Clinical screening as compared with DNA analysis in families with multiple endocrine neoplasia type 2A

Unusual case of multiple endocrine neoplasia type 2A syndrome without medullary thyroid carcinoma

OBJECTIVE

To present an unusual case of multiple endocrine neoplasia type 2A (MEN 2A) syndrome and to describe how this case differs from the typical clinical features and usual genetic variations seen in classic MEN 2A syndrome.

METHODS

We describe the work-up, diagnosis, and treatment course of a patient who presented with multi-focal pheochromocytomas, parathyroid adenoma, thyroid abnormalities, and a RET mutation.

RESULTS

A 65-year-old man with previously treated pheochromocytoma presented with a parathyroid adenoma, multiple thyroid nodules, and a RET polymorphism. C-cell hyperplasia (CCH) or medullary thyroid carcinoma (MTC) occurs with nearly 100% penetrance in patients with MEN 2A syndrome. Our patient did not have CCH or frank MTC, but he expressed the other manifestations of the MEN 2A syndrome.

CONCLUSION

MEN 2A syndrome is characterized by the occurrence of MTC, pheochromocytomas, and parathyroid hyperplasia or adenomas. It is inherited in an autosomal dominant fashion, and more than 80% of patients with MEN 2A have a specific substitution on codon 634 of the RET proto-oncogene. Despite the nearly 100% penetrance of MTC or CCH in patients with MEN 2A, our patient did not have this. Additionally, he exhibited a RET mutation that is uncommonly seen in classic MEN 2A syndrome. Our patient may have a MEN 2A variant or a pseudo-MEN 2A syndrome.

Do the recent American Thyroid Association (ATA) Guidelines accurately guide the timing of prophylactic thyroidectomy in MEN2A?

BACKGROUND

In 2009, the American Thyroid Association (ATA) published consensus guidelines for timing of prophylactic thyroidectomy (PrThy) for treatment of hereditary medullary thyroid cancer (MTC). The aim of this study was to assess whether the clinical guidelines outlined in the ATA recommendations added to the specific mutation risk level could predict the presence of MTC on final pathology.

METHODS

A retrospective study was performed of patients undergoing PrThy. We evaluated mutation-based risk levels in combination with 2009 ATA guidelines for resection.

RESULTS

Overall, 54 patients underwent PrThy between 1972 and 2009. The median age at PrThy was 11.5 years (range, 2-68). Only 4 patients (8%) underwent PrThy prior to age 5 years. Most patients with MTC (16/22, 73%) had a level C mutation, and the youngest age of MTC in a level C mutation carrier was 5 years. The youngest age of MTC in level A or B carriers was 15 years. The single factor that predicted an overall decreased risk of MTC at the time of PrThy was meeting all ATA mutation-based postponement guidelines for surgical intervention (P = .04).

CONCLUSION

ATA guidelines that includes risk assessment of RET mutation are important in predicting the presence of MTC in patients who are candidates for prophylactic thyroidectomy and in determining the timing of operative resection.

Prophylactic thyroidectomy in multiple endocrine neoplasia type 2

Medullary thyroid carcinoma (MTC) is the main component of the autosomal dominant cancer syndrome multiple endocrine neoplasia type 2 (MEN 2). MEN 2 is caused by autosomal dominant gain-of-function mutations in the RET proto-oncogene. In RET-mutation carriers, an age-related progression has been documented from normal C-cells to premalignant C-cell hyperplasia and finally to MTC with or without cervical lymph node metastases. The time required for this neoplastic development as well as penetrance and aggressiveness of disease mainly depends on the specific RET mutation with a strong genotype-phenotype correlation. Recommendations for the timing of prophylactic thyroidectomy are based upon a model that utilizes these genotype-phenotype correlations to stratify mutations into four risk levels. The excellent prognosis for MTC diagnosed at its earliest stage underscores the importance of early diagnosis by RET-mutation analysis for hereditary MTC.

Personalized medicine: marking a new epoch in cancer patient management

Personalized medicine (PM) is defined as "a form of medicine that uses information about a person's genes, proteins, and environment to prevent, diagnose, and treat disease." The promise of PM has been on us for years. The suite of clinical applications of PM in cancer is broad, encompassing screening, diagnosis, prognosis, prediction of treatment efficacy, patient follow-up after surgery for early detection of recurrence, and the stratification of patients into cancer subgroup categories, allowing for individualized therapy. PM aims to eliminate the "one size fits all" model of medicine, which has centered on reaction to disease based on average responses to care. By dividing patients into unique cancer subgroups, treatment and follow-up can be tailored for each individual according to disease aggressiveness and the ability to respond to a certain treatment. PM is also shifting the emphasis of patient management from primary patient care to prevention and early intervention for high-risk individuals. In addition to classic single molecular markers, high-throughput approaches can be used for PM including whole genome sequencing, single-nucleotide polymorphism analysis, microarray analysis, and mass spectrometry. A common trend among these tools is their ability to analyze many targets simultaneously, thus increasing the sensitivity, specificity, and accuracy of biomarker discovery. Certain challenges need to be addressed in our transition to PM including assessment of cost, test standardization, and ethical issues. It is clear that PM will gradually continue to be incorporated into cancer patient management and will have a significant impact on our health care in the future.

