The Difference in Clinical Behavior of Gene Fusions Involving RET/PTC Fusions and THADA/IGF2BP3 Fusions in Thyroid Nodules

THADA-IGF2BP3 gene fusions in thyroid fine needle aspiration is involved in the pathway to "noninvasive follicular thyroid neoplasm with papillary-like nuclear features"

BACKGROUND

The increased usage and adaptation of molecular testing of thyroid fine needle aspirations (FNA) has expanded the variety and number of gene fusions identified. While the identified number of molecular alterations is increasing, the definitive association between preoperative molecular analysis and phenotype has yet to be established. The aim of this study was to examine Thyroid adenoma-associated (THADA)-IGF2BP3 molecular fusions with FNA categorization, surgical pathology diagnosis, and other molecular alterations detected by ThyroSeq Genomic Classifier testing.

METHODS

FNA cytology samples of thyroid nodules from 04/2017 to 01/2023 with the diagnosis of atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS; Bethesda III) or follicular neoplasm suspicious for follicular neoplasm (FN/SFN; Bethesda IV) with associated ThyroSeqV3 testing were reviewed. Parameters including patient demographics, FNA diagnosis, ThyroSeq V3 results, and surgical pathology follow up were examined.

RESULTS

87 out of 249 (35%) FNA specimens of thyroid nodules displayed molecular alterations. 64 cases (74%) had a cytology diagnosis of AUS and 23 (26%) had FN. RAS mutation was observed in 48 cases. On surgical follow-up, 17 (35%) cases showed non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), while 14 (29%) patients had a malignant diagnosis. THADA-IGF2BP3 fusions were seen in 8 cases, all with NIFTP on surgical pathology follow-up (100%).

CONCLUSIONS

Analysis of THADA-IGF2BP3 fusion, in our institutional series, shows close association with NIFTP cases. THADA-IGF2BP3 fusion, which seems to be a favorable prognostic indicator in general, may serve as a molecular marker for non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP).

Assessment of the risk of malignancy in Bethesda III thyroid nodules: a comprehensive review

The increasing prevalence of thyroid cancer emphasizes the need for a thorough assessment of risk of malignancy in Bethesda III nodules. Various methods ranging commercial platforms of molecular genetic testing (including Afirma® GEC, Afirma® GSC, ThyroSeq® V3, RosettaGX®, ThyGeNEXT®/ThyraMIR®, ThyroidPRINT®) to radionuclide scans and ultrasonography have been investigated to provide a more nuanced comprehension of risk estimation. The integration of molecular studies and imaging techniques into clinical practice may provide clinicians with improved and personalized risk assessment. This integrated approach we feel may enable clinicians to carefully tailor interventions, thereby minimizing the likelihood of unnecessary thyroid surgeries and overall crafting the optimal treatment. By aligning with the evolving landscape of personalized healthcare, this comprehensive strategy ensures a patient-centric approach to thyroid nodule and thyroid cancer management.