Prognostic significance of somatic RET oncogene mutations in sporadic medullary thyroid cancer: a 10-year follow-up study

Breast cancer subtypes express distinct receptor repertoires for tumor-associated macrophage derived cytokines

Infiltration of the tumor microenvironment by macrophages is associated with poor outcomes in breast cancer and other solid tumors, however the identity and roles of many of the soluble factors these macrophages produce remains to be elucidated in detail. In addition to producing angiogenic factors (e.g. VEGF), proteases (e.g. MMP9) and immunomodulatory factors (e.g. IL10) which, by modifying the local microenvironment, likely contribute to progression in the majority of solid tumors, we have evaluated the extent to which macrophage cytokines may differentially affect distinct breast cancer subtypes. We identified 23 cytokines produced in a culture model of human tumor-associated macrophages and report that basal and luminal breast cancer cell lines express different repertoires of receptors for these cytokines. These data suggest that tumor-associated macrophages make specific contributions to different breast cancer subtypes and that understanding the importance of these interactions will be crucial to developing subtype-specific therapies targeting the macrophage component of the breast tumor microenvironment.

Predominant RET Germline Mutations in Exons 10, 11, and 16 in Iranian Patients with Hereditary Medullary Thyroid Carcinoma

Medullary thyroid carcinoma occurs in both sporadic (75%) and hereditary (25%) forms. The missense mutations of RET proto-oncogene in MTC development have been well demonstrated. To investigate the spectrum of predominant RET germline mutations in exons 10, 11, and 16 in hereditary MTC in Iranian population, 217 participants were included. Genomic DNAs were extracted from the leukocytes using the standard Salting Out/Proteinase K method. Mutation detection was performed through PCR-RFLP and DNA sequencing. In 217 participants, 43 missense mutations were identified in exons 10 (6%), 11 (13%), and 16 (0.9%). Moreover, a novel germline mutation was detected in exon 11 (S686N). Also four different polymorphisms were found in intron 16 in eight patients. The obtained data showed the frequency profile of RET mutations in Iranian individuals with MTC (19.8%). The most frequent mutation in our population was C634G whereas in most population it was C634R. Altogether, these results underline the importance of the genetic background of family members of any patient with MTC.

MicroRNA profiling of sporadic and hereditary medullary thyroid cancer identifies predictors of nodal metastasis, prognosis, and potential therapeutic targets

PURPOSE

While the molecular basis of hereditary medullary thyroid cancer (HMTC) has been well defined, little is known about the molecular pathogenesis of sporadic medullary thyroid cancer (SMTC). In addition, microRNAs (miRNAs) have been shown to be important diagnostic and prognostic markers in cancer but have not been defined in MTC. Our aim was to study the miRNA profile of MTC to identify prognostic biomarkers and potential therapeutic targets.

EXPERIMENTAL DESIGN

MiRNA microarray profiling was carried out in fresh frozen tissues from patients with SMTC (n = 12) and HMTC (n = 7). Differential expression of three miRNAs was confirmed in a validation cohort of SMTC and HMTC samples (n = 45) using quantitative reverse transcriptase-PCR and correlated with clinical outcomes. The functional role of a selected miRNA was investigated in vitro in the human medullary thyroid carcinoma cell line (TT cells) using cell proliferation assays and Western blotting analysis.

RESULTS

MiRs-183 and 375 were overexpressed (P = 0.001; 0.031) and miR-9* was under-expressed (P = 0.011) in SMTC versus HMTC. Overexpression of miRs-183 and 375 in MTC predicted lateral lymph node metastases (P < 0.001; P = 0.001) and was associated with residual disease (P = 0.001; 0.003), distant metastases (P = 0.003; 0.001), and mortality (P = 0.01; 0.011). Knock down of miR-183 expression in the TT cell line induced a significant decrease in the viable cell count and upregulation of the protein LC3B, which is associated with autophagy.

CONCLUSIONS

Our data indicate that miRNAs play a pivotal role in the biology of MTC and represent an important class of prognostic biomarkers and therapeutic targets warranting further investigation.

Targeted therapies for advanced thyroid cancer

PURPOSE OF REVIEW

Thyroid cancer incidence has significantly increased and the majority of cases are represented by differentiated thyroid carcinomas that are characterized by a very good prognosis. Nevertheless, after initial treatment up to 15% of patients present disease persistence or relapse and those with locally advanced or metastasized cancers that do not respond to established therapies ultimately risk death. This scenario has started to change following the development of molecular targeted therapies. This review will focus on the principles behind the use of these novel therapies and on the results of the most recent clinical trials with tyrosine kinase inhibitors (TKIs) and other targeted therapies in thyroid cancer.

