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

Papillary thyroid carcinomas with and without BRAF V600E mutations are morphologically distinct

AIMS

  The BRAF V600E mutation resulting in the production of an abnormal BRAF protein has emerged as the most frequent genetic alteration in papillary thyroid carcinomas (PTCs). This study was aimed at identifying distinctive features in tumours with and without the mutation.

METHODS AND RESULTS

  Thirty-four mutation-positive and 22 mutation-negative tumours were identified by single-strand conformation polymorphism of the amplified BRAF V600E region in the tumour DNA. Mutation-positive tumours were more common in patients older than 45 years (24/33, P = 0.05), in classic (23/30, P = 0.01), tall cell (4/5) and oncocytic/Warthin-like (2/2) variants of PTC, and in subcapsular sclerosing microcarcinomas (4/4). In contrast, all 12 follicular variants (P < 0.0001) and two diffuse sclerosing variants were negative for the mutation. Mutation-positive tumours displayed infiltrative growth (32/34, P = 0.02), stromal fibrosis (33/34, P < 0.001), psammoma bodies (17/34, P = 0.05), plump eosinophilic tumour cells (22/34, P = 0.01), and classic fully developed nuclear features of PTC (33/34, P = 0.0001). Encapsulation was significantly associated with mutation-negative tumours (15/22, P = 0.02).

CONCLUSIONS

  BRAF V600E mutation-positive and negative PTCs are morphologically different. Recognition of their morphology may help in the selection of appropriate tumours for genetic testing.

The molecular diagnosis and management of thyroid neoplasms

PURPOSE OF REVIEW

The molecular work-up of thyroid nodules on fine needle aspiration (FNA) cytology samples has given clinicians a new level of diagnostic information. We focus this review on the molecular techniques used in the diagnosis of thyroid cancer, especially BRAF, and the resulting management considerations that are raised.

RECENT FINDINGS

BRAF testing offers both diagnostic and prognostic information; it has been used along with the Bethesda Thyroid FNA Classification System to offer preoperative guidance in the management of thyroid nodules. Various authors have successfully utilized molecular panels on cytologic specimens including mutations and rearrangements such as RAS and RET/PTC. Preoperative mutation detection allows initial management decisions to be made with a greater clinical confidence.

SUMMARY

BRAF molecular testing holds promise as a possible diagnostic tool for indeterminate FNAs, and as a determinant for planning initial clinical management of thyroid nodules. Further developments in the molecular approach to thyroid cancer are expected to allow greater individualization of patient care.

Pediatric thyroid cancer

Thyroid cancer is an uncommon childhood malignancy that presents primarily in young children or adolescent females and may be related to radiation exposure or genetic predisposition. Gene alterations, such as RET mutation or RET/PTC rearrangement, are not uncommon. Recent studies have lead to an increased understanding of the role of these particular gene alterations in the diagnosis, prognosis, and treatment of thyroid cancer. Surgery remains the mainstay of treatment for thyroid cancer followed by radioactive iodine when appropriate. In patients with MEN2, prophylactic thyroidectomy is recommended, although a delay in the initial diagnosis is common. With early aggressive treatment and long-term follow-up, these patients generally have excellent outcomes. Recent research suggests potential usefulness of novel therapies directed at oncogenic signaling pathways, modulators of growth, angiogenesis inhibitors, immunomodulators, and gene therapy.

Notch1 receptor as a marker of lymph node metastases in papillary thyroid cancer

Notch functions as an oncogene or tumor suppressor according to the type of malignancy, and the BRAF(V600E) mutation is commonly observed in thyroid cancer. However, the role of Notch and BRAF(V600E) in papillary thyroid cancer (PTC) is unclear. This study sought to elucidate the clinicopathological characteristics in patients with PTC regarding the expression of Notch1/Notch3 receptors and BRAF(V600E) mutation. Clinicopathological characteristics were evaluated according to the Notch1/Notch3 receptors and BRAF(V600E) mutation in 187 patients with PTC who underwent definitive surgery. Expression of the Notch1 receptor was significantly associated with poor prognostic markers including large tumor size, nodal metastasis, capsular invasion, and extrathyroidal extension. However, there was no significant association between the clinicopathological characteristics and Notch3 receptor expression/BRAF(V600E) mutation. In multivariate analysis, Notch1 receptor expression showed a significant relationship with lymph node metastasis (P = 0.04). Notch1 receptor may be a predictor of lymph node metastasis and may be related to poor prognostic markers in patients with PTC. Further investigation of Notch1 receptor may further the understanding of the pathogenesis of nodal metastasis in PTC.

Clinical outcome, role of BRAF(V600E), and molecular pathways in papillary thyroid microcarcinoma: is it an indolent cancer or an early stage of papillary thyroid cancer?

Most human thyroid cancers are differentiated papillary carcinomas (PTC). Papillary thyroid microcarcinomas (PTMC) are tumors that measure 1 cm or less. This class of small tumors has proven to be a very common clinical entity in endocrine diseases. PTMC may be present in 30-40% of human autopsies and is often identified incidentally in a thyroid removed for benign clinical nodules. Although PTMC usually has an excellent long-term prognosis, it can metastasize to neck lymph nodes; however deaths related to this type of thyroid tumor are very rare. Few data exist on molecular pathways that play a role in PTMC development; however, two molecules have been shown to be associated with aggressive PTMC. S100A4 (calcium-binding protein), which plays a role in angiogenesis, extracellular matrix remodeling, and tumor microenvironment, is over-expressed in metastatic PTMC. In addition, the BRAF(V600E) mutation, the most common genetic alteration in PTC, is present in many PTMC with extra thyroidal extension and lymph node metastasis. Importantly, recently developed selective [e.g., PLX4720, PLX4032 (Vemurafenib, also called RG7204)] or non-selective (e.g., Sorafenib) inhibitors of BRAF(V600E) may be an effective treatment for patients with BRAF(V600E)-expressing PTMCs with aggressive clinical-pathologic features. Here, we summarize the clinical outcome, cancer genetics, and molecular mechanisms of PTMC.

