The 2013 discovery of Telomerase reverse transcriptase (TERT) promoter mutations chr5, 1,295,228 C>T (C228T) and 1,295,250 C>T (C250T) in thyroid cancer represents an important event in the thyroid cancer field and much progress has occurred since then. This article provides a comprehensive review of this exciting new thyroid cancer field. The oncogenic role of TERT promoter mutations involves their creation of consensus binding sites for E-twenty-six transcriptional factors. TERT C228T is far more common than TERT C250T and their collective prevalence is, on average, 0, 11.3, 17.1, 43.2 and 40.1% in benign thyroid tumors, papillary thyroid cancer (PTC), follicular thyroid cancer, poorly differentiated thyroid cancer and anaplastic thyroid cancer, respectively, displaying an association with aggressive types of thyroid cancer. TERT promoter mutations are associated with aggressive thyroid tumor characteristics, tumor recurrence and patient mortality as well as BRAF V600E mutation. Coexisting BRAF V600E and TERT promoter mutations have a robust synergistic impact on the aggressiveness of PTC, including a sharply increased tumor recurrence and patient mortality, while either mutation alone has a modest impact. Thus, TERT with promoter mutations represents a prominent new oncogene in thyroid cancer and the mutations are promising new diagnostic and prognostic genetic markers for thyroid cancer, which, in combination with BRAF V600E mutation or other genetic markers (e.g. RAS mutations), are proving to be clinically useful for the management of thyroid cancer. Future studies will specifically define such clinical utilities, elucidate the biological mechanisms and explore the potential as therapeutic targets of TERT promoter mutations in thyroid cancer.
Rengyun Liu and Mingzhao Xing
Rengyun Liu and Mingzhao Xing
Two promoter mutations, chr5:1 295 228C>T and chr5:1 295 250C>T, in the gene for telomerase reverse transcriptase (TERT) have been recently identified in thyroid cancers and shown to be important in thyroid tumor pathogenesis. The diagnostic and prognostic potentials of testing for these mutations on thyroid fine-needle aspiration biopsy (FNAB) have not been investigated. Herein, we examined the two TERT promoter mutations along with the BRAF V600E mutation by direct DNA sequencing on 308 FNAB specimens preoperatively obtained from thyroid nodules with postoperatively confirmed pathological diagnoses. We found TERT promoter mutations in 0.0% (0/179) of benign thyroid nodules and 7.0% (9/129) of thyroid nodules of differentiated thyroid cancer, representing a 100% diagnostic specificity and 7.0% sensitivity, with the latter rising to 38.0% (49/129) when combined with BRAF V600E testing. Several TERT-promoter-mutation-positive thyroid nodules were cytologically indeterminate on FNAB. Approximately 80% of the TERT promoter mutation-positive thyroid nodules were thyroid cancers with aggressive clinicopathological behaviors, such as extrathyroidal invasion, lymph node metastases, distant metastases, disease recurrence or patient death. Thus, a positive TERT promoter mutation test not only definitively diagnoses a thyroid nodule as cancerous but also preoperatively identifies a cancer with aggressive potential. This is the first study, to our knowledge, of TERT promoter mutations on thyroid FNAB, demonstrating the value of this novel molecular testing in the diagnosis of thyroid nodules and preoperative risk stratification of thyroid cancer. Thus, testing of TERT promoter mutations on FNAB will enhance and improve the current molecular-based approaches to the management of thyroid nodules and thyroid cancer.
Xiaopei Shen, Rengyun Liu and Mingzhao Xing
A unique prognostic role of the genetic duet of BRAF V600E and TERT promoter mutations in papillary thyroid cancer (PTC) has been recently established, but the role of RAS mutation in this genetic interplay remains to be established. Using The Cancer Genome Atlas (TCGA) data of patients with PTC from 19 medical centers, we investigated the interactions among the three mutations in clinical outcomes of PTC. We found that BRAF and RAS mutations were mutually exclusive, but both were associated with TERT promoter mutations, with the genetic duet of BRAF/RAS and TERT mutations occurring in 34/388 (8.76%) patients. BRAF/RAS or TERT mutation had no or minimal effect alone, whereas coexisting BRAF/RAS and TERT mutations had a robust synergistic effect on poor clinicopathologic outcomes of PTC, including disease recurrence and patient mortality. For example, PTC recurrence rate was 52% with coexisting BRAF V600E/RAS and TERT promoter mutations vs 6.9% with no mutation, corresponding to a HR of 8.17 (95% CI 3.09–21.58), which remained significant at 14.71 (95% CI 2.79–77.61) after adjustment for clinicopathologic factors and institution. BRAF/RAS mutation or TERT mutation alone minimally affected Kaplan–Meier patient survival curves, whereas the genetic duet was associated with a sharp curve decline. Thus, by confirming and expanding previous findings in single-institution studies, this multicenter data analysis establishes a six-genotype genetic prognostic model for poor outcomes of PTC with a risk order of genetic duet of BRAF V600E/RAS mutation and TERT mutation >>>>BRAF V600E = TERT mutation alone >RAS mutation alone = wild-type genes.