RECENT FINDINGS

An understanding of the molecular events involved in cancer formation has prompted the development of numerous drugs that target key molecules implicated in angiogenesis and in the maintenance of the malignant phenotype of cancer cells. The results of several phase I and phase II studies and one phase III trial testing the efficacy of these drugs in advanced thyroid cancer are now available.

SUMMARY

Among the tested drugs, the TKIs sorafenib for differentiated thyroid carcinoma and vandetanib and XL184 for medullary thyroid carcinoma appear very effective and have reached phase III clinical trials. Second-generation TKIs and selective kinase inhibitors are showing even more promising profiles. Improved knowledge of the targets of the different drugs, combined with molecular profiling of the tumors to treat, will allow a tailored pharmacogenomic approach.

Medullary thyroid carcinoma: molecular signaling pathways and emerging therapies

Research on medullary thyroid carcinoma (MTC) over the last 55 years has led to a good understanding of the genetic defects and altered molecular pathways associated with its development. Currently, with the use of genetic testing, patients at high risk for MTC can be identified before the disease develops and offered prophylactic treatment. In cases of localized neck disease, surgery can be curative. However, once MTC has spread beyond the neck, systemic therapy may be necessary. Conventional chemotherapy has been shown to be ineffective; however, multikinase inhibitors have shown promise in stabilizing disease, and this year will probably see the approval of a drug (Vandetanib) for advanced unresectable or metastatic disease, which represents a new chapter in the history of MTC. In this paper, we explore newly understood molecular pathways and the most promising emerging therapies that may change the management of MTC.

Familial thyroid cancer: a review

Thyroid carcinomas can be sporadic or familial. Familial syndromes are classified into familial medullary thyroid carcinoma (FMTC), derived from calcitonin-producing C cells, and familial non-medullary thyroid carcinoma, derived from follicular cells. The familial form of medullary thyroid carcinoma (MTC) is usually a component of multiple endocrine neoplasia (MEN) IIA or IIB, or presents as pure FMTC syndrome. The histopathological features of tumors in patients with MEN syndromes are similar to those of sporadic tumors, with the exception of bilaterality and multiplicity of tumors. The genetic events in the familial C-cell-derived tumors are well known, and genotype-phenotype correlations well established. In contrast, the case for a familial predisposition of non-medullary thyroid carcinoma is only now beginning to emerge. Although, the majority of papillary and follicular thyroid carcinomas are sporadic, the familial forms are rare and can be divided into two groups. The first includes familial syndromes characterized by a predominance of non-thyroidal tumors, such as familial adenomatous polyposis and PTEN-hamartoma tumor syndrome, within others. The second group includes familial syndromes characterized by predominance of papillary thyroid carcinoma (PTC), such as pure familial PTC (fPTC), fPTC associated with papillary renal cell carcinoma, and fPTC with multinodular goiter. Some characteristic morphologic findings should alert the pathologist of a possible familial cancer syndrome, which may lead to further molecular genetics evaluation.

[Molecular pathology of thyroid tumors]

Molecular genetic analysis is gaining in significance for the differential diagnosis of thyroid tumours. Identifying specific mutations and/or rearrangements offers not only the possibility to distinguish benign from malignant tumours, but also to classify thyroid malignancies more precisely, which can have a substantial influence on the clinical management of patients. In recent years expression analysis of micro-RNA (miRNA) has become an additional tool to improve diagnostic accuracy in thyroid tumours. In addition to its diagnostic contribution, molecular genetic evaluation of thyroid tumours has significantly deepened our understanding of the development, progression and therapy of these tumours.

[Multiple endocrine neoplasia type 2]

Multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominant inherited cancer syndrome with the major components medullary thyroid carcinoma, pheochromocytoma and hyperparathyroidism. Due to the clinical course three distinct subtypes are distinguished, MEN 2A, MEN 2B and familial medullary thyroid carcinoma. The disease is caused by germ-line mutations of the RET proto-oncogene and the localization of these mutations correlates with the onset of the development of medullary thyroid carcinoma, which is crucial for the clinical course and outcome of the disease. It therefore has a substantial influence on the clinical management of the affected patients and their relatives. This review summarizes the morphology and clinic of MEN 2-associated tumors and their respective precursor lesions.

Familial thyroid neoplasia: impact of technological advances on detection and monitoring

PURPOSE OF REVIEW

To weigh the clinical impact of new technological insights into heritable thyroid malignancies.

