Association of BRAF V600E mutation with poor clinicopathological outcomes in 500 consecutive cases of papillary thyroid carcinoma

A comparison of prognostic classification systems for differentiated thyroid carcinoma

OBJECTIVE

To identify and compare prognostic classification systems based on basic tumour characteristics that were developed and/or validated for differentiated thyroid carcinoma (DTC).

DESIGN

Retrospective chart study.

METHODS

Literature was studied using PubMed. Fifteen different prognostic classification systems were identified, of which seven were developed or validated for DTC patients and were based on basic tumour characteristics. These systems were applied to 1225 DTC patients who were treated in our hospital between 1978 and 2002.

RESULTS

Log-rank analysis of Kaplan-Meier cancer-specific survival curves showed that the curve of the Tumor, Lymph-Node, Metastasis (TNM) system had the greatest discriminatory power (log-rank test, log P = -84.9). Cox-regression analysis showed that the TNM system was the most powerful determinant of cancer-specific survival curves. Proportion of variance explained (PVE) analysis showed that the TNM system had the highest PVE.

CONCLUSION

Of the prognostic classification systems analysed in this study, the TNM system performs best in all the three analyses, and is therefore the most suitable for predicting outcome in DTC-patients.

Prognostic utility of BRAF mutation in papillary thyroid cancer

Papillary thyroid cancer (PTC) is a common endocrine malignancy that frequently harbors the oncogenic T1799A BRAF mutation. As a novel prognostic molecular marker, this mutation has received considerable attention in recent years for its potential utility in the risk stratification and management of PTC. In PTC, BRAF mutation is closely associated with extrathyroidal extension, lymph node metastasis, advanced tumor stages, disease recurrence, and even patient mortality. Many of the responsible molecular derangements promoted by, or associated with, BRAF mutation have been identified, including over-expression of tumor-promoting genes, suppression of tumor-suppressor genes, and silencing of thyroid iodide-handling genes, resulting in impairment or loss of radioiodine avidity and hence the failure of radioiodine treatment of PTC. BRAF mutation can be readily tested on thyroid fine needle aspiration biopsy specimens, with high preoperative predictive probabilities for clinicopathological outcomes of PTC. As such, the knowledge of BRAF mutation status can facilitate more accurate risk stratification and better decision making at various steps in the management of PTC, from preoperative planning of initial surgical scale to postoperative decisions about appropriate radioiodine treatment and thyroid-stimulating hormone suppression, and to selections of appropriate surveillance modalities for PTC recurrence. The greatest utility of BRAF mutation status is in those cases where traditional clinicopathological criteria alone would otherwise be unreliable in the risk stratification and management of PTC. Use of this unique molecular marker, in conjunction with conventional clinicopathological risk factors, to assist the prognostication of PTC is likely to improve the efficiency of contemporary management of thyroid cancer.

BRAFV600E mutation in the pathogenesis of a large series of papillary thyroid carcinoma in Czech Republic

BACKGROUND

Activating point mutation of the BRAF gene, the most common genetic alteration reported in papillary thyroid carcinomas (PTC), has been associated with poor prognostic characteristics.

AIM

Our objective was to determine the frequency of BRAFV600E mutation in PTC tumor tissues from the period 1960-2007 and to correlate it with clinicopathological parameters.

SUBJECTS AND METHODS

DNAs were extracted from 242 PTCs, 23 sporadic medullary carcinomas, one anaplastic carcinoma and 6 poorly differentiated carcinomas. The presence of BRAFV600E mutation was determined using single strand conformation polymorphism method and verified by direct sequencing.

RESULTS

BRAFV600E mutation was detected in 81 of 242 PTCs (33.5%), in one of 6 poorly differentiated carcinomas (16.7%) and in anaplastic carcinoma. BRAFV600E mutation was much less frequent in the follicular variant compared to classical variant and mixed follicular- classical variant of PTCs (p=0.001). BRAFV600E mutation was significantly associated with presence of nodal metastasis (p=0.029), more advanced TNM stage (p=0.014) and recurrence of disease (p=0.008). The mutation correlated with a higher age at diagnosis (p=0.049) and with a greater tumor size (p=0.041). Multivariate analysis confirmed these findings. The prevalence of BRAFV600E mutation before 1986 was significantly lower than after it (p=0.008).

CONCLUSIONS

Our data suggest that BRAFV600E mutation is associated with high-risk clinicopathological characteristics of PTC and worse prognosis of patients. The frequency of the mutation significantly varied during the observed period but rather because of the different age distribution of patients in particular periods than as a consequence of Chernobyl accident.

