EP94 – Clinical and Genetic Comparison of Pediatric and Adult Thyroid Cancer Cohorts

•   Sykorova, Vlasta¹; Dvorakova, Sarka¹; Vaclavikova, Eliska¹; Vcelak, Josef¹; Katra, Rami²; Vlcek, Petr³; Sykorova, Pavla³; Kodetova, Daniela⁴; Lastuvka, Petr⁵; Betka, Jan⁵; Bavor, Petr⁶; Hoch, Jiri⁶; Bendlova, Bela¹ 1 Department of Molecular Endocrinology, Institute of Endocrinology, Prague, Czech Republic 2 Department of ENT, 2nd Faculty of Medicine, Charles University in Prague and and Motol University Hospital, Prague, Czech Republic 3 Department of Nuclear Medicine and Endocrinology, 2nd Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic 4 Departments of Pathology and Molecular Medicine, 2nd Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic 5 Department of Otorhinolaryngology and Head and Neck Surgery, 1st Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic 6 Department of Surgery, 2st Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic   Background/Purpose: Thyroid cancer in children and adolescent is a rare disease but with an increasing incidence. As same as in adults the most prevalent type is papillary thyroid carcinoma (PTC). Our aim was to describe the clinical and genetic comparison between pediatric and adult PTC. Methods: We analysed the cohorts of 56 pediatric PTC (5-18 years) and 460 adult PTC patients. DNA and RNA were extracted from tissue cancer samples. DNA was used for sequencing detection of TERT promotor C228T and C250T mutations with CEQ8000 and BRAF and RAS mutations with MiSeq. RNA was used for detection of expression of fused RET/PTC1 and RET/PTC3 using Real Time PCR. Clinical and pathological data were compared between both cohorts. Results: The pediatric cohort had more aggressive categories T3 and T4 (51 % vs. 27 % in adult) and more often lymph node metastasis (71 % vs. 42 % in adult) in TNM classification. BRAF V600E mutation in 8 pediatric patients (14 % vs. 37 % in adult), RAS mutation in one patient (1,8 % vs. 8 % in adult) and RET/PTC rearrangements in 11 patients (20 % vs. 5 % in adult) – 7 RET/PTC1, 3 RET/PTC3 and one RET/PTC1ex9 were detected. No TERT mutations were found in pediatric PTC in contrast to 12% in adults. Discussion & Conclusion: Pediatric thyroid carcinomas differ from the adult ones in more aggressive phenotype as well as in genetics, where more frequent rearrangements than point mutations were observed. Supported by AZV 16-32665A and MH CR RVO 00023761.