Activating point mutations of the BRAF gene have been recently reported in papillary thyroid carcinomas. In this study, we analyzed 320 thyroid tumors and six anaplastic carcinoma cell lines and detected BRAF mutations in 45 (38%) papillary carcinomas, two (13%) poorly-differentiated carcinomas, three (10%) anaplastic carcinomas, and five (83%) thyroid anaplastic carcinoma cell lines but not in follicular, Hürthle cell, and medullary carcinomas, follicular and Hürthle cell adenomas, or benign hyperplastic nodules. All mutations involved a T→A transversion at nucleotide 1796. In papillary carcinomas, BRAF mutations were associated with older age, classic papillary carcinoma or tall cell variant histology, extrathyroidal extension, and more frequent presentation at stages III and IV. All BRAF-positive poorly differentiated and anaplastic carcinomas contained areas of preexisting papillary carcinoma, and mutation was present in both the well-differentiated and dedifferentiated components. These data indicate that BRAF mutations are restricted to papillary carcinomas and poorly differentiated and anaplastic carcinomas arising from papillary carcinomas. They are associated with distinct phenotypical and biological properties of papillary carcinomas and may participate in progression to poorly differentiated and anaplastic carcinomas.

Background: The BRAF^V600E mutation is the most frequent genetic alteration in papillary thyroid carcinoma (PTC). The role of BRAF^V600E mutation as a poor prognostic factor has been controversially reported in series with short-term follow-ups. In this study we verified the prognostic value of the BRAF^V600E mutation in PTC patients with a long-term follow-up. Methods: We studied 102 PTC patients with a median follow-up of 15 yr. The BRAF^V600E mutation was analyzed by PCR-single-strand conformational polymorphism and sequencing. The correlation between the presence/absence of the BRAF^V600E mutation, clinicopathological features, and outcome of PTC patients were evaluated. Results: The BRAF^V600E mutation was found in 38 of 102 (37.3%) PTC patients, and was significantly more frequent in patients older than 60 yr (P = 0.02), in advanced stages (P = 0.03), and in cases with vascular invasion (P = 0.02). At univariate analysis the worst outcome for PTC patients was significantly correlated with clinicopathological features (i.e. age, tumor size, extrathyroid extension, lymph node and distant metastases, advanced stage, vascular endothelial growth factor expression, and vascular invasion) and the BRAF^V600E mutation (P < 0.002). However, at multivariate analysis only the BRAF^V600E mutation showed an independent correlation with the worst outcome (P = 0.03). Moreover, the survival curves of PTC patients showed a lower percentage of survivors in the BRAF^V600E-mutated group (P = 0.015). Conclusions: In this study the BRAF^V600E mutation correlated with the worst outcome for PTC patients, who were not only at a higher risk not to be cured but also for death. In particular, the BRAF^V600E mutation was demonstrated to be a poor prognostic factor independent from other clinicopathological features.

Context: Because very few studies have examined the correlation between BRAF mutations and clinicopathological features of papillary thyroid carcinoma (PTC), we analyzed here a large and homogeneous cohort of patients with PTC for the presence of the BRAF mutation. Objective: We examined BRAF mutations in a consecutive series of 500 PTC patients who underwent surgery in the Department of Surgery of the University of Pisa, and we correlated the presence of the mutation with clinicopathological parameters of the patients: age, gender, tumor size, presence of tumor capsule, extrathyroidal invasion, multicentricity, presence of node metastases, and tumor class. Design:BRAF (exon 15) mutation was examined by PCR-single strand conformational polymorphism followed by DNA sequencing in laser-capture microdissected tissue samples. Results: In this study, BRAF mutation was found in 219 of 500 cases (43.8%). In particular, we found the most common BRAF V600E mutation in 214 cases (42.8%), BRAF K601E mutation in three cases (0.6%), BRAF VK600–1E (0.2%) in one case, whereas in one case we found a new 14-bp deletion with concomitant 2-bp insertion, VKSR600–3del and T599I, respectively. BRAF V600E was associated with extrathyroidal invasion (P < 0.0001), multicentricity (P = 0.0026), presence of nodal metastases (P = 0.0009), class III vs. classes I and II (P < 0.00000006), and absence of tumor capsule (P < 0.0001), in particular in follicular- and micro-PTC variants. By multivariate analysis, the absence of tumor capsule remained the only parameter associated (P = 0.0005) with BRAF V600E mutation. Conclusions: Our data suggest that BRAF V600E mutation is associated with high-risk PTC and in particular in follicular variant with invasive tumor growth.