RECENT FINDINGS

Medullary thyroid carcinoma and familial nonmedullary thyroid cancers represent the small minority of thyroid cancers that are inherited. New insights into the genetic alterations and molecular mechanisms implicated in these tumors are serving to refine the clinical tools available for their initial diagnosis as well as subsequent follow-up. In addition to an analysis of rearranged during transfection mutations and calcitonin profiles in medullary thyroid carcinoma, this review includes emphasis on familial nonmedullary thyroid cancer syndromes, including genetic findings in familial papillary thyroid cancer, familial adenomatous polyposis, Cowden syndrome, Carney complex, and Werner syndrome.

SUMMARY

Genetic mutational information is increasingly available on medullary and familial nonmedullary thyroid cancer and their associated syndromes. The clinical significance of this information for affected patients and their families continues to undergo evaluation.

Targeted molecular therapies in thyroid carcinoma

Thyroid cancer incidence has significantly increased in the last three decades and many patients seek medical attention for its treatment every year. Among follicular cell-derived tumors, the majority are differentiated thyroid carcinomas (DTC), whose prognosis is very good with only 15% of the cases presenting disease persistence or recurrence after initial treatment. Medullary thyroid carcinoma has a worse prognosis, especially in patients with diffused cancers at the time of initial surgery. Traditional treatment options for persistent or recurrent disease include additional surgery, radioiodine treatment and TSH-suppression in DTC patients; external beam radiotherapy, and cytotoxic chemotherapy, often have low efficacy and many patients with advanced disease ultimately die. In the last two decades many of the molecular events involved in cancer formation have been uncovered. This knowledge has prompted the development of novel therapeutic strategies mainly based on the inhibition of key molecular mediators of the tumorigenic process. In particular the class of small-molecule tyrosine kinase inhibitors was enriched by many compounds that have reached clinical trials and in some cases have had approval for clinical use in specific cancers. Many of these compounds entered clinical trials also for locally advanced or metastatic thyroid carcinomas showing very promising results.

Medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) accounts for 5-8% of all thyroid cancers. MTC is mainly sporadic in nature, but an hereditary pattern [multiple endocrine neoplasia type 2 (MEN 2)] is present in 20-30% of cases, transmitted as an autosomal-dominant trait due to germline mutations of the RET proto-oncogene. About 98% of patients with MEN 2 have germline mutations in exons 5, 8, 10, 11, 13, 14, 15 or 16 of the RET gene. The primary treatment of both hereditary and sporadic forms of MTC is total thyroidectomy and removal of all neoplastic tissue present in the neck. The therapeutic option for lymph node surgery should be dictated by the results of presurgical evaluation. After total thyroidectomy, measurements of serum calcitonin (CT) and carcinoembryonic antigen are of paramount importance in the postsurgical follow-up of patients with MTC as they reflect the presence of persistent or recurrent disease. Complete remission is demonstrated by undetectable and stimulated serum CT measurement. On the contrary, if serum CT is detectable under basal conditions or becomes detectable after stimulation, the patient is probably not cured, but imaging techniques will not demonstrate any disease until serum CT approaches levels >150 pg/ml. The tumour metastasises early to both paratracheal and lateral cervical lymph nodes. Metastases outside the neck may occur in the liver, lungs, bones and, less frequently, brain and skin. Surgery is the main treatment for local and distant metastases whenever feasible. Systemic chemotherapy with dacarbazine, 5-fluorouracil and doxorubicin (alone or in combination) has shown very limited efficacy, achieving only partial responses in the range of 10-20% and of short duration. Several kinase inhibitors are currently under evaluation and preliminary results are promising. Familial cases must be identified by searching for RET proto-oncogene mutations in the proband and in family members. Carriers of the RET gene are candidates for prophylactic thyroidectomy at different ages depending on the risk associated with the specific RET mutations.

The evolving field of tyrosine kinase inhibitors in the treatment of endocrine tumors

Activation of tyrosine kinase receptors (TKRs) and their related pathways has been associated with development of endocrine tumors. Compounds that target and inactivate the kinase function of these receptors, tyrosine kinase inhibitors (TKIs), are now being applied to the treatment of endocrine tumors. Recent clinical trials of TKIs in patients with advanced thyroid cancer, islet cell carcinoma, and carcinoid have shown promising preliminary results. Significant reductions in tumor size have been described in medullary and papillary thyroid carcinoma, although no complete responses have been reported. Case reports have described significant tumor volume reductions of malignant pheochromocytomas and paragangliomas. In addition, these compounds showed an initial tumoricidal or apoptotic response followed by long-term static effects on tumor growth. Despite the promising preliminary results, this class of therapeutic agents has a broad spectrum of adverse effects, mediated by inhibition of kinase activities in normal tissues. These adverse effects will have to be balanced with their benefit in clinical use. New strategies will have to be applied in clinical research to achieve optimal benefits. In this review, we will address the genetic alterations of TKRs, the rationale for utilizing TKIs for endocrine tumors, and current information on tumor and patient responses to specific TKIs. We will also discuss the adverse effects related to TKI treatment and the mechanisms involved. Finally, we will summarize the challenges associated with use of this class of compounds and potential solutions.

