ECE2022 Eposter Presentations Thyroid (219 abstracts)
Routine molecular testing of fine needle aspiration biopsies of thyroid nodules
Vlasta Sykorova 1 , Jitka Moravcova 1 , Eliska Vaclavikova 1 , Barbora Pekova 1 , Karolina Mastnikova 1 , Josef Vcelak 1 , Zdenek Novak 2 , Petra Pacesova 2 , Tereza Grimmichova 2 , Jan Jiskra 3 & Bela Bendlova 1
1Institute of Endocrinology, Department of Molecular Endocrinology, Prague, Czech Republic; 2Institute of Endocrinology, Department of Clinical Endocrinology, Prague, Czech Republic; 3General University Hospital in Prague, Department of Endocrinology and Metabolism, 3rd Department of Medicine, Prague, Czech Republic
Objectives: Fine needle aspiration biopsy (FNAB) together with ultrasonography is a necessary tool for diagnosis and follow up of thyroid nodules. Molecular testing is increasingly used mainly for indeterminate categories of the Bethesda System for Reporting Thyroid Cytopathology revised in 2017. Our aim was to introduce a routine molecular analysis of the main genetic causes of thyroid cancer.
Methods: Since 2017 we have analyzed 1171 samples of patients with thyroid nodules. We gradually established testing procedure mainly in samples evaluated as Bethesda categories III and above. First, we analyze DNA for the most common mutation V600E in the BRAF gene using allele specific Real Time PCR (LC480, Roche). BRAF-positive samples are screened for TERT mutations using direct sequencing (CEQ 8000, Beckman Coulter). BRAF-negative samples are analyzed by next generation sequencing using the Thyro-ID panel (MiSeq, Illumina) examining other 12 genes. The samples negative in the NGS panel are subjected to detection of 23 fusion genes including ALK, BRAF, GLIS, NTRK1, NTRK3, PPARG, RET genes using Real Time PCR. In samples suspected of MTC, we search for RET mutations.
Results: In total, BRAF mutation was detected in 146 patients, RAS mutations in 72 patients, RET mutations in 4 patients, TERT mutations in 20 patients and fusion genes in 43 patients. In 21 patients we detected genetic variants in the other genes (TP53, PTEN, PIK3CA, KIT, TSHR). From our cohort, in 390 patients post-surgical histopathological evaluation has been known. Positive predictive values of RET, BRAF, TERT, KRAS, HRAS, NRAS mutations and fusion genes were 100%, 98.4%, 93.3%, 75%, 60%, 42.1% and 97.6% respectively, if borderline tumors were not included in malignancy. In the BRAF-positive cohort was a case of follicular adenoma with BRAF K601E mutation and in the TERT-positive cohort one case of follicular tumor of uncertain malignant potential with TERT and NRAS mutation.
Conclusions: We established molecular testing of thyroid nodules that significantly contributed to clinical management of patients in the Czech Republic. BRAF, RET and TERT mutations and RET/PTC and ETV6/NTRK3 fusion genes are associated with almost 100% risk of malignancy or even worse prognosis, therefore according to ETA guidelines from 2017 and recent publications their carriers are recommended for the total thyroidectomy. The risk of malignancy of RAS mutations is lower and rather a lobectomy is recommended. Supported by AZV NU21-01-00448 and MH CR RVO 00023761.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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