Impact of gross extrathyroidal extension into major neck structures on the prognosis of papillary thyroid carcinoma according to the american joint committee on cancer eighth edition

Abstract

This study investigated the impact of gross extrathyroidal extension into major neck structures on the prognosis of papillary thyroid carcinoma according to changes in the American Joint Committee on Cancer (AJCC)/Tumor-Node-Metastasis staging system. Overall, 183 patients with gross extrathyroidal extension into major neck structures were enrolled. The 10-year disease-specific survival (DSS) of patients in each stage showed appropriate correlation and stratification with the AJCC eighth edition. However, the 10-year DSS rate in stage III was better than the expected 10-year DSS rate, according to the AJCC eighth edition. Patients in stage III were subcategorized into three new groups: stage IIIA, patients with only recurrent laryngeal nerve invasion; stage IIIB, patients with superficial invasion of the aerodigestive tract; and stage IIIC, patients with intraluminal invasion of the aerodigestive tract. The prognostic differences among these three groups and stage IVA were examined. Although the DSS rate of patients in stage IIIA was excellent, that of patients with T4a disease was worse due to the progression of aerodigestive tract infiltration. Of the four groups, the time to locoregional recurrence was the shortest for patients in stage IVA. The distant recurrent-free survival for patients in stages IIIC and IVA tended to be worse than those for patients in stages IIIA and IIIB. These results indicate that the progression of aerodigestive tract infiltration has an impact on the incidence of distant recurrence, and the presence of T4b disease has an impact on the incidence of distant and locoregional recurrences.