Significance of telomerase reverse-transcriptase promoter mutations in differentiated thyroid cancer

Background: Telomerase reverse-transcriptase (TERT) encodes the reverse transcriptase of telomerase, and TERT promoter mutations are enriched in advanced thyroid cancer. In this study, we aimed to characterize the clinicopathologic biology of differentiated thyroid cancer harboring TERT promoter mutations in Taiwan. Materials and Methods: Consecutive adult patients treated with differentiated thyroid cancer between 2017 and 2019 were included in this study. Mutational testing for the TERT promoter was performed by DNA-based polymerase chain reaction. Results: Among 389 patients included in the analysis, 22 (5.7%) had papillary or follicular thyroid cancer harboring TERT promoter mutations, including C228T (n = 18), C250T (n = 3), and CC242TT (n = 1). The frequency of BRAF V600E mutation was 73%. TERT promoter mutations were significantly associated with older age, tall cell variant of papillary thyroid cancer, extrathyroidal extension, positive surgical margins, lymphovascular invasion, perineural invasion, and distant metastasis. The generalized additive model showed that patient age was positively and almost linearly correlated with the likelihood of the presence of TERT promoter mutations. Conclusion: The frequency of TERT promoter mutations is relatively low in patients with differentiated thyroid cancer in Taiwan. These tumors carry unfavorable clinicopathologic features, present in a more advanced stage, and probably predict worse prognosis.