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

Neoplasia endócrina múltipla tipo 2

O termo neoplasia endócrina múltipla tipo 2 (NEM 2) foi sugerido em 1968, por Steiner e cols., para diferenciar a síndrome clínica caracterizada pela presença de carcinoma medular de tireóide (CMT), feocromocitoma e hiperparatireoidismo, então denominada síndrome de Sipple, da síndrome de Wermer ou NEM tipo 1, que acomete as glândulas paratireóides, pâncreas e hipófise. Sizemore e cols. (1974) complementaram a diferenciação através da classificação da NEM 2 em 2 subgupos: pacientes com CMT, feocromocitoma, hiperparatireoidismo e aparência normal (NEM 2A) e pacientes sem acometimento das paratireóides e fenótipo caracterizado por ganglioneuromatose intestinal e hábitos marfanóides (NEM 2B). CMT é usualmente o primeiro tumor a ser diagnosticado. O diagnóstico do CMT determina que seja avaliada a extensão da doença e rastreamento do feocromocitoma e hiperparatireoidismo. O diagnóstico de CMT esporádico ou hereditário é realizado através da análise molecular do proto-oncogene RET. Neste artigo são discutidos os aspectos fisiopatológicos, as anormalidades genéticas e os aspectos clínicos da NEM 2. A abordagem diagnóstica e terapêutica nos indivíduos afetados, carreadores assintomáticos e familiares em risco também são discutidos. Os avanços relacionados ao rastreamento genético e intervenção precoce permitiram uma melhoria no prognóstico a longo prazo. No entanto, ainda não dispomos de tratamento eficaz para doença metastática.

Lessons from genes mutated in multiple endocrine neoplasia (MEN) syndromes

Multiple endocrine neoplasia (MEN) types 1 and 2 syndromes are rare hereditary cancer syndromes expressing a variety of endocrine and non-endocrine neoplasias and lesions. The improving of both molecular and clinical genetics knowledge helps health care providers in the whole spectrum of the clinical managements of MEN patients. The MEN1 gene, a tumour suppressor gene, is responsible of MEN1 syndrome, and is probably involved in the regulation of several cell functions, including DNA replication and repair and transcriptional machinery. RET proto-oncogene encodes for a receptor tyrosine kinase protein whose expression is fundamental for appropriate migration, development and differentiation of neuroendocrine cells originating from neural crest. Currently, DNA testing makes possible the early identification of germline mutation in asymptomatic mutant gene carriers in both MEN syndromes. Consequently, the combination of new genetic and diagnostic tools could permit a precocious detection of MEN-associated neoplasms, and in particular the identification of a strong genotype-phenotype correlations in MEN2 syndrome demonstrates an improving outcome and quality of life for affected subjects.

Nine novel germline gene variants in the RET proto-oncogene identified in twelve unrelated cases

We report nine novel DNA alterations in the RET proto-oncogene in 12 unrelated cases identified by DNA sequencing of exons 10 and 11 of the gene. The novel variants K666E, IVS9-11G-->A, D631V in cis with H665Q, D631E (with C634Y), E623K (in trans with C618S), 616delGAG (in trans with C609Y), Y606C, C630R, and R635-T636insELCR;T636P were detected in patients with various clinical presentations ranging from thyroid goiter, medullary thyroid carcinoma, and pheochromocytoma to classic multiple endocrine neoplasia type 2A. When novel DNA alterations are found, extended family studies can be helpful in determining the clinical significance of such findings. Segregation within families suggests that K666E and T636insELCR;T636P are likely to be disease-causing mutations. However, the mechanism by which they affect the normal activity of the RET receptor is unclear. Absence of segregation with disease was observed for E623K and 616delGAG. For the remainder of the DNA alterations, family studies were not possible, and the clinical significance of these novel variants needs further assessment. Additional case reports, animal models, and/or functional studies are needed to determine the clinical significance of these newly identified variants.

RET proto-oncogene: a review and update of genotype-phenotype correlations in hereditary medullary thyroid cancer and associated endocrine tumors

Hereditary medullary thyroid carcinoma (MTC) is caused by autosomal dominant gain-of-function mutations in the RET proto-oncogene. Associations between specific RET mutations (genotype) and the aggressiveness of MTC and presence or absence of other endocrine neoplasms (phenotype) are well documented. Mutations in six exons (10, 11, 13, 14, 15, and 16) located in either cysteine-rich or tyrosine kinase domains cause one of three distinctive clinical subtypes: familial MTC, multiple endocrine neoplasia (MEN) type 2A (including variants with Hirschsprung's disease and cutaneous lichen amyloidosis), and MEN 2B. Hallmarks of MEN 2A include MTC, pheochromocytoma, and hyperparathyroidism. MEN 2B is associated with an earlier onset of MTC and pheochromocytoma, the absence of hyperparathyroidism, and the presence of striking physical stigmata (e.g., coarse facies, ganglioneuromatosis, and marfanoid habitus). Familial MTC is not associated with other endocrine neoplasms; however, the accurate distinction between familial MTC and MEN 2A may be difficult in kindreds with small size, incomplete histories, or a predominance of young individuals who may not have yet fully manifested the syndrome. Genetic testing detects greater than 95% of mutation carriers and is considered the standard of care for all first-degree relatives of patients with newly diagnosed MTC. Recommendations on the timing of prophylactic thyroidectomy and the extent of surgery are based upon a model that utilizes genotype- phenotype correlations to stratify mutations into three risk levels.

Familial medullary thyroid cancer: clinical aspects and prognosis

OBJECTIVE

To assess clinical features and long-term results of treatment of familial medullary thyroid carcinoma (FMTC).

DESIGN

Retrospective analysis of all patients with familial forms of MTC diagnosed between 1949-2000 and treated in our unit.

