OP88 – Molecular testing of indeterminate thyroid nodules for informed surgical management

      Bongers, Pim1, Verzijl, Raoul1, So, Tsz-Ying2, Pasternak, Jesse3, Devon, Karen3, Wasserman, Jonathan4, Khalouei, Sam2, Yee, Denise2, Mou, Jody2, Wang, Jenny2, Blumberg, Jeffery5, Freeman, Jeremy5, Macmillan, Christina2, Lerner-Ellis, Jordan2 1 Department of Surgery, University Medicale Centre Utrecht, Utrecht, the Netherlands 2 Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada 3 Department of Surgery, University Health Networks, Toronto, Ontario, Canada 4 Department of Paediatrics, division endocrinoly, University of Toronto, Toronto, Ontario, Canada 5 Department of Otolaryngology, Mount Sinai Hospital, Toronto, Ontario, Canada   Background: Thyroid cancer incidence has increased 3-fold over the last decades, yet accurate initial diagnosis continues to be challenging. The fine-needle aspiration biopsy (FNAB) is followed by cytology to distinguish benign from malignant nodules and is the most accurate diagnostic test for thyroid cancer. However, FNAB testing is limited because cytology is indeterminate more than 30% of the time, often providing no definitive conclusions to inform surgical management. Objectives: This project aims to develop a cost-conscious genetic test currently not offered in Canada for common genetic variants found in thyroid cancer. These include BRAF and RAS gene point mutations and RET/PTC RNA fusion products. Methods: A pipeline was established for FNA sample collection and storage, nucleic acid extraction, PCR amplification and sequencing for confirmation of mutations. Results: FNA material from surgically resected thyroids provided sufficient quantity and quality of DNA for PCR amplification of BRAF and H-/K-/N-RAS genes assessed by optical density readings. Reverse-transcription of RNA was sufficient to produce quality cDNA. RNA could be obtained to perform RT-PCR and detection of fusion genes. Discussion & Conclusion: This genetic test is feasible as sufficient quantities and quality of DNA and RNA was extracted from thyroid specimens and used to amplify the above genes for sequencing. FNA genetic test results may complement FNAB cytology to increase diagnostic yield and better determine which patients will benefit from surgery. The next steps include applying this technology to patient thyroid biopsy samples and expanding the diagnostic test to include additional gene markers.   References:
    1. Howell, G. M., Hodak, S. P., & Yip, L. (2013, July). RAS Mutations in Thyroid Cancer. The Oncologist, 18, 926-932.
    2. Labourier, E., Shifrin, A., Busseniers, A. E., Lupo, M. A., Manganelli, M. L., Andruss, B., & Wylie, D. (2015, July). Molecular Testing for miRNA, mRNA, and DNA on Fine-Needle Aspiration Improves the Preoperative Diagnosis of Thyroid Nodules With Indeterminate Cytology. The Journal of Clinical Endocrinology & Metabolism, 100(7), 2743-2750.
    3. Nikiforov, Y. E., Ohori, P. N., Hodak, S. P., Carty, S. E., LeBeau, S. O., Ferris, R. L., & Yip, L. (2011, August 31). Impact of Mutational Testing on the Diagnosis and Management of Patients with Cytologically Indeterminate Thyroid Nodules: A Prospective Analysis of 1056 FNA Samples. Journal of Clinical Endocrinology and Metabolism, 96(11), 3390-3397.
    4. Romei, C., & Elisei, R. (2012, April). RET/PTC Translocations and Clinico-Pathological Features in Human Papillary Thyroid Carcinoma. Frontiers in Endocrinology, 3(54), 1-8.


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