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

[PURPOSE] 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.

[METHODS] 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.

[RESULTS] 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).

[CONCLUSION] An elevated NLR is associated with inferior clinical outcomes across multiple cancers, with the magnitude of its prognostic impact varying by treatment modality.