Decreasing tumor size of thyroid cancer in Germany: institutional experience 1995-2009

OBJECTIVE

Decreasing tumor size in a population over time is widely interpreted as a measure of effectiveness of cancer screening programs. Nonetheless, thyroid cancer size is rarely analyzed as a function of time. This study aimed to explore secular trends of thyroid cancer diameter in Germany.

DESIGN

Retrospective analysis of 1644 thyroid cancer patients from a large referral center for thyroid cancer (1995-2009).

METHODS

Calculation of largest tumor diameters for each type of cancer as a function of time periods and birth cohorts.

RESULTS

Over the past 25 years, subdivided into 5-year periods by year of thyroidectomy (1985-1989; 1990-1994; 1995-1999; 2000-2004; 2005-2009), tumor diameters diminished from 25 to 16 mm (P=0.025) for medullary thyroid cancer and from 28 to 18 mm (P=0.017) for papillary thyroid cancer. This reduction was greater for hereditary medullary thyroid cancer (from 27 to 11 mm; P=0.088) than sporadic medullary thyroid cancer (from 23 to 19 mm; P=0.11). No decline was observed for follicular thyroid cancer (means of 45 to 42 mm; P=0.52). From the first (1921-1940) to the most recent birth cohort (1981-2000), tumor size fell from 22 to 10 mm (P<0.001) for medullary thyroid cancer, from 24 to 22 mm (P<0.001) for papillary thyroid cancer, and from 49 to 38 mm (P=0.011) for follicular thyroid cancer. The reduction of medullary thyroid cancers affected exclusively patients with hereditary disease (from 20 to 7 mm; P<0.001).

CONCLUSION

The consistency and robustness of these data signify powerful secular trends toward smaller papillary, follicular, and medullary thyroid cancers. The causes and consequences of these trends warrant further investigation.

Factors predicting outcome of total thyroidectomy in young patients with multiple endocrine neoplasia type 2: a nationwide long-term follow-up study

Background

Multiple endocrine neoplasia type 2 (MEN 2) is caused by a RET mutation in chromosome 10. All MEN 2 patients develop medullary thyroid carcinoma (MTC). The age-related risk of MTC is associated with the type of RET mutation. Our aim was to identify prognostic factors associated with recurrent MTC in MEN 2 patients.

Methods

In a nationwide case–control study, all patients who underwent total thyroidectomy in the Netherlands under the age of 20 years were classified into standard (1), high (2), or very high risk (3) for MTC based on RET-mutation type. Disease-free patients were compared with those with recurrent disease.

Results

A total of 93 patients were included in the study. Sixty-six percent had MTC on histology, the youngest being 1 year old. Codon 634 was most affected. Sixteen (18%) patients had persistent or recurrent disease, one of whom died. Significantly associated determinants of outcome in univariate analysis were higher age at surgery, no age-appropriate prophylactic surgery according to risk level, elevated preoperative calcitonin levels, affected codon, and the presence of lymph node metastases at surgery. On multivariate analysis only age of surgery was the single independent factor associated with persistent disease.

Conclusions

Prophylactic thyroidectomy beyond the recommended age is associated with persistent/recurrent disease. In addition, codon 634 mutation is associated with a high risk of recurrence requiring early surgery for all these patients.

Medullary thyroid cancer: RET testing of an archival material

Medullary thyroid carcinoma (MTC) might be sporadic (75%) or hereditary (25%). Until the mid nineties the diagnosis of hereditary MTC was based on family history, clinical evaluation, histological detection of C-cell hyperplasia and tumor multifocality. Patients and families with hereditary MTC might be missed? Today mutation analysis of the RET proto-oncogene is routinely performed on DNA. Departments of pathology often store tissue specimens from performed surgical procedures. The purpose of this study was to examine if analysis of DNA extracted from formalin fixed archival tissue might be a possible method to identify not previously known cases of hereditary MTC. In 23 cases, tissue analysis was performed, and in 2 patients (9%) a mutation was identified, but in both cases the most likely explanation was contamination with tumor tissue. The ability to detect RET mutations was confirmed by testing of non-tumor tissue from patients with known hereditary MTC. This study shows that genetic testing of archival MTC material is technically possible and might be a way of identifying patients with previously not recognized hereditary MTC.

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.

Multiple endocrine neoplasia type 2 RET protooncogene database: repository of MEN2-associated RET sequence variation and reference for genotype/phenotype correlations

Multiple endocrine neoplasia type 2 (MEN2) is an inherited, autosomal-dominant disorder caused by deleterious mutations within the RET protooncogene. MEN2 RET mutations are mainly heterozygous, missense sequence changes found in RET exons 10, 11, and 13-16. Our group has developed the publicly available, searchable MEN2 RET database to aid in genotype/phenotype correlations, using Human Genome Variation Society recommendations for sequence variation nomenclature and database content. The MEN2 RET database catalogs all RET sequence variation relevant to the MEN2 syndromes, with associated clinical information. Each database entry lists a RET sequence variation's location within the RET gene, genotype, pathogenicity classification, MEN2 phenotype, first literature reference, and comments (which may contain information on other clinical features, complex genotypes, and additional literature references). The MEN2 phenotype definitions were derived from the International RET Mutation Consortium guidelines for classification of MEN2 disease phenotypes. Although nearly all of the 132 RET sequence variation entries initially cataloged in the database were from literature reports, novel sequence variation and updated phenotypic information for any existing database entry can be submitted electronically on the database website. The database website also contains links to selected MEN2 literature reviews, gene and protein information, and RET reference sequences. The MEN2 RET database (www.arup.utah.edu/database/MEN2/MEN2_welcome.php) will serve as a repository for MEN2-associated RET sequence variation and reference for RET genotype/MEN2 phenotype correlations.

