Extent of Extrathyroidal Extension as a Significant Predictor of Nodal Metastasis and Extranodal Extension in Patients with Papillary Thyroid Carcinoma.

Abstract

Extrathyroidal extension (ETE) and extranodal extension (ENE) indicate poor prognosis for patients with papillary thyroid carcinoma (PTC). The relationships among ETE, ENE, and nodal metastasis (N1) have not been thoroughly studied. In this study, we examined the relationships among the extent of ETE, N1, ENE, and posttreatment recurrence in patients with PTC. This study enrolled 1693 consecutive patients with previously untreated PTC who underwent thyroidectomy between 2006 and 2009. The extent of ETE was graded based on intraoperative and pathological findings, and central and lateral neck (N1b) nodal metastases and ENE were pathologically determined. Univariate and multivariate analyses were used to identify the association of clinicopathological factors with recurrence-free survival (RFS) and to define the relationships among the extent of ETE, N1, and ENE. Of 1693 patients, 1087 (64.2 %) had ETE and 201 (11.9 %) had ENE. Pathologically positive lymph nodes were found in 783 patients (46.2 %), of whom 236 (30.1 %) had N1b. During the median follow-up of 86 months, 90 (5.3 %) patients had recurrences. Multivariate analyses showed that multifocality, ETE, T and N classification, the risk of structural recurrence proposed by the American Thyroid Association, and ENE were independent variables for RFS (P < .05). Patients with macroscopic ETE had a 13-fold increased risk of recurrence, and ETE had significant relationships with N1, N1b, and ENE (all P < .001). Local extension, nodal involvement, and ENE contribute to posttreatment recurrence of PTC. Macroscopic ETE predicts nodal metastasis and ENE, which are adverse pathologic features.