Mixed Medullary-follicular-derived carcinomas of the thyroid gland

Tumors of the thyroid are subclassified based on the cell of origin and commonly include follicular-derived tumors and C-cell-derived tumors. The most common follicular-derived tumors are papillary carcinoma and follicular carcinoma, whereas the malignant C-cell-derived tumor is medullary thyroid carcinoma. Rare cases in the literature describe patients who have follicular-derived and C-cell-derived tumors in the same thyroid gland. These can be synchronous but anatomically separate carcinomas, or they can show some mixing of the 2 components. The mixture may be at an interface, as in collision tumors, or can be throughout the entire lesion, as in true mixed medullary-follicular-derived carcinomas. The clinical, histologic, and molecular features of these mixed tumors and the classification guidelines are reviewed.

Synchronous metastatic medullary and papillary thyroid carcinomas in a patient with germline RET mutation: case report, molecular analysis, and implications for pathogenesis

The occurrence of medullary thyroid carcinoma (MTC) in patients with germline RET mutation is well established, but the occasional occurrence of papillary thyroid carcinoma (PTC) in this setting remains unexplained. We report a case of synchronous MTC and PTC in a patient with germline RET mutation, and investigate the molecular pathogenesis of these two tumors. A 48-year-old man presented with cervical lymphadenopathy and was found to have metastatic MTC involving cervical and mediastinal lymph nodes. He underwent thyroidectomy and debulking of metastatic disease. The resected thyroid showed bilateral MTC and a 1-cm PTC. His lymph node metastases were predominantly MTC along with a small focus of metastatic PTC. Molecular testing using peripheral blood revealed a germline RET point mutation (Val804Met). Both tumors were analyzed for the BRAF (Val600Glu) mutation and the RET/PTC1 translocation. The PTC was positive for the BRAF mutation but negative for RET/PTC1. The MTC was negative for both abnormalities. We conclude that the MTC was caused by the germline RET mutation, while the PTC was caused by a somatic BRAF mutation. The occurrence of PTC in patients with germline RET mutations appears to be purely coincidental.

Sporadic and familial medullary thyroid carcinoma: state of the art

Medullary thyroid cancer (MTC) accounts for 5% to 10% of all thyroid cancers. The high frequency of familial cases mandates screening and genetic testing. The aggressiveness and age of onset of familial MTC differs depending on the specific genetic mutation, and this should determine the timing and extent of surgery. Sporadic MTC can present at any age, and it is usually associated with a palpable mass and the presence of nodal metastases. Surgery is standard treatment for any patient presenting with resectable MTC. Further studies are needed to investigate the role of radiation therapy in the palliation and local control of postresection and advanced-stage MTC. New systemic therapies for metastatic disease are being investigated. Targeted molecular therapies, based on knowledge of the pathways affected by RET mutations, are being tested in multiple clinical trials.

Targeting the RET pathway in thyroid cancer

The RET (rearranged during transfection) protooncogene encodes a single pass transmembrane receptor that is expressed in cells derived from the neural crest and the urogenital tract. As part of a cell-surface complex, RET binds glial derived neurotrophic factor (GDNF) ligands in conjunction with GDNF-family alpha co-receptors (GFRalpha). Ligand-induced activation induces dimerization and tyrosine phosphorylation of the RET receptor with downstream activation of several signal transduction pathways. Activating germline RET mutations play a central role in the development of the multiple endocrine neoplasia (MEN) syndromes MEN2A, MEN2B, and familial medullary thyroid carcinoma (FMTC) and also in the development of the congenital abnormality Hirschsprung's disease. Approximately 50% of patients with sporadic MTC have somatic RET mutations, and a significant portion of papillary thyroid carcinomas result from chromosomal inversions or translocations, which activate RET (RET/PTC oncogenes). The RET protooncogene has a significant place in cancer prevention and treatment. Timely thyroidectomy in kindred members who have inherited a mutated RET allele, characteristic of MEN2A, MEN2B, or FMTC, can prevent MTC, the most common cause of death in these syndromes. Also, recently developed molecular therapeutics that target the RET pathway have shown activity in clinical trials of patients with advanced MTC, a disease for which there has been no effective therapy.

