Very early detection of RET proto-oncogene mutation is crucial for preventive thyroidectomy in multiple endocrine neoplasia type 2 children: presence of C-cell malignant disease in asymptomatic carriers

Sporadic Medullary Thyroid Carcinoma: Towards a Precision Medicine

Medullary thyroid carcinoma (MTC) is a neuroendocrine malignant tumor originating from parafollicular C-cells producing calcitonin. Most of cases (75%) are sporadic while the remaining (25%) are hereditary. In these latter cases medullary thyroid carcinoma can be associated (multiple endocrine neoplasia type IIA and IIB) or not (familial medullary thyroid carcinoma), with other endocrine diseases such as pheochromocytoma and/or hyperparathyroidism. RET gene point mutation is the main molecular alteration involved in MTC tumorigenesis, both in sporadic and in hereditary cases. Total thyroidectomy with prophylactic/therapeutic central compartment lymph nodes dissection is the initial treatment of choice. Further treatments are needed according to tumor burden and rate of progression. Surgical treatments and local therapies are advocated in the case of single or few local or distant metastasis and slow rate of progression. Conversely, systemic treatments should be initiated in cases with large metastatic and rapidly progressive disease. In this review, we discuss the details of systemic treatments in advanced and metastatic sporadic MTC, focusing on multikinase inhibitors, both those already used in clinical practice and under investigation, and on emerging treatments such as highly selective RET inhibitors and radionuclide therapy.

Multiple endocrine neoplasia type 2B: A report of a rare case

Multiple endocrine neoplasia type 2 (MEN2) is caused by RET proto-oncogene mutations and characterized by the presence of medullary carcinoma of the thyroid, pheochromocytoma, marfanoid features and mucosal neuromas of the tongue, lips, inner cheeks and inner eyelids. MEN type 2B is also known as mucosal neuroma syndrome. Oral presentations are sometimes the earliest signs of this condition. Early identification of this syndrome is important because affected patients often develop medullary thyroid carcinoma and pheochromocytoma. This article reports a 43-year-old male patient with mucosal neuromas and previous history of thyroidectomy due to medullary carcinoma.

RET Proto-oncogene Gene Mutation Is Related to Cervical Lymph Node Metastasis in Medullary Thyroid Carcinoma

RET proto-oncogene (RET) mutations were proved to be related to the development of medullary thyroid carcinoma (MTC). We aimed to analyze the role of RET mutations in cervical lymph node metastasis in patients with MTC. Forty-nine patients with preoperatively diagnosed MTC by fine-needle aspiration cytology (FNAC) who underwent bilateral total thyroidectomy with cervical lymphadenectomy were included. Postoperative RET gene test and pathological analysis were performed with the surgical specimens; serum calcitonin (Ctn) and carcinoembryonic antigen (CEA) levels were tested pre- and postoperatively, to evaluate the association between RET mutations and cervical lymph node metastasis in MTC. In these 49 patients, the RET mutation rates of Exon 11, Exon 10, Exon 11&13, Exon 13, and Exon 16 were 20.4%, 4.1%, 38.8%, 22.4%, and 0%, respectively. The lymph node metastasis rates of patients with RET mutation in the central and lateral compartments were 71.4% and 64.3%, respectively, versus 28.6% and 14.3% of patients without RET mutation. The preoperative basal serum levels of Ctn (234.8 ± 188.4 vs. 44.4 ± 27.5, p < 0.01) and postoperative Ctn (49.8 ± 86.4 vs. 3.7 ± 2.2, p = 0.001) in MTC patients with RET mutations were significantly higher than those in MTC patients without RET mutation. In addition, the preoperative (50.2 ± 76.7 vs. 7.4 ± 6.8, p = 0.001) and postoperative serum levels of CEA (13.2 ± 19.5 vs. 1.3 ± 1.6, p < 0.01) in MTC patients with RET mutations were significantly higher than those in MTC patients without RET mutation (p < 0.05). RET mutation was related to cervical lymph node metastasis in patients with MTC, especially the mutation in Exon 11&13. Patients with RET mutation in Exon 11&13 might be regarded as the predictor for prophylactic ipsilateral total cervical lymphadenectomy even without clear evidence of lateral cervical lymph node metastasis.

[Solitary ganglioneuroma of the oropharynx]

Mucosal neuromas, or ganglioneuromas, attract attention as a frequent component of multiple endocrine neoplasia (MEN) syndrome type 2B. The paper describes a clinical and morphological case of solitary oropharyngeal ganglioneuroma in a 60-year-old man, whose observation has not revealed its apparent association with the MEN syndrome.

A pioneering RET genetic screening study in the State of Ceará, Brazil, evaluating patients with medullary thyroid cancer and at-risk relatives: experience with 247 individuals

OBJECTIVE

Initial diagnosis of medullary thyroid carcinoma (MTC) is frequently associated with advanced stages and a poor prognosis. Thus, the need for earlier diagnoses and detection in relatives at risk for the disease has led to increased use of RET genetic screening.

SUBJECTS AND METHODS

We performed RET screening in 247 subjects who were referred to the Brazilian Research Consortium for Multiple Endocrine Neoplasia (BRASMEN) Center in the State of Ceará. Direct genetic sequencing was used to analyze exons 8, 10, 11, and 13-16 in MTC index cases and specific exons in at risk relatives. Afterward, clinical follow-up was offered to all the patients with MTC and their affected relatives.

RESULTS

RET screening was performed in 60 MTC index patients and 187 at-risk family members. At the initial clinical assessment of the index patients, 54 (90%) were diagnosed with apparently sporadic disease and 6 (10%) diagnosed with hereditary disease. After RET screening, we found that 31 (52%) index patients had sporadic disease, and 29 (48%) had hereditary disease. Regarding at-risk relatives, 73/187 were mutation carriers. Mutations in RET codon 804 and the rare p.M918V mutation were the most prevalent.

CONCLUSIONS

Performing RET screening in Ceará allowed us to identify a different mutation profile in this region compared with other areas. RET screening also enabled the diagnosis of a significant number of hereditary MTC patients who were initially classified as sporadic disease patients and benefited their relatives, who were unaware of the risks and the consequences of bearing a RET mutation.

GDNF and the RET Receptor in Cancer: New Insights and Therapeutic Potential

The Glial cell line-derived neurotrophic Family Ligands (GFL) are soluble neurotrophic factors that are required for development of multiple human tissues, but which are also important contributors to human cancers. GFL signaling occurs through the transmembrane RET receptor tyrosine kinase, a well-characterized oncogene. GFL-independent RET activation, through rearrangement or point mutations occurs in thyroid and lung cancers. However, GFL-mediated activation of wildtype RET is an increasingly recognized mechanism promoting tumor growth and dissemination of a much broader group of cancers. RET and GFL expression have been implicated in metastasis or invasion in diverse human cancers including breast, pancreatic, and prostate tumors, where they are linked to poorer patient prognosis. In addition to directly inducing tumor growth in these diseases, GFL-RET signaling promotes changes in the tumor microenvironment that alter the surrounding stroma and cellular composition to enhance tumor invasion and metastasis. As such, GFL RET signaling is an important target for novel therapeutic approaches to limit tumor growth and spread and improve disease outcomes.