CXCR4 expression correlates with the degree of tumor infiltration and BRAF status in papillary thyroid carcinomas

Emerging evidence indicates that interactions between chemokine receptors and their ligands may have a critical role in several steps of tumor development, including tumor growth, progression, and metastasis. In this report, we retrospectively evaluated CXCR4 expression in a consecutive series of 200 papillary thyroid carcinomas. We investigated the relationship between the clinicopathological features of the tumors and mutations in the BRAF gene to verify whether overexpression of CXCR4 is linked to more aggressive behavior in thyroid tumors. CXCR4 protein expression was evaluated by immunohistochemical staining. A final staining score was calculated by adding the score representing the percentage of positive cells to the intensity score. The CXCR4 expression of each papillary thyroid carcinoma sample was normalized by calculating the z score for each final staining score. Univariate analysis was used to correlate CXCR4 expression with the papillary thyroid carcinoma variant, the degree of neoplastic infiltration, the American Joint Commission on Cancer stage, the presence of lymphocytic thyroiditis and the mutation status of the BRAF gene. Multiple regression analysis confirmed a strong association between CXCR4, BRAF mutation and the degree of neoplastic infiltration. These data clearly indicate that the chemokine receptor expression induced by oncogenic activation could be the major determinant of the local aggressiveness of neoplastic cells. In conclusion, our data indicate that CXCR4 expression and BRAF mutation status could cooperatively induce and promote a more aggressive phenotype in papillary thyroid carcinoma through several pathways and specifically increase the tumors' spread outside of the thyroid gland.

Managing thyroid microcarcinomas

Papillary thyroid microcarcinomas (PTMCs) are the most common form of classic papillary thyroid carcinoma (PTC). PTMCs are typically discovered by fine-needle- aspiration biopsy (FNAB), usually with sensitive imaging studies, or are found during thyroid surgery in a patient without a previously known history of thyroid carcinoma. However, the definition of PTMC has not always been universally accepted, thus creating controversy concerning the diagnosis and treatment of PTMC. The aim of this review is to summarize the clinical features of PTMC and identify the widely differing opinions concerning the diagnosis and management of these small ubiquitous thyroid tumors.

Is diffuse and peritumoral lymphocyte infiltration in papillary thyroid cancer a marker of good prognosis?

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most frequently diagnosed endocrine neoplasia, representing 70 to 80% of all diagnosed thyroid cancers. Furthermore, Hashimoto's thyroiditis is a frequent inflammatory thyroid disease and the main cause of hypothyroidism. The relationship between Hashimoto's thyroiditis and PTC remains controversial.

METHODS

Surgery for PTC was performed at our institution on 157 consecutive patients. They were classified by the degree of lymphocyte infiltration (LI). LI was classified as diffuse LI or peritumoral LI (only in or around the tumor), or absent. In addition, age, gender, tumor size, histopathological findings, lymph-node metastasis, extra- thyroidal extension, multifocal tumor, coexistence of LI and clinical outcomes were analyzed.

RESULTS

Out of the 141 patients included in the study, 83 (59%) had diffuse LI and 22 (16%) had peritumoral LI. In 36 patients (25%) LI was absent. A comparison of patients in the 3 groups revealed no significant difference in their genders, ages, smoking status, thyroid function, or nodule size at the time of surgery. The characteristics of PTC showed no differences in lymph-node metastasis, tumor invasion into contiguous neck structures, angioinvasion, or PTC subtypes. Tumor-node-metastasis (TNM) classification and classes did not differ among the 3 groups. During the follow-up, 64 out of 141 patients with PTC (55%) had recurrences from 6 to 130 months after the initial treatment. After a mean follow-up period of 8 yr we observed a significantly (p=0.01) high recurrence (66.6%) in the LI absent group with 24 of 36 patients when compared to patients from the diffuse LI group (32 out of 83 patients; 38.5%) and peritumoral LI group (8 out of 22 patients; 25%).

CONCLUSIONS

Although the role of the inflammatory-immune cells is complex and little understood, we found a more favorable course of PTC in the presence of LI (diffuse or peritumoral); this supports the hypothesis that LI represents a form of immune reaction to control tumor growth and proliferation.

Evidence of oncogene-induced senescence in thyroid carcinogenesis

Oncogene-induced senescence (OIS) is a growth arrest triggered by the enforced expression of cancer-promoting genes and acts as a barrier against malignant transformation in vivo. In this study, by a combination of in vitro and in vivo approaches, we investigate the role of OIS in tumours originating from the thyroid epithelium. We found that expression of different thyroid tumour-associated oncogenes in primary human thyrocytes triggers senescence, as demonstrated by the presence of OIS hallmarks: changes in cell morphology, accumulation of SA-β-Gal and senescence-associated heterochromatic foci, and upregulation of transcription of the cyclin-dependent kinase inhibitors p16(INK4a) and p21(CIP1). Furthermore, immunohistochemical analysis of a panel of thyroid tumours characterised by different aggressiveness showed that the expression of OIS markers such as p16(INK4a), p21(CIP1) and IGFBP7 is upregulated at early stages, and lost during thyroid tumour progression. Taken together, our results suggest a role of OIS in thyroid carcinogenesis.

BRAF V600E mutation does not predict recurrence after long-term follow-up in TNM stage I or II papillary thyroid carcinoma patients

The BRAF V600E mutation may serve as a marker of disease recurrence in well-differentiated papillary thyroid cancer (PTC). Our aim was to study if TNM stage I or II PTC patients, with and without recurrence after long-term follow-up would differ in BRAF status. BRAF status was retrospectively determined in tumour tissue from a cohort of low-risk PTC patients (n = 461) with and without recurrence after 16 years of follow-up. Initial treatment was total thyroidectomy (TTE) and radioiodine remnant ablation (RRA). Forty-six patients (9.9%) experienced disease recurrence. BRAF mutation was positive in 66% (17/26) of patients with and 68% (17/25) without recurrence (p = NS). Fifty per cent of BRAF positive and 53% of BRAF negative patients experienced disease recurrence (p = NS). Time to recurrence was 52 (range 18-144) and 36 (range 16-71) months, respectively (p = NS). Primary tumour size, nodal metastasis and local infiltration at presentation did not differ between BRAF positive and negative patients (2.0 vs 2.2 cm, 21% vs 35% and 6% vs 12%, respectively, all p = NS). Taken together, BRAF V600E is common in Finnish patients with low-risk PTC but does not predict recurrence after long-term follow-up after initial treatment with TTE and RRA.