Multiple endocrine neoplasia type 2

Multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominantly inherited tumor syndrome subclassified into three distinct syndromes: MEN 2A, MEN 2B and familial medullary thyroid carcinoma. In MEN 2 families, medullary thyroid carcinoma, pheochromocytomas and parathyroid adenomas occur with a variable frequency, also depending on the specific genetic defect involved. In 1993, the responsible MEN2 gene was identified. The genetic defect in these disorders involves the RET proto-oncogene on chromosome 10. The germline RET mutations result in a gain-of-function of the RET protein. Extensive studies on large families revealed that there is a strong genotype-phenotype correlation. In this review, guidelines for early diagnosis, including MEN2 gene mutation analysis, and treatment, including preventive surgery, periodic and clinical monitoring, have been formulated, enabling improvement of life expectancy and quality of life. Identification of the RET protein has also provided new insights into its function, and the specific pathways it effects involved in cell proliferation, migration, differentiation and survival. In the near future, identification of biological tumor markers will enable target-directed intervention and may prevent and/or delay progression of both primary and residual tumor growth.

Phase II study of safety and efficacy of motesanib in patients with progressive or symptomatic, advanced or metastatic medullary thyroid cancer

PURPOSE

This phase II study investigated the efficacy and tolerability of motesanib, an investigational, highly selective inhibitor of vascular endothelial growth factor receptors 1, 2, and 3; platelet-derived growth factor receptor; and Kit in advanced medullary thyroid cancer (MTC).

PATIENTS AND METHODS

Patients with locally advanced or metastatic, progressive or symptomatic MTC received motesanib 125 mg/d orally for up to 48 weeks or until unacceptable toxicity or disease progression. The primary end point was objective response by independent review. Other end points included duration of response, progression-free survival, safety, pharmacokinetics, and changes in tumor markers.

RESULTS

Of 91 enrolled patients who received motesanib, two (2%) achieved objective response (95% CI, 0.3% to 7.7%); their duration of response was 32 weeks (censored) and 21 weeks (disease progressed). Eighty-one percent of patients had stable disease (48% had durable stable disease > or = 24 weeks), 8% had disease progression as best response, and 9% were not evaluated; 76% experienced a decrease from baseline in target lesion measurement. Median progression-free survival was 48 weeks (95% CI, 43 to 56 weeks). Among patients with tumor marker analysis, 69 (83%) of 83 and 63 (75%) of 84 had decreased serum calcitonin and carcinoembryonic antigen during treatment, respectively, compared with baseline. The most common treatment-related adverse events were diarrhea (41%), fatigue (41%), hypothyroidism (29%), hypertension (27%), and anorexia (27%). In pharmacokinetic analyses, motesanib trough concentrations were lower compared with differentiated thyroid cancer patients from the same study.

CONCLUSION

Although the objective response rate was low, a significant proportion of MTC patients (81%) achieved stable disease while receiving motesanib.

Thyroid cancer in young adults

The incidence of thyroid cancer in young adults is rising. Differentiated carcinoma (ie, papillary, follicular, and their variants) and medullary thyroid carcinoma (MTC) represent the two most common subtypes, with differing etiologies, prognoses, and management strategies. Ultrasound (US)-guided fine needle aspiration (FNA) is the best initial test for evaluating a nodule or mass suspicious for malignancy. Tumor histology, in addition to radiographic findings and clinical presentation, guides surgical management, the need for adjuvant therapies, and the optimal approach to long-term follow-up. Radioactive iodine (RAI) is used to reduce recurrence and improve survival for differentiated thyroid carcinomas (DTCs). Emerging systemic therapies provide options for patients with progressive metastatic MTC or radio-resistant DTC. Overall, the prognosis for the most common thyroid malignancy, papillary thyroid carcinoma (PTC), is excellent. The treatment of young adult thyroid cancer patients occurs optimally as part of a multidisciplinary coordination of care.

Medullary thyroid carcinoma and biomarkers: past, present and future

The clinical management of patients with persistent or recurrent medullary thyroid carcinoma (MTC) is still under debate, because these patients either have a long-term survival, due to an indolent course of the disease, or develop rapidly progressing disease leading to death from distant metastases. At this moment, it cannot be predicted what will happen within most individual cases. Biomarkers, indicators which can be measured objectively, can be helpful in MTC diagnosis, molecular imaging and treatment, and/or identification of MTC progression. Several MTC biomarkers are already implemented in the daily management of MTC patients. More research is being aimed at the improvement of molecular imaging techniques and the development of molecular systemic therapies. Recent discoveries, like the prognostic value of plasma calcitonin and carcino-embryonic antigen doubling-time and the presence of somatic RET mutations in MTC tissue, may be useful tools in clinical decision making in the future. In this review, we provide an overview of different MTC biomarkers and their applications in the clinical management of MTC patients.