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.

Tenascin C in medullary thyroid microcarcinoma and C-cell hyperplasia

Tenascin C (Tn-C) is an extracellular matrix glycoprotein that is expressed early in carcinogenesis including intraepithelial neoplastic lesions of different organs. In this study, we analyze whether stroma reaction seen by Tn-C expression is detected early in tumorigenesis of medullary thyroid carcinoma (MTC) including medullary microcarcinoma and C-cell hyperplasia (CCH), which is accepted to be a precursor lesion of MTC in the setting of RET oncogene germ-line mutation. Tn-C was expressed in the stroma of all medullary microcarcinoma and in the stroma next to CCH. Stromal Tn-C expression was significantly more often seen in CCH with concomitant MTC than in isolated CCH of hereditary as well as nonhereditary cases (p = 0.001 and p = 0.016, respectively). We conclude that Tn-C expression and thus early stroma remodeling is seen in medullary microcarcinoma and CCH. Stromal Tn-C expression seems to be an indicator of a further step in carcinogenesis of MTC irrespective of a RET oncogene germ-line mutation.

[Hereditary thyroid cancer]

Hereditary thyroid carcinomas are present in about 5% of differentiated (DTC) and 25% of medullary thyroid carcinomas (MTC). They are part of a multiorgan tumour syndrome (e. g. FAP Gardner's syndrome with DTC and MEN 2 syndrome with MTC) or confined to the thyroid gland. Hereditary thyroid carcinomas typically show multifocal growth and occur in young patients. Due to germ cell mutations as the underlying cause of disease, partial thyroidectomies that may be justified in early sporadic carcinomas are not indicated in this type of tumours. In the case of hereditary DTC, the genetic basis of the disease has been demonstrated only in syndromatic tumour variants. In most nonsyndromatic cases, specific genetic alterations have not yet been identified. In both types of hereditary DTC, prophylactic thyroidectomy is not warranted due to the favourable prognosis of tumours that do not differ from sporadic ones. Point mutations of the RET proto-oncogene have been known for 15 years to be the genetic basis of hereditary MTC. Recently several new mutations were discovered; however, final conclusions regarding their clinical significance are not possible at present. Basically it has been shown that the clinical aggressivity of tumour development follows a genotype-phenotype correlation (risk groups 1-3). However, in mutations of all risk classes there exists a wide spectrum of different stages of hereditary C-cell disease in individual risk groups. Regarding time and extent of prophylactic thyroidectomy (without or with lymph node dissection) a combined molecular-biochemical concept including the use of pentagastrin-stimulated calcitonin values is therefore recommended.

[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.

Multiple endocrine neoplasia syndromes

The multiple endocrine neoplasia (MEN) syndromes are rare autosomal-dominant conditions that predispose affected individuals to benign and malignant tumors of the pituitary, thyroid, parathyroids, adrenals, endocrine pancreas, paraganglia, or nonendocrine organs. The classic MEN syndromes include MEN type 1 and MEN type 2. However, several other hereditary conditions should also be considered in the category of MEN: von Hippel-Lindau syndrome, the familial paraganglioma syndromes, Cowden syndrome, Carney complex, and hyperparathyroidism jaw-tumor syndrome. In addition, researchers are becoming aware of other familial endocrine neoplasia syndromes with an unknown genetic basis that might also fall into the category of MEN. This article reviews the clinical features, diagnosis, and surgical management of the various MEN syndromes and genetic risk assessment for patients presenting with one or more endocrine neoplasms.

Normal perioperative serum calcitonin levels in patients with advanced medullary thyroid carcinoma: case report and review of the literature

CONTEXT

Medullary thyroid carcinoma (MTC), a tumor of the parafollicular C cells of the gland, comprises 3-5% of all malignant thyroid neoplasms. Calcitonin, a polypeptidic hormone secreted by the neoplastic cells, is considered a very sensitive and specific MTC tumor marker. Patients with MTC usually present elevated serum calcitonin levels, which correlate with tumor burden and prognosis.

OBJECTIVES

To describe a case of advanced MTC with normal serum calcitonin and review the literature on this subject.

DESIGN

A case study was performed.

INTERVENTION

There were no interventions.

PATIENTS

A case of advanced MTC with normal serum calcitonin was studied.

RESULTS

Serum calcitonin was measured by two distinct assays, a chemiluminescent immunometric and an in-house two-site monoclonal antibody-based immunofluorometric assay. To rule out a "hook effect," or posttranslational modifications of calcitonin molecule, serum dilutions and tumor immunohistochemistry for calcitonin with the same antibodies used for serum calcitonin measurements were performed. Serum calcitonin levels were within the normal range in both assays, whereas the tumor stained strongly positive for calcitonin. These findings suggest that the tumor was able to produce but not to secrete the calcitonin protein. Five other cases of advanced MTC with normal serum calcitonin levels had been previously reported.