Old and new insights in the treatment of thyroid carcinoma

Thyroid cancer is the endocrine tumor that bears the highest incidence with 33 550 new cases per year. It bears an excellent prognosis with a mortality of 1530 patients per year (Jemal et al.; 2007). We have been treating patients with thyroid carcinoma during many years without many innovations. Recently, we have assisted to the development of new agents for the treatment of this disease with unexpected good results. Here we present a review with the old and new methods for the treatment of this disease.

Papillary microcarcinoma in comparison with larger papillary thyroid carcinoma in BRAF(V600E) mutation, clinicopathological features, and immunohistochemical findings

BACKGROUND

Papillary thyroid microcarcinoma (PMC; <or=1 cm) is thought to take a benign course during the lifetime. However, recent studies showed high recurrence rates for PMC.

METHODS

We analyzed the clinicopathological features, long-term prognosis, and some molecular characteristics including BRAF(V600E) mutation by retrospectively reviewing the records of 1150 patients with papillary thyroid carcinoma (PTC), 278 with PMC, and 868 with PTC >1 cm.

RESULTS

The prevalence of extrathyroidal invasion (52.2%) and initial nodal metastasis (34.9%) in patients with PMC was surprisingly high and almost as high as that for patients with PTC (72.4% and 51.8%, respectively). The rate of recurrent or persistent disease did not differ between patients with PMC and PTC (recurrent or persistent disease, 6.1% vs 14.1%; 53.4- vs 84.2-month follow-up; n = 98 vs 647; corrected p = .112). The frequency of BRAF(V600E) mutation was similar in patients with PMC and PTC (65.6% vs 67.2%). Immunohistochemical staining showed no different expression pattern according to the tumor size.

CONCLUSION

These results suggest that PMC is not an occult cancer and it can act like larger PTC. Therefore, PMC should not be underestimated in practice.

Detectable BRAF mutation in serum DNA samples from patients with papillary thyroid carcinomas

BACKGROUND.: An activating point mutation of the BRAF oncogene results in a V600E amino acid missense mutation found in a majority of papillary thyroid carcinomas (PTC). METHODS.: In this study, 28 matched tumor and serum samples obtained from patients with both benign and malignant thyroid disorders were analyzed for BRAF mutation using a gap-ligase chain reaction technique. RESULTS.: The BRAF mutation was absent in tumor DNA samples obtained from patients with benign adenomas, follicular neoplasms or carcinoma, and thyroid lymphoma. In contrast, 5 of 14 PTC tumors were positive for the BRAF mutation. Moreover, 3 of 14 patients with PTC were positive for BRAF mutation in serum and tumor. Of these 3 patients, 2 had lymph node metastasis and 2 had PTC in background of the Hashimoto's thyroiditis. CONCLUSIONS.: The detection of free circulating mutant BRAF in patients with PTC is possible and future studies are warranted to determine its clinical significance.

BRAF mutation in papillary thyroid carcinoma: pathogenic role and clinical implications

Papillary thyroid cancer (PTC) is the most common endocrine malignancy, accounting for 85-90% of all thyroid cancers. Genetic alternations involving the mitogen-activated protein kinase (MAPK) pathway are frequently demonstrated in PTC, such as RET/PTC, RAS, and B-type Raf kinase (BRAF) mutations. Over 90% of BRAF mutations are T1799A, resulting in a BRAF(V600E) mutation. BRAF(V600E) is present in approximately 50% of PTC and also found in aggressive histologic variants and PTC-derived anaplastic thyroid cancer, but is rare in follicular variants, and not found in follicular thyroid cancer. The tumorigenic role of BRAF(V600E) in the development of PTC was documented in thyroid-targeted BRAF(V600E) transgenic mice, and rat thyroid cells overexpressed with BRAF(V600E) suggested that BRAF(V600E) is an initiator of tumorigenesis and is required for tumor progression in PTC. Most clinical studies have demonstrated an association of BRAF(V600E) mutation with aggressive clinicopathologic characteristics and high tumor recurrence, although the results are controversial. The association is also observed in patients with papillary thyroid microcarcinomas and low-risk PTC. As a highly specific and unique mutation in PTC, testing for BRAF(V600E) in fine-needle aspiration specimens has been shown to refine the diagnostic accuracy of PTC in indeterminate cytology. Preoperative BRAF(V600E) analysis in low-risk patients may provide important value for prognostication, and these patients might benefit from receiving more intensive management and frequent follow-up. BRAF-targeted therapies have been developed to treat various human cancers including advanced thyroid cancers. Preclinical results are encouraging, but the anticancer effects of clinical trials are disappointing. Studies of multi-kinase inhibitors and/or combination with other regimens are underway in the treatment of advanced thyroid cancers. In this article, we review the pathogenesis of PTC, and the clinical implications of BRAF(V600E) mutation in the diagnosis, prognosis and potential targeted therapeutic strategies for thyroid cancers.

