Pretreatment lymphocyte-to-monocyte ratio as a predictor of survival among patients with ovarian cancer: a meta-analysis

INTRODUCTION: In this meta-analysis, we analyzed retrospective cohort studies that assessed the prognostic potential of the pretreatment lymphocyte-to-monocyte ratio (LMR) among patients with ovarian cancer (OC). MATERIALS AND METHODS: We comprehensively searched electronic databases, including PubMed and Embase, from inception through October 2018. A random-effects model was used to calculate pooled HRs and their 95% CIs for overall survival (OS) and progression-free survival (PFS). The low LMR group was treated as the reference group. RESULTS: Twelve studies, including 3,346 OC cases at baseline, were included. Overall, our results indicated that LMR was positively associated with both OS (HR: 1.85, 95% CI: 1.50–2.28, P<0.001; I(2)=76.5%) and PFS (HR: 1.70, 95% CI: 1.49–1.94, P<0.001; I(2)=24.4%) among OC patients. Stratified analyses indicated that, for OS, the LMR’s protective effect was more evident in studies conducted among younger patients (<55 years) than in those conducted among older patients (≥55 years; P for interaction =0.017), which was confirmed by meta-regression analysis (P=0.004). CONCLUSION: This study suggested that a higher pretreatment LMR level was associated with a favorable prognosis among OC patients. Future large-scale prospective clinical trials are needed to confirm the prognostic value of LMR among OC patients.