CONCLUSIONS

We present an unusual case of advanced MTC with normal serum calcitonin levels. Awareness of MTC cases presenting with normal serum calcitonin levels is important in clinical practice and is particularly relevant to centers that use this test for screening.

Genodermatoses with malignant potential

PURPOSE OF REVIEW

The delineation of syndromes carrying a predisposition to malignancy has led to great insights into the molecular biology of malignancy. Many such syndromes have cutaneous findings which can precede the development of neoplasia. Early recognition of the cutaneous stigmata of the genodermatoses with malignant potential can lead to early diagnosis and initiation of proper screening and treatment when indicated.

RECENT FINDINGS

This article reviews 'classic' genodermatoses with malignant potential and highlights recent recommendations for screening and treatment. Additionally more recently delineated syndromes and their cutaneous findings are discussed.

SUMMARY

Certain inherited syndromes with a risk of neoplasia exhibit characteristic cutaneous findings. Recognition of these findings by the astute practitioner can lead to early intervention which can impact the course of these rare diseases.

Genotype-phenotype based surgical concept of hereditary medullary thyroid carcinoma

BACKGROUND

Since DNA tests have enabled reliable identification of asymptomatic RET (rearranged during transfection) gene carriers, myriads of publications have appeared on genotype-phenotype relationships. A comprehensive appraisal of this body of evidence using evidence-based methodology is pending.

METHODS

This study was based on systematic evaluation of the literature using evidence-based criteria.

RESULTS

(1) There is a distinct age-related progression of hereditary medullary thyroid carcinoma (MTC) in carriers of RET mutations (grade C). (2) Among the high-risk RET mutations, those in codon 634 cause higher penetrance rates of the multiple endocrine neoplasia 2A phenotype (MTC, pheochromocytoma, and parathyroid hyperplasia/adenoma) than mutations in codons 609, 611, 618, and 620, irrespective of the amino acid substituting for cysteine (grade C). (3) DNA-based screening is superior to calcitonin-based screening in asymptomatic RET carriers (grade C). (4) Using a worst-case scenario, i.e., considering the earliest finding of MTC in asymptomatic RET carriers, pre-emptive thyroidectomy should be performed before that time (grade C) to be truly prophylactic. Specifically, for carriers of highest-risk mutations (codon 918): within the first year of life; for carriers of high-risk mutations (codon 609, 611, 618, 620, 630, and 634): before the age of 5 years; and for carriers of least-high risk mutations (codon 768, 790, 791, 804, and 891): before the age of 5-10 years. Strict adherence to these grade C recommendations can result in undertreatment of the former (codon 634) and overtreatment of the latter.

CONCLUSIONS

These genotype-phenotype correlations provide a solid foundation on which to base surgical concepts, leaving little room for randomized controlled clinical trials.

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.

Medullary thyroid carcinoma--update and present management controversies

INTRODUCTION

Medullary thyroid carcinoma (MTC) is a rare thyroid malignancy arising from the parafollicular C cells. It accounts for 5-10% of thyroid malignancies and occurs in sporadic and hereditary forms. There are still many controversial aspects relating to the diagnosis and management of this unusual tumour in its various forms. The present article addresses the more important of these issues.

METHODS

A literature review was performed using Pubmed database combined with additional original papers obtained from citations in those articles identified in the original literature search. Only those articles which related specifically to the controversial issues addressed in this review were included.

RESULTS

Genetically determined tumours constitute approximately 25% of MTC and have special clinical interest because of their association with other endocrinopathies including phaeochromocytoma and hyperparathyroidism in the multiple endocrine neoplasia syndromes (MEN IIa and MEN IIb). Familial medullary thyroid carcinoma (FMTC) is a rare form not associated with any other endocrinopathies. The genetic basis for these familial tumours derives from a series of missense germline mutations in the RET protooncogene. Genetic testing by DNA analysis facilitates identification of family members at risk who can now be offered early 'prophylactic thyroidectomy' with an increased prospect of surgical success and long-term survival. MTC is a tumour which does not take up radioactive iodine, is relatively radioresistant and poorly responsive to chemotherapy. Therefore, surgery is the only treatment which can offer the prospect of cure. Total thyroidectomy with central and lateral nodal dissection can achieve biochemical cure (normocalcitonaemia) in more than 80% of cases. Compartmental orientated microdissection of cervical nodes has significantly improved the results of primary surgery but even so a group of 20% of patients will prove to have recurrent or residual disease. These cases require detailed investigation by a variety of techniques including ultrasound, cross-sectional imaging, nuclear imaging and laparoscopy with liver biopsy to exclude disseminated disease and select those patients who can be offered a prospect of cure by further neck surgery. Such an approach may be associated with successful normalisation of calcitonin levels in about 40%.

CONCLUSIONS

It is hoped that in the near future new medical therapies may become available to treat MTC which still has a 10-year survival of only 60-80% in spite of the application of meticulous surgical techniques.

