Extranodal extension of lymph node metastasis as a prognostic indicator of recurrence and survival in papillary thyroid carcinoma

Background and Objectives Stratification of extranodal extension (ENE) extent has the potential to improve the accuracy of risk estimations in papillary thyroid carcinoma (PTC). This study examined the prognostic importance of nodal factors, including ENE, in PTC patients. Methods This study enrolled 2071 consecutive patients with treatment-naive PTC who underwent thyroidectomy between 2006 and 2010. Microscopic/macroscopic ENE was determined by pathological and operative findings. Univariate and multivariate analyses were used to identify the relationship of factors with recurrence and survival in all study patients and in the node-positive subset. Results Of 2071 patients, 975 (47.1%) had positive lymph nodes, and 271 (13.1%) and 70 (3.4%) had microscopic and macroscopic ENE, respectively. During a median follow-up of 96 months, 114 (5.5%) patients had post-treatment recurrence. Multivariate analyses showed that, in all patients, the number of positive nodes, lymph node ratio, ENE status, and ATA risk group were independent variables affecting recurrence (P < 0.05). T4 and macroscopic ENE were independent variables associated with shorter overall survival (P < 0.05). Macroscopic ENE was significantly associated with macroscopic extrathyroidal extension. Conclusion Macroscopic ENE has a significant adverse impact on recurrence and survival after treatment for PTC. ENE is considered a high risk factor for recurrence.