The utility of ThyroSeq(R) in the management of indeterminate thyroid nodules by fine-needle aspiration

Objective We aim to evaluate the impact of ThyroSeq(R) in the management of indeterminate thyroid nodules (ITN), including Bethesda III and IV nodules. Methods ITNs that underwent ThyroSeq testing between 2016 and 2019 were retrospectively reviewed. A control cohort included ITNs without molecular testing. Cytological, molecular, and histological data were collected. Results We identified 202 ITNs that underwent molecular testing (128 in Bethesda III and 74 in Bethesda IV). Mutations were found in 58 nodules with mutation rates of 21.9% in Bethesda III and 40.5% in Bethesda IV. In this cohort, 49 cases had surgical resection with a resection rate of 24.3% (49/202, 15.6% in Bethesda III and 39.2% in Bethesda IV). Among the resected cases, 42 cases had positive molecular results. Thyroid cancer was diagnosed in 21 nodules with a malignancy detection rate of 10.4%. In the other cohort, we identified 236 ITNs (158 in Bethesda III and 78 in Bethesda IV). Surgical resection was performed in 127 cases, with a resection rate of 53.8% (127/236, 46.2% in Bethesda III and 69.2% in Bethesda IV). Thyroid cancer was diagnosed in 21 nodules, with a malignancy detection rate of 8.9%. The risk of malignancy (ROM) recalculated based on positive ThyroSeq results was significantly higher (21.4%-35.5% in Bethesda III and 50%-60% in Bethesda IV) than that without molecular testing (4.4%-9.6% in Bethesda III and 17.9%-25.9% in Bethesda IV). Conclusion We concluded that ThyroSeq significantly decreased the surgical resection rate (from 53.8% to 24.3%) without significantly affecting the malignancy detection rate in ITNs. Furthermore, positive molecular testing significantly increased ROM in ITNs. We believe that the recalculated ROM should be incorporated into the management of ITNs.