Prognostic factors of papillary and follicular carcinomas in Japan based on data of kuma hospital

There are some important prognostic factors for papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC). In this paper, clinicopathological features significantly affecting patient prognosis are described based on our data as well as others. Distant metastasis at diagnosis is the most important prognostic factor for both PTC and FTC. Other than that, preoperative and intraoperative findings are important to evaluate the biological behavior of PTC. Extrathyroid extension, large lymph-node metastasis, and extranodal tumor extension that can be evaluated preoperatively or intraoperatively are significant prognostic factors for PTC patients. In contrast, pathological findings are important not only for diagnosis of FTC, but also for the evaluation of its biological character. Grade of invasiveness (minimally or widely invasive) and degree of differentiation (well differentiated or including a poorly differentiated component) greatly affect the prognosis of FTC patients.

Molecular analysis of thyroid tumors

Thyroid cancer is the most common endocrine malignancy, and its incidence is rising in the USA and other countries. Papillary and follicular thyroid carcinomas are the two most common types of thyroid cancer. Non-overlapping genetic alterations, including BRAF and RAS point mutations, and RET/PTC and PAX8/PPARγ rearrangements, are found in more than 70% of papillary and follicular thyroid carcinomas. These represent the most common genetic alterations in thyroid cancer, as well as molecular markers of diagnostic and prognostic significance. The use of these and other emerging molecular markers will likely improve the diagnosis of malignancy in thyroid nodules as well as facilitate more individualized operative and postoperative management. Herein, we provide a brief overview of the common genetic alterations in papillary and follicular thyroid carcinoma and discuss the diagnostic and prognostic significance thereof.

The association of the BRAF(V600E) mutation with prognostic factors and poor clinical outcome in papillary thyroid cancer: a meta-analysis

BACKGROUND

The effects of the BRAF(V600E) mutation on prognostic factors and poor clinical outcomes in papillary thyroid cancer (PTC) have not been fully quantified. The authors performed comprehensive meta-analysis to assess the strength of associations between these conditions and the BRAF(V600E) mutation.

METHODS

The authors identified the clinical studies that examined the association of the BRAF(V600E) mutation in surgical specimens with clinicopathologic outcomes between January 2003 and October 2010 using the Medline database. One hundred thirty-one relevant studies were hand-searched. The authors selected 27 studies that included 5655 PTC patients. They calculated the pooled odds ratios (ORs) or risk ratios with 95% confidence intervals (CIs) for each study using a random effect model.

RESULTS

The average prevalence rate of the BRAF(V600E) mutation was 49.4%. In 26 studies, compared with the patients who had the wild-type BRAF genes, the PTC patients with the BRAF(V600E) mutation had increased ORs of an extrathyroidal invasion (OR, 2.14; 95% CI, 1.68-2.73), a lymph node metastasis (OR, 1.54; 95% CI, 1.21-1.97), and an advanced TNM stage (OR, 2.00; 95% CI, 1.61-2.49). In 8 studies, patients with the mutation had 2.14-fold increased risk of recurrent and persistent disease (95% CI, 1.67-2.74). The associations were generally consistent across the different study populations.

CONCLUSIONS

This meta-analysis demonstrates that the BRAF(V600E) mutation is closely related to the high-risk clinicopathological factors and poorer outcome of PTC. The results obtained here suggest that the BRAF(V600E) mutation should be considered as a poor prognostic marker in PTC and may lead to better management for individual patients.

Molecular genetics and diagnosis of thyroid cancer

Thyroid cancer is a common type of endocrine malignancy, and its incidence has been steadily increasing in many regions of the world. Initiation and progression of thyroid cancer involves multiple genetic and epigenetic alterations, of which mutations leading to the activation of the MAPK and PI3K-AKT signaling pathways are crucial. Common mutations found in thyroid cancer are point mutation of the BRAF and RAS genes as well as RET/PTC and PAX8/PPARγ chromosomal rearrangements. The mutational mechanisms seem to be linked to specific etiologic factors. Chromosomal rearrangements have a strong association with exposure to ionizing radiation and possibly with DNA fragility, whereas point mutations probably arise as a result of chemical mutagenesis. A potential role of dietary iodine excess in the generation of BRAF point mutations has also been proposed. Somatic mutations and other molecular alterations have been recognized as helpful diagnostic and prognostic markers for thyroid cancer and are beginning to be introduced into clinical practice, to offer a valuable tool for the management of patients with thyroid nodules.

BRAFV600E mutation does not serve as a prognostic factor in Korean patients with papillary thyroid carcinoma

OBJECTIVES

In recent years, BRAF(V600E) mutation has emerged as a promising prognostic marker for risk stratification of patients with papillary thyroid carcinoma (PTC). However, routine use of this marker has been questioned. In some parts of the world, particularly in Korea, the incidence of BRAF(V600E) mutation is too high to have true prognostic value. The relatively low number of tumors without BRAF(V600E) mutation would prejudice the efficient use of this marker in the Korean population.

METHODS

The study involved 107 patients with histologically confirmed conventional PTC after surgical management for thyroid cancer from April 2010 to December 2010. BRAF(V600E) mutation analysis was performed by polymerase chain reaction (PCR)-based amplification of DNA extracted from paraffin-embedded tumor specimens, and the relationship between BRAF(V600E) mutation and various prognostic factors was investigated.

RESULTS

BRAF(V600E) mutation was found to be present in 85 (79.4%) of 107 patients with conventional PTC. Analysis of the clinical characteristics as function of the presence or absence of BRAF(V600E) mutation revealed no differences between the BRAF(V600E)-positive and BRAF(V600E)-negative patients. Moreover, BRAF(V600E) mutation was not correlated with any of the prognostic factors including age ≥45 years, male gender, tumor size ≥1cm, multifocality, extra-thyroidal extension, concurrent Hashimoto's thyroiditis, and lymph node metastasis neither in the univariate nor in the multivariate analysis.

CONCLUSIONS

BRAF(V600E) mutation does not significantly reflect tumor aggressiveness in Korean patients with conventional PTC. We consider that BRAF(V600E) mutation does not possess prognostic value in Korea, where it is prevalent, and where most of the PTC types are conventional.