Constitutive RET tyrosine kinase activation in hereditary medullary thyroid cancer: clinical opportunities

The ground-breaking discovery of genotype-phenotype relationships in hereditary medullary thyroid cancer has greatly facilitated early prophylactic thyroidectomy. Its timing depends not solely on a positive gene test but, more importantly, on the type of the REarranged during Transfection (RET) mutation and its underlying mode of RET receptor tyrosine kinase activation. In the past decade, the therapeutic corridor opened by molecular information has been defined down to a remarkable level of detail. Based on mutational risk profiles, preemptive thyroidectomy is recommended at 6 months of age for carriers of highest-risk mutations, before the age of 5 years for carriers of high-risk mutations, and before the age of 5 or 10 years for carriers of least-high-risk mutations. Additional lymph node dissection may not be needed in the absence of increased preoperative basal calcitonin levels. Better comprehension of RET function should enable the design of targeted therapies for RET carriers beyond surgical cure in whom the DNA-based 'window of opportunity' has been missed.

Medullary thyroid cancer: management guidelines of the American Thyroid Association

BACKGROUND

Inherited and sporadic medullary thyroid cancer (MTC) is an uncommon and challenging malignancy. The American Thyroid association (ATA) chose to create specific MTC Clinical Guidelines that would bring together and update the diverse MTC literature and combine it with evidence-based medicine and the knowledge and experience of a panel of expert clinicians.

METHODS

Relevant articles were identified using a systematic PubMed search and supplemented with additional published materials. Evidence-based recommendations were created and then categorized using criteria adapted from the United States Preventive Services Task Force, Agency for Healthcare Research and Quality.

RESULTS

Clinical topics addressed in this scholarly dialog included: initial diagnosis and therapy of preclinical disease (including RET oncogene testing and the timing of prophylactic thyroidectomy), initial diagnosis and therapy of clinically apparent disease (including preoperative testing and imaging, extent of surgery, and handling of devascularized parathyroid glands), initial evaluation and treatment of postoperative patients (including the role of completion thyroidectomy), management of persistent or recurrent MTC (including the role of tumor marker doubling times, and treatment of patients with distant metastases and hormonally active metastases), long-term follow-up and management (including the frequency of follow-up and imaging), and directions for future research.

CONCLUSIONS

One hundred twenty-two evidence-based recommendations were created to assist in the clinical care of MTC patients and to share what we believe is current, rational, and optimal medical practice.

Correlation of RET somatic mutations with clinicopathological features in sporadic medullary thyroid carcinomas

Screening of REarranged during Transfection (RET) gene mutations has been carried out in different series of sporadic medullary thyroid carcinomas (MTC). RET-positive tumours seem to be associated to a worse clinical outcome. However, the correlation between the type of RET mutation and the patients' clinicopathological data has not been evaluated yet. We analysed RET exons 5, 8, 10-16 in fifty-one sporadic MTC, and found somatic mutations in thirty-three (64.7%) tumours. Among the RET-positive cases, exon 16 was the most frequently affected (60.6%). Two novel somatic mutations (Cys630Gly, c.1881del18) were identified. MTC patients were divided into three groups: group 1, with mutations in RET exons 15 and 16; group 2, with other RET mutations; group 3, having no RET mutations. Group 1 had higher prevalence (P=0.0051) and number of lymph node metastases (P=0.0017), and presented more often multifocal tumours (P=0.037) and persistent disease at last control (P=0.0242) than group 2. Detectable serum calcitonin levels at last screening (P=0.0119) and stage IV disease (P=0.0145) were more frequent in group 1, than in the other groups. Our results suggest that, among the sporadic MTC, cases with RET mutations in exons 15 and 16 are associated with the worst prognosis. Cases with other RET mutations have the most indolent course, and those with no RET mutations have an intermediate risk.

Occurrence of medullary thyroid carcinoma, bronchial carcinoid tumor, and papillary thyroid carcinoma in a family bearing the RET G691S polymorphism