Mutation analysis of the RET proto-oncogene and early thyroidectomy: results of a Portuguese cancer centre

BACKGROUND

Evidence that germline mutations in the RET proto-oncogene are the underlying cause of the familial form of medullary thyroid carcinoma (MTC) made it possible to identify gene carriers with a very high degree of accuracy. Aiming to define the mutational profile observed in our patients and to assess gene carriers' compliance with an early surgery, we reviewed results of molecular analysis of RET performed at our institution since 1994.

METHODS

One hundred fifty-eight individuals were screened for germline mutations of the RET proto-oncogene. Seventy-seven patients had apparently sporadic MTC; 8 patients had both MTC and pheochromocytoma or MTC and clinical features of multiple endocrine neoplasia type 2B despite a negative family history; 8 patients were known to belong to affected kindreds; and 65 individuals were at-risk individuals to develop MTC.

RESULTS

A germline mutation in RET was identified in 4% of apparently sporadic MTC patients, in 100% of patients with MTC and pheochromocytoma or MTC and clinical features of multiple endocrine neoplasia type 2B, and in 100% of probands of clinically established kindreds. The most affected codon was 634 (58%) followed by codon 804 (16%). Among at-risk individuals, 49% were identified as gene carriers. Seven individuals were submitted to prophylactic thyroidectomy (mean age, 17.7 +/- 12.5 years; range: 3-42 years), and all but 1 had MTC.

CONCLUSIONS

RET mutational spectrum observed in the present population disclosed a higher frequency of codon 804 mutations than expected. Compliance with an early prophylactic surgery seemed to be influenced not only by medical advice and cultural factors but also by the aggressiveness of disease in gene carriers' families.

ASCO/SSO review of current role of risk-reducing surgery in common hereditary cancer syndromes

BACKGROUND

A significant portion of cancers are accounted for by a heritable component, which has increasingly been linked to mutations in specific genes. Clinical interventions have been formulated for mutation carriers within affected families. The primary interventions for mutation carriers of highly penetrant syndromes are surgical.

METHODS

The American Society of Clinical Oncology and the Society of Surgical Oncology formed a task force charged with presenting an educational symposium on surgical management of hereditary cancer syndromes at annual society meetings, and this resulted in a position paper on this topic. The content of both the symposium and the position paper was developed as a consensus statement.

RESULTS

This article addresses hereditary breast, colorectal, ovarian/endometrial, and multiple endocrine neoplasias. A brief introduction on the genetics and natural history of each disease is provided, followed by detailed descriptions of modern surgical approaches, clinical and genetic indications, timing of prophylactic surgery, and the efficacy of surgery (when known). Although several recent reviews have addressed the role of genetic testing for cancer susceptibility, this article focuses on the issues surrounding surgical technique, timing, and indications for surgical prophylaxis.

CONCLUSIONS

Risk-reducing surgical treatment of hereditary cancer is a complex undertaking. It requires a clear understanding of the natural history of the disease, realistic appreciation of the potential benefits and risks of these procedures in potentially otherwise healthy individuals, and the long-term sequelae of such interventions, as well as the individual patient's and family's perceptions of surgical risk and anticipated benefit.

Multiple endocrine neoplasia type 2

Multiple Endocrine Neoplasia Type 2 (MEN2) is a rare hereditary complex disorder characterized by the presence of medullary thyroid carcinoma (MTC), unilateral or bilateral pheochromocytoma (PHEO) and other hyperplasia and/or neoplasia of different endocrine tissues within a single patient. MEN2 has been reported in approximately 500 to 1000 families worldwide and the prevalence has been estimated at approximately 1:30,000. Two different forms, sporadic and familial, have been described for MEN2. Sporadic form is represented by a case with two of the principal MEN2-related endocrine tumors. The familial form, which is more frequent and with an autosomal pattern of inheritance, consists of a MEN2 case with at least one first degree relative showing one of the characteristic endocrine tumors. Familial medullary thyroid carcinoma (FMTC) is a subtype of MEN2 in which the affected individuals develop only medullary thyroid carcinoma, without other clinical manifestations of MEN2. Predisposition to MEN2 is caused by germline activating mutations of the c-RET proto-oncogene on chromosome 10q11.2. The RET gene encodes a single-pass transmembrane tyrosine kinase that is the receptor for glial-derived neurotrophic growth factors. The combination of clinical and genetic investigations, together with the improved understanding of the molecular and clinical genetics of the syndrome, helps the diagnosis and treatment of patients. Currently, DNA testing makes possible the early detection of asymptomatic gene carriers, allowing to identify and treat the neoplastic lesions at an earlier stage. In particular, the identification of a strong genotype-phenotype correlation in MEN2 syndrome may enable a more individualized treatment for the patients, improving their quality of life. At present, surgical treatment offers the only chance of cure and therefore, early clinical and genetic detection and prophylactic surgery in subjects at risk are the main therapeutic goal.

