The early identification of aggressive forms of cancer is of high importance in treating papillary thyroid cancer (PTC). Disease dissemination is a major factor influencing patient survival. Mutation status of BRAF oncogene, BRAF V600E, is proposed to be an indicator of disease recurrence; however, its influence on PTC dissemination has not been deciphered. This study aimed to explore the association of the frequency of BRAF V600E alleles in PTC with disease dissemination. In this study, 173 PTC samples were analyzed, measuring the proportion of BRAF V600E alleles by qPCR, which was then normalized against the proportion of tumor cells. Semiquantitative analysis of BRAF V600E mutant protein was performed by immunohistochemistry. The BRAF V600E mutation was present in 60% of samples, while the normalized frequency of mutated BRAF alleles ranged from 1.55% to 92.06%. There was no significant association between the presence and/or proportion of the BRAF V600E mutation with the degree of PTC dissemination. However, the presence of the BRAF mutation was significantly linked with angioinvasion. This study’s results suggest that there is a heterogeneous distribution of the BRAF mutation and the presence of oligoclonal forms of PTC. It is likely that the BRAF mutation alone does not significantly contribute to PTC aggressiveness.

Objectives: The response to radioiodine therapy (RAI) in differentiated thyroid cancer (DTC) patients is one of the most important factors that determines the treatment outcome and overall prognosis. The objective of this study is to determine the correlation between BRAF^V600E and TERT promoter (TERTp) mutation in tumor samples of DTC patients with the response to RAI as well as correlation with clinical and pathohistological features. Methods: Samples of 110 DTC patients (80 with intermediate and high risk of disease recurrence-IHR and 30 with distant metastases) were analyzed for BRAF^V600E and TERTp mutation (BRAF/TERT) and 89 patients were assessed for the response to RAI. Results: Sixty-one (55.5%) patients had BRAF^V600E mutation, 30 (27.3%) had TERTp mutation, while 21 (19.1%) patients had both mutations. In the IHR group, the study showed a statistically significant association between genotype BRAF/TERTp and treatment outcome (p = 0.04). IHR DTC patients with BRAF-/TERT- finding showed in general an excellent response to RAI, while patients with BRAF/TERT co-mutation had a predominantly incomplete or indeterminate response. In DTC patients with BRAF/TERT co-mutation that presented with distant metastases, a tendency to a higher frequency of RAI-refractory (RAI-R) disease was recorded, but without statistical significance. The pathohistological and clinical features that significantly correlated with BRAF/TERT status are age at diagnosis, locoregional lymph node involvement, the largest positive lymph node diameter, tumor angioinvasion and the presence of distant metastases. Conclusions: BRAF/TERT co-mutation may be associated with a less favorable disease course and poorer response to RAI. However, findings in patients with distant metastases should be considered exploratory due to the limited sample size.