Prognostic Value of Pretreatment Monocyte-to-Lymphocyte Ratio in Prostate Cancer: A Focused Systematic Review and Corrected Meta-analysis

Vollständiger Abstract

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Background : The monocyte-to-lymphocyte ratio (MLR) is an inexpensive systemic inflammatory marker, but its prognostic value in prostate cancer remains uncertain. This focused review evaluated whether pretreatment MLR is associated with overall survival (OS). Methods : A broader systematic search of Semantic Scholar, Scopus, PubMed/MEDLINE, Crossref, the Cochrane Library, and Web of Science identified studies of blood-cell ratios in prostate cancer. For this focused analysis, reports were rechecked for direct MLR measurement or a mathematically convertible reciprocal lymphocyte-to-monocyte ratio (LMR), an extractable hazard ratio (HR) with 95% confidence interval (CI), and OS. Log HRs were harmonized to compare high versus low MLR and pooled with a random-effects inverse-variance model. Study quality was assessed using the Newcastle-Ottawa Scale. Results : Three studies involving a total of 427 patients were included in the overall survival analysis. Two studies evaluated metastatic prostate cancer, while one study included non-metastatic patients. Elevated MLR was significantly associated with poorer overall survival, with a pooled hazard ratio (HR) of 2.59 (95% CI 1.84–3.63; p < 0.00001). No significant heterogeneity was observed among the included studies (I² = 0%; χ² = 0.26, p = 0.88; Tau² = 0.00), indicating a highly consistent prognostic effect across studies. Conclusions : Elevated MLR was associated with poorer overall survival in patients with prostate cancer, with a consistent direction of effect across the included studies. However, MLR-specific prognostic evidence remains sparse and is currently insufficient to support routine clinical use. Further studies using contemporary MLR-specific searches, standardized ratio definitions, prespecified cutoffs, and adequately adjusted prospective cohorts are required to validate its prognostic utility.