Differential miRNA expression profiles in variants of papillary thyroid carcinoma and encapsulated follicular thyroid tumours

Background:

Recent studies showed a significant upregulation of distinct microRNAs (miRNAs) in papillary thyroid carcinoma (PTC). The objective of this study was to explore whether this upregulation could also be assigned to distinct histomorphological variants of PTC, especially the follicular variant and other encapsulated follicular thyroid tumours.

Methods:

We used total RNA of 113 formalin-fixed paraffin-embedded tissues of 50 PTCs ((10 conventional type (PTC-CT), 10 tall cell variants (PTC-TCVs), 30 follicular variants (PTC-FVs)), 10 follicular adenomas (FAs), 10 multinodular goitres (MNGs), 21 follicular thyroid carcinomas and 22 well-differentiated tumours of unknown malignant potential (WDT-UMP) to analyse the miRNA expression pattern of five selected miRNAs (146b, 181b, 21, 221 and 222) using RT–PCR TaqMan miRNA assay to explore the diagnostic utility of this method.

Results:

The mean values of the expression pattern of all miRNAS in PTCs show a statistically significant difference from those in MNG and FA with fold changes up to 90 for miRNA 146b, P<0.001. No differences in expression pattern could be showed between MNG and FA. The PTC-FVs differ significantly from FA in all five miRNAS, from MNG in three and from WDT-UMP in one miRNA with fold changes between 1.7 and 21.2, but failed to be of diagnostic value regarding individual cases with substantial overlaps.

Conclusion:

We conclude that analysis of a set of five selected miRNAS distinguish common variants of PTC from FA/MNG but failed to be a useful diagnostic method in individual and doubtful cases, especially in the differential diagnosis of encapsulated follicular thyroid tumours.

Molecular diagnostics and predictors in thyroid cancer

BACKGROUND

The accuracy of cancer detection in thyroid nodules by fine-needle aspiration (FNA) cytology and prognostication of thyroid cancer needs further improvement and can benefit from testing for molecular alterations known to occur in thyroid tumors.

SUMMARY

Recent studies have demonstrated the feasibility of mutation detection in clinical FNA samples from thyroid nodules and their contribution to improving the diagnostic accuracy of FNA cytology. It appears that molecular testing is most beneficial for thyroid FNA samples with indeterminate cytology, where it can resolve the diagnosis in a significant number of cases. In addition to BRAF mutation, which has been studied most extensively, detection of RAS, RET/PTC, and PAX8/PPARgamma mutations also contribute substantially to cancer diagnosis. Some of these molecular markers, particularly BRAF, can also be used for tumor prognostication. In clinical setting, molecular testing of thyroid FNA samples and surgically removed tumors should utilize a restricted number of techniques that provide high accuracy and specificity of mutation detection.

CONCLUSION

Testing for cancer-specific mutations in thyroid FNA samples and surgically removed tumor tissues increases diagnostic accuracy of FNA cytology and offers better prognostication of thyroid cancer.

Clinicopathologic and molecular disease prognostication for papillary thyroid cancer

Despite its increasing incidence over the last 30 years, the mortality rate of papillary thyroid cancer (PTC) has decreased significantly. Nevertheless, a minority of patients still present with an aggressive form of PTC that can lead to death, even after a prolonged period of survival. Many classifications exist that allow one to stratify the clinical risk of recurrence and death in patients with PTC; however, the parameters upon which they are established are pathological and molecular and, therefore, are revealed only after surgery. The preoperative identification of these aggressive variants of PTC would allow one to schedule a more aggressive operation (e.g., total thyroidectomy together with central and/or mono- or bi-lateral node dissections) in patients with high-risk PTC. This article reviews the parameters used most commonly to differentiate low-risk PTCs from their more aggressive variants and describes some of the newest molecular therapies for this latter group of tumors.

BRAF mutational analysis in papillary carcinomas with mixed follicular and papillary growth patterns

BACKGROUND

Current literature suggests that up to 60% of papillary carcinomas have mutations in the BRAF gene. However, follicular variant of papillary carcinoma has a much lower frequency of mutation. Tumors with mixed patterns of growth, including distinctive area of follicular and papillary growth, have not been well studied for the presence of the BRAF gene mutation.

DESIGN

Cases of papillary carcinoma were identified with well-defined conventional papillary growth pattern, alongside other areas with follicular growth pattern. The tumor stage was obtained, along with demographic information. The different growth pattern areas were separately microdissected and DNA was extracted from the resulting tissue fragments. Polymerase chain reaction was performed for an amplicon in BRAF exon 15 that includes the mutation site. Cycle sequencing was performed using the BigDye Terminator kit and analysis was performed on an ABI automated sequencer (Applied Biosystems). The forward and reverse sequences were analyzed for point mutations.

