Prognostic impact of NLR, PLR, MLR, and SII in gastric cancer patients treated with immune checkpoint inhibitors: A Systematic Review and meta-analysis

Gastric cancer remains a significant global health burden, with immune checkpoint inhibitors showing variable effectiveness in treatment outcomes. This systematic review and meta-analysis examined the prognostic significance of hematologic inflammatory indices in advanced gastric cancer patients receiving immune checkpoint inhibitor. We conducted a comprehensive search of PubMed, EMBASE, and Cochrane CENTRAL databases through August 2023, focusing on neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), and systemic immune-inflammation index (SII). Our analysis included eighteen studies encompassing 2,061 patients with advanced gastric cancer undergoing immune checkpoint inhibitor treatment. The meta-analysis demonstrated that elevated pretreatment inflammatory indices were consistently associated with worse clinical outcomes. High NLR showed significant associations with poor overall survival (adjusted HR: 1.73, 95% CI: 1.38–2.17) and progression-free survival (adjusted HR: 2.16, 95% CI: 1.30–3.58). Similarly, elevated PLR correlated with worse overall survival (adjusted HR: 1.77, 95% CI: 1.38–2.25) and progression-free survival (adjusted HR: 1.56, 95% CI: 1.22–1.99). High MLR and SII also demonstrated significant associations with poorer overall survival outcomes. Higher pretreatment NLR, PLR, MLR, and SII were associated with poorer survival in advanced gastric cancer patients receiving immune checkpoint inhibitors, suggesting a potential role for these simple blood-based indices in risk stratification that warrants confirmation in prospective studies.