Bilateral Medullary Thyroid Carcinoma in a 3-Year-Old Female Patient with Multiple Endocrine Neoplasia 2A Syndrome Undergoing Prophylactic Thyroidectomy: Should Current Guidelines Be Revised?

BACKGROUND

Multiple endocrine neoplasia (MEN) 2A is an autosomal dominant disorder that results from a mutation in the RET proto-oncogene on chromosome 10. Almost all of the affected patients develop medullary thyroid carcinoma (MTC). The American Thyroid Association recommends prophylactic thyroidectomy in MEN 2A pediatric patients, with the age of the recommended thyroidectomy varying according to the codon mutation present.

OBJECTIVES

This report questions the reliability of the currently placed guidelines and whether the age threshold for prophylactic thyroidectomy in patients with known codon 634 mutations should be lowered, in parallel with an earlier evaluation of calcitonin levels in the serum.

METHODS

We report the preoperative diagnosis as well as operative and postoperative course of a 3-year-old female patient with MEN 2A (codon 634 mutation) who underwent prophylactic thyroidectomy. The postoperative histopathologic findings are presented and discussed.

RESULTS

Despite the prophylactic nature of the operation, in parallel with a borderline calcitonin increase in the serum, bilateral MTC was discovered on pathology.

CONCLUSION

It is likely that the current guidelines should be revised to recommend calcitonin screening and prophylactic thyroidectomy at an earlier age for MEN 2A patients with known codon 634 mutations.

65 YEARS OF THE DOUBLE HELIX: Exploiting insights on the RET receptor for personalized cancer medicine

The focus of precision cancer medicine is the use of patient genetic signatures to predict disease occurrence and course and tailor approaches to individualized treatment to improve patient outcomes. The rearranged during transfection (RET) receptor tyrosine kinase represents a paradigm for the power of personalized cancer management to change cancer impact and improve quality of life. Oncogenic activation of RET occurs through several mechanisms including activating mutations and increased or aberrant expression. Activating RET mutations found in the inherited cancer syndrome multiple endocrine neoplasia 2 permit early diagnosis, predict disease course and guide disease management to optimize patient survival. Rearrangements of RET found in thyroid and lung tumors provide insights on potential disease aggressiveness and offer opportunities for RET-targeted therapy. Aberrant RET expression in a subset of cases is associated with tumor dissemination, resistance to therapies and/or poorer prognosis in multiple cancers. The potential of RET targeting through repurposing of small-molecule multikinase inhibitors, selective RET inhibitors or other novel approaches provides exciting opportunities to individualize therapies across multiple pathologies where RET oncogenicity contributes to cancer outcomes.

Diagnostic Procedures in the Follow-Up of Patients Affected by Men Type 2

Multiple endocrine neoplasia type 2 (MEN 2) is an inherited disease caused by germline mutations in the RET proto-oncogene. The most distinctive MEN 2 variants are MEN 2A, MEN 2B and familial medullary thyroid cancer (FMTC). The hallmark of these syndromes is the development of medullary thyroid carcinoma (MTC), which occurs in almost all patients with MEN 2 syndromes. Other endocrinopathies are variably expressed. Pheochromocytoma and hyperparathyroidism occur in patients with MEN 2A with a frequency of about 50% and 30%, respectively. In this paper we summarize the most relevant diagnostic methods to detect and monitor MTC, pheochromocytoma and hyperparathyroidism.

A comprehensive review on MEN2B

MEN2B is a very rare autosomal dominant hereditary tumor syndrome associated with medullary thyroid carcinoma (MTC) in 100% cases, pheochromocytoma in 50% cases and multiple extra-endocrine features, many of which can be quite disabling. Only few data are available in the literature. The aim of this review is to try to give further insights into the natural history of the disease and to point out the missing evidence that would help clinicians optimize the management of such patients. MEN2B is mainly characterized by the early occurrence of MTC, which led the American Thyroid Association to recommend preventive thyroidectomy before the age of 1 year. However, as the majority of mutations are de novo, improved knowledge of the nonendocrine signs would help to lower the age of diagnosis and improve long-term outcomes. Future large-scale studies will be aimed at characterizing more in detail the main characteristics and outcomes of MEN2B.

When should genetic testing be performed in patients with neuroendocrine tumours?

Neuroendocrine tumours (NETs) are a heterogenous group of tumours arising from neuroendocrine cells in several sites around the body. They include tumours of the gastroenteropancreatic system, phaeochromocytoma and paraganglioma and medullary thyroid cancer. In recent years, it has become increasingly apparent that a number of these tumours arise as a result of germline genetic mutations and are inherited in an autosomal dominant pattern. The number of genes implicated is increasing rapidly. Identifying which patients are likely to have a germline mutation enables clinicians to counsel patients adequately about their future disease risk, and allows for earlier detection of at-risk patients through family screening. The institution of screening and surveillance programmes may in turn lead to a major shift in presentation patterns for some of these tumours. In this review, we examine the features which may lead a clinician to suspect that a patient may have an inherited cause of a NET and we outline which underlying conditions should be suspected. We also discuss what type of screening may be appropriate in a variety of situations.

Distribution of RET Mutations in Multiple Endocrine Neoplasia 2 in Denmark 1994-2014: A Nationwide Study

BACKGROUND

Germline mutations of the REarranged during Transfection (RET) proto-oncogene cause multiple endocrine neoplasia 2 (MEN2). It is unclear whether the distribution of RET mutations varies among populations. The first nationwide study of the distribution of RET mutations was conducted, and the results were compared to those of other populations.

METHODS

This retrospective cohort study included 1583 patients who underwent RET gene testing in one of three centers covering all of Denmark between September 1994 and December 2014. Primary testing method was Sanger sequencing, which included exons 8-11 and 13-16. Mutations were defined according to the ARUP database July 1, 2016.

RESULTS

RET mutations were identified in 163 patients from 36 apparently unrelated families. Among the 36 families 13 (36.1%) carried mutations in codon 611, four (11.1%) in codon 618, three (8.3%) in codon 620, one (2.8%) in codon 631, six (16.7%) in codon 634, one (2.8%) in codon 790, one (2.8%) in codon 804, one (2.8%) in codon 852, one (2.8%) in codon 883, and five (13.9%) in codon 918. Among the 13 families with codon 611 mutations, 12 had the p.C611Y mutation.

CONCLUSIONS

The distribution of RET mutations in Denmark appears to differ from that of other populations. Mutations in codon 611 were the most prevalent, followed by more frequently reported mutations. This might be due to a possible founder effect for the p.C611Y mutation. However, further studies are needed to find possible explanations for the skewed mutational spectrum in Denmark.

