Endocrine Abstracts

Background: Various molecular mechanisms play a role in the pathogenesis of papillary thyroid cancer(PTC). Understanding the underlying pathogenesis and genetic changes is needed to improve clinical outcomes in PTC. In this study, it was aimed to determine the frequency of, BRAF ^V600E TERT promoter and NRAS mutations in Turkish patients with papillary thyroid cancer, the relationship of mutations between clinicopathological features and distant metastasis and the prognostic and predictive value of mutations.

Methods: In the study, mutations were detected by PCR and direct sequencing method from the paraffin-embedded tumor tissues of 42 PTC patients over 18 years of age who were followed up in Hacettepe University Hospital and archived in the Department of Pathology between 2004-2021, with 16 distant metastasis and 26 without distant metastasis patients and their relationship with clinicopathological features was determined. Pearson′s, chi-square and Mann-Whitney U tests were used for statistical analysis. A value of P<0.005 was considered statistically significant.

Results: The overall frequency of BRAF ^V600E mutation was 64.3% (27/42), BRAF positivity was found in %22.2 (6/15) of patients with distant metastasis and 77.8% (21/25) in those without (P=0.006). There was no statistically significant difference between BRAF^V600E mutation and age at diagnosis, gender, tumor size, histological variant, extrathyroidal invasion, multifocality, lymphovascular invasion, capsule invasion, lymph node metastasis, recurrens and distant metastasis. The survival rate was found to be lower in BRAF^V600E positive cases (3.7%) than in negative cases (96.3%) (P=0.03). The frequency of TERT promoter mutation was found to be 9.5% (4/42). These mutations were all mutations at position C228T. No statistically significant difference between TERT promoter mutation and age at diagnosis, gender, tumor size, histological variant, extrathyroidal invasion, multifocality, lymphovascular invasion, capsule invasion, lymph node metastasis, recurrens and distant metastasis. There was no statistically significant difference for clinicopathological features and distant metastasis in cases with BRAF ^V600E and TERT promoter mutations and in cases with both.

Conclusions: In contrast with the observations in other populations, BRAF ^V600E was found to be higher in Turkish PTC cases without distant metastasis compared to ones with distant metastasis. The combination of BRAF ^V600E and TERT promoter mutations in PTC is not prognostic or predicitive for distant metastasis.