RESULTS

DNA extraction and polymerase chain reaction amplification was successful in all cases. Seventy percent of the tumors were positive for the BRAF mutation. In comparing the follicular and the papillary growth patterned areas, the BRAF mutation was concordant in all cases. Four cases had an additional separate focus of microscopic papillary carcinomas. These were negative for the BRAF mutation.

CONCLUSIONS

Papillary carcinomas of the thyroid with papillary growth and areas of follicular growth have a high frequency of BRAF mutations. The BRAF mutational profile is identical in the follicular areas and in the conventional papillary growth areas. These molecular data support the common diagnostic decision that a tumor with any amount of conventional papillary growth should be designated as a conventional papillary carcinoma, regardless of the presence of follicular growth pattern areas.

Seven-year follow-up of a juvenile female with papillary thyroid carcinoma with poor outcome, BRAF mutation and loss of expression of iodine-metabolizing genes

BACKGROUND

Recent studies reported that BRAF V600E mutation, the most prevalent genetic event found in papillary thyroid carcinoma, is an independent poor prognostic marker. Additionally, it correlates with a less differentiated tumor stage due to reduced expression of key genes involved in iodine metabolism. We previously described a patient with BRAF V600E mutation in primary tumor and a new mutation (V600E+K601del) in the matched-lymph node metastases. In the present study we report an unusual clinical behavior of PTC and correlate with BRAF mutational status and level of expression of TSHR and NIS.

METHODS

Quantitative PCR (qPCR) was used to evaluate the NIS and TSHR level of expression in matched papillary thyroid carcinoma and adjacent normal tissue.

RESULTS

In this study, we presented a seven-year follow up of a juvenile papillary thyroid carcinoma patient who had an aggressive tumor harboring BRAF mutation, and failed to conventional therapy. We found a markedly decrease of NIS and TSHR expression in primary PTC compared to adjacent normal thyroid tissue.

CONCLUSION

Our findings suggest that BRAF mutational status and decreased NIS and TSHR expression in this patient may reduce radioiodine uptake and lead to a negative response to radioiodine therapy.

A morpho-molecular diagnosis of papillary thyroid carcinoma: BRAF V600E detection as an important tool in preoperative evaluation of fine-needle aspirates

BACKGROUND

Although most thyroid nodule fine-needle aspiration (FNA) diagnoses are definitive or nearly definitive, about 30% of them are not read as definitively benign or malignant, the so-called indeterminate or suspicious FNA diagnosis. The prevalence of malignancy in FNA samples with these diagnoses varies from 10% to 52%. The first aim of this study was to determine if BRAF V600E analysis of thyroid FNA cytological smears could be performed with a relatively simple protocol. We also sought to determine if assessing the presence of BRAF gene mutations in preoperative FNA cytology slides would provide diagnostic information for FNA samples with a reading of indeterminate or suspicious thyroid lesions.

METHODS

DNA was extracted directly from FNA-stained smears of 111 patients with thyroid lesions having different cytological diagnoses. There was 1 cystic nodule, 20 microfollicular proliferations without atypia, 32 that were suspicious for papillary carcinoma, 56 papillary thyroid carcinomas (PTC), and 2 poorly differentiated carcinomas. The BRAF V600E mutational status was determined by sequencing analysis in all patients. The histopathological diagnosis was obtained in all cases.

RESULTS

We observed that 56/90 (62.3%) patients received a definitive diagnosis of PTC when only cytology was used. After molecular analysis, the BRAF V600E mutation was detected in 18/32 (56.2%) cases with a cytology of suspicious for papillary carcinoma and 41/56 (73.2%) with PTC. According to the morpho-molecular analysis (i.e., traditional cytology combined with BRAF V600E analysis) 74/90 (82.2%) patients could be assigned a definitive diagnosis of PTC. Therefore, the addition of molecular analysis yielded an increase of 20% in the sensitivity compared to cytology alone.

CONCLUSIONS

The method of molecular analysis of thyroid FNA smears described here can be easily performed after the FNA, thereby avoiding inconvenience and additional time during the FNA and permitting later analysis of samples having indeterminate cytology features. The increased sensitivity of this preoperative morpho-molecular analysis should provide information that is useful in deciding the extent of thyroid surgery for thyroid nodules that are indeterminate or suspicious on cytology.

Primary tumour diameter as a risk factor for advanced disease features of differentiated thyroid carcinoma

OBJECTIVE

To study the relationship between primary tumour size and the risk of advanced disease features (multifocal or locally invasive disease, lymph-node or distant metastases) in differentiated thyroid carcinoma (DTC).

DESIGN

A retrospective chart review study.

PATIENTS

The study sample comprised 935 papillary (PTC) and 291 follicular thyroid carcinoma (FTC) patients treated in our hospital from 1978 to 2007.

