ETA2023 Poster Presentations Translational 2 (9 abstracts)
Molecular analysis of multiple foci of sporadic medullary thyroid carcinoma suggests that they are intrathyroidal metastases from the same primary tumor
Jacqueline Almeida 1 , Raffaele Ciampi 2 , Roberta Casalini 3 , Teresa Ramone 4 , Sara Mori 4 , Virginia Cappagli 4 , Gabriele Materazzi 5 , Clara Ugolini 4 , Fulvio Basolo 6 , Laura Ward 7 , Rossella Elisei 8 & Cristina Romei 9
1Medical Clinical Department, University of Campinas, São Paulo, Brazil, Department of Clinical and Experimental Medicine, Endocrinology Unit, University of Pisa; University of Pisa; Department of Clinical and Experimental Medicine, Endocrinology Unit, Pisa, Italy; 2Department of Clinical and Experimental Medicina, Endocrinology Unit, University of Pisa, University of Pisa, Department of Clinical and Experimental Medicine, Endocrinology Unit, Pisa, Italy; 3, University of Pisa, Endocrine Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy, Department of Clinical and Experimental Medicine, Pisa, Italy; 4Unità DI Endocrinologia, Dipartimento DI Medicina Clinica e Sperimentale, Università DI Pisa, Pisa, Italia, Italy; 5Unità DI Endocrinologia, Dipartimento DI Medicina Clinica e Sperimentale, Università DI Pisa, Pisa, Italia, University of Pisa, Department of Surgical, Medical, Molecular Pathology and Critical Area, Italy; 6University of Pisa, Department of Surgical, Medical, Molecular Pathology and Critical Area, University of Pisa, Pisa, Italy, Department of Surgical, Medical and Molecular Pathology and Critical Care Medicine, Pisa, Italy; 7Medical Clinical Department, University of Campinas, São Paulo, Brazil; 8Oncology Section of the Endocrine Unit, Department of Clin and Exp Medicine, University Pisa, Pisa, Italy; 9Endocrine Unit, University of Pisa, Department of Clinical and Experimental Medicine, Pisa, Italy
Sporadic medullary thyroid cancer (sMTC) presents mutations of the RET proto-oncogene in about 50% of the cases and of the RAS proto-oncogene in about 20% of the cases. In about 15% of cases, sMTC is multifocal and it is not known whether multiple foci can be considered as intrathyroidal metastases of the main tumor focus or if they can be considered as independent tumors. To clarify this issue, we examined the mutation profile of multiple intrathyroidal tumor foci to verify if they share the same somatic mutations present in the main focus. We analyzed 34 cases of sMTC that had at least 1 tumor focus in addition to the main tumor. There were 13 cases that harbored 1 additional focus, 16 with two other foci, 4 with three foci and 1 with four other foci. DNA was extracted from paraffin-embedded (FFPE) tumor tissue or by fresh frozen tissues. For FFPE samples, DNA was specifically recovered from the tumor focus as indicated by the pathologist. Primary tumors were analyzed by Next-Generation Sequencing (NGS) using a custom panel in the IONS5 platform. Mutations were then validated by Sanger Sequencing and/or droplet-digital-PCR (ddPCR); the mutation observed in the main tumor focus was tracked in secondary tumor foci by ddPCR and/or by Sanger Sequencing. Five out of 34 sMTC cases (15%) included in this study had no detectable mutation in the main focus, 28 (82%) had one single mutation, and 1 (3%) had three different somatic mutations. Among the 28 cases with a single mutation: 26 (93%) harbored a somatic RET mutation, 1 (3.5%) had a HRAS mutation and 1 (3.5%) had KRAS. We demonstrated that in 33/34 investigated cases, the mutation profile of the main tumor focus was the same in all foci of the same patient. The mutation profile was not confirmed in 1/4 tumor foci of the only patient harboring 3 different somatic mutations in the main tumor focus. In conclusion, we show that virtually all tumor foci of the same patient had the same mutation; these data support the hypothesis that different tumor foci of the same patient are likely intrathyroidal metastases from the same primary tumor and not independent foci.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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