RESULTS

Fifty five patients (25 males, 30 females) were identified with at least two first-degree relatives affected by medullary thyroid cancer; 26 were classified as MEN 2A, 1 as MEN 2B and 28 as FMTC. Median age at diagnosis was 35 years (MEN 2A), 25 (MEN 2B) and 47.5 (FMTC). Median follow-up was 9 years (range: 4-24). Total or near-total thyroidectomy was performed in all patients and 11 received adjuvant external beam radiotherapy. Cause specific survival was 89% at 10 years and 77% at 20 years for MEN patients, 51% and 32% for those with sporadic MTC, and 46% and 26% for those with FMTC. In multivariate analysis, factors predicting survival were presence of metastases, nodal status and age at diagnosis.

CONCLUSIONS

Improved survival rates associated with familial types of MTC can be accounted for by the earlier stage at which disease is detected and the younger age at presentation. These observations emphasize the need for early detection in those at risk.

Medullary thyroid carcinoma: including MEN 2A and MEN 2B syndromes

Medullary thyroid carcinoma (MTC) is a rare malignancy with several distinctive features that distinguish its management from other thyroid cancers. First, MTC may be sporadic (75% of cases), or may occur as a manifestation of the hereditary syndrome Multiple Endocrine Neoplasia type 2 (MEN 2) (25% of cases). Additionally, while MTC is more difficult to cure than differentiated thyroid cancer and has higher rates of recurrence and mortality, it is usually a slow growing tumor compared with other malignancies. Finally, unlike differentiated thyroid cancer, there is no known effective systemic therapy for MTC. MTC cells do not concentrate radioactive iodine, and MTC does not respond well to external beam radiation or conventional cytotoxic chemotherapy. These distinguishing features should be considered in planning surgical management of MTC.

Inherited medullary thyroid cancer and the duty to warn: revisiting Pate v. Threlkel in light of HIPAA

Familial medullary thyroid cancer (FMTC) is one of the few autosomal dominant cancers for which genetic testing provides a clear medical indication for prophylactic and/or curative therapy, and for which prophylactic thyroidectomy, followed by thyroid hormone replacement, presents a relatively low morbidity risk. Medullary thyroid cancer (MTC) is a particularly aggressive type of thyroid cancer, and screening by traditional biochemical markers yields a high proportion of advanced stage diagnoses in individuals from FMTC families. This is particularly hazardous since there are no curative systemic treatments for MTC. Genetic testing for germline mutations of the RET proto-oncogene provides a reliable method of identifying at-risk family members in those FMTC families in which a mutation has been identified in the proband. Prophylactic thyroidectomy in such at-risk family members has significantly reduced the proportion of advanced stage MTC diagnoses in MTC families. Since a clear medical benefit exists for genetic testing in family members, and a clear danger to family members exists in the absence of genetic counseling, establishing genetic diagnosis as standard of care has critical legal and ethical implications for medical providers caring for probands and family members. The "duty to warn," reinforced by the courts in the legal case of Pate v. Threlkel, may override recent confidentiality legislation, known as the HIPAA Privacy Rules, which came into effect April 12, 2003.

Counselling in multiple endocrine neoplasia syndromes: from individual experience to general guidelines

Counselling of patients and closely related family members has to take a central place in management of hereditary diseases, like multiple endocrine neoplasia (MEN) syndromes including von Hippel-Lindau (VHL) disease. In the strategy of health care, preventive medicine such as periodic clinical examination of families at-risk needs a high priority, because in general it is assumed that continuity in attendance is cost-effective. Counselling has to be based on individual medical experience of the doctor, adjusted to common guidelines and the findings in the family. Information leaflets, appropriate outpatient departments and an extensive network of specialists will facilitate continuity in care. Flow diagrams involving practical guidelines for diagnosis, treatment and follow up need to be applicable and after adjustment, should be accepted generally. Specially trained paramedics for counselling are required as a network that will guarantee periodic clinical examination and secure optimal prevention. Such paramedics will coordinate nationwide multidisciplinary guidance, and organize preventive and emergency cure for these patients. They will be supervised by expert clinicians in the field, and collaborate with specialists for social and psychological issues, patient organizations and clinical genetic centres. All of these professionals are responsible together for providing patients with up to date clinical information (via newsletters, Internet, etc.). Recently, in the Netherlands, a project was initiated to guarantee continuity in care and study the delivery of care. In order to realize this plan, funding has to be provided in the current research programme. In a future system support has to be obtained on a continuous base, preferably by the government and health care insurers and supervised by the national institute for health care.

Advances in the management of hereditary medullary thyroid cancer

This work draws on recent advances during the era of codon-oriented prophylactic surgery for hereditary medullary thyroid cancer (MTC). Milestones included identification of RET (REarranged during Transfection) as the susceptibility gene, introduction of prophylactic surgery on evidence of a RET germline mutation, revelation of genotype-phenotype correlations within the MEN 2 spectrum and demonstration of age-related progression of MTC. Novel surgical techniques, notably systemic microdissection and compartment-oriented surgery, have greatly enhanced surgical cure. Uncovering molecular pathways from RET genotype to MEN 2 phenotype should provide treatment options for RET mutation carriers whose MTC currently is too advanced for cure.

