Clinical and prognostic value of neutrophil-lymphocyte ratio for patients with thyroid cancer A meta-analysis

Background: Although the malignant degree is relatively low and overall prognosis is excellent, some patients with thyroid cancer still experience metastasis during the follow-up, which leads to their possible death. Pretreatment neutrophil-to-lymphocyte ratio (NLR) has been recommended as a biomarker for the prediction of metastasis and prognosis in patients with cancers. However, its value in thyroid cancer remains inconclusive. This study aimed to comprehensively evaluate the prognostic and clinicopathological significance of NLR for thyroid cancer by a meta-analysis. Methods: Eligible studies were identified by searching PubMed, EMBASE, and Cochrane Library databases. The associations between NLR level and disease-free survival (DFS) or clinicopathological parameters were estimated by calculating hazard ratio (HR) or effect size with 95% confidence interval (CI). Results: Nine studies consisting of 3081 patients were enrolled. Results of meta-analysis showed that elevated NLR was not significantly associated with unfavorable DFS overall, but subgroup analysis of multivariate-adjusted studies demonstrated an elevation in pretreatment NLR predicted poor DFS (HR = 3.51, 95%CI = 1.42-8.70). Overall, a high level of NLR was significantly correlated with larger tumor size (standardized mean difference [SMD] = 0.49, 95%CI = 0.33-0.64), and metastasis status (risk ratio [RR] = 1.70, 95%CI = 1.10-2.64). The association with tumor size was still significant in the stratified analyses by country and histology type (Asian: SMD = 0.719, 95%CI = 0.44-0.98; non-Asian: SMD = 0.36, 95%CI = 0.17-0.56; medullary thyroid carcinoma: SMD = 0.57, 95%CI = 0.09-1.05; papillary thyroid carcinoma: SMD = 0.48, 95%CI = 0.31-0.64). The association between NLR and metastasis was only significant for papillary thyroid carcinoma subtype (RR = 1.82, 95%CI = 1.04-3.20). Conclusion: Pretreatment NLR may serve as an excellent biomarker for prediction of tumor growth, metastasis, and prognosis in patients with thyroid cancer.