Identification of Driving ALK Fusion Genes and Genomic Landscape of Medullary Thyroid Cancer

The genetic landscape of medullary thyroid cancer (MTC) is not yet fully understood, although some oncogenic mutations have been identified. To explore genetic profiles of MTCs, formalin-fixed, paraffin-embedded tumor tissues from MTC patients were assayed on the Ion AmpliSeq Cancer Panel v2. Eighty-four sporadic MTC samples and 36 paired normal thyroid tissues were successfully sequenced. We discovered 101 hotspot mutations in 18 genes in the 84 MTC tissue samples. The most common mutation was in the ret proto-oncogene, which occurred in 47 cases followed by mutations in genes encoding Harvey rat sarcoma viral oncogene homolog (N = 14), serine/threonine kinase 11 (N = 11), v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (N = 6), mutL homolog 1 (N = 4), Kiesten rat sarcoma viral oncogene homolog (N = 3) and MET proto-oncogene (N = 3). We also evaluated anaplastic lymphoma kinase (ALK) rearrangement by immunohistochemistry and break-apart fluorescence in situ hybridization (FISH). Two of 98 screened cases were positive for ALK FISH. To identify the genomic breakpoint and 5’ fusion partner of ALK, customized targeted cancer panel sequencing was performed using DNA from tumor samples of the two patients. Glutamine:fructose-6-phosphate transaminase 1 (GFPT1)-ALK and echinoderm microtubule-associated protein-like 4 (EML4)-ALK fusions were identified. Additional PCR analysis, followed by Sanger sequencing, confirmed the GFPT1-ALK fusion, indicating that the fusion is a result of intra-chromosomal translocation or deletion. Notably, a metastatic MTC case harboring the EML4-ALK fusion showed a dramatic response to an ALK inhibitor, crizotinib. In conclusion, we found several genetic mutations in MTC and are the first to identify ALK fusions in MTC. Our results suggest that the EML4-ALK fusion in MTC may be a potential driver mutation and a valid target of ALK inhibitors. Furthermore, the GFPT1-ALK fusion may be a potential candidate for molecular target therapy.

Little is known about the molecular biology of medullary thyroid cancer (MTC), which is a rare disease. Genomics are increasingly being used to improve our knowledge about disease biology and to identify therapeutic targets in many cancers. Here, we report the largest genomic results of MTC to date. MTC tissue frequently included several mutations. For the first time, anaplastic lymphoma kinase (ALK) rearrangements were detected in MTC: one case with a glutamine:fructose-6-phosphate transaminase 1 (GFPT1)-ALK fusion, and another case with an echinoderm microtubule-associated protein-like 4 (EML4)-ALK fusion. The fusion mechanism of the novel GFPT1-ALK fusion was successfully investigated using molecular biology techniques. In addition, an inhibitor of ALK (crizotinib) dramatically decreased the number of metastatic MTC lesions harboring the EML4-ALK fusion, thus verifying the fusion as a promising target in MTC. Our findings suggest that using rapidly improving sequencing techniques and accumulated genomic data to comprehensively perform genetic analyses on rare tumors, such as MTC, will help to improve the poor prognosis of orphan diseases.

Medullary thyroid carcinoma: surgical treatment advances

Since medullary thyroid cancer (MTC) was first recognized as a distinct tumor in 1959, it became clear that MTC is more difficult to cure than papillary thyroid cancer and has higher rates of recurrence and mortality. MTC represents 5-8% of thyroid cancers. It derives from parafollicular cells of the ultimobranchial body derived from the neural crest. MTC secretes calcitonin and other hormonal peptides and is considered part of the amine precursor uptake and decarboxilation system. MTC may occur either as a hereditary or nonhereditary entity. Hereditary MTC can occur either alone as the familial MTC or as the thyroid manifestation of multiple endocrine neoplasia (MEN) type 2 syndromes (MEN 2A MEN 2B). Activating point mutations of the RET proto-oncogene have demonstrated to be causative of the familial form of medullary thyroid cancer, both isolated familial MTC and associated with MEN 2A and 2B. In the last 10 years, major improvements and new technologies have been proposed and applied in thyroid surgery; among these are molecular diagnosis with genetic screening and mini-invasive video-assisted thyroidectomy. The history of thyroid surgery starts with Billroth, Kocher and Halsted, who developed the technique for thyroidectomy between 1873 and 1910. Prophylactic surgery for patients carrying a positive RET proto-oncogene has proven to be highly effective in curing those likely to experience the development of MTC. Video-assisted procedures with central compartment dissection have proved feasible for patients carrying a positive RET proto-oncogene. This paper reviews relevant medical literature published in the English language on surgery of MTC in well-controlled trials. We discuss the particular ethical and legal issues that thyroid prophylactic surgery raises. Searches were last updated in February 2007.

Diagnosis and surgical treatment of multiple endocrine neoplasia type 2A

BACKGROUND

This study aims to introduce the diagnosis and surgical treatment of the rare disease multiple endocrine neoplasia type 2A (MEN 2A).

METHODS

Thirteen cases of MEN 2A were diagnosed as medullary thyroid carcinoma (MTC) and pheochromocytoma by biochemical tests and imaging examination. They were treated by bilateral adrenal tumor excision or laparoscopic surgery.

RESULTS

Nine patients were treated by bilateral adrenal tumor excision and the remaining four were treated by laparoscopic surgery for pheochromocytoma. Ten patients were treated by total thyroidectomy and bilateral lymph nodes dissection and the remaining three were treated by unilateral thyroidectomy for MTC. Up to now, three patients have died of MTC distant metastasis.

CONCLUSIONS

We confirmed that MEN 2A can be diagnosed by biochemical tests and imaging examination when genetic testing is not available. Surgical excision is the predominant way to treat MEN 2A; pheochromocytoma should be excised at first when pheochromocytoma and MTC occur simultaneously.

Unusual thyroid tumors: a review of pathologic and molecular diagnosis

The most common thyroid neoplasms are either follicular derived (papillary, follicular and Hürthle cell lesions) or C-cell derived (medullary carcinoma). The diagnosis of these tumors can usually be made at the histologic level, with immunohistochemical stains necessary in some circumstances. Specific molecular mutations have been described that can be diagnostically useful or explain, in part, their pathogenesis, including the well-known Ret/PTC and PPARgamma-PAX8 translocations, point mutations in the Ret, Ras and BRAF genes, and loss of heterozygosity of multiple different tumor suppressor genes. Some unusual tumors of the thyroid gland are more difficult to diagnose. In examining these lesions, the pathologist may use the hematoxylin and eosin-stained morphology, coupled with an analysis of the immunohistochemical staining profiles and possibly analysis of the underlying molecular mutational patterns. These less common thyroid tumors include tall cell and cribriform-morular variants of papillary carcinoma, hyalinizing trabecular tumor, mucoepidermoid and sclerosing mucoepidermoid carcinoma with eosinophilia, poorly differentiated (insular) carcinoma, and undifferentiated (anaplastic) carcinoma. The diagnostic features of these rare tumors, including the histology, immunohistochemical expression profiles and the known molecular mutational profiles of each, are reviewed.

Multiple endocrine neoplasia type 2 and familial medullary thyroid carcinoma: an update

CONTEXT

Over the last decade, our knowledge of the multiple endocrine neoplasia (MEN) type 2 syndromes MEN2A and MEN2B and familial medullary thyroid carcinoma (FMTC) has expanded greatly. In this manuscript, we summarize how recent discoveries have enhanced our understanding of the molecular basis of these diseases and led to improvements in the diagnosis and management of affected patients.