Timing and extent of surgery in patients with familial medullary thyroid carcinoma/multiple endocrine neoplasia 2A-related RET mutations not affecting codon 634

In hereditary medullary thyroid carcinoma (MTC), recommendations regarding timing and extent of surgery are mainly based on the data of patients with the codon 634 RET mutation, which is the most often affected codon. Little is known about whether these recommendations may also be applied to patients with less common RET mutations. We ascertained the data from 140 patients with FMTC/MEN2A-related RET mutation not affecting codon 634 who have been treated at three specialized centers. The several RET mutations found affected codons 611 (n = 17), 618 (n = 22), 620 (n = 17), 768 (n = 9), 790 (n = 24), 791 (n = 21), 804 (n = 23), and 891 (n = 7). For each codon, the age of the youngest patient with MTC only (41, 7, 18, 29, 13, 47, 20, and 15 years, respectively), MTC with lymph node metastases (46, 24, 21, 34, 46, 47, 50, and 76 years, respectively), and MTC with distant metastases (52, 69, 43, 68, 57, - , - , and 75 years, respectively) was determined. All patients with lymph node metastases had elevated basal calcitonin levels. Based on these data, a more individual recommendation regarding timing and extent of surgery can be given. Because neither gender nor the type of nucleotide substitution for a specific codon appeared to have a significant influence on the age of onset, this recommendation should be based on the affected codon, the age of the patient, and the calcitonin level. Recurrent laryngeal nerve palsy (n = 6) and hypoparathyroidism (n = 3) were rather rare and were found only in patients older than 30 and 43 years, respectively, giving evidence that surgery in young patients can be performed safely.

Inherited predisposition to cancer: a historical overview

The hereditary predisposition to cancer dates historically to interest piqued by physicians as well as family members wherein striking phenotypic features were shown to cluster in families, inclusive of the rather grotesque cutaneous findings in von Recklinghausen's neurofibromatosis, which date back to the sixteenth century. The search for the role of primary genetic factors was heralded by studies at the infrahuman level, particularly on laboratory mouse strains with strong susceptibility to carcinogen-induced cancer, and conversely, with resistance to the same carcinogens. These studies, developed in the 19th and 20th centuries, continue today. This article traces the historical aspects of hereditary cancer dealing with identification and ultimate molecular genetic confirmation of commonly occurring cancers, particularly of the colon in the case of familial adenomatous polyposis and its attenuated form, both due to the APC germline mutation; the Lynch syndrome due to mutations in mismatch repair genes, the most common of which were found to be MSH2, MLH1, and MSH6 germline mutations; the hereditary breast-ovarian cancer syndrome with BRCA1 and BRCA2 germline mutations; the Li-Fraumeni (SBLA) syndrome due to the p53 mutation; and the familial atypical multiple mole melanoma in association with pancreatic cancer due to the CDKN2A (p16) germline mutation. These and other hereditary cancer syndromes have been discussed in some detail relevant to their characterization, which, for many conditions, took place in the late 18th century and, in the more modern molecular genetic era, during the past two decades. Emphasis has been placed upon the manner in which improved cancer control will emanate from these discoveries.

Cost analysis of DNA-based testing in a large Canadian family with multiple endocrine neoplasia type 2

One of the major goals of genetic testing is the reduction of morbidity and mortality. Given the appropriate circumstances, this can result in reduction in health care costs. Such savings can be demonstrated most effectively in large families with mutations in well characterized, dominantly acting genes. In our large family, a point mutation TGC>CGC in exon 10 of the RET proto-oncogene, which results in a missense mutation (Cys620Arg), was identified in two individuals. The proband has medullary thyroid carcinoma (MTC), as did her deceased mother. One son has MTC and Hirschsprung's disease. The proband's mother had nine siblings; the proband has three siblings, another son, and 69 maternal cousins. Genetic testing has been performed on the closest relatives and has identified four individuals with, and 54 individuals without, a familial RET mutation. Significant cost savings have been realized in both genetic testing and clinical surveillance. In this family, for every at-risk individual identified as a true-negative, the minimum yearly savings in clinical surveillance is 508 dollars per person. As demonstrated by this case, economic costs of genetic diagnostics should take into account the potential saved monies in tests, both molecular and clinical.

Diagnosis and management of medullary thyroid carcinoma

Successful treatment of MTC depends heavily on early diagnosis and treatment. Often, this is not possible for sporadic MTC; however, genetic testing for hereditary MTC makes this possible if genetic carriers have surgery before C cells undergo malignant transformation. All patients who have MTC should be tested for RET mutations, including putative sporadic cases. The leukocytes of suspected carriers and sporadic MTC cases should be tested for MEN2-associated germ-line mutations by polymerase chain reaction amplification of the appropriate RET gene exons, including 10, 11,13, 14, 15, and 16 (see Table I). When a RET mutation is found, all first-degree relatives must be screened to determine which individuals carry the gene. If these exons are negative, the other 15 should be sequenced because a small risk of hereditary MTC remains if no germ-line mutation is found. The probability that a first-degree relative will inherit an autosomal dominant gene for MTC from an individual who has sporadic MTC in whom no germ-line mutation is found is 0.18% . Patients who have MEN2B or RET codon 883 or 918 mutation should have a total thyroidectomy within the first 6 months of life, preferably within the first month of life. Patients who have 634 mutations, which account for approximately 70% of all MTC mutations, should undergo thyroidectomy by age 5 years. The recommendations for the timing of prophylactic thyroidectomy are not consistent for the less common mutations (see Table 2). There is a balance between performing prophylactic thyroidectomy earlier than at the youngest age at with MTC has been reported to occur for a specific RET mutation (see Fig. 3 and Table 2) and the complications of thyroidectomy, including permanent hypoparathyroidism and laryngeal nerve damage. Preoperative measurement of plasma free metanephrine and neck ultrasonography always should be done if the diagnosis of MTC is known preoperatively. Initial treatment of MTC is total thyroidectomy, regardless of its genetic type or putative sporadic nature, because surgery offers the only chance for a cure. Treatment with 1311 has no place in the management of MTC. Plasma CT measurements provide an accurate estimate of tumor burden and are especially useful in identifying patients who have residual tumor. Pentagastrin- or calcium-stimulated plasma CT testing is useful in identifying CCH or early MTC in carriers of RET mutations that are associated with late onset MTC. Pheochromocytoma may occur before or after MTC and is an important cause of mortality, even in young patients. HPT is an important aspect of MEN2A and requires surgery according to current guidelines for the management of primary HPT. Early thyroidectomy and appropriate management of pheochromocytoma clearly have modified the course of this disease, but more research is necessary in kindreds who have rare MTC mutations. Moreover, new treatments for widespread MTC are necessary because current chemotherapy agents offer little benefit. New drugs that lock the action of tyrosine kinase offer some hope.

