TERT, BRAF, and NRAS in primary thyroid cancer and metastatic disease

Abstract

Context: Little is known about the frequency of key mutations in thyroid cancer metastases and its relationship with the primary tumor genotype. Objectives: To evaluate the frequency of TERT promoter (TERTp), BRAF, and NRAS mutations in metastatic thyroidcarcinomas, analyzingprimarythyroidtumors, lymphnodemetastases (LNMs),anddistant metastases. Design and Patients:Mutation analysiswas performed in 437 tissue samples from204 patients,mainly with papillary thyroid carcinomas (PTCs; n = 180), including 196 LNMs and 56 distant metastases. All the distant metastases included corresponded to radioiodine-refractory metastatic tissue. Results:Wefound the following mutation frequency in primary PTCs, LNMs, and distant metastases, respectively: TERTp: 12.9%, 10.5%, and 52.4%; BRAF: 44.6%, 41.7%, and 23.8%; and NRAS: 1.2%, 1.3%, and 14.3%. There was a significant concordance between the primary tumor genotype and the corresponding LNM for all the genes, in particular BRAF-mutated PTC. The overall concordance between primary tumors and respective distant metastases was low. In the group of patients with PTCs, we found a high frequency of TERTp mutations and a low frequency of BRAF mutations in distant metastases, in comparison with the paired primary tumors. When present in distant metastases, BRAF mutations frequently coexisted with TERTp mutations. Conclusions: When the genotype of primary tumors is compared with the genotype of LNMs, the concordance is high for all the genes studied. On the other hand, distant metastases show an enrichment in TERTp mutations and a decrease in BRAF mutations. TERTp mutations may play a role in distant metastases.