Association of the neutrophil to lymphocyte ratio and clinical outcomes in patients with lung cancer receiving immunotherapy: a meta-analysis

Objectives To explore the relationship between the pretreatment or post-treatment neutrophil to lymphocyte ratio (NLR) and overall survival (OS)/progression-free survival (PFS) in patients with lung cancer receiving immunotherapy. Design We searched several databases to collect relevant studies conducted until July 2019. We carefully reviewed the full text of the included publications and combined the HRs and 95% CIs to assess the association between the NLR and survival time in patients with lung cancer receiving immunotherapy. Data sources PubMed, the Cochrane Library, Embase and Web of Science Eligibility criteria Studies reporting the prognostic value of the NLR in patients with lung cancer receiving immunotherapy were enrolled. Data extraction and synthesis Basic information on the articles and patients (NLR cut-off value, NLR at baseline and HRs with 95% CIs for OS and PFS) was extracted by two authors independently. The pooled HRs of OS and PFS were synthesised using the random effects or fixed effects model. Results Twenty-three studies with 2068 patients were enrolled. Among all patients, 1305 (64.0%) were men and 643 (31.4%) were diagnosed with squamous cell carcinoma (SCC). In a pooled analysis of OS and PFS from all studies, an elevated NLR predicted poor OS (HR=1.62; 95% CI: 1.41 to 1.87; p<0.001) and PFS (HR=1.47; 95% CI: 1.25 to 1.72; p<0.001). Subgroup analyses stratified showed that the post-treatment NLR was not significantly related to OS and that patients in Asia had significantly higher HRs than those in Europe and America. Furthermore, the proportion of SCC and baseline NLR could affect the prognostic value of the NLR. Conclusions Our study found that an elevated NLR was associated with poor OS and PFS in patients with lung cancer receiving immunotherapy and that several clinical factors might have an impact on the predictive value of the NLR in the survival of patients with lung cancer.