Expression Profiles Provide Insights into Early Malignant Potential and Skeletal Abnormalities in Multiple Endocrine Neoplasia Type 2B Syndrome Tumors

Identifying the molecular basis for genotype-phenotype correlations in human diseases has direct implications for understanding the disease process and hence for the identification of potential therapeutic targets. To this end, we performed microarray expression analysis on benign (pheochromocytomas) and malignant (medullary thyroid carcinomas, MTCs) tumors from patients with multiple endocrine neoplasia (MEN) type 2A or 2B, related syndromes that result from distinctive mutations in the RET receptor tyrosine kinase. Comparisons of MEN 2B and MEN 2A MTCs revealed that genes involved in the process of epithelial to mesenchymal transition, many associated with the tumor growth factor beta pathway, were up-regulated in MEN 2B MTCs. This MEN 2B MTC profile may explain the early onset of malignancy in MEN 2B compared with MEN 2A patients. Furthermore, chondromodulin-1, a known regulator of cartilage and bone growth, was expressed at high levels specifically in MEN 2B MTCs. Chondromodulin-1 mRNA and protein expression was localized to the malignant C cells, and its high expression was directly associated with the presence of skeletal abnormalities in MEN 2B patients. These findings provide molecular evidence that associate the previously unexplained skeletal abnormalities and early malignancy in MEN 2B compared with MEN 2A syndrome.

Video assisted prophylactic thyroidectomy and central compartment nodes clearance in two RET gene mutation adult carriers

Activating point mutations of RET gene have been demonstrated to be causative of the familial form of medullary thyroid cancer (MTC), both isolated (FMTC) and associated to other endocrine neoplasia [multiple endocrine neoplasia (MEN) 2A and 2B]. In RET gene mutation carriers, who are prone to developing MTC, prophylactic thyroidectomy is recommended to obtain their definitive cure. The simultaneous excision of the central node compartment is mandatory when the stimulation pentagastrin test for serum calcitonin is positive. Although the minimally invasive video assisted thyroidectomy (MIVAT) is nowadays currently adopted in many centers, it has never been employed for the prophylactic thyroidectomy of RET gene mutation carriers. The fear of obtaining an incomplete lymphadenectomy of the central compartment was the main reason for this reluctance. Since RET gene mutation carriers have often normal thyroid volume and, if involved, small lymph nodes, they indeed represent the best candidates to this approach especially when considering that they are usually young and concerned about the cosmetic results and the period of hospitalization. The excellent results obtained by MIVAT in the last few years induced us to propose this procedure together with a central compartment lymphadenectomy to 2 RET gene mutation carriers recently found by genetic screening. As assessed by a negative pentagastrin stimulation test performed after 6 months from the MIVAT, they were definitively cured without any surgical complication with the exception of a transient hypoparathyroidism. They showed a great satisfaction for both the cosmetic results and the very short period of hospitalization, thus supporting the idea that MIVAT can be used in association with the central node dissection for the prophylactic treatment of RET mutation gene carriers whose thyroid volume is still normal.

Phenotypic expression of a family with multiple endocrine neoplasia type 2A due to a RET mutation at codon 618

Background

Multiple endocrine neoplasia type 2A (MEN2A) is caused by missense mutations in the RET proto-oncogene on chromosome 10. This paper reports the phenotypic expression of a family with MEN2A, in which serine substitutes for cysteine at codon 618 in exon 10 of the RET gene. It was first claimed that medullary thyroid cancer (MTC) with this rare mutation led to mild disease; this has recently been updated to intermediate–high risk, based on stratified genetic information.

Methods

The family was mapped over six generations. In 1971 family members were invited to join a screening programme. Genetic testing was started in 1994.

Results

Twenty-two individuals with MTC were identified, 16 by the screening programme. One screened patient had a phaeochromocytoma and four had hyperparathyroidism. At surgery for MTC 12 patients had local tumour metastases and two young patients also had liver metastases. No screened patient died from MTC during a mean observation time of 19 years. Six other family members were diagnosed with MTC by signs and symptoms, five of whom died from MTC.

Conclusion

Because of the great interindividual differences in tumour aggressiveness within the family it is impossible to predict whether an individual gene carrier will have an aggressive MTC or not. This unpredictability is an additional argument, besides those obtained in stratified genetic studies, for operating on gene carriers at young age.

Carcinoma medular de tireóide: aspectos moleculares, clínico-oncológicos e terapêuticos

O carcinoma medular de tireóide (CMT) pode ocorrer na forma esporádica ou familiar. O CMT hereditário é parte das síndromes de neoplasia endócrina múltipla (NEM) 2A e 2B, carcinoma medular de tireóide familiar (CMTF) ou outras formas. Mutações de linhagem germinativa do proto-oncogene RET causam a forma hereditária da neoplasia e os testes genéticos atualmente disponíveis formam a base para o manejo adequado da hereditariedade do tumor, visto que o diagnóstico precoce melhora significativamente o prognóstico no indivíduo afetado e nos carreadores. Nos últimos anos, vários estudos têm demonstrado uma correlação entre mutações codon-específica do RET e os diferentes fenótipos da NEM 2A, que pode, em parte, ser explicada por diferenças na intensidade da indução da dimerização do receptor. No presente artigo, revisamos os avanços nos mecanismos moleculares, diagnóstico e tratamento, bem como relatamos a nossa experiência no manejo dessa forma rara de neoplasia tireoidiana.

