted OS, DFS, and RFS in breast cancer (p < 0.05), with high LMR associated with improved outcomes. However, the association between higher LMR and longer DMFS in breast cancer was uncertain. LMR's predictive value for OS and DFS remained significant in different regions, sample size, LMR threshold, follow-up, and timing. The predictive effect of LMR were different in different molecular subtypes of breast cancer. CONCLUSION: This meta-analysis identified the prognostic value of LMR for OS and DFS in breast cancer. However, selection bias existed due to the predominance of retrospective studies, and considerable heterogeneity was observed for some indicators. Further research is necessary to confirm these findings.