Risk factors of skip lateral lymph node metastasis in papillary thyroid carcinoma.

PURPOSE: Cervical lymph node metastasis is a prognostic factor of papillary thyroid carcinoma (PTC). This study aimed to investigate clinicopathological features and risk factors of skip lateral lymph node metastasis in PTC patients. METHODS: We retrospectively reviewed medical records of patients who underwent simultaneous total thyroidectomy with therapeutic central compartment lymph node dissection (LND) and lateral LND for primary PTC from 2014 to 2019. Univariate and multivariate logistic regression analyses were performed to identify clinicopathologic risk factors for skip metastasis. Receiver-operating characteristic (ROC) curves were constructed using the results of the multiple logistic regression analysis to identify data points with the highest sensitivity and lowest false-negative rate. RESULTS: The frequency of skip metastasis was approximately 12.8% (50/390). Multivariate logistic regression analysis showed that age (odds ratio [OR], 1.033; 95% confidence interval [CI], 1.008-1.059; P = 0.010), tumor size (OR 0.251; 95% CI 0.129-0.490; P < 0.001) and tumor located in the upper portion (OR 0.378; 95% CI 0.200-0.715; P = 0.003) were independent risk factors of skip metastasis (all P < 0.05). The ROC curves showed that the cut-off value of age for predicting skip metastasis was 44.5 years old (sensitivity = 0.620, specificity = 0.618, area under the curve [AUC] = 0.627, P = 0.004); the cut-off value of the tumor diameter for predicting skip metastasis was 1.05 cm (sensitivity = 0.503, specificity = 0.760, AUC = 0.682, P < 0.001). CONCLUSIONS: Skip metastasis was common in PTC. The PTC patients with age > 44.5 years, tumor diameter < 1.05 cm and tumor located in the upper portion should be carefully evaluated for skip metastasis.