Ret Germline Mutation In Codon 791 In A Family Representing 3 Generations From Age 5 To Age 70 Years: Should Thyroidectomy Be Performed?

OBJECTIVE

To describe a kindred with a rare RET germline mutation in codon 791 and discuss potential management strategies.

METHODS

We present clinical and biochemical data as well as results of mutation analysis in our study subjects and provide an overview of related published reports.

RESULTS

Multiple endocrine neoplasia type 2 (MEN 2) is a familial cancer syndrome characterized by the development of medullary thyroid carcinoma (MTC), pheochromocytoma, and parathyroid hyperplasia or adenoma. Germline mutations in RET are responsible for this autosomal dominant syndrome. Familial MTC is a variant of MEN 2A and can be caused by RET mutations in codon 791. Deaths from gene carriers with mutations in these codons have not yet been reported. In general, gene carriers with these RET mutations have late-onset MTC. Because only a few kindreds with this specific mutation have been identified and no long-term follow-up data are available, management of these patients can be a challenge. We illustrate the difficulties with decisions about not only when to perform thyroidectomy in these patients but also whether thyroidectomy should even be considered in such gene carriers with a benign course. Our reported kindred included four carriers with a codon 791 RET germline mutation, one of whom had the rare concomitant occurrence of acromegaly and MEN 2A. The 70-year-old mother had acromegaly and hyperparathyroidism but normal serum calcitonin levels and normal findings on thyroid ultrasound examination. She refused pentagastrin testing and any surgical intervention. The 37-year-old daughter had hypothyroidism, a small thyroid gland, and negative results of pentagastrin stimulation testing of calcitonin. The 18-year-old grandson also had a negative pentagastrin test result and normal thyroid ultrasound findings. The 5-year-old granddaughter had normal results of thyroid ultrasonography. In all patients, we recommended thyroidectomy.

CONCLUSION

Prospective studies are needed to clarify which patients with codon 791 RET germline mutation should undergo thyroidectomy.

The pathology of preclinical medullary thyroid carcinoma

Medullary carcinoma of the thyroid (MTC) occurs sporadically, or in familial forms in familial medullary thyroid carcinoma and multiple endocrine neoplasia types 2A and 2B. In the familial forms it is associated with well-characterized, germline mutations in the RET protooncogene. The mutation sites differ in MEN2A and MEN2B, and MTC develops at an earlier age and is more aggressive in MEN2B. Screening of relatives of affected individuals for such mutations can identify those at risk of developing MTC and total thyroidectomy can be carried out in the first decade of life before the development of clinical disease. Analysis of such removed thyroid glands shows abnormalities of the parafollicular C-cells in almost all cases. The abnormalities range from C-cell hyperplasia, either diffuse or nodular, to microcarcinoma and occasionally frank MTC. The abnormalities are bilateral and affect the upper two thirds of the thyroid lobes. Microcarcinomas may be visible with the naked eye, but often they are identified only on microscopy. Histopathological examination of the entire gland is essential.

Early malignant progression of hereditary medullary thyroid cancer

BACKGROUND

An age-related progression from C-cell hyperplasia to medullary thyroid carcinoma is associated with various germ-line mutations in the rearranged during transfection (RET) proto-oncogene that could be used to identify the optimal time for prophylactic surgery.

METHODS

In this European multicenter study conducted from July 1993 to February 2001, we enrolled patients who had a RET point mutation in the germ line, were 20 years of age or younger, were asymptomatic, and had undergone total thyroidectomy after confirmation of the RET mutation. Exclusion criteria were medullary thyroid carcinomas of more than 10 mm in greatest dimension and distant metastasis.

RESULTS

Altogether, 207 patients from 145 families were identified. There was a significant age-related progression from C-cell hyperplasia to medullary thyroid carcinoma and, ultimately, nodal metastasis in patients whose RET mutations were grouped according to the extracellular- and intracellular-domain codons affected and in those with the codon 634 genotype. No lymph-node metastases were noted in patients younger than 14 years of age. The age-related penetrance was unaffected by the type of amino acid substitution encoded by the various codon 634 mutations. The codon-specific differences in the age at presentation of cancer and the familial rates of concomitant adrenal and parathyroid involvement suggest that the risk of progression was based on the transforming potential of the individual RET mutation.

CONCLUSIONS

These data provide initial guidelines for the timing of prophylactic thyroidectomy in asymptomatic carriers of RET gene mutations.

Oncogenes in thyroid cancer

There have been significant advances in our understanding of carcinogenesis at the molecular level over the last 25 years. Oncogenes are of major interest as part of our search for knowledge surrounding the aetiology of cancer. There are several oncogenes associated with thyroid cancer. Detailed investigation of the nature and function of these tumour genes has provided important insights into both the tumour biology and the complex biochemical pathways of normal cellular functioning. Our knowledge of oncogene biology offers the hope of better diagnostic, therapeutic and prognostic modalities in our fight against this and other common cancers. Development of specific thyroid tumour markers and gene therapy is now a realistic prospect to supplement our present armamentarium of surgery and radiotherapy. This review aims to outline the pertinent information gained so far from studies of these oncogenes and provides both clinical relevance and fuel for further interest amongst the ENT thyroid community in this exciting area of research.

Malignant progression from C-cell hyperplasia to medullary thyroid carcinoma in 167 carriers of RET germline mutations

BACKGROUND

Hereditary medullary thyroid carcinoma (MTC) is the most common and potentially life-shortening phenotypic manifestation of RET (rearranged during transfection) germline mutations. If a distinct time lag between the successive stages of malignant progression were identifiable, the information could be used to individualize prophylactic surgery. The study objective was to investigate the impact of RET genotype on disease progression from C-cell hyperplasia (CCH) to MTC.

