Neutrophil-to-lymphocyte ratio as a prognostic predictor for patients with cancer treated with stereotactic body radiation therapy: A meta-analysis

Stereotactic body radiation therapy (SBRT) is effective for the treatment of cancer. Neutrophil-to-lymphocyte ratio (NLR) is a common prognostic factor in predicting survival of patients with cancer. Previous studies have reported that NLR may be able to predict survival of patients with cancer treated with SBRT; however, the results are inconsistent. Therefore, the present study performed a meta-analysis to pool the data of prognostic prediction using NLR for patients with cancer who underwent SBRT. PubMed, Google Scholar, Embase and The Cochrane Library were used to search for articles published before October 2020. Pooled hazard radios (HRs) with 95% confidence intervals (CIs) were used to evaluate the association of NLR levels with patient outcome following SBRT. The primary endpoint was overall survival (OS). Subgroup analyses were used to detect sources of heterogeneity. Publication bias was assessed by Egger's test and Begg's test. A total of nine studies involving 1,010 participants were included in the present meta-analysis. Univariate and multivariate analyses revealed that elevated NLR predicted a worse outcome for OS (HR, 1.35; 95% CI, 1.22-1.49; P<0.001 and HR, 1.29; 95% CI, 1.16-1.44; P<0.001, respectively), regardless of pre- and post-treatment groups. Subgroup analysis demonstrated that the prospective group showed more significant heterogeneity (I(2)=57.7%; P=0.124) than the retrospective group (I(2)=0%) and overall (I(2)=47.5%). In conclusion, both pre- and post-SBRT elevated NLRs were revealed to be independently associated with poor survival in patients with cancer who received SBRT.