RET mutations play an important role in the development of human neuroendocrine tumors. The prevalence of the RET polymorphism G691S of exon 11 is higher in patients with medullary thyroid carcinoma (MTC) as compared to the general population. A weak association between RET polymorphisms and sporadic papillary thyroid carcinoma (PTC) has also been described. We hereby describe the association of MTC, bronchial carcinoid tumor, and PTC in a familial setting. A 75-yr-old woman developed MTC 7 yr after successful treatment of a bronchial carcinoid. Serum calcitonin was 12.9 pg/ml with a peak response to pentagastrin (151.0 pg/ml). The patient underwent total thyroidectomy and a genetic mutational analysis of the RET gene. Histological evaluation confirmed MTC with no evidence of lymph nodes involvement. After thyroidectomy serum calcitonin was <2.0 pg/ml. A germline missense mutation at codon 691 in exon 11 of the RET gene was found. The mutational analysis was extended to the patient's offspring, and her daughter was found to bear the G691S polymorphism of RET. Wild type RET gene was found in the son. The daughter, who showed a nodular goiter, autoimmune thyroiditis and normal serum calcitonin, also underwent thyroidectomy. Histologic examination of the thyroid revealed an incidental PTC. This is the first description of a bronchial carcinoid tumor occurring in association with MTC. The occurrence of apparently unrelated NET in the same subject, or within a family, should be regarded as a challenge for deeper investigations into the possible oncogenic role of this genetic alteration.

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.

[Indication and performance of endocrine surgery. The significance of molecular genetic examination]

The molecular genetic changes from certain endocrine tumors are already understood, reflecting as they do the etiology of these sporadic familial disorders. This already has clinical consequences to the treatment of familial endocrine tumors, which often appear in the course of syndromatic disorders. These consequences consist in slight changes to surgical technique, the search for other active and usually endocrinal tumors, and examination of family members for other gene carriers (of disease-specific mutations) and the most suitable prophylactic tumor therapy. In contrast, for sporadic endocrine tumors there exists far less clinically relevant knowledge. Starting with anamnesis and clinical findings of active endocrine tumors, we discuss the current possibilities for molecular genetic determination of disease-specific mutations (germline and tumor DNA) and their effect on surgical procedure.

Routine serum calcitonin measurement in the evaluation of thyroid nodules

Calcitonin (CT) is secreted mainly by parafollicular C cells. In normal subjects, serum CT (sCT) levels are low and barely detectable by commonly used assays. Increased sCT levels are highly suggestive of medullary thyroid carcinoma (MTC). Since the clinical manifestation of MTC is a thyroid nodule, either single or in the context of a multinodular goitre, the routine measurement of sCT in the evaluation of thyroid nodule(s) facilitates the diagnosis of MTC. sCT measurement is indeed more sensitive than cytology in finding MTC. There are two major benefits from this clinical practice: (a) the surgeon is alerted to the need to perform total thyroidectomy and central compartment lymphadenectomy, which is the minimal surgical treatment for MTC; and (b) the outcome of MTC is favourably affected because it is usually identified at a less advanced stage. However, other non-MTC causes of hypercalcitoninaemia and false sCT positivity do exist and must be recognized. The differential diagnosis is possible using previously validated assays against possible sources of interference, and performing stimulation tests with pentagastrin or, eventually, calcium infusion.

Familial thyroid carcinoma: a diagnostic algorithm

Thyroid carcinomas derived from follicular cells are the most common endocrine malignancies, and papillary thyroid carcinoma (PTC) is the most common type. Although, the majority of papillary and follicular thyroid carcinomas (FTCs) are sporadic, familial forms have been described in recent years. Familial syndromes are classified into familial medullary thyroid carcinoma and familial nonmedullary thyroid carcinoma. Multifocal papillary carcinoma is the most frequent presentation of familial nonmedullary thyroid carcinoma, and based on clinico-pathologic findings it is divided into 2 groups. The first includes familial syndromes characterized by a predominance of nonthyroidal tumors, such as familial adenomatous polyposis, PTEN-hamartoma tumor syndrome, Carney complex type 1, and Werner syndrome. The second group includes familial syndromes characterized by a predominance of NMTC, such as pure familial (f) PTC with or without oxyphilia, fPTC with papillary renal cell carcinoma, and fPTC with multinodular goiter. Medullary thyroid carcinoma is derived from calcitonin-producing C cells. The familial form accounts for 20% to 25% of cases, and is usually a component of multiple endocrine neoplasia (MEN) IIA or IIB, or presents as pure familial medullary thyroid carcinoma syndrome. C-cell hyperplasia is the precursor lesion of these heritable syndromes. Some characteristic morphologic findings should alert the pathologist of a possible familial cancer syndrome, which may lead to further molecular genetic evaluation.