METHODS

An institutional series of 167 (67 index, 100 nonindex) consecutive carriers of RET gene point mutations in exons 10, 11, 13, 14, or 16 who underwent total thyroidectomy between November 1994 and November 2002.

RESULTS

Regarding codons 618, 620, 634, 768, 790, and 804, patient age at diagnosis differed significantly depending on the type of pathology encountered (CCH, MTC without and with nodal metastasis). The variability in age, which may reflect the number of necessary somatic mutations, explained the pathological strata in 38% (codon 634) to 77% (codon 768) of patients. Conversely, 62% (codon 634) to 23% (codon 768) of variability in age at different pathological strata may have been determined by the RET genotype.

CONCLUSIONS

The pace of malignant progression of the RET genotype should be taken into account when considering prophylactic thyroidectomy in RET gene carriers.

Medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a neuroendocrine malignancy that occurs in hereditary (25%) and sporadic (75%) clinical settings. MTC is present in all patients with the multiple endocrine neoplasia type 2 syndromes. MTCs produce calcitonin, the measurement of which can indicate the presence of tumors in people who are at risk and the effectiveness of therapy in treated patients. Surgical cure is possible in young patients with multiple endocrine neoplasia type 2 who undergo preventative thyroidectomy (approximately 50% of patients who are diagnosed with a palpable thyroid mass) and in some patients with recurrent nodal metastatic disease in the neck. Mortality from MTC is caused by tumor invasion of the trachea, great vessels in the neck, or mediastinum or by the effects of distant metastatic disease. Surgery for cervical recurrence can prevent death from tracheal invasion. The role of radiation therapy is not well defined. There is no effective systemic therapy for MTC. Activating mutations in a tyrosine kinase receptor gene (RET) are present in most MTCs, and experience with tyrosine kinase inhibitors and other agents in clinical trials is critical for the identification of effective systemic treatment.

Management of hereditary thyroid cancer in children

Hereditary thyroid cancer in childhood occurs in the setting of Multiple Endocrine Neoplasia types 2A and 2B, and familial medullary thyroid carcinoma, FMTC. Prophylactic thyroidectomy in childhood has been recommended in patients found to have inherited mutations in the RET protooncogene, to prevent the development of medullary thyroid carcinoma. In this report are presented the clinical and genetic aspects of hereditary thyroid cancer in children, as well as surgical recommendations and medium-term outcome results.

Potential Absence of Prognostic Implications of Severe Preoperative Hypercalcitoninemia in Medullary Thyroid Carcinoma

OBJECTIVE

To evaluate preoperative hypercalcitonine-mia further as a marker of prognosis in patients with medullary thyroid carcinoma (MTC).

METHODS

We reviewed the clinical and laboratory data in six patients (four men and two women, 39 to 76 years old)--three with sporadic MTC, one with familial MTC, and two with multiple endocrine neoplasia type 2A--who had preoperative basal serum calcitonin levels of 400 to 16,000 pg/mL (normal, 0 to 19). Pentagastrin stimulation was performed in patients who had preoperative basal calcitonin levels less than 1,000 pg/mL, and responses ranged from 2,600 to 8,500 pg/mL. Thyroidectomy revealed intrathyroidal MTC in four patients; MTC and nodal metastatic lesions were present in two. The tumor cells were immunoreactive with anti-calcitonin immunoperoxidase staining.

RESULTS

Serum calcitonin and carcinoembryonic antigen levels were normal postoperatively. In serial postoperative evaluation during a follow-up period of 2 to 9 years, stimulated peak plasma calcitonin levels after pentagastrin or calcium infusion were normal (in five patients) or near normal (in one patient), without clinical evidence of recurrent disease. The two patients with nodal metastatic disease have had normal calcitonin levels during a mean duration of follow-up of approximately 3 years.

CONCLUSION

Pronounced preoperative hypercalci-toninemia does not necessarily preclude a favorable short-term outcome in patients with MTC.

Surgical treatment of medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a malignancy of the parafollicular C cells of the thyroid gland. It occurs sporadically or as part of the multiple endocrine neoplasia type 2 (MEN 2) syndromes. Patients who have inherited a mutation in the RET proto-oncogene should have thyroidectomy early in life to prevent formation and spread of this cancer. Most patients with sporadic disease present with a palpable neck mass. The diagnosis is made by fine needle aspiration biopsy and by measuring calcitonin levels in the blood. Primary treatment consists of surgical resection including a total thyroidectomy, central neck nodal dissection and functional lateral neck nodal dissections. Most patients with a palpable primary tumour have nodal disease present at the time of operation, and nodal involvement is often bilateral. Adequate resection of the primary tumour and cervical lymph nodes is important to optimize outcome and minimize the risk of recurrent disease. Proper handling of the parathyroid glands prevents hypoparathyroidism. Following primary surgical resection, more than half of the patients will have recurrent disease with persistent elevation of calcitonin levels. Currently, there is no adequate systemic therapy for treating recurrent disease. Surgical reoperation or conservative observation are the best available options. Diagnostic laparoscopy for liver evaluation is the most sensitive diagnostic test to detect the presence of distant metastases.