EVIDENCE ACQUISITION

We reviewed the English literature through PubMed from 2000 to the present, using the search terms medullary thyroid carcinoma, multiple endocrine neoplasia type 2, familial medullary thyroid carcinoma, RET proto-oncogene, and calcitonin.

EVIDENCE SYNTHESIS

Over 70 RET mutations are known to cause MEN2A, MEN2B, or FMTC, and recent findings from studies of large kindreds with these syndromes have clouded the relationship between genotype and phenotype, primarily because of the varied clinical presentation of different families with the same RET mutation. This clinical variability has also confounded decisions about the timing of prophylactic thyroidectomy for MTC, the dominant endocrinopathy associated with these syndromes. A distinct advance has been the demonstration through phase II and phase III clinical trials that molecular targeted therapeutics are effective in the treatment of patients with locally advanced or metastatic MTC.

CONCLUSIONS

The effective management of patients with MEN2A, MEN2A, and FMTC depends on an understanding of the variable behavior of disease expression in patients with a specific RET mutation. Information gained from molecular testing, biochemical analysis, and clinical evaluation is important in providing effective management of patients with either early or advanced-stage MTC.

A differential diagnosis of inherited endocrine tumors and their tumor counterparts

Inherited endocrine tumors have been increasingly recognized in clinical practice, although some difficulties still exist in differentiating these conditions from their sporadic endocrine tumor counterparts. Here, we list the 12 main topics that could add helpful information and clues for performing an early differential diagnosis to distinguish between these conditions. The early diagnosis of patients with inherited endocrine tumors may be performed either clinically or by mutation analysis in at-risk individuals. Early detection usually has a large impact in tumor management, allowing preventive clinical or surgical therapy in most cases. Advice for the clinical and surgical management of inherited endocrine tumors is also discussed. In addition, recent clinical and genetic advances for 17 different forms of inherited endocrine tumors are briefly reviewed.

Molecular epidemiology of multiple endocrine neoplasia 2: implications for RET screening in the new millenium

OBJECTIVE

Twenty years ago, the groundbreaking discovery that rearranged during transfection (RET) mutations underlie multiple endocrine neoplasia 2 (MEN2) and familial medullary thyroid cancer (FMTC) ushered in the era of personalized medicine. MEN2-associated signs, taking time to manifest, can be subtle. This study sought to clarify to what extent conventional estimates of 1:200 000-500 000 underestimate the incidence of RET mutations in the population.

DESIGN

Included in this retrospective investigation were 333 RET carriers born between 1951 and 2000 and operated on at the largest German surgical referral center (286 carriers) or elsewhere (47 carriers).

METHODS

To estimate the incidence of RET mutations, the number of RET carriers born in Germany in five decades (1951-1960, 1961-1970, 1971-1980, 1981-1990, and 1991-2000) was divided by the corresponding number of German live births.

RESULTS

Owing to improved diagnosis and capture of FMTC and MEN2 patients, minimum incidence estimates increased over time: overall from 5.0 (1951-1960) to 9.9 (1991-2000) per million live births and year (P=0.008), and by American Thyroid Association/ATA class from 1.7 to 3.7 for ATA class C (P=0.008); from 1.8 to 2.7 for ATA class A (P=0.017); from 1.5 to 2.2 for ATA class B (P=0.20); and from 0 to 1.4 for ATA class D mutations per million live births and year (P=0.008). Based on 1991-2000 incidence estimates the prevalence in Germany is ∼1:80 000 inhabitants.

CONCLUSIONS

The molecular minimum incidence estimate of ≈1:100 000 was two- to fivefold greater than conventional estimates of 1:200 000-500 000.

RET codon 618 mutations in Saudi families with multiple endocrine neoplasia Type 2A and familial medullary thyroid carcinoma

BACKGROUND AND OBJECTIVES

Certain diseases such as multiple endocrine neoplasia (MEN) 2A, MEN 2B, familial and sporadic medullary thyroid carcinoma (MTC) and renal dysgenesis are related to abnormalities of the RET protein. Our aim was to evaluate the frequency of RET mutation in 10 Saudi families with MEN type 2A and familial MTC.

DESIGN AND SETTING

A cross-sectional prospective study of patients followed up at King Abdulaziz University Hospital and King Abdulaziz Medical City, Jeddah, between March 2001 and March 2011.

PATIENTS AND METHODS

Genomic DNA was isolated from peripheral blood leukocytes of all subjects by standard procedures. Exons 10, 11, 13, 14 and 16 of the RET proto-oncogene were analyzed by single-strand conformation polymorphism, direct DNA sequencing and/or restriction enzyme analysis.

RESULTS

We screened 79 subjects for the RET mutation. Of which 43 subjects had hereditary MTC were en.rolled in this study. MEN type 2A was identified in 25 subjects; MTC was diagnosed in all 25 subjects (100%), pheochromocytoma in 13 subjects (52%) and hyperparathyroidism in 4 subjects (16%). The most frequent genotype in patients with MEN 2A syndrome was a codon 618 mutation (46.6%), followed by a codon 634 mutation (44.2%). Among the 5 families with MEN 2A, 3 had a mutation at codon 634, whereas 2 had a mutation at codon 618.

CONCLUSION

The most frequent RET proto-oncogene mutation in our series was in codon 618 (exon 10).

2012 European thyroid association guidelines for genetic testing and its clinical consequences in medullary thyroid cancer

Twenty-five percent of medullary thyroid cancers (MTC) are familial and inherited as an autosomal dominant trait. Three different phenotypes can be distinguished: multiple endocrine neoplasia (MEN) types 2A and 2B, in which the MTC is associated with other endocrine neoplasias, and familial MTC (FMTC), which occurs in isolation. The discovery that germline RET oncogene activating mutations are associated with 95-98% of MEN 2/FMTC syndromes and the availability of genotyping to identify mutations in affected patients and their relatives has revolutionized the diagnostic and therapeutic strategies available for the management of these patients. All patients with MTC, both those with a positive familial history and those apparently sporadic, should be submitted to RET genetic screening. Once an RET mutation has been confirmed in an index patient, first-degree relatives should be screened rapidly to identify the 50% who inherited the mutation and are therefore at risk for development of MTC. Relatives in whom no RET mutation is identified can be reassured and discharged from further follow-up, whereas RET-positive subjects (i.e. gene carriers) must be investigated and a therapeutic strategy initiated. These guideline recommendations are derived from the most recent studies identifying phenotype-genotype correlations following the discovery of causative RET gene mutations in MEN 2 eighteen years ago. Three major points will be discussed: (a) identification of patients and relatives who should have genetic screening for RET mutations, (b) management of asymptomatic gene carriers, and (c) ethics.