Predicting malignancy in thyroid nodules: molecular advances

Over the last several years, a clearer understanding has developed of the genetic alterations underlying thyroid carcinogenesis. This knowledge can be used to tackle 1 of the challenges facing thyroidologists: management of the indeterminate thyroid nodule. Despite the accuracy of fine-needle aspiration cytology, many patients undergo surgery to diagnose malignancy and better diagnostic tools are required. A number of biomarkers have recently been studied and show promise in this setting. In particular, BRAF, RAS, PAX8-PPARγ, microRNAs, and loss of heterozygosity have each been demonstrated as useful molecular tools for predicting malignancy and can potentially guide decisions regarding surgical management of nodular thyroid disease. This review summarizes the current literature surrounding each of these markers, highlights our institution's prospective analysis of these markers, and describes the subsequent incorporation of molecular markers into a management algorithm for thyroid nodules.

Is the BRAF(V600E) mutation useful as a predictor of preoperative risk in papillary thyroid cancer?

OBJECTIVE

Recent studies have shown that a BRAF(V600E) reflects poor prognosis, mainly in Western countries. However, some clinicians in Japan have suggested that the BRAF(V600E) mutation is not associated with a poor prognosis. Therefore, we investigated a relationship between BRAF(V600E) mutation and clinicopathologic factors.

METHODS

From September 2008 to December 2009, we performed routine analysis of the BRAF(V600E) mutation using thyroid cancer tissue from 424 patients who underwent thyroidectomy with cervical lymph node dissection.

RESULTS

The BRAF(V600E) mutation was found in 335 of 424 cases (79%) and was higher in classic papillary thyroid carcinoma (PTC) (79.7%) than in the follicular variant of PTC (62.5%) (P = .019). On univariate analysis, the BRAF(V600E) mutation was associated with extrathyroidal extension (P = .009) and variants of PTC (P = .019), but a high-risk Metastasis, Patient Age, Completeness of resection, local Invasion and Tumor Size (MACIS) score (≥ 6) (P = .146) and lymph node metastasis (P = .628) were not significantly associated with the BRAF(V600E) mutation. Multivariate analysis showed that extrathyroidal extension is independently associated with the BRAF(V600E) mutation (relative ratio: 2.466; 95% confidence interval, 1.213-5.011; P < .013).

CONCLUSION

It is not clear that the BRAF(V600E) mutation is useful for prediction of poor prognosis of PTC.

Preoperative BRAF Mutation Has Different Predictive Values for Lymph Node Metastasis according to Tumor Size

Objective. To investigate whether BRAF mutation of papillary thyroid carcinoma (PTC) has different predictive values for regional lymph node (LN) metastasis according to tumor size.

Study Design. Prospective cohort study.

Setting. A tertiary hospital.

Subjects and Methods. From January 2009 to August 2009, the authors prospectively enrolled 102 consecutive patients with unifocal PTC based on the findings of ultrasonography-guided fine-needle aspiration biopsy (FNAB). BRAF mutation was tested on preoperative FNAB specimens. Total thyroidectomy and bilateral central neck dissection (± lateral neck dissection) was performed for all patients. Among 102 patients, 71 who were confirmed to have unifocal PTC by the surgical pathology were finally selected. The 71 patients were classified into 3 groups according to their tumor size: group I, ≤0.5 cm; group II, >0.5 cm and ≤1 cm; and group III, >1 cm. LN metastasis was evaluated in the surgical specimen as a dependent variable. The authors investigated whether BRAF mutation is predictive of LN metastasis in each group.

Results. Overall, BRAF mutation was a significant predictor of LN metastasis ( P = .045). When patients were classified into 3 groups, frequency of LN metastasis increased with tumor size: 4.8%, 50.0%, and 66.7% ( P < .001). However, the frequency of BRAF mutation was not different among 3 groups: 61.9%, 56.3%, and 72.2% ( P = .536). BRAF mutation was predictive of LN metastasis only in group II ( P = .026).

Conclusion. BRAF mutation of PTC may have differential predictive values for LN metastasis, according to tumor size.

Reflex BRAF testing in thyroid fine-needle aspiration biopsy with equivocal and positive interpretation: a prospective study

BACKGROUND

The BRAF V600E mutation has been reported in 50%-80% of papillary thyroid carcinoma (PTC) cases and is highly specific for PTC. Reflex BRAF testing may improve the diagnostic accuracy of thyroid fine-needle aspiration (FNA) tests having equivocal cytologic interpretations and provide prognostic information that helps guide management in patients with PTC.

PATIENTS AND METHODS

Cases with equivocal thyroid FNA readings (indeterminate and suspicious for PTC) or a positive diagnosis for PTC and concomitant BRAF mutation analysis were included in this prospective study. BRAF mutation analysis was performed by polymerase chain reaction combined with single-strand conformation polymorphism gel electrophoresis using lavage fluid obtained from needle rinsing. The results of histopathologic follow-up were correlated with the cytologic interpretations and BRAF status.

RESULTS

One hundred fifty-seven FNAs with equivocal or positive cytologic interpretations were eligible for the study. All but one (99.4%) FNAs were found to have sufficient DNA quality and quantity for the assay. Based on the follow-up diagnosis of nodules after surgical resection, the sensitivity for diagnosing PTC was 63.3% with cytology alone and 80.0% with the combination of cytology and BRAF testing, respectively. No false positives were noted with either cytology or BRAF mutation analysis. All PTCs with extrathyroidal extension and of tall-cell variant were postive for BRAF mutation.

CONCLUSIONS

BRAF V600E mutation analysis can be easily performed on cytologic preparation using lavage fluids obtained from needle rinsing. By combining morphologic evaluation and BRAF testing, there is a substantial improvement in the preoperative identification of PTC when compared with cytology alone. Patients with equivocal cytologic diagnosis and BRAF V600E mutation are candidates for total thyroidectomy ± central lymph node dissection.

Molecular diagnostics of thyroid tumors

CONTEXT

Thyroid cancer is the most common type of endocrine malignancy and its incidence is steadily increasing. Papillary carcinoma and follicular carcinoma are the most common types of thyroid cancer and represent those tumor types for which use of molecular markers for diagnosis and prognostication is of high clinical significance.