ASCO/SSO review of current role of risk-reducing surgery in common hereditary cancer syndromes

Although the etiology of solid cancers is multifactorial, with environmental and genetic factors playing a variable role, a significant portion of the burden of cancer is accounted for by a heritable component. Increasingly, the heritable component of cancer predispositions has been linked to mutations in specific genes, and clinical interventions have been formulated for mutation carriers within affected families. The primary interventions for mutations carriers for highly penetrant syndromes such as multiple endocrine neoplasias, familial adenomatous polyposis, hereditary nonpolyposis colon cancer, and hereditary breast and ovarian cancer syndromes are primarily surgical. For that reason, the American Society of Clinical Oncology (ASCO) and the Society of Surgical Oncology (SSO) have undertaken an educational effort within the oncology community. A joint ASCO/SSO Task Force was charged with presenting an educational symposium on the surgical management of hereditary cancer syndromes at the annual ASCO and SSO meetings, resulting in an educational position article on this topic. Both the content of the symposium and the article were developed as a consensus statement by the Task Force, with the intent of summarizing the current standard of care. This article is divided into four sections addressing breast, colorectal, ovarian and endometrial cancers, and multiple endocrine neoplasia. For each, a brief introduction on the genetics and natural history of the disease is provided, followed by a detailed description of modern surgical approaches, including a description of the clinical and genetic indications and timing of prophylactic surgery, and the efficacy of prophylactic surgery when known. Although a number of recent reviews have addressed the role of genetic testing for cancer susceptibility, including the richly illustrated Cancer Genetics and Cancer Predisposition Testing curriculum by the ASCO Cancer Genetics Working Group (available through http://www.asco.org), this article focuses on the issues surrounding the why, how, and when of surgical prophylaxis for inherited forms of cancer. This is a complex process, which requires a clear understanding of the natural history of the disease and variance of penetrance, a realistic appreciation of the potential benefit and risk of a risk-reducing procedure in a potentially otherwise healthy individual, the long-term sequelae of such surgical intervention, as well as the individual patient and family's perception of surgical risk and anticipated benefit.

Disparities between male and female patients with thyroid cancers: sex difference or gender divide?

OBJECTIVE

This investigation was undertaken to quantify histopathological disparities between male and female patients with sporadic and hereditary thyroid cancers, which may reflect a biological 'sex difference' or a behavioural 'gender divide'.

DESIGN

Retrospective cohort analysis (November 1994-January 2006).

PATIENTS

1298 Consecutive surgical patients with sporadic papillary (n = 587), sporadic follicular (n = 232), sporadic medullary (n = 320), and hereditary medullary thyroid cancers (n = 159) from a tertiary referral centre.

MEASUREMENTS

Age at diagnosis of cancer, primary tumour diameter, frequency of extrathyroidal extension, lymph node and distant metastases, and cancer subtypes.

RESULTS

Primary diameters of sporadic tumour entities (papillary, 26.0 vs. 19.3 mm; follicular, 54.9 vs. 35.1 mm; and medullary, 27.9 vs. 20.8 mm), but not hereditary medullary cancers, were significantly (P

CONCLUSIONS

Our data emphasize the need for earlier diagnosis and intervention in male patients to ensure that male sex will cease sometime to constitute an ominous prognostic marker of advanced thyroid cancer.

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MESH Headings

• Adenocarcinoma, Papillary/pathology
• Adenocarcinoma, Papillary/surgery
• Adult
• Analysis of Variance
• Biopsy, Needle
• Carcinoma, Medullary/genetics
• Carcinoma, Medullary/pathology
• Carcinoma, Medullary/surgery
• Carcinoma, Papillary, Follicular/pathology
• Carcinoma, Papillary, Follicular/surgery
• Cross-Sectional Studies
• Female
• Humans
• Lymphatic Metastasis
• Male
• Middle Aged
• Neoplasm Invasiveness
• Neoplasm Recurrence, Local/pathology
• Neoplasm Recurrence, Local/surgery
• Neoplasm Staging
• Retrospective Studies
• Sex Factors
• Thyroid Neoplasms/pathology
• Thyroid Neoplasms/surgery
• Thyroidectomy

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Affiliation(s)

Andreas Machens Departments of General, Visceral and Vascular Surgery, Martin Luther University Halle-Wittenberg, Halle, Saale, Germany.
Steffen Hauptmann
Henning Dralle

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Video-assisted central compartment lymphadenectomy in a patient with a positive RET oncogene: initial experience

BACKGROUND

Prophylactic surgery for patients carrying a positive RET proto-oncogene proved to be highly effective in curing those likely to experience the development of a medullary carcinoma. Video-assisted procedures have been proved feasible for central compartment dissection.

METHODS

A total of 15 patients (7 men and 8 women) with a positive RET proto-oncogene underwent total thyroidectomy and central compartment lymphadenectomy via a video-assisted approach. The mean age of the patients was 32.5 years. The echographically estimated mean volume was 10.3 ml, and the mean diameter of the main nodule was 8.8 mm. Preoperative ultrasound showed an absence of lateral neck lymph node involvement in all cases. No drain was used. Direct laryngoscopy was performed in all cases 1 month after surgery.

RESULTS

The mean operative time was 67.3 min. A transient hypoparathyroidism occurred in one patient, and a permanent hypoparathyroidism occurred in another patient. No laryngeal nerve palsy was present. All the patients were discharged on postoperative day 1. Histology showed a medullary carcinoma in 10 patients and diffuse C-cell hyperplasia in 5 patients. The mean number of lymph nodes removed was 5.1. None of these nodes proved to be metastatic. Calcitonin levels were undetectable in all six patients who had a follow-up period longer than 1 year.