Extended RET gene analysis in patients with apparently sporadic medullary thyroid cancer: clinical benefits and cost

RET sequencing has become an important tool in medullary thyroid cancer (MTC) evaluation and should be performed even in the absence of family history of MTC. The most commonly studied exons in index cases are 8, 10, 11, and 13-16. To address the ATA guidelines regarding the sequencing of the entire coding region of RET, we selected 50 patients with sporadic MTC (sMTC) without mutations in the hot spot regions of RET for extended investigation of exons 1-7, 9, 12, 17, 18, and 19. Twenty-seven of 50 patients presented with one or more features suggesting familial disease. We found only a new RET variant (p.Gly550Glu) in one patient with MTC. Several polymorphisms were observed, and their frequency was histogram scaled by exons and introns. Eight patients were also included for somatic mutation search. We estimated the sequencing cost by stratifying into four investigation approaches: (1) hot spot exons in a new patient, (2) the remaining exons if the hot spots are negative in a patient with suspected familial disease, (3) a relative of a carrier for a known RET mutation, and (4) tumor sequencing. In spite of the increasing number of variants being described in MTC, it appears that there is no direct clinical benefit in extending RET germ line analysis beyond the hot spot regions in sMTC. The cost evaluation in apparent sMTC using a tiered approach may help clinicians make more suitable decisions regarding the benefits of investigating only the hot spots against the entire coding region of RET.

Management of thyroid carcinoma in children and young adults

Thyroid cancers represent the largest group of pediatric carcinomas. Unlike other cancers of childhood, they have not been prospectively studied; instead adult data has been extrapolated to childhood and adolescent treatment. In this article we review the treatment of both well differentiated thyroid cancer (WDTC), as well as medullary thyroid cancer (MTC). The approach to both cancers relies on a low threshold of suspicion, and a willingness to biopsy suspicious lesions. Surgery remains the primary method of curing these patients, although radioactive iodine (RAI) may offer some benefit in WDTC for selected patients. For patients with MTC new medications, such as Vandetanib, may offer some adjuvant benefit following surgery. Lastly, suppression of thyroid stimulating hormone (TSH) may be one of the most beneficial treatments for WDTC.

Extrapancreatic malignancies in patients with pancreatic cancer: epidemiology and clinical consequences

OBJECTIVES

To investigate the incidence, characteristics, and prognostic impact of prior extrapancreatic malignancies on patients with pancreatic cancer (PDAC).

METHODS

Records from 1733 patients who underwent surgery for PDAC were analyzed for the occurrence of prior extrapancreatic malignancies. Patients' records showing extrapancreatic malignancies were then analyzed for tumor type, epidemiological data, risk factors, PDAC tumor stage, and long-term survival.

RESULTS

A total of 239 patients with PDAC (13.8%) had a history of 271 extrapancreatic tumors; 26 patients had a history of two pancreatic cancers, and 3 patients had 3 extrapancreatic cancers. The most common extrapancreatic tumors were breast cancer (56 patients) and prostate cancer (41 patients), followed by colorectal, reno/urothelial, and gynecologic tumors (39, 32, and 23 patients, respectively). No significant difference in overall survival was found between patients with PDAC with or without extrapancreatic malignancies.

CONCLUSIONS

Pancreatic cancer is associated with extrapancreatic malignancies in a remarkable number of patients. A history of extrapancreatic malignancies does not influence prognosis and should not be an obstacle to a curative therapeutic approach. Surveillance of patients with extrapancreatic malignancies, especially breast, prostate, and colorectal cancer, could allow for earlier PDAC diagnosis and therefore improve prognosis of these patients.

Multiple Endocrine Neoplasia Type 2B: Early Diagnosis by Multiple Mucosal Neuroma and Its DNA Analysis

Multiple endocrine neoplasia type 2B (MEN 2B) is a rare disease caused by germline mutations in the RET proto-oncogene and is transmitted in an autosomal dominant fashion. It is characterized by medullary thyroid carcinoma, pheochromocytoma and mucosal neuroma developing in the tongue, lip, intestinal tract, palate etc. Among these neoplasias, mucosal neuroma generally develops from early childhood. Therefore, early detection and proper treatment can minimize the disease course. Here we describe a 9-year-old male who presented with multiple verrucous papules and nodules on his lips, tongue and gingiva that were there since birth. Histologic findings of his lips and tongue showed well-defined nerve bundles and DNA analysis revealed a M918T mutation at codon 918 of the RET oncogene. He was diagnosed early as having MEN 2B according to his genetic and phenotypic features.

Influence of lymph node metastases on survival in pediatric medullary thyroid cancer

PURPOSE

Lymph node metastases (LNM) from medullary thyroid cancer (MTC) are common in adults and are a poor prognostic factor. Less is known about LNM in children, who often have hereditary forms of MTC. Guidelines recommend prophylactic thyroidectomy in early childhood, but randomized prospective trials are not feasible. We hypothesized that LNM is associated with poor prognosis in children.

METHODS

Patients with MTC 21 years or younger from the National Cancer Data Base from 1985 to 2007 were studied. Multivariable logistic regression was used to identify factors associated with lymph node evaluation. Survival was estimated using the Kaplan-Meier method.

RESULTS

Of 430 patients, 276 (64.2%) had nodal evaluation with LNM present in 121 (28.1%). Older patients, those with tumors larger than 2 cm, and those with involved margins were more likely to have LNM (all P < .05). Patients undergoing total thyroidectomy, those with involved margins, and older patients were more likely to undergo lymph node evaluation after controlling for patient, tumor, and hospital factors (all P < .05). Over time an increasing number of patients with MTC have undergone total thyroidectomy. Patients 16 to 21 years of age had lower 10-year overall survival compared to patients 0 to 15 years old (88.7% vs 98.1%, P = .005). Lymph node metastases were also associated with decreased 10-year overall survival (84.4% vs 100%, P < .001).

CONCLUSIONS

In pediatric MTC, LNM predict poorer overall survival. Adequate lymph node assessment can provide valuable prognostic information for the pediatric MTC patient. Lymph node assessment should be considered for older pediatric patients undergoing surgery for hereditary MTC or biopsy confirmed MTC.

Pediatric head and neck malignancies

PURPOSE OF REVIEW

Although head and neck masses represent a common entity in children, malignancy is uncommon. The otolaryngologist may be the first physician to see these children, and early recognition of malignancy is of obvious importance. This review aims to discuss the cause, diagnosis, investigation, treatment options, and prognosis for the most common head and neck malignancies of childhood.

RECENT FINDINGS

Over recent years, significant developments have been made in characterizing the epidemiologic, phenotypic, and genotypic variability of childhood head and neck cancers. Improved awareness of tumor biology is reflected by more sophisticated diagnostics, estimates of prognosis, and an increasing individualization of treatment regimens.

SUMMARY

The latest evidence for the diagnosis and management of childhood head and neck malignancy is summarized. The rarity of these tumors inevitably results in a paucity of high-level evidence to guide treatment. A combination of translational research from tumor biology studies, multicenter clinical trials, and smaller case series and case reports will continue to guide new advances in diagnosis and treatment.

Medullary thyroid carcinoma identified within the first year of life in children with hereditary multiple endocrine neoplasia type 2A (codon 634) and 2B

CONTEXT

Early prophylactic thyroidectomy in patients with multiple endocrine neoplasia (MEN) type 2 offers the best chance for a normal life expectancy.