OBJECTIVE

To review the most common molecular alterations in thyroid cancer and their diagnostic and prognostic utility.

DATA SOURCES

PubMed (US National Library of Medicine)-available review articles, peer-reviewed original articles, and experience of the author.

CONCLUSIONS

The most common molecular alterations in thyroid cancer include BRAF and RAS point mutations and RET/PTC and PAX8/PPAR γ rearrangements. These nonoverlapping genetic alterations are found in more than 70% of papillary and follicular thyroid carcinomas. These molecular alterations can be detected in surgically resected samples and fine-needle aspiration samples from thyroid nodules and can be of significant diagnostic use. The diagnostic role of BRAF mutations has been studied most extensively, and recent studies also demonstrated a significant diagnostic utility of RAS, RET/PTC, and PAX8/PPAR γ mutations, particularly in thyroid fine-needle aspiration samples with indeterminate cytology. In addition to the diagnostic use, BRAF V600E mutation can also be used for tumor prognostication, as this mutation is associated with higher rate of tumor recurrence and tumor-related mortality. The use of these and other emerging molecular markers is expected to improve significantly the accuracy of cancer diagnosis in thyroid nodules and allow more individualized surgical and postsurgical management of patients with thyroid cancer.

Both BRAF V600E mutation and older age (≥ 65 years) are associated with recurrent papillary thyroid cancer

PURPOSE

This study was designed to examine the aggressive features of BRAF-positive papillary thyroid cancer (PTC) and association with age.

METHODS

We compared the clinicopathologic parameters and BRAF V600E mutation status of 121 elderly (age ≥65 years) PTC patients who underwent thyroidectomy from January 2007 to December 2009 to a consecutive cohort of 98 younger (age <65 years) PTC patients.

RESULTS

Younger and elderly PTC patients had similar incidences of BRAF-positive tumors (41% vs. 38%; p = 0.67). The elderly cohort was more likely to have smaller tumors (mean 1.6 vs. 2.1 cm; p = 0.001), present with advanced TNM stage (36% vs. 19%; p = 0.008), and have persistent/recurrent disease (10% vs. 1%; p = 0.006). BRAF-positive status was associated with PTC that were tall cell variant (p < 0.001), had extrathyroidal extension (p < 0.001), lymph node involvement (p = 0.008), advanced (III/IV) TNM stage (p < 0.001), and disease recurrence (p < 0.001). Except for lymph node involvement, the association between aggressive histology characteristics at presentation and BRAF-positive PTC also was observed within the age-defined cohorts. In short-term follow-up (mean, 18 months), persistent/recurrent PTC was much more likely to occur in patients who were both BRAF-positive and elderly (22%).

CONCLUSIONS

BRAF mutations are equally present in younger and older patients. Aggressive histology characteristics at presentation are associated with BRAF-positive PTC, irrespective of age. However, the well-established association of BRAF with recurrence is limited to older (age ≥65 years) patients.

Novel molecular targeted therapies for refractory thyroid cancer

The incidence of thyroid cancer continues to increase and this neoplasia remains the most common endocrine malignancy. No effective systemic treatment currently exists for iodine-refractory differentiated or medullary thyroid carcinoma, but recent advances in the pathogenesis of these diseases have revealed key targets that are now being evaluated in the clinical setting. RET (rearranged during transfection)/PTC (papillary thyroid carcinoma) gene rearrangements, B-Raf gene mutations, and vascular endothelial growth factor receptor 2 (VEGFR-2) angiogenesis pathways are some of the known genetic alterations playing a crucial role in the development of thyroid cancer. Several novel agents have demonstrated promising responses. Of the treatments studied, multi-kinase inhibitors such as axitinib, sorafenib, motesanib, and XL-184 have shown to be the most effective by inducing clinical responses and stabilizing the disease process. Randomized clinical trials are currently evaluating these agents, results that may soon change the management of thyroid cancer.

Prognostic significance of ki-67 labeling index in papillary thyroid carcinoma

BACKGROUND

Ki-67 is a useful tool for evaluating cell proliferative activity in various tumors. Although the utility of Ki-67 labeling index (LI) to diagnose thyroid neoplasms has been investigated, little is known regarding the relationship between Ki-67 LI and the biological behavior of papillary thyroid carcinoma. In this study, we examined Ki-67 in 371 patients with papillary thyroid carcinoma to elucidate this issue.

METHODS

A total of 371 patients with papillary carcinoma who underwent initial and locally curative surgery between 1996 and 1997 were enrolled in this study. We immunohistochemically investigated Ki-67 LI in their primary lesions and compared this finding with various clinicopathological features, including patient prognosis.

RESULTS

Ki-67 LI was ≤1% in 213 patients (57%) and among the remaining 158, 35 showed Ki-67 LI >3%. Ki-67 LI was associated with patient age, massive extrathyroid extension, and distant metastasis at surgery. Of 363 patients without distant metastasis at surgery, 54 (15%) showed carcinoma recurrence during follow-up (average 124 months) and the disease-free survival (DFS) of patients with Ki-67 LI >1% was significantly worse than that of those with Ki-67 LI <1% (p < 0.0001). On multivariate analysis, Ki-67 LI was recognized as an independent prognostic factor for the DFS of patients. Although only eight patients died of carcinoma in our series, patients with Ki-67 LI >3% showed a significantly worse cause-specific survival (CSS) than those with Ki-67 LI <3% (p < 0.0001).

CONCLUSIONS

Careful evaluation of Ki-67 LI in primary lesions can predict DFS and CSS of patients with papillary thyroid carcinoma.

Molecular analysis of thyroid tumors

In the recent years, a large number of molecular alterations in thyroid cancer has been discovered and characterized. Some of these markers may have significant diagnostic utility, can be used for tumor prognostication, and serve as potential therapeutic targets. The diagnostic utility of these markers is of particular importance in thyroid fine-needle aspiration samples. Some molecular markers, such as BRAF, offer help in risk stratification and can be potentially used to optimize surgical and postsurgical management of patients with thyroid cancer. This review discusses major molecular alterations known to occur in thyroid cancer, focusing on those markers that have been extensively characterized, carry clinical significance, and are being introduced into pathology practice.

