title: Highly Concordant Key Genetic Alterations in Primary Tumors and Matched Distant Metastases in Differentiated Thyroid Cancer.
abstract: Distant metastases uncommonly occur in differentiated thyroid carcinoma (DTC), but they are a frequent cause of thyroid cancer-related death. Genomic alterations in metastatic tumors, and the relationship with their corresponding primary tumors in DTC, are poorly understood. The objective of this study was to investigate whether genetic alterations in primary tumors are concordant with distant metastases in DTC patients.
  
  
  
  Surgical samples from primary and matched distant metastatic tumor pairs from 17 DTC patients, and three additional unpaired metastatic tumors from two patients, were analyzed using targeted next-generation sequencing (Ion Torrent Ampliseq cancer panel) with a focus on known recurrent somatic mutations in thyroid cancer. Additionally, TERT promoter mutations were assessed by direct sequencing.
  
  
  
  BRAF mutations were found in 8/10 patients with papillary thyroid carcinoma (PTC). A NRAS mutation was detected in one patient with follicular variant PTC. TERT promoter mutations were detected in 8/10 patients with PTC, and most were coexistent with a BRAF mutation (7/8 BRAF-positive PTC patients, and one BRAF-negative PTC patient). In follicular thyroid carcinoma, NRAS was the most frequently observed mutation (4/9 patients), followed by HRAS (two patients) and KRAS (one patient). TERT promoter mutations were found in 6/7 RAS-positive follicular thyroid carcinoma patients. Key somatic alterations such as BRAF and RAS mutations were highly concordant between primary and matched metastatic tumors without discrepancies. The BRAF or RAS mutant allelic frequency was higher in matched metastatic tumors than in the corresponding primary tumors (35% vs. 25% for BRAF mutation, p = 0.04; and 40% vs. 34% for RAS mutation, p = 0.002). TERT promoter mutations were also mostly concordant in matched tumors (concordance rate 93%).
  
  
  
  BRAF, RAS, and TERT mutations are highly prevalent in metastatic DTC, and are concordant between primary and metastatic DTC. This high concordance suggests that primary tumors may reflect the key somatic alterations in matched metastatic DTC. Frequent coexistent TERT promoter and BRAF or RAS mutations in metastatic DTC also suggests its important role in the progression of DTC.
authors.affiliation: 1 Department of Endocrinology and Metabolism, Seonam University , Myongji Hospital, Goyang, Korea.
authors.forename: Seo Young
authors.initials: SY
authors.lastname: Sohn
authors.affiliation: 2 Samsung Genome Institute, Samsung Medical Center , Seoul, Korea.|3 Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine , Suwon, Korea.
authors.forename: Woong Yang
authors.initials: WY
authors.lastname: Park
authors.affiliation: 2 Samsung Genome Institute, Samsung Medical Center , Seoul, Korea.
authors.forename: Hyun Tae
authors.initials: HT
authors.lastname: Shin
authors.affiliation: 2 Samsung Genome Institute, Samsung Medical Center , Seoul, Korea.
authors.forename: Joon Seol
authors.initials: JS
authors.lastname: Bae
authors.affiliation: 4 Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul, Korea.
authors.forename: Chang Seok
authors.initials: CS
authors.lastname: Ki
authors.affiliation: 5 Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul, Korea.
authors.forename: Young Lyun
authors.initials: YL
authors.lastname: Oh
authors.affiliation: 6 Division of Endocrinology and Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul, Korea.
authors.forename: Sun Wook
authors.initials: SW
authors.lastname: Kim
authors.affiliation: 6 Division of Endocrinology and Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul, Korea.
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Chung
mesh_terms: D000328:Adult; D000368:Aged; D002291:Carcinoma, Papillary / Q000235:genetics* / Q000473:pathology; D004252:DNA Mutational Analysis; D018450:Disease Progression; D005260:Female; D020558:GTP Phosphohydrolases / Q000235:genetics; D005787:Gene Frequency; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D009362:Neoplasm Metastasis / Q000235:genetics* / Q000473:pathology; D011401:Promoter Regions, Genetic; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D019098:Telomerase / Q000235:genetics; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000473:pathology
chemical_list: D008565:Membrane Proteins; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; C509186:TERT protein, human; D019098:Telomerase; D020558:GTP Phosphohydrolases; C579846:NRAS protein, human