OBJECTIVE

To analyze the results of thyroidectomy performed during the first year of life in six patients with MEN 2A (codon 634) or MEN 2B (codon 918) syndrome.

DESIGN AND SETTING

A university hospital-based prospective study from 2001 to 2008.

SUBJECTS AND METHODS

Six family members affected either by MEN 2A (n=3) or MEN 2B (n=3) syndrome were identified through neonatal genetic screening.

RESULTS

Total thyroidectomy was performed at a median age of 0.8 year in the six patients, with central lymph node dissection in five. Bilateral millimetric medullary thyroid carcinoma (MTC) was found in all patients, with a unilateral lymph node micrometastasis in two of the three MEN 2B patients. Before thyroidectomy, MEN 2B patients had much higher basal serum calcitonin levels than those with MEN 2A and controls. After thyroidectomy, with a median follow-up of 3.3 years, the six patients had no evidence of persistent MTC.

CONCLUSION

Bilateral millimetric MTC may be present during the first year of life in these patients, with lymph node metastases also occurring in MEN 2B patients. These results support a total thyroidectomy at the age of about one year in MEN 2A (codon 634) children with an abnormal serum calcitonin level, and a total thyroidectomy with central neck dissection within the first weeks of life in MEN 2B patients.

Clinical and oncological features of children and young adults with multiple endocrine neoplasia type 2A

BACKGROUND

RET genotype analysis allows identification of asymptomatic carriers at risk of developing medullary thyroid carcinoma (MTC). However, there is still controversy regarding the ideal timing and extent of prophylactic thyroidectomy due to the wide spectrum of clinical presentation. Surveillance of a large number of young patients is crucial to advance our understanding of the natural course of the disease. This study aimed to describe the clinical presentation, oncological features, and treatment outcome of children and young adults harboring RET mutations followed at our institution from 1997 to 2007.

METHODS

Forty-one individuals aged < or =25 years from 17 independent multiple endocrine neoplasia type 2A kindred were studied. Twenty-one individuals presented with thyroid nodules at diagnosis, and 20 were disease free at physical examination.

RESULTS

Preoperative basal calcitonin levels were elevated in 85.7% of patients with clinical disease and in 54.5% of asymptomatic carriers. Thyroid ultrasonography (US) showed one or more nodules in 69.0% of the patients. A positive correlation between age at surgery and tumor-node-metastasis (TNM) stages was observed (p < 0.001). None of the patients under 15 years of age presented lymph node or distant metastasis. After a follow-up of 4.4 +/- 1.4 years all asymptomatic patients were disease free based on physical examination, cervical US, and undetectable serum calcitonin levels. In the group of patients with clinical disease, 47.6% have persistent disease (follow-up of 12.0 +/- 5.9 years). Indeed, palpable thyroid nodule at diagnosis was significantly associated with persistent disease (p < 0.001, odds ratio [OR] 1.9, 95% confidence interval [CI 95%] 1.27-2.87). Of note, none of the patients who presented lymph node metastasis at diagnosis were cured by surgical intervention (p < 0.001, OR 5.0, CI 95% 1.45-17.0).

CONCLUSION

Our data show a time-dependent MTC progression. The presence of a palpable thyroid nodule and lymph node metastasis at diagnosis was associated with persistent or recurrent disease after surgical procedure.

Histopathologic and Clinical Features of Medullary Microcarcinoma and C-Cell Hyperplasia in Prophylactic Thyroidectomies for Medullary Carcinoma: A Study of 42 Cases

Context.—Prophylactic thyroidectomies are increasingly performed on patients at risk for developing medullary thyroid carcinoma (MTC); consequently, pathologists are more commonly encountering these specimens in routine practice.

Objective.—To describe the detailed clinicopathologic features of prophylactic thyroidectomies for medullary carcinoma.

Design.—We present a retrospective series of 42 prophylactic thyroidectomies for MTC performed for one or more of the following: family history of multiple endocrine neoplasia (MEN) or MTC, elevated serum calcitonin level, or detection of a RET proto-oncogene mutation.

Results.—Patients included 22 men and 20 women (mean age, 26.2 years). Among those with known RET proto-oncogene mutations, affected sites included exons 10, 11, 14, and 16. In 93% (n = 39) of cases, either C-cell hyperplasia (n = 36), medullary microcarcinoma (MMC; n = 29), or medullary macrocarcinoma (n = 1) was found. C-cell hyperplasia was often multifocal (n = 30) and bilateral (n = 23) and included both nonnodular and nodular patterns. A total of 94% of C-cell hyperplasia cases and all MMC cases were microscopically detectable using hematoxylin-eosin stains. The MMCs were characterized by a complex microarchitectural pattern with a desmoplastic stromal response (n = 29) and focal amyloid deposition (n = 12). Most MMCs exhibited a solid pattern (n = 24) of round, polygonal, spindled, or plasmacytoid-shaped cells. Only 1 case of MMC showed evidence of metastatic disease to a pretracheal lymph node.

Conclusions.—Based upon our clinicopathologic findings and review of the literature, we conclude that thyroidectomies in at-risk patients are very frequently associated with C-cell hyperplasia and/or MMC; however, the clinical prognosis for these patients is very good.

Skip metastases in medullary thyroid carcinoma: a single-center experience

PURPOSE

Total thyroidectomy (TT) with level VI and VII central neck dissection is the initial treatment for medullary thyroid carcinoma (MTC) without identifiable neck metastasis. Level II to V lateral neck dissection is performed if neck metastasis is present or suspected. We conducted this study to identify the frequency and clinical determinants of skip neck metastasis in MTC.

METHODS

We reviewed the medical records of 32 patients who underwent TT and bilateral neck dissection for MTC. The clinical features were correlated with pN status in the central versus lateral compartments of the neck.

RESULTS

Neck lymph node metastasis (pN+) was found in 20 patients (62.5%) and skip metastases were found in 7 (35%) patients. The sensitivity of the pN status of the central compartment of the neck to predict the pN status of the lateral compartment of the neck was 53.8% and specificity was 63.2%. We found pN+ in 90% of the patients with lymph nodes >15 mm in diameter versus 50% in those with lymph nodes <15 mm in diameter.

CONCLUSIONS

There is skip metastasis in MTC. It is unsafe to use the lymph node status of the central compartment of the neck to define the pN status of the lateral neck. A lymph node greater than 15 mm in diameter is related to pN status.

Medullary thyroid carcinoma in a 2-month-old male with multiple endocrine neoplasia 2B and symptoms of pseudo-Hirschsprung disease: a case report

A 5-week-old male patient was seen for symptoms suggestive of Hirschsprung disease (abdominal distension, failure to thrive, and explosive defecation). Rectum biopsies revealed an intestinal ganglioneuromatosis, which is usually associated with multiple endocrine neoplasia (MEN) syndrome type 2B. The ensuing molecular genetic analysis revealed a M918T mutation of the RET protooncogene, which is associated with early-onset medullary thyroid carcinoma (MTC). Therefore, total thyroidectomy and central lymphadenectomy were performed at the age of 9 weeks. Histology showed a medullary microcarcinoma. This report of MTC occurrence within the first weeks of life underlines the importance of early diagnosis and thyroidectomy in patients with MEN 2B syndrome. Because many patients with MEN 2A and B show gastrointestinal symptoms before the development of MTC, the possibility of MEN 2 should be recognized, and genetic testing for the presence of RET mutations should be included in the explorative diagnosis for megacolon.