CONCLUSION

Video-assisted central compartment lymphadenectomy was proved to be effective and safe. The procedure demonstrated a complication rate comparable with that for the conventional procedure, a better cosmetic outcome, and less postoperative pain. Although the video-assisted access proved to be a valid option for the treatment of patients carrying a positive RET proto-oncogene, a greater number of cases with a longer follow-up period is necessary to estimate the impact of the video-assisted approach on central neck lymphadenectomy.

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.

Medullary Thyroid Cancer

The goal in managing patients who have MTC is to detect and surgically remove disease at an early stage. Tumor marker-based biochemical screening and DNA-based genetic screening have created the opportunity for effective prophylactic surgery in patients at risk for hereditary MTC. Complete surgical resection is critical for cure because cervical reoperation for persistent or recurrent disease benefits only select patients. With the advent of therapies that target the RET-activated pathways, new hope may be emerging for patients who have locally advanced or metastatic disease.

Isolated intestinal ganglioneuromatosis with a new mutation of RET proto-oncogene

A 13-year-old boy with a history of juvenile polyps of the colon was subsequently found to have isolated intestinal ganglioneuromatosis without any other features characteristic of multiple endocrine neoplasia (MEN) 2B. Screening for MEN 2B revealed a polymorphism of the RET proto-oncogene at codon 691 with a glycine to serine conversion. This mutation has not been described before in association with ganglioneuromatosis and MEN 2B. The phenotype and presentation are compared with those of previous case reports.

NEW ERA: PROPHYLACTIC SURGERY FOR PATIENTS WITH MULTIPLE ENDOCRINE NEOPLASIA-2A

BACKGROUND

The surgical management of patients with multiple endocrine neoplasia-2A (MEN-2A) continues to evolve with specific genotype-phenotype correlations allowing for a more tailored approach. In this study, we report the surgical management of one of the largest MEN-2A families with a rearranged during transfection (RET) codon 804 mutation.

METHOD

This is a cohort study comprising all at-risk kindred within a single known MEN-2A family. Prophylactic total thyroidectomy with lymph node dissection was recommended to all mutation carriers aged 5 years and older.

RESULTS

There were a total of 48 at-risk individuals in the MEN-2A kindred, with 22 patients undergoing thyroidectomy after appropriate preoperative evaluation. A total of 9 patients had medullary thyroid cancer including 5 with a normal preoperative calcitonin level. A total of 11 patients had C-cell hyperplasia and 7 showed histological evidence of parathyroid disease. Only the index case had a phaeochromocytoma.

CONCLUSIONS

Genetic testing for germline mutations in the RET proto-oncogene has allowed precise identification of affected RET carriers and provided the opportunity for prophylactic or 'preclinical' surgery to treat and in fact to prevent medullary thyroid cancer. This concept of prophylactic surgery based on a genetic test is likely to be applied more widely as the tools of molecular biology advance.

Phenotypic multiple endocrine neoplasia type 2B, without endocrinopathy or RET gene mutation: implications for management

The multiple endocrine neoplasia (MEN) type 2B is an autosomal dominant condition characterized by aggressive medullary C-cell tumors, pheochromocytoma, and a discrete physical appearance (marfanoid habitus, prominent corneal nerve fibers, thick lips, and mucosal and intestinal neuromas). A specific point mutation in the RET proto-oncogene is present in 95% cases. Occasionally cases present with the characteristic physical appearance of MEN 2B but no identifiable germline mutation or endocrinopathy, and it has been suggested that these patients may represent a discrete subgroup termed pure mucosal neuroma syndrome (MNS). We present a patient with MNS, who had a thyroidectomy at age 14.5 years with normal thyroid histology. Direct sequencing of all 20 exons of the RET gene showed no mutation. This case supports the suggestion that pure MNS can exist in the absence of an identifiable RET gene mutation. We suggest that prophylactic thyroidectomy is unnecessary in these patients although they should still be screened for endocrinopathy on a regular basis.

Isthmus-Preserving Total Bilobectomy: An Adequate Operation for C-Cell Hyperplasia

BACKGROUND

Autopsy studies show that C cells deriving from the ultimobranchial body and migrating into the thyroid do not reach the isthmus region and are distributed along the vertical axes of thyroid lobes. This was confirmed in a surgical series of 58 patients (34 with preoperatively normal and 24 with elevated serum calcitonin) where no calcitonin-positive cells were demonstrable immunohistochemically within separately investigated isthmi. Consequently, isthmus-preserving total bilateral lobectomy (IPTB) may be regarded as an adequate surgical procedure for C-cell hyperplasia (CCH).