Thyroid cancer gender disparity

Cancer gender disparity in incidence, disease aggressiveness and prognosis has been observed in a variety of cancers. Thyroid cancer is one of the fastest growing cancer diagnoses worldwide. It is 2.9-times more common in women than men. The less aggressive histologic subtypes of thyroid cancer are more common in women, whereas the more aggressive histologic subtypes have similar gender distribution. The gender disparity in incidence, aggressiveness and prognosis is well established for thyroid cancer but the cause of the disparity is poorly understood. The aim of this article is to evaluate the current evidence on the cause of thyroid cancer gender disparity. Dietary and environmental factors do not appear to have a significant role in thyroid cancer gender disparity. Common somatic mutations in BRAF, rearranged in transformation/papillary thyroid carcinomas (RET/PTC) and neurotrophin receptor-tyrosine kinase (NTRK) also do not account for the gender disparity in thyroid cancer. While reproductive factors would seem a logical hypothesis to account for the gender disparity, there appears to be no conclusive effect on the risk of developing thyroid cancer. Recent studies on estrogen receptor status in thyroid cancer show a difference in the receptor subtypes expressed based on the histology of thyroid cancer. Moreover, the response to estrogen is dependent on the specific estrogen receptor expressed in thyroid cancer cells. However, what determines the tumor-specific sex hormone receptor expression is unclear. No established molecular factors appear to explain gender differences in thyroid cancer. Therefore, the application of high-throughput genomic and proteomic approaches to the study of thyroid cancer gender disparity could be helpful for better understanding the molecular basis for gender differences in thyroid and other cancers.

Well differentiated follicular thyroid neoplasia: impact of molecular and technological advances on detection, monitoring and treatment

Our understanding of the molecular mechanisms responsible for follicular thyroid cell oncogenesis has been advanced significantly in recent years. Specific genetic alterations and the molecular pathways they affect have been associated with particular histologic subtypes of well-differentiated thyroid cancer and are now being evaluated for their utility as clinical tools with diagnostic, prognostic and even therapeutic relevance. This paper focuses on the most common and clinically relevant genetic alterations shown to be consistently associated with well-differentiated thyroid carcinoma. We review the impact of recent molecular and technological advances on thyroid cancer standard of care and the practice of clinical medicine.

Summary statement: utility of molecular marker testing in thyroid cancer

The use of molecular markers for thyroid cancer diagnosis, prognosis, and surveillance have been an exciting area of study and change. Recent investigative focus on promising new markers will very likely lead to improvements in the diagnostic utility of fine needle aspiration biopsy (FNAB) in predicting malignancy, as well as provide more accurate prognostic information pre- and postoperatively. The 2010 Annual Meeting of the American Association for Endocrine Surgeons featured a symposium dedicated to molecular marker testing in thyroid cancer and its potential clinical applicability.

BRAF(V600E) mutation is associated with an increased risk of nodal recurrence requiring reoperative surgery in patients with papillary thyroid cancer

BACKGROUND

The role of the B-isoform of the Raf kinase (BRAF) mutation BRAF(V600E) as an independent prognostic factor in papillary thyroid cancer (PTC) remains controversial. Some studies suggest that tumors containing BRAF(V600E) have decreased radioiodine avidity and present a greater risk of nodal recurrence and distant metastases.

METHODS

Paraffin-embedded specimens from consecutive patients who underwent surgery for PTC before 2003 were independently reviewed by an endocrine pathologist. DNA was extracted, amplified by polymerase chain reaction, and the presence of the BRAF(V600E) mutation was determined by restriction digest. Tumor characteristics and long-term disease outcomes were analyzed according to BRAF(V600E) status.

RESULTS

BRAF(V600E) was identified in 60 (59%) of 101 patients. At a median follow-up of 106 months, the overall disease-free survival was 78%. Clinically evident nodal recurrence occurred in 11% of BRAF(V600E)-positive patients, and all patients required lateral neck dissection (P = .02). In contrast, subclinical nodal recurrence occurred in 7% of BRAF(V600E)-negative patients, and all recurrences were successfully ablated with radioactive iodine. There was a trend toward poorer disease-free survival among patients with stage III/IV PTC and BRAF(V600E) mutation (P = .08). All 5 disease-related deaths occurred in patients with BRAF(V600E)-positive primary tumors (P = .06).

CONCLUSION

The BRAF(V600E) mutation in PTC is associated with an increased risk of palpable nodal recurrence and the need for reoperative surgery.

Mutational and clinico-pathological analysis of papillary thyroid carcinoma in Serbia

Molecular pathogenesis of papillary thyroid carcinoma (PTC) is largely associated with mutational changes in the BRAF, RAS family and RET genes. Our aim was to assess clinico-pathological and prognostic correlations of these PTC-specific gene alterations, with a particular emphasis on the BRAF mutation, in a group of 266 Serbian PTC patients, for the first time. The reference center-based retrospective cohort included 201 (75.6%) females and 65 (24.4%) males aged 48.0±16.1 years (8-83 years old, range) diagnosed and treated for PTC during 1993-2008. Follow-up period was 53.1±41.6 months (7-187 months, range). BRAF and RAS mutations were determined by direct sequencing of genomic DNA. RET/PTC rearrangements were analyzed by RT-PCR/Southern blotting. Genetic alterations were detected in 150/266 tumors (56.4%). One tumor displayed two genetic alterations. The BRAF(V600E) was found in 84/266 (31.6%) cases, RAS mutations in 11/266 (4.1%) and RET/PTC in 55/266 (20.7%; 42/266 (15.8%) RET/PTC1 and 13/266 (4.9%) RET/PTC3). On multivariate analysis BRAF(V600E) was associated with the classical papillary morphology (P = 0.05), the higher pT category (P = 0.05) and advanced clinical stage (P = 0.03). In a proportional hazard model, BRAF(V600E) did not appear to be an independent risk factor for the faster recurrence (P = 0.784). We conclude that under the extensive thyroid surgery and limited application of radioiodine ablation BRAF(V600E) may not be an indicator of poorer disease-free survival during the short to middle follow-up period. However, it has a potential to contribute to patients stratification into high- and low-risk groups.