[Multiple endocrine neoplasia type 2]

Multiple endocrine neoplasia type 2 (MEN2) is an hereditary disease with a prevalence of 1/5000. Three phenotypic variants have been identified: MEN2A associates medullary thyroid carcinoma (MTC) to pheochromocytoma in about 20-50% of cases and to primary hyperparathyroidism in 5-20% of cases; MEN2B associates MTC to pheochromocytoma in 50% of cases, to marphanoid habitus and to mucosal and digestive ganglioneuromatosis whereas in familial isolated medullary thyroid carcinoma (FMTC), the other components of the disease are absent. In MEN2, natural history of the disease and a common embryologic origin (neural crest) may explain the phenotypes observed in the organ involved, beginning from the stage of hyperplasia to adenoma and cancer. MEN2 is an inherited autosomal dominant disease with a complete penetrance, related to germline mutation in the proto-oncogene RET. MTC represent the most frequent circumstance of diagnosis. Pheochromocytoma and HPT may reveal the disease unfrequently and are systematically associated to undiagnosed MTC which is present yet. Analysis of the RET gene allows to confirm the diagnosis of MEN2 by identifying the causal germline mutation. Management of MEN2 patients include thyroidectomy associated to cervical central and bilateral lymph nodes dissection for MTC, unilateral adrenalectomy for unilateral pheochromocytoma or bilateral adrenalectomy when both glands are involved, and selective resection of pathologic parathyroid glands for HPT. Familial genetic screening detects at risk subjects who will develop the disease and allows to manage them at the earliest stage of the disease by perform early or prophylactic thyroidectomy such giving them the best chance of cure. Prognosis of MEN2 is mainly related to the stage-dependant prognosis of MTC, thus pointing the necessity of a complete thyroid surgery for index cases with MTC and the earliest thyroidectomy for screened at risk subjects.

The Role of Prophylactic Surgery in Cancer Prevention

BACKGROUND

Since the human genome has been sequenced many mysteries of cell biology have been unravelled, thereby clarifying the pathogenesis of several diseases, particularly cancer. In members of kindreds with certain hereditary diseases, it is now possible early in life to predict with great certainty whether or not a family member has inherited the mutated allele causing the disease. In hereditary malignancies this has been particularly important, because in affected family members there is the possibility of removing the organ destined to develop cancer before malignancy develops or while it is in situ. At first consideration, it would appear that "prophylactic surgery" would have a place in many hereditary malignancies; however, the procedure has applicability only if certain criteria are met: (1) the genetic mutation causing the hereditary malignancy must have a very high penetrance and be expressed regardless of environmental factors; (2) there must be a highly reliable test to identify patients who have inherited the mutated gene; (3) the organ must be removed with minimal morbidity and virtually no mortality; (4) there must be a suitable replacement for the function of the removed organ; and (5) there must be a reliable method of determining over time that the patient has been cured by "prophylactic surgery."

CONCLUSIONS

In this monograph we review several hereditary malignancies and consider those where prophylactic surgery might be useful. As we learn, there are various barriers to performing the procedure in many common hereditary cancer syndromes. The archetype disease syndromes, which meet each of the five criteria mentioned above and where prophylactic surgery is most useful, are the type 2 multiple endocrine neoplasia (MEN) syndromes: MEN2A, MEN2B, and the related familial medullary thyroid carcinoma. An additional benefit of the Human Genome Project, has been the development of pharmacologic and biologic compounds that block the metabolic pathway(s) activated by specific genetic mutations. Many of these compounds have shown efficacy in patients with locally advanced or metastatic cancers, and there is the likelihood that they will prove beneficial in preventing the outgrowth of malignant cells in patients destined to develop a hereditary cancer.

Familial medullary carcinoma prevention, risk evaluation, and RET in children of families with MEN2

The ability to predict the risk of MEN2 and medullary thyroid carcinoma (MTC) by genetic RET proto-oncogene analysis has provided an essential tool in identifying patients in whom thyroid cancer can be prevented by prophylactic thyroidectomy but emphasizes the need for clear policy guidelines. Children of families with RET cysteine mutations (exons 10, 11, 13, and 16) may develop early metastatic tumours and require prophylactic thyroidectomy. The 918 mutation associated with MEN2B is associated with early aggressive behaviour and distant metastatic spread. This has led to active screening of affected families underlining the need for specific intervention strategies.

AIM

To evaluate the risk to children of families with MEN2 and to assess the risk and determine the treatment.

METHODS

Twenty-five patients from 10 families with MEN2 phenotypes were screened for RET mutations. Polymerase chain reaction amplification was performed on all 21 exons of the RET proto-oncogene, followed by heteroduplex single-strand conformation polymorphism (HEX-SSCP) analysis. Polymerase chain reaction products demonstrating variation in the HEX-SSCP gels were subjected to automated DNA sequencing analysis.

RESULTS

Eleven significant RET mutations were detected in affected families. Eight index cases received initial thyroidectomy for established MTC (plus 2 advised). In the family members screened, 3 prophylactic thyroidectomies (2 with early MTC) were performed and a further 2 recommended. An exon 10 C620W missense mutation (the "Janus" gene) was detected in a patient with Hirschsprung's disease plus 1 family member.

CONCLUSION

RET analysis of MEN has revolutionized the management of children of families with MEN2 and allowed surgical prediction and prophylaxis to take place. The presence of an exon 10 C620W mutation in association with Hirschsprung's disease was difficult to assess. We suggest possible guidelines for management of families with MTC and the role of genetic testing in their evaluation.

De novo multiple endocrine neoplasia type 2B with noncardiogenic pulmonary edema as the presenting symptom

Multiple endocrine neoplasia (MEN) type 2B is a rare hereditary disorder characterized by medullary thyroid carcinoma, pheochromocytoma, and neuroma. Early signs of MEN 2B are usually neuroma, gastrointestinal problems, and medullary thyroid carcinoma. Noncardiogenic pulmonary edema is rare as a presenting symptom. We report a 31-year-old male who was admitted to our hospital because of noncardiogenic pulmonary edema. He was 168 cm in height, weighed 55 kg, and had an arm span of 166 cm. No marfanoid habitus was evident, but thickened lips and tongue neuroma were present. Chronic constipation had been present since childhood, and the patient had a two-year history of untreated hypertension. Noncardiogenic pulmonary edema and toxic megacolon were noted, and abdominal computed tomography revealed bilateral adrenal tumors. Ultrasonography of the thyroid showed two mass lesions. Intubation and mechanical ventilation were performed because of severe hypoxemia. Endocrinological examinations showed high levels of serum and urinary fractionated catecholamines, serum calcitonin, serum carcinoembryonic antigen, and serum intact parathyroid hormone. It was suggested that the high level of catecholamine from pheochromocytoma had caused the pulmonary edema. RET gene analysis showed a codon 918 mutation in exon 16 resulting in an ATG (methionine) to ACG (threonine) substitution, but analysis of the patient's parents showed the wild type. Therefore, the patient was diagnosed as having de novo MEN 2B. He underwent laparoscopic bilateral adrenectomy and total thyroidectomy. However, the values of serum calcitonin and CEA did not decrease to the normal ranges. Patients with early-stage MEN 2B have distinct characteristics that can aid early detection of the disease, thus possibly allowing them to be saved.

