Association between neutrophil-to-lymphocyte ratio and differentiated thyroid cancer: a meta-analysis

The association between neutrophil-to-lymphocyte ratio (NLR) and differentiated thyroid cancer (DTC) is undecided. To rectify this question, we conducted a systematic meta-analysis based on 7 prospective cohort studies published between 2013 and 2015, comprising 7349 patients. Six of these cohorts included pretreatment (baseline) NLR data for patients with thyroid nodules. The meta-analysis of these 6 cohorts showed that the NLR of patients with DTC (4617 cases) was statistically similar to patients with benign nodules only (1666 cases), with a mean difference (MD) of 0.19 (95% CI: -0.09 to 0.46; I-2 = 93%; P < 0.001). No significant difference in NLR was found between patients with DTC and patients with benign nodules. Two studies addressed an association between NLR and papillary thyroid carcinoma in patients stratified by age < 45 and >= 45 years (496 and 891 cases, respectively); the pooled MD was 0.09 (95% CI: -0.37 to 0.55; I-2 = 92.2%, P < 0.001). An elevated NLR seems not a reliable indicator of progressing DTC in patients with goiters, and there was no difference in NLR between patients aged < 45 years and those aged >= 45 years. Well-designed and large-scale investigations are warranted to understand the value of NLR in the prognosis of DTC.