Next generation sequence-based targeted somatic mutation analysis in thyroid nodules with pathologically diagnosed as indeterminate cytology

Abstract

Purpose: The management of indeterminate thyroid nodules remains a topic of ongoing debate, particularly regarding the differentiation of malignancy. Somatic mutation analysis offers crucial insights into tumor characteristics. This study aimed to assist the clinical management of indeterminate nodules with somatic mutation analysis.

Methods: Aspiration samples from 20 indeterminate thyroid nodules were included in the study. A next-generation sequencing panel containing 67 genes was used for molecular profiling. The results were compared with pathology data from surgical material, which is considered the gold standard. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated.

Results: Variants in six genes (NRAS, BRAF, TP53, TERT, PTEN, PIK3CA) were detected in 10 out of 20 samples. We identified nine Tier 1 or 2 variants in 10 (67 %) out of 15 malignant nodules (NRAS, BRAF, TP53, TERT, PTEN, PIK3CA) and one Tier 2 (PIK3CA) variant in one out of five benign nodules. The study demonstrated an NPV of 40 %, a PPV of 90 %, a specificity of 80 %, and a sensitivity of 60 %.

Conclusion: Based on the detected molecular markers, at least nine patients (45 %) could be managed correctly without needing a repeat FNAB attempt. This study underscores the clinical practicality of molecular tests in managing nodules with indeterminate cytology. Additionally, this study emphasizes the importance of considering the patient's age when determining the DNA- or RNA-based genetic testing method. Finally, we discussed the significance of the somatic mutation profile and its impact on the current pathological classification.

Keywords: Cytology; Molecular testing; Somatic mutation; Thyroid cancer; Thyroid nodule.