RET as a diagnostic and therapeutic target in sporadic and hereditary endocrine tumors

The RET gene encodes a receptor tyrosine kinase that is expressed in neural crest-derived cell lineages. The RET receptor plays a crucial role in regulating cell proliferation, migration, differentiation, and survival through embryogenesis. Activating mutations in RET lead to the development of several inherited and noninherited diseases. Germline point mutations are found in the cancer syndromes multiple endocrine neoplasia (MEN) type 2, including MEN 2A and 2B, and familial medullary thyroid carcinoma. These syndromes are autosomal dominantly inherited. The identification of mutations associated with these syndromes has led to genetic testing to identify patients at risk for MEN 2 and familial medullary thyroid carcinoma and subsequent implementation of prophylactic thyroidectomy in mutation carriers. In addition, more than 10 somatic rearrangements of RET have been identified from papillary thyroid carcinomas. These mutations, as those found in MEN 2, induce oncogenic activation of the RET tyrosine kinase domain via different mechanisms, making RET an excellent candidate for the design of molecular targeted therapy. Recently, various kinds of therapeutic approaches, such as tyrosine kinase inhibition, gene therapy with dominant negative RET mutants, monoclonal antibodies against oncogene products, and nuclease-resistant aptamers that recognize and inhibit RET have been developed. The use of these strategies in preclinical models has provided evidence that RET is indeed a potential target for selective cancer therapy. However, a clinically useful therapeutic option for treating patients with RET-associated cancer is still not available.

An introduction to managing medullary thyroid cancer

MTC is a rare neuroendocrine thyroid tumour accounting for 3% to 10% of all thyroid malignancies. It can occur in a sporadic and a hereditary clinical setting. Hereditary MTC may either occur alone (familial MTC, FMTC) or as part of multiple endocrine neoplasia (MEN) type 2A, or MEN 2B. These disorders are due to germline mutations in the RET (REarranged during Transfection) gene. In carriers of MEN 2B-associated RET mutations, prophylactic thyroidectomy is indicated before the first year of life. In the case of MEN 2A-associated germline RET mutations with a high-risk profile, total thyroidectomy is warranted before the age of 2 years and certainly before the age of 4 years. At that age the risk of invasive MTC and metastases is acceptably low. Depending on the type of RET mutation, thyroidectomy can take place at an older age in patients with a lower risk profile. In case of elevated basal or stimulated serum calcitonin, preventive surgery including total thyroidectomy and central compartment dissection should be performed regardless of age. When MTC presents as a palpable tumour, total thyroidectomy should be combined with extensive lymph node dissection of levels II-V on both sides and level VI to prevent locoregional recurrences.

An association of multiple endocrine neoplasia 2B, a RET mutation; constipation; and low substance P-nerve fiber density in colonic circular muscle

BACKGROUND

Multiple endocrine neoplasia (MEN) 2B is a rare hereditary syndrome that results from an activating mutation of the RET proto-oncogene. The RET gene is involved in the development of the enteric nervous system. Patients with MEN 2B have enlarged enteric ganglia and may be affected by gastrointestinal dysmotility. A deficiency of the neurotransmitter substance P (SP) has been identified in both pediatric and adult patients with chronic constipation.

METHODS

Three patients, in whom constipation was the presenting symptom and MEN 2B had been provisionally diagnosed, underwent genetic analysis. Seromuscular colonic biopsies were taken for immunofluorescence imaging in all 3 patients. A retrospective review of the patient notes was undertaken.

RESULTS

All 3 patients had constipation refractory to conservative treatment. Genetic analyses in the 3 patients confirmed an identical RET mutation (Met918Thr). Immunofluorescence imaging in all 3 patients identified grossly enlarged myenteric plexus ganglia but surprisingly a low density of SP-labeled nerve fibers in the colonic circular muscle. Nitric oxide synthase and vasoactive intestinal peptide labeling were not reduced.

CONCLUSION

The results show an association between MEN 2B and its most common RET mutation, colonic dysmotility, and low density of SP in the colonic circular muscle. Larger numbers of patients need to be studied to investigate whether low SP is primarily associated with the constipation or RET mutation and if it is a common feature of MEN 2B.

Presymptomatic thyroidectomy in multiple endocrine neoplasia 2a

AIMS

To evaluate the value of prophylactic total thyroidectomy in multiple endocrine neoplasia 2a (MEN 2a), based on results of genetic testing, in a presymptomatic early stage of the disease.

METHODS

Fourteen presymptomatic patients genetically diagnosed and surgically treated at our centre. We analysed age, gender, location of the RET mutation, calcitonin tests, surgery, histologic findings, TNM classification, and postoperative follow-up.

RESULTS

The 14 patients belonged to two families with MTC (MEN 2a). Median age was 16 years. The RET mutation was located in codon 618 and 634. Basal calcitonin (CT) levels were normal in all patients. Twelve had pathologic peak CT measurements. Total thyroidectomy was performed in all and associated central neck dissection in 12 patients. Pathohistologic assessment showed C-cell hyperplasia in all specimens and 11 MTCs; the median size of the tumours was 0.2 cm; two patient had lymph-node metastases. According to TNM, three had stage 0, nine had stage I, one had stage II, and one had stage III disease. Postsurgery basal and peak CT values were normal in all but one patients, indicating a biochemical curative rate of 95%. Calcitonin determination did not distinguish between MTC and C-cell hyperplasia.

CONCLUSION

Prophylactic thyroidectomy based on genetic testing allows identification and treatment of patients at an early stage of the disease. Pathologic peak CT values are markers for the presence of microscopic MTC and should be considered in selecting operative procedures for these patients.

Multiple endocrine neoplasia: paediatric perspective

Neuroendocrine tumours constitute a heterogeneous association of neoplasms, originated from a common precursor cell population. They include endocrine glands, such as the pituitary, the parathyroids, the cells of the neuroendocrine adrenals, endocrine islets within glandular tissue (thyroid, pancreas) and dispersed cells (diffuse endocrine system). Neuroendocrine tumours can occur sporadically or in a familial context, such as multiple endocrine neoplasia (MEN) syndromes. These are inherited autosomal dominant cancer syndromes, transmitted with 100% penetrance. They are categorized into MEN type 1 and type 2. The dream of each physician who treats cancer is to develop a strategy that will have a significantly favourable impact on morbidity and mortality associated with malignant tumours. This has been achieved as a result of improved screening and early treatment strategies in MEN. MEN 2 and medullary thyroid carcinoma (MTC) are of special relevance in childhood, because they require urgent and early diagnosis and treatment. The explication of the genetic basis of MTC has revolutionised management of the familial forms of this tumour.