PATIENTS AND METHODS

IPTB was performed from October 2001 to December 2004 in 64 patients, 59 patients with nodular goiter and slightly to moderately elevated serum calcitonin (stimulated under 500 pg/ml) (group A, apparently sporadic cases) and in 5 patients undergoing prophylactic surgery for hereditary medullary thyroid carcinoma (MTC) with intermediate- or low-risk RET mutations (non-634) (group B). The surgical procedure focused on meticulous total extracapsular resection of both thyroid lobes, preservation of an isthmus remnant of about 3 ml (smaller in children), and histologic workup of the border zones of resection in addition to that of the completely removed lobes. When malignancy could be proven intraoperatively (7 patients) or when the isthmus turned out to contain nodular lesions (4 patients), completion total thyroidectomy (plus lymphadenectomy) was performed as a one-stage procedure. Second-stage total thyroidectomy was performed in 3 cases. Thus, IPTB was the definitive surgical procedure in 50 patients (45 of group A and all 5 of group B).

RESULTS

In all of the 50 definite IPTB cases, postoperative serum calcitonin was below the measurable limit (2 pg/ml); stimulated calcitonin was below the measurable limit in 47 (including all of group B) and was measurable in 3 sporadic cases in a lower-normal range between 2.4 and 3.5 pg/ml. Genetic screening of the apparently sporadic cases with CCH was positive in one (codon 791). The risk of recurrent laryngeal nerve paralysis seems not to be elevated (0% permanent); permanent hypocalcemia occurred in 1 patient (2%). Follow-up data of 37 patients, median 18 (6-36) months, showed continuously nonmeasurable serum calcitonin with one exception, where it was in the normal range after 18 months. All IPTB patients are still under substitution therapy with L-thyroxine (median 125 mug/day) with decreasing tendency in all 3 children after prophylactic operation, the latter also showing an increasing volume of well-vascularized isthmi (from 1.5 to 2.5 ml).

CONCLUSION

IPTB reliably removes all C cells. There may not be need for total thyroidectomy (TTx) in cases with CCH. When necessary, completion TTx can be performed easily without additional risk. IPTB leaves a functionally relevant remnant, corresponding to that of a subtotal resection. This might be of importance especially for prophylactic surgery in children where the isthmus can compensate for the loss of thyroid function with time.

Multiple endocrine neoplasia type 2 and the RET protooncogene: from bedside to bench to bedside

Although the initial characterization of the various MEN-2 associated phenotypes (familial medullary thyroid cancer, multiple endocrine neoplasia 2A and 2B) evolved at the bedside, it was at the bench where the underlying RET (REarranged during Transfection) germline mutations were identified. Molecular information has revolutionized our understanding and continues to transform the clinical management of this fascinating endocrine tumor syndrome of neural crest derivation, which consists of medullary thyroid cancer, pheochromocytoma, and parathyroid hyperplasia/adenoma. DNA-based identification of RET carriers did not require comprehension of the gene, but was a prerequisite for clarifying gene function and devising biologic compounds blocking RET phosphorylation. With the continuing expansion of our knowledge about the underlying molecular mechanisms and our growing therapeutic abilities, multiple endocrine neoplasia type 2 is gradually returning home to the bedside, closing the loop from bedside to bench to bedside.

Prophylaktische Chirurgie der Schilddrüse

Early diagnosis for thyroid carcinoma, potentially before neoplastic transformation has taken place, would allow preventive and thus curative surgical intervention. Identifying and characterizing the RET proto-oncogene as the disease-causing gene for hereditary medullary thyroid carcinoma and then establishing a genotype-phenotype correlation served as the prerequisite for the risk-adapted prophylactic surgical approach practised today. Carriers of RET mutations associated with very aggressive tumour behaviour should be subjected to prophylactic thyroidectomy within the 1st year of life. For individuals harbouring less virulent types of mutations, prophylactic intervention is recommended at 5-20 years. Although genetic research on hereditary nonmedullary thyroid cancer is still in progress, initial results indicate the need of prophylactic surgical treatment also for this subgroup of thyroid neoplasia.

Experience of prophylactic thyroidectomy in multiple endocrine neoplasia type 2A kindreds with RET codon 804 mutations

OBJECTIVE AND DESIGN

Genetic screening in multiple endocrine neoplasia type 2 (MEN 2) has led to specific management guidelines based on genotype-phenotype analysis. However, there is controversy regarding the appropriate age for prophylactic thyroidectomy in families with mutations in codon 804 in exon 14 of the RET proto-oncogene, where medullary thyroid cancer (MTC) may not develop until adulthood. We prospectively studied two MEN 2A families, one with the V804L and the other with the V804M RET mutation, to report our experience of genetic and biochemical screening and prophylactic thyroidectomy. Family 1 is one of the largest MEN 2A families in the literature, where 22 prophylactic thyroidectomies have been performed.

PATIENTS AND RESULTS

C-cell hyperplasia (CCH) was found in 23 out of 25 thyroidectomy specimens from family members of ages 5 years and upwards. MTC was found in 10 out of 18 adults of age 25 years upwards, including the family 2 proband, who was found to have MTC with lymph node metastases at age 28. Phaeochromocytoma was only observed in one patient, but six cases of histologically confirmed hyperparathyroidism were seen in family 1.

CONCLUSION

We suggest that prophylactic thyroidectomy should not be delayed until adulthood in MEN 2A families carrying codon 804 RET mutations, but should be performed when there is CCH, before the development of MTC, as close as possible to age 6 years, which is the age of the youngest reported case of MTC in '804' families.