Prognostic Role of Bethesda System for Conventional Papillary Thyroid Carcinoma

Abstract

The aim of our study was to investigate the role of Bethesda System for Reporting Thyroid Cytopathology (BSRTC) from ultrasonography (US)-guided fine needle aspiration biopsy (FNAB) as a potential prognostic marker in the conventional papillary thyroid carcinoma (PTC). This study was approved by our institutional review board and informed consent was waived. Between January 2013 and December 2013, 397 patients who had undergone US-guided FNAB and underwent subsequent surgery for conventional PTC were enrolled. US features were interpreted using the Thyroid Imaging Reporting and Data System (TIRADS) and FNAB results were classified according to the BSRTC. The association between Bethesda category and histopathologic result including extrathyroidal extension and lymph node metastasis was evaluated using a logistic regression analysis after controlling for US features and clinicopathologic variables of the PTC. Of the 397 conventional PTCs, 31(7.8 %) were Bethesda category III, 82(20.7 %) were category V and 284 (71.5 %) were category VI. Among Bethesda categories, significant difference was found in the presence of extrathyroidal extension (Bethesda category III, 3.2% [7 of 220]; category V, 19.1% [42 of 220]; category VI, 77.7% [171 of 220]; P < .001) and lymph node metastasis (Bethesda category III, 3.8% [6 of 156]; category V, 16.7 % [26 of 156]; category VI, 79.5 % [124 of 156]; P < .001). Multivariate analysis showed that the Bethesda category was independently predictive of extrathyroidal extension (P=.013) lymph node metastasis (P=.035) in conventional PTC. Bethesda category of conventional PTCs was independently associated with extrathyroidal extension or lymph node metastasis. Conventional PTCs with higher Bethesda category at FNAB or larger pathologic tumor size tended to show extrathyroidal extension or lymph node metastasis .