The spectrum of papillary thyroid carcinoma variants

Papillary thyroid carcinoma is the most common type of thyroid malignancy. The diagnostic features of these tumors include characteristic nuclear cytology. However, many variants have been reported with different morphology and molecular profiles. Although the vast majority of papillary thyroid carcinomas have an excellent prognosis, some variants of papillary thyroid carcinoma can have a more aggressive course. With this increased attention to papillary thyroid carcinoma variants has come the need to sort out which variants are clinically important and should be recognized by practicing pathologists. The main objectives of this review article are to (1) summarize the gross and histopathologic features of papillary thyroid carcinoma; (2) provide an overview of the subtypes of papillary thyroid carcinoma and their prognosis; (3) discuss established and emerging data on the immunohistochemical findings that are helpful in differential diagnosis; and (4) summarize molecular findings and pathogenesis of these lesions.

The utility of BRAF testing in the management of papillary thyroid cancer

This review summarizes the current literature surrounding BRAF and its significance in thyroid cancer.

Over the last decade, investigators have developed a clearer understanding of the genetic alterations underlying thyroid carcinogenesis. A number of biomarkers involved in the pathogenesis of differentiated thyroid cancer have undergone intensive study, not only for their role in tumorigenesis, but also for their potential utility as diagnostic and prognostic indicators and therapeutic targets. This review summarizes the current literature surrounding BRAF and its significance in thyroid cancer. Further, we discuss how molecular analysis can be integrated into management algorithms for thyroid nodules and papillary thyroid cancer. We also review what is known, to date, about the association of BRAF and papillary microcarcinoma as well as using targeted therapies for BRAF as adjuvant treatment for metastatic papillary thyroid cancer.

BRAF status of follicular variant of papillary thyroid carcinoma and its relationship to its clinical and cytological features

BACKGROUND

The cytological discrimination between benign and malignant follicular-patterned lesions of the thyroid can represent a diagnostic challenge, even for experienced pathologists. To attempt to clarify this diagnostic problem, we analyzed the BRAF status of thyroid tumors in a group of patients with follicular variant of papillary thyroid carcinoma (FVPTC) and its correlation with cytomorphological features.

METHODS

The BRAF status was evaluated in a total of 187 patients in whom FVPTC was consecutively diagnosed by histology between January 2006 and January 2009. Each case had a previous fine-needle aspiration diagnosis classified according to the British Thyroid Association Guidelines categorized as inadequate (Thy1) (n = 19), benign (Thy2) (n = 19), follicular lesion and follicular lesion with atypia (Thy3) (n = 109), suspicious of PTC (Thy4) (n = 29), or malignant (Thy5) (n = 11). The first 68 cases were selected for a morphological study by a quantitative analysis of four cytological features (grooves, intranuclear cytoplasmatic inclusions, number of cells per high power field (400 ×), and mean nuclear diameter) of the carcinomas.

RESULTS

The BRAF status of each tumor was correlated with the cytological classes. 54.5% and 27.6% of Thy5 and Thy4, respectively, were BRAF-mutated, against 12.1% of follicular lesions and 9.3% of follicular lesion with atypia (Thy3). This comparison was statistically significative (p = 0.0017). Among the 68 cases selected for the cyto-morphological study, the BRAF status frequency was similar to that of the total case series. No significant differences were found correlating the cytological classes with the number of cells, the number of grooves, and the mean cell diameters. Only the number of intranuclear cytoplasmatic inclusions were associated (p < 0.05) with the Thy5 cytological class.

CONCLUSIONS

BRAF is mutated in a low percentage of FVPTC, and most of these mutated cases are suspicious or positive on fine-needle aspiration. BRAF analysis is of limited value in the preoperative diagnosis of FVPTC.

[BRAF V600E mutation in papillary thyroid carcinoma: prevalence and detection in fine needle aspiration specimens]

BRAF V600E mutation in papillary thyroid carcinoma (PTC): prevalence and detection in fine needle aspiration (FNA) specimens.

BACKGROUND AND OBJECTIVE

The activating mutation of the BRAF gene, T1799A, is the most common and specific genetic alteration in PTC. In the present study, our aims were to confirm these data and investigate the feasibility of BRAF mutation detection in FNA specimens.

METHODS

In a retrospective study, we examined paraffin-embedded surgical samples of 57 PTC and 51 non-PTC thyroid tumors for the presence of BRAF mutation by dideoxy sequencing. We analyzed thyroid aspirates (drop and washed-out solution) and smears from 31 patients who underwent thyroidectomy, before intraoperative frozen sections, and 25 archival thyroid FNA smears.

RESULTS

The BRAF mutation was present in 58 % of PTC. Among non-PTC thyroid tumors, only one medullary thyroid carcinoma contained the BRAF mutation. BRAF mutation was correctly detected from the FNA-derived materials. Considering the search of BRAF mutation in preoperative FNA smears, the diagnosis of PTC would have been affirmed in 31 % (4/13) of indeterminate and suspicious FNA.

CONCLUSION

BRAF mutation detection in FNA specimens is feasible and could be used as an adjunct tool for preoperative diagnosis of PTC classified as indeterminate and suspicious with conventional cytology (categories 3, 4 and 5 according to NCI/Bethesda 2008 terminology).

Genetic alterations in the RAS/RAF/mitogen-activated protein kinase and phosphatidylinositol 3-kinase/Akt signaling pathways in the follicular variant of papillary thyroid carcinoma

BACKGROUND

The follicular variant of papillary thyroid carcinoma (FVPTC) is the second most common histotype among papillary thyroid cancers (PTCs). Although the prognosis of FVPTC is similar to the conventional phenotype, differential diagnostic difficulties may not be uncommon with other follicular thyroid neoplasms, and little is known about their genetic alterations. Defining these alterations may lead to the identification of diagnostic and biologic markers.

