Prognostic value of the neutrophil-to-lymphocyte ratio in gastric cancer patients treated with PD-1/PD-L1 inhibitors: a systematic Review and meta-analysis

The neutrophil-to-lymphocyte ratio (NLR), as an easily obtainable inflammatory indicator, has shown prognostic value in various solid tumors. However, its prognostic value in patients with gastric cancer treated with programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitors remains uncertain. This meta-analysis aimed to systematically evaluate the prognostic value of NLR in this population. We systematically searched PubMed, Embase, Web of Science, the Cochrane Library, Wanfang, and China National Knowledge Infrastructure from inception to September 2024. We included studies of patients with gastric cancer treated with PD-1/PD-L1 inhibitors that reported associations of NLR with overall survival (OS), progression-free survival (PFS), objective response rate (ORR), or disease control rate (DCR). A random-effects model was used to pool multivariable-adjusted hazard ratios (HRs) or odds ratios (ORs), and subgroup and sensitivity analyses were performed. A total of 25 articles (2,074 patients) were included. High NLR was significantly associated with shorter OS (HR = 2.06, 95% CI: 1.76–2.40, I² = 46%) and PFS (HR = 1.70, 95% CI: 1.50–1.92, I² = 19%). Higher NLR was also associated with lower ORR (OR = 0.53, 95% CI: 0.34–0.84) and lower DCR (OR = 0.47, 95% CI: 0.29–0.77), although these findings are based on only three studies each and should be considered exploratory. Subgroup analyses suggested numerical variation in pooled estimates, but differences between subgroups were not formally tested. NLR shows potential as a candidate biomarker for clinical risk stratification, although these findings are hypothesis-generating and require validation in prospective, well-controlled cohorts.