Level V Metastasis, a Novel Predicative Factor for Recurrence in N1b Papillary Thyroid Carcinoma

Background: Lymph nodal (LN) metastasis, classified as pN1b, is considered as an independent poor prognostic factor for Papillary thyroid carcinoma (PTC) patients. However, whether LN metastasis can serve as a predictive factor for recurrence or disease-free survival of N1b PTC is still plagued by controversy. Methods: The N1b PTC patients who underwent total thyroidectomy and unilateral modified radical neck dissection (MRND) by the same surgical team in Ningbo NO.2 Hospital from March, 1998 to March, 2015 were included in this study. The clinical and pathological characteristics of each patient were recorded in detail. Univariate and multivariate Cox proportional hazards regression models were performed to analyze the associations between clinicopathological characteristics with recurrence. Kaplan–Meier analysis and log-rank test were used for the analysis of overall RFS and level V metastasis. Results: A total of 214 patients were eligible for the final analyses. Of the 214 finally included patients with N1b PTC, 39 patients were classified with recurrence and 175 without recurrence. The final univariate and multiple Cox proportional hazards analysis only suggested level V metastasis as the independent predictive factor of N1b PTC recurrence (HR: 4.11; 95% CI:1.22–11.05, P=0.028). The patients with level V metastasis showed a significantly lower 10-year RFS rate (P=0.031) as illustrated by Kaplan–Meier analysis and log-rank test. Conclusion: Level V metastasis is a novel indicator for tumor recurrence and 10-year RFS in patients with N1b PTC.