Solitary versus multiple carcinoid tumors of the ileum: a clinical and pathologic review of 68 cases

It is well known that small intestinal carcinoid tumors may occur as solitary or multiple lesions. However, the biologic significance of multiple carcinoid tumors has not been clearly defined. The purpose of this study was to compare the clinical and pathologic features and prognosis of patients with solitary versus multiple carcinoid tumors of the ileum. Sixty-eight patients, including 50 with solitary and 18 with multiple carcinoid tumors, were included in the study. Hematoxylin and eosin-stained slides from routinely processed tumor resection specimens of the ileum were evaluated for a variety of histologic features such as tumor size, depth of invasion, tumor stage, and venous, perineural, and lymphovascular invasion. Follow-up and clinical data, such as patient age, gender, presenting complaints, presence of synchronous or metachronous malignancies, and presence of the carcinoid syndrome, were obtained and the results were compared between the two patient groups. Fifty patients with solitary carcinoid tumors (male/female ratio, 27:23) and 18 patients with multiple tumors (male/female ratio, 7:11) were identified. Patients with multiple carcinoid tumors were significantly younger than patients with solitary tumors at the time of diagnosis (55 years vs 63 years, p = 0.006). There was a high association between multiple carcinoid tumors and the carcinoid syndrome (4 of 18 vs 1 of 50, p = 0.004) as compared with patients with solitary carcinoid tumors. There was also an association between tumor multiplicity and venous invasion, but this relationship was not statistically significant (p = 0.07). The follow-up period was similar for both groups (mean 36 months, median 26 months, range 1-139 months). A significantly higher proportion of patients with multiple carcinoid tumors were either alive with disease or died of disease (56%) compared with those with solitary carcinoid tumors (18%, p = 0.002), and this relationship persisted in multivariate analysis (p = 0.02). Overall, no significant differences were observed between these two patient groups with respect to other clinicopathologic features such as tumor size, depth of invasion, presence of distant metastases, lymphatic or perineural invasion, or presence of an associated malignancy (p >0.05). In conclusion, we found that patients with multiple carcinoid tumors are younger, have a significantly greater risk of developing the carcinoid syndrome, and have a poorer prognosis than patients with solitary tumors.

The importance of paternal family history in hereditary breast cancer is underappreciated by health care professionals

OBJECTIVES

Cancer genetics clinics have been established in many major oncology centers worldwide in recent years. For such specialized clinics to fulfill their function, primary care physicians need to identify high-risk patients for referral.

METHODS

We conducted a survey to evaluate the level of awareness of breast cancer risk factors and hereditary breast cancer among health care providers and patients.

RESULTS

284 health care professionals, 221 medical students, 104 breast cancer patients and 177 cancer-free women participated in the study. Less than half of the patients with breast cancer were aware of their risk for another breast cancer or of the increased breast cancer risk of their sisters and daughters. Less than one quarter of the health care professionals and medical students knew the importance of paternal family history in the evaluation for hereditary breast cancer. Only about half of the health care professionals and medical students and less than one third of the breast cancer patients and cancer-free women knew about genetic testing and prophylactic mastectomy as options for women at risk for hereditary breast cancer.

CONCLUSIONS

Health care providers and medical students lack basic genetic knowledge and are not aware of emerging diagnostic and preventive options for hereditary breast cancer. Inclusion of cancer genetics in the continuing medical education of health care providers is important to promote such awareness.

Review of multiple endocrine neoplasia type 2A in children: therapeutic results of early thyroidectomy and prognostic value of codon analysis

OBJECTIVES

The aim of this study was first to investigate whether early total thyroidectomy (ETT; 1-5 years of age) can prevent medullary thyroid carcinoma with persistent or recurrent disease (PRD) in pediatric patients with multiple endocrine neoplasia type 2A (MEN-2A) and second, to evaluate the strength of codon analysis in children with MEN-2A as prognostic parameter.

METHODS

Case reports and review of the literature for pediatric patients with MEN-2A were conducted. Inclusion criteria were age (0-20 years) and histologic degree of C-cell disease (normal = N, C-cell hyperplasia = CCH, medullary thyroid carcinoma = MTC, metastatic MTC = MMTC). To evaluate therapeutic results of ETT (1-5 years) versus late total thyroidectomy (LTT; 6-20 years), age-dependent histologic stages of C-cell disease and postoperative occurrence of PRD were compared. Prognostic value of specific codons, age-dependent histologic distribution, and long-term outcome were analyzed.

RESULTS

In a total of 260 cases, 42 (16%) underwent ETT, and 218 (84%) underwent LTT. Histologic analysis showed significant difference between ETT versus LTT (57% vs 76%) regarding malignant stage of C-cell disease (of combined rate of MTC and MMTC). Long-term outcome was documented in 74 patients (28%). During a median follow-up period of 2 years (range: 0-15 years), 21 of 65 of the LTT group versus 0 of 9 of the ETT group suffered PRD. Information about codon analysis was available in 150 patients (58%). Mutated codons were c634 (63%), c618 (19%), c620 (9%), and c804 (6%). Codon-related histologic analysis resulted in prognostic differences: 81% of patients with c634-mutation had MCT or MMTC in contrast to c804 (44%), c618 (34%), and c620 (7%). Fifteen of 17 MMTC and 7 of 9 PRD occurred in patients with c634-mutation.

CONCLUSIONS

1) ETT until 5 years of age in MEN-2A gene carriers results in significant reduction of MTC and MMTC in favor of CCH and improved disease-free long-term outcome. 2) Codon analysis is an important prognostic factor. Timing of TT could be individualized based on codon-specific prognosis. Until more detailed knowledge is available, consequent genetic and biochemical screening is mandatory for appropriate individual timing of ETT before age of 5 years.

