Extranodal Tumor Extension to Adjacent Organs Predicts a Worse Cause‐specific Survival in Patients with Papillary Thyroid Carcinoma

Abstract

We previously reported that massive extrathyroid extension has an independent prognostic value in patients with thyroid papillary carcinoma. However, tumor extension to adjacent organs can be observed not only in primary tumor but also in metastatic nodes. In this study we investigated the clinical significance of extranodal tumor extension to adjacent organs (nodal ex) in papillary thyroid carcinoma. We classified all cases into three categories based on the degree of nodal ex: nodal ex0, no apparent extranodal tumor extension; nodal ex1, hard metastatic nodes with perinodal growth extending to adjacent organs, which require separation of the nodes from the organs; and nodal ex2, metastatic nodes with perinodal growth completely invading the adjacent organs and requiring excision of nodes together with these organs. We investigated the clinical significance of each grade in 1,692 patients who underwent initial surgery for papillary carcinoma between 1987 and 1995. The presence of nodal ex was significantly linked to various clinicopathological features such as male gender, N1b, large number of metastatic nodes, pT4a, and distant metastasis. On univariate analysis, patients with either nodal ex1 or ex2 showed significantly worse disease-free and cause-specific survival rates, although these rates did not differ between patients with nodal ex1 and those with nodal ex2. Furthermore, multivariate analysis demonstrated that nodal ex independently predicts worse cause-specific survival of these patients. Presence of nodal ex significantly reflects the biologically aggressive behaviors of papillary carcinoma and has a prognostic value, especially for cause-specific survival of patients.