MEASUREMENTS

Kaplan-Meier analyses and log-rank tests were performed to calculate tumour size-adjusted cumulative risk of advanced disease features.

RESULTS

Accounting for primary tumour diameter, there were no significant differences in cumulative risks of multifocal carcinoma (P = 0.12) or distant metastases (P = 0.49) between PTC and FTC. PTC showed higher cumulative risks of local invasion (P < 0.0001) or lymph-node metastases (P < 0.0001). The cumulative risk of tumour multifocality increased 5%/cm of primary tumour diameter. The cumulative risk of local invasion or lymph-node metastases in PTC and of distant metastases in DTC increased exponentially at a threshold tumour diameter of 10 mm. In FTC, lymph-node metastases are associated almost exclusively with primary tumours showing extrathyroidal growth.

CONCLUSIONS

Starting with a 1 cm primary tumour diameter, increasing tumour size is associated with an exponentially increasing risk of local invasion or lymph-node or distant metastases of DTC. The current classification of carcinomas < 2 cm as T1 is therefore questionable.

High rate of BRAF and RET/PTC dual mutations associated with recurrent papillary thyroid carcinoma

PURPOSE

Papillary thyroid carcinoma (PTC), the most common thyroid malignancy, usually possesses BRAF mutation or rearranged in translation (RET)/PTC rearrangements. PTC usually possesses BRAF mutation or RET/PTC rearrangements. The mutation status of patients with recurrent PTC has never been characterized in a large population.

EXPERIMENTAL DESIGN

Mutation status was determined in a cohort of 54 patients with recurrent PTC and analyzed for clinicopathologic relationships. BRAF and ras mutations were determined by PCR and sequencing of genomic DNA. RET/PTC rearrangements were analyzed by reverse transcription-PCR.

RESULTS

BRAF mutation in exon 15 (V600E) was found in 42/54 (77.8%) recurrent PTC patients. The RET/PTC rearrangements were detected in 9 of 54 (16.7%) patients. In addition, 5 of 54 (9.3%) recurrent PTC patients had both a BRAF mutation and a RET/PTC rearrangement. The prevalence of tumors with dual mutations found in the recurrent population far exceeds the frequency historically reported for patients with primary PTC. Patients with dual mutations were significantly older (80% older than 45 years) than patients with a BRAF mutation alone (38% older than 45 years).

CONCLUSIONS

Recurrent PTC is significantly associated with a predominant BRAF mutation. RET/PTC rearrangements, although commonly associated with primary PTCs in younger patients, are uncommonly found in recurrent PTC patients. In addition, the incidence of dual mutations was higher in patients with recurrent PTC than in those primary PTC, as reported by others.

Oncocytic variant of papillary thyroid carcinoma associated with Hashimoto's thyroiditis: a case report and review of the literature

Identification of Hürthle cells on fine-needle aspiration (FNA) of the thyroid leads to a wide differential diagnosis including benignand malignant entities. We report the cytological and histological findings of a patient with an oncocytic variant of papillary thyroid carcinoma (PTC) with concurrent Hashimoto's thyroiditis. FNA revealed a lymphoplasmacytic infiltrate with Hürthle cells demonstrating abnormal chromatin patterns, nuclear enlargement, pleomorphism, intranuclear cytoplasmic invaginations, and foci of papillary aggregates. Because of the degree of nuclear atypia and suspicion for concurrent papillary thyroid carcinoma, a total thyroidectomy was performed revealing a papillary arrangement of Hürthle cells with classic PTC nuclear changes and associated Hashimoto's thyroiditis. This report discusses cytopathological features of a rare variant of PTC (oncocytic subtype) in the background of Hashimoto's thyroiditis. We also briefly discuss the differential diagnosis and diagnostic pitfalls of Hürthle cell lesions, with a review of the literature.

High prevalence of BRAF mutation in a Brazilian cohort of patients with sporadic papillary thyroid carcinomas: correlation with more aggressive phenotype and decreased expression of iodide-metabolizing genes

BACKGROUND

Although several studies undoubtedly demonstrated that BRAF mutation is an important genetic event in the pathogenesis of papillary thyroid carcinoma (PTC), its prognostic significance and correlation with less differentiated states remains unclear. It has been suggested that the discrepancy may be at least partially due to the insufficient number of cases analyzed, epidemiologic factors, and a combination of different variants of PTC included in these studies.

METHODS

In this context, the prevalence of the BRAF mutation in a Brazilian cohort of PTCs (n = 120) was first assessed and correlated with clinicopathologic features. The BRAF exon 15 mutation was evaluated by direct sequencing. Furthermore, using quantitative polymerase chain reaction, the issue of whether the expression level of the iodide-metabolizing genes (NIS and TSHR) was correlated with BRAF mutational status was investigated.

