Endocrine Abstracts

Background: The purpose of this study was to assess the role of ultrasound (US) in predicting tumor invasiveness in follicular thyroid carcinoma (FTC) based on the World Health Organization (WHO) classification and telomerase reverse transcriptase (TERT) promoter mutation.

Materials and Methods: This retrospective study included 54 surgically confirmed FTC patients who underwent preoperative US and TERT mutation analysis. The WHO classification consisted of minimally invasive (MI-FTC), encapsulated angioinvasive (EA-FTC), and widely invasive (WI-FTC) types. The alternative classification was composed as follows: Group 1 (MI-FTC; EA-FTC with wild type [WT]-TERT), Group 2 (WI-FTC with WT-TERT), and Group 3 (EA-FTC with mutant [M]-TERT; WI-FTC with M-TERT). Each nodule was categorized based on the US pattern according to the K-TIRADS and ACR-TIRADS. For statistical analysis, the Jonckheere-Terpstra and Cochran-Armitage tests were used.

Results: Among the 54 FTCs, there were 29 (53.7%) MI-FTCs, 16 (29.6%) EA-FTCs, and 9 (16.6%) WI-FTCs. The alternative classification included 42 (77.8%) Group 1, 5 (9.3%) Group 2, and 7 (13.0%) Group3. Neither benign nor low suspicion US category was assigned to WI-FTC and alternative groups 2 and 3. In both classification groups, lobulation, irregular margin, and final assessment category showed significant differences (all ps < 0.04) and incidences of lobulation, irregular margin, and high suspicion category had a trend to increase with the increasing tumor invasiveness (all ps for trend < 0.006). In the WHO groups, hypoechogenicity differed significantly among the groups (P = 0.0112) and tended to increase in proportion as tumor invasiveness increased (P for trend = 0.0145). Meanwhile, in the alternative groups, so did punctate echogenic foci (P = 0.0256, P for trend = 0.0245).

Conclusion: Increasing tumor invasiveness in FTC based on the WHO classification and TERT promoter mutation is significantly correlated with the probability of displaying malignant US features using both K-TIRADS and ACR-TIRADS.

Clinical Relevance/Implications: A recent study proposed molecular marker-based risk stratification of FTC using TERT promoter mutations and WHO classification to better predict clinical outcome. Our study suggests that US prediction of tumor invasiveness in FTC is highly correlated with the WHO morphological classification as well as newly proposed TERT promoter mutation-based risk stratification.