CD147 expression as a significant prognostic factor in differentiated thyroid carcinoma

CD147 is 1 of the molecules involved in regulating the expression of matrix metalloproteinases (MMPs). The goal of this study was to analyze the expression of CD147 in differentiated thyroid carcinoma (DTC) tissues as well as its association with the clinicopathologic features of DTC patients and its prognostic significance. During our research, CD147 expression in 156 patients who underwent operation for DTC [100 with papillary thyroid carcinoma (PTC) and 56 with follicular thyroid carcinoma (FTC)] were examined by immunostaining on paraffin-embedded tumor specimens. Then, the association of CD147 expression with clinicopathologic characteristics and patients' prognosis was analyzed. As a result, CD147 was expressed in cancerous lesions but not in normal tissues. Overall, 55 of 156 (35.26%) cases showed low CD147-positive expression, 52 of 156 (33.33%) showed intermediate CD147-positive expression, and 49 of 156 (31.41%) showed high CD147-positive expression. Positive CD147 staining was associated significantly with various clinicopathologic features, such as extrathyroidal invasion (P = 0.02), lymph node metastasis (P = 0.01), and depth of tumor invasion (P < 0.01). Patients with low CD147 expression showed better survival rates than those with intermediate and high expression (90.91% for low expression, 82.69% for intermediate expression, and 65.31% in high expression, respectively; P < 0.05 for analyses). Using Cox regression analysis of the 156 patients, high expression of CD147, extrathyroidal invasion, lymph node metastasis, and the pathologic grading of tumor invasion seemed to be independent prognostic indicators (P < 0.01, P = 0.02, P < 0.01, and P < 0.01, respectively). Therefore, we conclude that the expression of CD147 may be useful to predict the prognosis of DTC patients.

Clinicopathologic evaluation of immunohistochemical CD147 and MMP-2 expression in differentiated thyroid carcinoma

OBJECTIVE

CD147 is one of the molecules involved in regulating the expression of matrix metalloproteinases (MMPs). The goal of this study was to analyze the expression levels of CD147 and MMP-2 in differentiated thyroid carcinomas (DTCs) tissues, as well as their associations with the clinicopathologic features of DTC patients.

METHODS

CD147 and MMP-2 expression in 156 patients who underwent operation for DTC (100 with papillary thyroid carcinomas and 56 with follicular thyroid carcinomas) were examined by immunostaining on paraffin-embedded tumor specimens. The Spearman correlation was calculated between the expression levels of CD147 and MMP-2 in DTC tissues. Then, the association of their expression with clinicopathologic characteristics was analyzed.

RESULTS

CD147 and MMP-2 were expressed mainly in cancerous lesions, but also expressed in some normal tissues. A total of 55 and 58 in 156 (35.26 and 37.18%, respectively) cases showed low CD147- and MMP-2-positive expression; 52 and 50 in 156 (33.33 and 32.05%, respectively) cases showed intermediate CD147- and MMP-2-positive expression and 49 and 48 in 156 (31.41 and 30.77%, respectively) cases showed high CD147- and MMP-2-positive expression. The Spearman analysis indicated that the expression level of CD147 was positively correlated with that of MMP-2 significantly (rs = 0.86, P = 0.02). Positive CD147 and MMP-2 immunostaining associated significantly with extrathyroidal invasion (P = 0.02, 0.03), lymph node metastasis (P = 0.01, 0.01) and depth of tumor invasion (P < 0.01, =0.01).

CONCLUSIONS

The results have been demonstrated that the expression of CD147 and MMP-2 may be an important feature of DTC. The detection of these two markers may increase the ability of clinicians to investigate the progression of DTC patients.

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.

Familial non-medullary thyroid carcinoma: an update

Familial thyroid cancer can arise from follicular cells (familial non-medullary thyroid carcinoma (FNMTC)) or from the calcitonin-producing C-cell (familial medullary thyroid carcinoma). This is usually a component of multiple endocrine neoplasias (MEN) IIA or IIB, or as pure familial medullary thyroid carcinoma syndrome. The genetic events in the familial C-cell-derived tumors are known and genotype-phenotype correlations are well established. In contrast, the case for a familial predisposition of non-medullary thyroid carcinoma is only now beginning to emerge. Although the majority of papillary (PTC) and follicular thyroid carcinomas (FTC) are sporadic, familial tumors account for over 5% of cases. The presence of multifocal papillary carcinoma is a common feature of FNMTC. The familial follicular cell-derived tumors or non-medullary thyroid carcinomas encompass a heterogeneous group of diseases, including diverse syndromic-associated tumors and non-syndromic tumors. Based on clinico-pathologic findings, FNMTC is divided into two groups. The first includes familial syndromes characterized by a predominance of non-thyroidal tumors, such as familial adenomatous polyposis (FAP), PTEN hamartoma tumor syndrome (PHTS), Carney complex type 1, and Werner syndrome. The second group includes familial syndromes characterized by a predominance of NMTC, such as pure familial (f) PTC with or without oxyphilia, fPTC with papillary renal cell carcinoma, and fPTC with multinodular goiter. Some characteristic morphologic findings should alert the pathologist of a possible familial cancer syndrome, which may lead to further molecular genetic evaluation.