RESULTS

A high prevalence of the BRAF mutation was found in PTC cases (48%). The BRAF mutation was found to be significantly associated with the classic variant of PTC (66%; P < .0001), although it was found in the follicular variant as well (21%). Subtype stratification demonstrated that the BRAF V600E mutation was associated with tumor size, extrathyroid invasion, the presence of lymph node metastasis and risk of disease recurrence, and mortality in patients with the classic variant of PTC. Moreover, the expression levels of NIS and TSHR were remarkably lower in PTCs harboring the BRAF V600E mutation.

CONCLUSIONS

These findings provide further evidence that BRAF might be associated with a more aggressive phenotype and less differentiated state due to decreased expression of iodide-metabolizing genes. The search for a BRAF mutation in the current study population appears to be valuable for predicting prognosis and guiding management in patients with PTC.

BRAFV600E mutation and X-linked inhibitor of apoptosis expression in papillary thyroid carcinoma

BACKGROUND

The BRAF mutation V600E (BRAF(V600E)) is the most common genetic alteration in papillary thyroid carcinoma (PTC), while overexpression of X-linked inhibitor of apoptosis (XIAP) has been found in various tumors. Both of these events are implicated in carcinogenesis, tumor progression, recurrence, etc. There are few reports, however, of the BRAF(V600E) mutation and XIAP overexpression in PTC patients. The aim of this study was to investigate the frequency of the BRAF(V600E) mutation in PTC and its relationship to clinicopathological parameters and the expression of XIAP.

METHODS

Genomic DNA was extracted from 123 paraffin-embedded PTC tumor tissue samples and amplified for analysis of the V600E mutation in exon 15 of the BRAF gene by polymerase chain reaction. XIAP expression was examined by immunohistochemical methods in 46 PTCs, 18 benign nodular goiters, and 10 Hashimoto's thyroiditis samples.

RESULTS

The BRAF(V600E) mutation was found in 34.1% of PTC, and was especially prevalent in the classic type. BRAF(V600E) was significantly correlated with younger age at diagnosis (p = 0.026), tumor size (p = 0.009), and histological variants (p = 0.024). There was a trend towards association with extrathyroidal invasion (p = 0.067). By logistic regression analysis, a significant relationship was found between tumor size and the BRAF(V600E) mutation (p = 0.03). XIAP was expressed in 82.6% of PTCs, which was a higher percentage than observed in the group of benign thyroid disorders (35.7%, p < 0.001). Neither the intensity (p = 0.611) nor the extent (p = 0.723) of XIAP staining was correlated with the presence of BRAF(V600E) in PTC patients.

CONCLUSIONS

These data indicate that BRAF(V600E) is associated some of the aggressive clinicopathological features of PTC including younger age at diagnosis, larger tumor size, and classic histological type, as well as also extrathyroidal invasion. XIAP-positive staining was more prevalent in PTCs than in the benign thyroid disorders. Although BRAF(V600E) and XIAP expression are commonly seen in PTC, their presence together seems unrelated.

Detection and molecular characterization of a novel BRAF activated domain mutation in follicular variant of papillary thyroid carcinoma

To assess the mutational status of BRAF in FVPTC, we directly sequenced the genomic DNA of 30 primary FVPTC samples. BRAF mutations were found in only 4 (13%) tumors. We also identified a previously unknown (novel) mutation in the activation kinase domain of the BRAF (A598V), replacing alanine with valine. Functional analysis showed that this mutation led to the up-regulation of the BRAF kinase activity and its downstream signaling factors. The effect of this mutation on the structural formation of the protein is highlighted. Our results confirm the infrequency of BRAF (V600E) mutation in FVPTC and identify a novel (A598V) mutation of this gene.

Role of B-Raf(V600E) in differentiated thyroid cancer and preclinical validation of compounds against B-Raf(V600E)

B-Raf(V600E), an oncogenic protein kinase, is the most frequent genetic alteration in papillary thyroid carcinomas (PTC). PTC represents 80-90% of all thyroid cancers and over the past five years, more than 200 manuscripts have been published about the relationship between "B-Raf(V600E) and thyroid cancer". B-Raf(V600E) genetically arises from a transversion point mutation (valine-to-glutamate substitution at amino acid residue-600, V600E) and leads to over activation of the mitogen-activated protein kinases (MAPK) signaling pathway. The MAPK pathway is essential for transmitting proliferation signals generated by cell surface receptors and cytoplasmic signaling elements to the nucleus. In many cancers, including thyroid cancer, B-Raf(V600E) appears to play a crucial role in cell proliferation, survival and de-differentiation. In thyroid cancer, the V600E mutation occurs with greater frequently in aggressive subtypes of PTC, and in individuals that present at advanced stages of disease with extra-thyroidal extension and/or lymph node metastases. B-Raf(V600E) is considered a marker of aggressive disease in both PTC (>1 cm) and micro-PTC (</=1 cm), and interestingly, is associated with both loss of I-131 avidity and PTC recurrence. Though treatment of patients with thyroid cancer is usually successful and most patients are rendered disease-free, to date there are no effective therapies for patients with invasive, non-radioiodine sensitive tumors or metastatic disease. In this article we will review the relation between B-Raf(V600E) and PTC, as well as both non-selective and selective pharmacological agents currently under investigation for treatment of B-Raf(V600E) positive PTC.

