Association of the neutrophil to lymphocyte ratio and clinical outcomes in cancers: a systematic review and meta-analysis

This meta-analysis aimed to evaluate the pan-cancer prognostic value of the neutrophil-to-lymphocyte ratio (NLR) for risk stratification in patients with cancer. We systematically searched Embase, PubMed, Google Scholar, and the Cochrane Library. The analysis included prospective studies, randomized controlled trials (RCTs), and post-hoc RCT analyses reporting multivariate-adjusted associations between the NLR and survival outcomes. Elevated NLR was significantly associated with worse overall survival (HR 1.61, 95% CI 1.44–1.80) and progression-free survival (HR 1.42, 1.27–1.59). Subgroup analyses by cancer type showed consistent associations in lung (OS-HR 2.29, 1.56–3.37; PFS-HR 1.73, 1.13–2.65), colorectal (OS-HR 1.88, 1.49–2.36; PFS-HR 1.43, 1.12–1.82), gastric (OS-HR 1.65, 1.46–1.87; PFS-HR 1.88, 1.14–3.11), and breast cancers (OS-HR 1.53, 1.27–1.83; PFS-HR 1.45, 1.29–1.64). Analysis by treatment modality revealed differential prognostic effects, including for chemotherapy (OS-HR 1.48, 1.34–1.65; PFS-HR 1.34, 1.14–1.57), immunotherapy (OS-HR 3.07, 1.65–5.71; PFS-HR 1.94, 1.12–3.36), surgery (OS-HR 1.90, 1.44–2.52), and targeted therapy plus chemotherapy (OS-HR 1.56, 1.28–1.90; PFS-HR 1.46, 1.22–1.76). An elevated NLR is associated with inferior clinical outcomes across multiple cancers, with the magnitude of its prognostic impact varying by treatment modality.