In papillary thyroid carcinomas (PTCs), rearrangements of the RET receptor (RET/PTC) and activating mutations in the BRAF or RAS oncogenes are mutually exclusive. Here we show that the 3 proteins function along a linear oncogenic signaling cascade in which RET/PTC induces RAS-dependent BRAF activation and RAS- and BRAF-dependent ERK activation. Adoptive activation of the RET/PTC-RAS-BRAF axis induced cell proliferation and Matrigel invasion of thyroid follicular cells. Gene expression profiling revealed that the 3 oncogenes activate a common transcriptional program in thyroid cells that includes upregulation of the CXCL1 and CXCL10 chemokines, which in turn stimulate proliferation and invasion. Thus, motile and mitogenic properties are intrinsic to transformed thyroid cells and are governed by an epistatic oncogenic signaling cascade.

The BRAF(V600E) mutation, the most frequent genetic alteration in papillary thyroid carcinoma (PTC), was demonstrated to be a poor prognostic factor. The aim of this study was to evaluate its prognostic significance in a large cohort of low-risk intrathyroid PTC. Among the 431 consecutive PTC patients, we selected 319 patients with an intrathyroid tumor and no metastases (T1-T2, N0, M0). The BRAF(V600E) mutation was analyzed by PCR-single-strand conformation polymorphism analysis and direct genomic sequencing. The correlation between the presence/absence of the mutation, the clinical-pathological features, and the outcome of the PTC patients was investigated. The BRAF(V600E) mutation was present in 106 of 319 PTC patients (33.2%). Its prevalence was also the same in subgroups identified according to the level of risk. The BRAF(V600E) mutation correlated with multifocality, aggressive variant, absence, or infiltration of the tumoral capsule. BRAF(V600E)-mutated PTC also required a higher number of radioiodine courses to obtain disease-free status. The BRAF(V600E) mutation was the only prognostic factor predicting the persistence of the disease in these patients after 5 yr of follow-up. The BRAF(V600E) mutation was demonstrated to be a poor prognostic factor for the persistence of the disease independent from other clinical-pathological features in low-risk intrathyroid PTC patients. It could be useful to search for the BRAF(V600E) mutation in the workup of low-risk PTC patients to distinguish those who require less or more aggressive treatments. In particular, the high negative predictive value of the BRAF(V600E) mutation could be useful to identify, among low-risk PTC patients, those who could avoid 131-I treatment.

Point mutations in BRAF are genetic hallmarks of papillary thyroid carcinoma (PTC). In this retrospective study, we examined thyroid aspirates and corresponding paraffin-embedded surgical samples for the presence of BRAF mutations. Altogether, we examined 96 cases, including 69 PTCs, 19 follicular adenomas, and eight nontoxic nodular goiters for BRAF; 60 of these samples were also examined for RET/PTC rearrangements. The results were correlated with the cytological diagnosis and the final histopathology. The BRAF mutation (V599E) was detected in 38% of the samples that were PTC on histopathology; RET/PTC was found in 18% of the PTC cases. In all the cases, the presence of the genetic alteration was confirmed in the surgically resected tumor. The identification of BRAF mutation and RET/PTC refined the diagnosis of PTC in five of 15 samples that were considered either indeterminate or insufficient at cytology. No mutation was found in aspirates of follicular adenomas and nontoxic nodular goiters. These results indicate that BRAF mutation and RET/PTC rearrangements are molecular markers of PTC that can be applied to FNA in adjunct to traditional cytology.