BRAF mutation in papillary thyroid carcinoma in a Japanese population: its lack of correlation with high-risk clinicopathological features and disease-free survival of patients

Recent studies have demonstrated that BRAF(V600E) mutation is a common event in papillary thyroid carcinoma and a majority of these lesions have shown a direct relationship between BRAF(V600E) mutation and aggressive characteristics, including a worse patient prognosis. However, there are no studies from Japan regarding this issue in a large series with adequate postoperative follow-up periods. We investigated BRAF(V600E) mutation in 631 patients with papillary carcinoma having median follow-up periods of 83 months. The prevalence of BRAF(V600E) mutation was 38.4%, and the rate was higher in carcinoma larger than 1.0 cm but did not successively increase with tumor size. Furthermore, the prevalence did not significantly increase in cases demonstrating high-risk biological features such as clinically apparent lymph node metastasis, massive extrathyroid extension, advanced age, distant metastasis at surgery, and advanced Stage. The disease-free survival of patients with BRAF(V600E) mutation did not differ from that of those without BRAF(V600E) mutation. These findings indicate that, although BRAF(V600E) mutation may play some roles in local carcinoma development, there is no evidence that BRAF(V600E) mutation significantly reflects the aggressive characteristics and poor prognosis of patients with papillary carcinoma in Japan.

Molecular alterations in hereditary and sporadic thyroid and parathyroid diseases

Thyroid and parathyroid diseases are fairly common and can be either hereditary or sporadic in nature. Tumors and tumor-like processes account for the majority of surgical pathology specimens in both of these endocrine organs. Molecular alterations are well known to occur in both the hereditary and the sporadic settings, and include alterations in tumor suppressor genes and oncogenes. The genetic pathways of tumors of parathyroid and thyroid are beginning to be well understood and are proving to be useful diagnostic, prognostic, and potential therapeutic targets. The molecular alterations in parathyroid and thyroid tumors and tumor-like processes are reviewed, with a focus on the potentially clinically useful diagnostic markers.

Perspectives for improved and more accurate classification of thyroid epithelial tumors

CONTEXT

Histologic examination of thyroid nodules is the current standard to distinguish benign from malignant thyroid epithelial tumors and to classify histologic subtypes. This review analyzes the problems in histological differential diagnosis as well as contradictions between histology and molecular data and describes possibilities to combine histology with molecular data in an effort to more accurately classify thyroid epithelial tumors.

EVIDENCE ACQUISITION

Published literature, addressing the current recommendations for thyroid tumor classification, as well as literature on the application of histology and molecular studies on the etiology of thyroid tumors is analyzed.

EVIDENCE SYNTHESIS

The current histologic criteria to classify thyroid tumors, especially follicular-patterned tumors, are hampered by considerable interobserver variability. The detection of somatic mutations via genotyping and the definition of potentially informative gene expression signatures by microarray analyses, which can distinguish cancer subtypes as well as low- and high-risk cohorts, have recently demonstrated significant diagnostic potential. Moreover, in a routine diagnostic setting, micro-RNA profiling appears most promising due to their relative stability and the high accuracy of their expression profiles.

CONCLUSIONS

It is very likely that molecular definitions of thyroid tumors mentioned in the current World Health Organization classification will be further developed, leading to future progress in defining thyroid tumor types by an integrated histologic and molecular approach. These integrated classifications need to be evaluated for their specific impact on thyroid tumor diagnosis and prognosis.

Characterization of a novel complex BRAF mutation in a follicular variant papillary thyroid carcinoma

INTRODUCTION

Activating mutations of the BRAF oncogene are frequently detected in papillary thyroid carcinoma (PTC) and have been associated with a worse prognosis. The amino acid substitution V600E accounts for 90% of all oncogenic BRAF mutations and is typically detected in classic PTCs, whereas other less frequent BRAF mutations seem to be associated with other PTC histotypes.