METHODS

In this study, the authors evaluated genetic alterations and downstream-activated signals of the Ras/Raf-mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/v-akt murine thymoma viral oncogene (Akt) (PI3K/Akt) signaling pathways in 30 FVPTC tissue specimens. Tumors and matched normal thyroid samples were tested for RAS, for the v-raf murine sarcoma viral oncogene (BRAF) substitution of valine (V) for glutamate (E) at codon 600 (the V600E mutation), for phosphatase and tensin homolog (PTEN), for catalytic PI3k p110 subunit alpha (PIK3CA), for AKT, and for the presence of rearranged during transfection (ret) proto-oncogene/PTC (RET-PTC) and paired box-8 (PAX8)/peroxisome proliferator-activated receptor gamma (PPARgamma) fusion protein (PAX8-PPARgamma) rearrangements by direct sequencing and reverse transcriptase-polymerases chain reaction analyses, respectively. Western blot analysis was used to assess the effects of these gene abnormalities on the activation of the 2 pathways.

RESULTS

Genetic alterations were identified in 70% of FVPTCs. Activation of the MAPK and PI3K pathways was observed in 74% and 22% of tumors, respectively. The alterations that were identified in the genes of the 2 pathways were mutually exclusive. Chromosomal RET-PTC and PAX8-PPARgamma rearrangements were observed in 20% and 17% of tumors, respectively. It was noteworthy that some FVPTCs with RET-PTC had the coactivation of both pathways.

CONCLUSIONS

RET-PTC and PAX8-PPARgamma rearrangements and mutations of the neuroblastoma RAS viral oncogene homolog N-RAS at codon 61 were the most common genetic alterations in FVPTCs. Activation of the MAPK pathway was a frequent event in FVPTCs, and the PI3K signaling pathway could be coactivated in RET-PTC tumors. These findings may have important therapeutic implication in patients with FVPTC.

Impact of pathognomonic genetic alterations on the prognosis of papillary thyroid carcinoma. ESES vienna presentation

INTRODUCTION

BRAF mutations and RET or NTRK1 rearrangements were identified as causing events that drive the malignant transformation of the thyroid follicular cell. The impact of these alterations on the course of papillary thyroid carcinoma (PTC) is still unsettled.

PATIENTS AND METHODS

Tumor tissues of 290 (98 male, 192 female) patients were intra-operatively snap frozen or harvested from archival paraffin-embedded blocks and used for extraction of DNA and RNA. Comprehensive analysis of RET/PTC and NTRK1 rearrangements was carried out by multiplex screening RT-PCR, hybrid-specific RT-PCR and sequencing of detected hybrids. A mutation-specific PCR was used for BRAF analysis.

RESULTS

The BRAF V600E mutation was detected in 122/290 (42%), RET rearrangements in 20/137 (14.6%), and NTRK1 rearrangements in 15/93 (16.1%) PTCs. One hundred forty one out of 290 (48.6%) PTCs demonstrated none of the genetic alterations studied. Eight PTCs expressed two different mutations (1 RET/PTC + BRAF, 6 NTRK1 + BRAF, 1 RET/PTC + NTRK1). Tumor-specific survival analysis (mean follow-up, 5.5 years) demonstrated no significant difference, but a tendency toward worse prognosis of BRAF-positive patients compared to BRAF-negative patients or rearrangement-positive patients, respectively.

CONCLUSION

Long-term follow-up data on large tumor panels are needed to disclose significant survival differences of prognostic predictors on PTC. This study provides further evidence that patients harboring BRAF-V600E-positive PTCs may experience an unfavorable course of the disease compared to patients with tumors carrying other genetic alterations.

Surgical implications of B-RafV600E mutation in fine-needle aspiration of thyroid nodules

BACKGROUND

Management of patients with thyroid nodules is based on establishing an accurate diagnosis; however, differentiating benign from malignant lesions preoperatively is not always possible using current cytological techniques. Novel molecular testing on cytological material could lead to clearer treatment algorithms. B-Raf(V600E) mutation is the most common genetic alteration in thyroid cancer, specifically found in papillary thyroid cancer (PTC), and usually reported to be associated with aggressive disease.

DATA SOURCE

A literature search using PubMed identified all the pertinent literature on the identification and utilization of the B-Raf(V600E) mutation in thyroid cancer.

CONCLUSIONS

The utility of using B-Raf mutation testing for nodules with indeterminate cytology is limited since many of those nodules (benign and malignant) do not harbor B-Raf mutations. However, when the pathologist sees cytological features suspicious for PTC, B-Raf(V600E) mutation analysis may enhance the assessment of preoperative risks for PTC, directing a more aggressive initial surgical management when appropriate.

Dual priming oligonucleotide-based multiplex PCR analysis for detection of BRAFV600E mutation in FNAB samples of thyroid nodules in BRAFV600E mutation-prevalent area

BACKGROUND

To evaluate the diagnostic value of dual priming oligonucleotide (DPO)-based multiplex polymerase chain reaction (PCR) for the detection of BRAF(V600E) mutations in ultrasound-guided fine-needle aspiration biopsy (US-FNAB) of thyroid nodules.

METHODS

Our institutional review board approved this retrospective study, and informed consent was not required from patients. The 130 patients underwent US-FNAB to evaluate BRAF status in thyroid nodules. In FNAB washouts, DPO-based multiplex PCR, direct DNA sequencing, and PCR-restriction fragment length polymorphism (RFLP) were used to detect BRAF(V600E). The diagnostic performance of these methods was calculated. We compared cytologic results by BRAF status.

RESULTS

Diagnostic accuracy and sensitivity were highest when screening with DPO-based multiplex PCR. BRAF(V600E) positivity was a useful marker at thyroid nodules with "suspicious for papillary thyroid carcinoma" or "inadequate" cytological result.

CONCLUSIONS

DPO-based multiplex PCR may be an alternative to direct DNA sequencing because of its high sensitivity, high accuracy, and simplicity. BRAF(V600E) may be a useful additional diagnostic marker in BRAF(V600E)-prevalent areas.

Thyroid cancer epidemiology and prognostic variables

Thyroid cancer comprises a broad spectrum of diseases with variable prognoses. Although most patients with this disease have excellent overall survival, there are some who do not fare so well. With the worldwide increase in incidence, the need to identify which tumours pose the greatest risk to patients is more acute than ever. This paper will discuss this rising trend in incidence with an analysis of the possible reasons for the increase. In addition, the paper will explore the factors that portend a worse prognosis for the individual patient. Finally, the limitations of the current staging systems will be discussed, with particular emphasis on why they are not as informative in the management of patients with thyroid cancer.

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.