Usefulness of pre-thyroidectomy neutrophil–lymphocyte, platelet–lymphocyte, and monocyte–lymphocyte ratios for discriminating lymph node and distant metastases in differentiated thyroid cancer

OBJECTIVE: This study aimed to analyze the relationship of neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), and monocyte-lymphocyte ratio (MLR) with clinicopathological characteristics of patients with differentiated thyroid cancer (DTC). METHODS: This retrospective study included 390 patients with DTC who had complete blood cell counts available at the time of surgery. NLR, PLR, and MLR were calculated, and the risk of cancer-related death, structural recurrence, and response to therapy were assessed using the eighth edition of the tumor-node-metastasis classification, American Thyroid Association (ATA) Risk Stratification System, and ATA Response to Therapy Reclassification, respectively. RESULTS: PLR was higher in patients with distant metastasis than in those without (133.15±43.95 versus 119.24±45.69, p=0.0345) and lower in patients with disease-free status (117.72±44.70 versus 131.07±47.85, p=0.0089) than in those who experienced persistent disease or death. Patients aged ≥55 years had a higher MLR than those aged <55 years (0.26±0.10 versus 0.24±0.12, p=0.0379). Higher MLR (odds ratio [OR]: 8.775, 95% confidence interval [CI]: 1.532-50.273, p=0.0147), intermediate ATA risk (OR: 4.892, 95% CI: 2.492-9.605, p≤0.0001), and high ATA risk (OR: 5.998, 95% CI: 3.126-11.505, p≤0.0001) were risk factors associated with active disease. NLR was not significantly different among the studied variables. Receiver operating characteristic curve cut-off values for NLR, PLR, and MLR were able to differentiate distant metastasis from lymph node metastasis (NLR>1.93: 73.3% sensitivity and 58.7% specificity, PLR>124.34: 86.7% sensitivity and 69.2% specificity, MLR>0.21: 80% sensitivity and 45.2% specificity). CONCLUSION: Cut-off values of NLR, PLR, and MLR differentiated distant metastasis from lymph node metastasis with good sensitivity and accuracy. PLR was associated with disease-free status and it was higher in DTC patients with distant metastasis, persistent disease, and disease-related death. MLR was a risk factor for active disease.