CASE

Screening for activating BRAF mutations in a series of 83 PTCs identified the most common V600E mutation in 39 cases (histologically, 38 classic PTCs and 1 sclerosing variant PTC) and a complex in-frame mutation involving amino acids V600-S605 in a stage III multicentric follicular variant PTC, occurring in a 50-year-old female patient, who was affected by hypothyroidism in autoimmune thyroiditis and had a family history of PTC and autoimmune thyroiditis. Since the identified BRAF mutation was novel in the literature, bioinformatic modeling was performed to predict its impact on BRAF activity. Although the mutation resulted in loss of a phosphorylation site in the activation loop of BRAF, it was predicted to increase BRAF kinase activity by mimicking an activating phosphorylation.

CONCLUSIONS

This study, which reports a new BRAF mutation, highlights the usefulness of bioinformatic modeling in the prediction of functional effects of new mutations and indicates that mutation-specific screening tests might miss some rare BRAF mutations. These facts should be taken into consideration in the molecular diagnosis of thyroid cancer and in the design of therapeutic protocols based on inhibitors of the BRAF pathway.

Clinical implications of BRAF mutation in thyroid carcinoma

Significant progress has recently been made in the clinical management of papillary thyroid carcinoma. The accuracy of diagnosis and prognostic stratification of this type of carcinoma are high but still fall below 100%. Lack of effective treatments for advanced stage papillary thyroid carcinoma leads to death in some patients. Approximately half of all such carcinomas harbor mutations in the gene encoding the serine/threonine-kinase B-type Raf kinase (BRAF), resulting in constitutive activation of the mitogen-activated protein kinase-extracellular-signal-regulated kinases signal transduction pathway. There is intriguing evidence that BRAF mutation testing of papillary thyroid carcinoma might improve the diagnosis, prognostic stratification and treatment of these tumors but large, prospective trials are needed to define the actual clinical impact of these approaches.

What is New on Thyroid Cancer Biomarkers

Thyroid cancer harbours in about 5% of thyroid nodules. The majority of them are well-differentiated cancers originating from the follicular epithelium, and are subdivided into papillary and follicular carcinomas. Undifferentiated carcinomas and medullary thyroid carcinomas arising from C cells are less common.

Although most thyroid nodules are benign, distinguishing thyroid cancer from benign lesions is crucial for an appropriate treatment and follow-up. The fine needle aspiration cytology (FNAC) allows the diagnosis of nature of thyroid nodules in the majority of cases. However, FNAC has some limitations, particularly in the presence of follicular lesions which can appear dubious in rare instances even at histology.

In an effort to improve diagnostic accuracy and offer new prognostic criteria, several immunohistochemical and molecular markers have been proposed. However, most of them have to be validated on large series before being used in routine practice.

Cytological and molecular diagnosis of solid variant of papillary thyroid carcinoma: a case report

Papillary thyroid carcinoma (PTC) composed by predominant solid areas is diagnosed as a distinct variant on histological samples. Here we present a case of PTC recognized preoperatively by fine needle cytology as a solid variant. This diagnosis was made by combining cytology with the detection of the BRAF^VK600-1E mutation, the molecular hallmark of the solid variant of PTC. Histological and molecular evaluation of the surgical specimen confirmed this pre-operative diagnosis. Thus combining cytology to BRAF molecular analysis is useful to refine the cytological diagnosis of this variant also on FNC specimens.

BRAF mutation in papillary thyroid cancer: pathogenic role, molecular bases, and clinical implications

In recent years, the T1799A B-type Raf kinase (BRAF) mutation in thyroid cancer has received enthusiastic investigation, and significant progress has been made toward understanding its tumorigenic role and clinical significance. Among various thyroid tumors, this mutation occurs uniquely in papillary thyroid cancer (PTC), the most common endocrine malignancy, and some apparently PTC-derived anaplastic thyroid cancers. Many studies have found this mutation to be associated with those clinicopathological characteristics of PTC that are conventionally known to predict tumor progression and recurrence, including, for example, old patient age, extrathyroidal invasion, lymph node metastasis, and advanced tumor stages. Direct association of BRAF mutation with the clinical progression, recurrence, and treatment failure of PTC has also been demonstrated. The BRAF mutation has even been correlated with PTC recurrence in patients with conventionally low-risk clinicopathological factors. Some molecular mechanisms determining BRAF mutation-promoted progression and the aggressiveness of PTC have recently been uncovered. These include the down-regulation of major tumor suppressor genes and thyroid iodide-metabolizing genes and the up-regulation of cancer-promoting molecules, such as vascular endothelial growth factor, matrix metalloproteinases, nuclear transcription factor kappaB, and c-Met. Thus, BRAF mutation represents a novel indicator of the progression and aggressiveness of PTC. Significant advances have also occurred in the preclinical testing of new therapeutic strategies targeting the MAPK pathway aberrantly activated by BRAF mutation and other related mutations. New mitogen extracellular kinase (MEK) inhibitors developed recently are particularly promising therapeutic agents for thyroid cancer. With these advances, it has become clearer that BRAF mutation will likely have significant impact on the clinical management of PTC.