Meta-analysis of indels causing human genetic disease: mechanisms of mutagenesis and the role of local DNA sequence complexity

A relatively rare type of mutation causing human genetic disease is the indel, a complex lesion that appears to represent a combination of micro-deletion and micro-insertion. In the absence of meta-analytical studies of indels, the mutational mechanisms underlying indel formation remain unclear. Data from the Human Gene Mutation Database (HGMD) were therefore used to compare and contrast 211 different indels underlying genetic disease in an attempt to deduce the processes responsible for their genesis. Each indel was treated as if it were the result of a two-step insertion/deletion process and was assessed in the context of 10 base-pairs DNA sequence flanking the lesion on either side. Several indel hotspots were noted and a GTAAGT motif was found to be significantly over-represented in the vicinity of the indels studied. Previously postulated mechanisms underlying micro-deletions and micro-insertions were initially explored in terms of local DNA sequence regularity as measured by its complexity. The change in complexity consequent to a mutation was found to be indicative of the type of repeat sequence involved in mediating the event, thereby providing clues as to the underlying mutational mechanism. Complexity analysis was then employed to examine the possible intermediates through which each indel could have occurred and to propose likely mechanisms and pathways for indel generation on an individual basis. Manual analysis served to confirm that the majority of indels (>90%) are explicable in terms of a two-step process involving established mutational mechanisms. Indels equivalent to double base-pair substitutions (22% of the total) were found to be mechanistically indistinguishable from the remainder and may therefore be regarded as a special type of indel. The observed correspondence between changes in local DNA sequence complexity and the involvement of specific mutational mechanisms in the insertion/deletion process, and the ability of generated models to account for both the number and identity of the bases deleted and/or inserted, makes this approach invaluable not only for the analysis of indel formation, but also for the study of other types of complex lesion.

RET proto-oncogene mutations affecting codon 790/791: A mild form of multiple endocrine neoplasia type 2A syndrome?

BACKGROUND

In patients with multiple endocrine neoplasia type 2A syndrome, prophylactic thyroidectomy is generally recommended at the age of 5 to 6 years. Whether this recommendation is justified for exon 13 mutations is unknown.

METHODS

We analyzed the clinical data from 40 patients harboring RET codon 790/791 mutations (exon 13) who had been treated in 4 specialized centers.

RESULTS

Mean age was 35.2 +/- 21.6 years (range, 5.1-69.0 years). Thirteen patients were index patients (mean age, 57.7 +/- 11.3 years), 27 patients were screening patients (mean age, 24.4 +/- 16.5 years). In the index group, pT-category was: T0, n = 2; T1, n = 6; T2, n = 2; T3, n = 1; and T4, n = 2. Lymph node metastases were found in 5 patients and distant metastases in 1 patient. Postoperatively, 69% of index patients were biochemically cured. In the screening group, pT-category was: T0, n = 19; T1, n = 7; and T2, n = 1. Lymph node metastases were found in 2 patients. Postoperatively, 93% of screening patients were biochemically cured. The youngest patient with medullary thyroid carcinoma was 13.8 years, the youngest patient with lymph node metastases was 46.4 years.

CONCLUSIONS

Patients with RET codon 790/791 mutations seemed to have a less aggressive clinical course compared with patients with classic multiple endocrine neoplasia type 2A syndrome. Still, index patients had a lower biochemic cure rate in comparison with screening patients. Timely total thyroidectomy including lymph node dissection is warranted.

Comparison of Two Provocative Tests for Calcitonin in Medullary Thyroid Carcinoma: Omeprazole vs Pentagastrin

Background: Provocative tests for calcitonin (CT) are fundamental in the diagnosis and follow-up of C-cell disease and in the detection of hereditary medullary thyroid carcinoma (MTC) carriers with unknown RET mutations. A recent report has proposed omeprazole, which can increase endogenous gastrin (GT), as a new provocative test for MTC.

Methods: We compared the omeprazole test (20 mg twice a day for 4 days) to the pentagastrin test (0.5 μg/kg of body weight) for the diagnosis and management of MTC. Twenty healthy individuals and 20 MTC patients with mildly or moderately increased basal CT serum concentrations underwent the pentagastrin and omeprazole tests.

Results: In MTC patients, the pentagastrin test produced a significantly higher increase in serum CT than did omeprazole. After the pentagastrin injection, several patients reported unpleasant side effects, including substantial tightness in 38 of 40 participants. No adverse effects were observed during the omeprazole test. A significant direct correlation was recorded between CT% (ratio of CT peak to basal value × 100) and GT% (ratio of GT peak to basal value × 100) during the omeprazole test in MTC patients (r = 0.73; P <0.001).

Conclusions: In spite of several adverse effects, pentagastrin remains the best provocative test for the diagnosis of MTC. Omeprazole may be useful when pentagastrin is contraindicated or refused because of the unpleasant side effects, but further validation is needed.

New therapeutic and surgical approaches for sporadic and hereditary pheochromocytoma

Pheochromocytoma is a rare, surgically correctable cause of hypertension. Modern medical blockade has significantly improved patient survival and morbidity. The last decade has seen the identification of the genes responsible for several hereditary causes of pheochromocytoma. Evaluation of these patients has demonstrated different catecholamine profiles associated with the different syndromes. Genetic testing and new, more sensitive catecholamine tests are allowing better, earlier diagnosis of affected patients. Some patients with small tumors deemed nonfunctional by traditional methods may be safely observed until function is demonstrated. Laparoscopic surgery has supplanted the use of open surgery in the management of these tumors. Adrenocortical-sparing surgery may be performed using laparoscopy in patients with hereditary forms of pheochromocytoma.

Clinical characteristics and genetic screening of an extended family with MEN2A

MEN-2A is characterized by medullary thyroid carcinoma (MTC) with pheochromocytoma and sometimes parathyroid adenoma. In affected members of the family, the risk of MTC is about 100%. Biochemical screening allows tumors to be detected early but even at this stage treatment is not always curative. Missense mutations in exon 10 and 11 of the RET proto-oncogene are associated with MEN-2A. Early detection of this mutation by DNA analysis allows the identification of the carriers of the gene. We performed genetic screening in 88 members of an extended family with MEN-2A and found 18 members positive for RET mutation (Cys634Gly). Only three of these 18 RET positive cases had a previous diagnosis of medullary cancer and/or pheochromocytoma. Up to now, 12 of the RET positive cases have undergone thyroidectomy. There was extended disease with cervical lymph node metastasis in 6 of them, bilateral medullary microcancer in 3 and c-cell hyperplasia in the remaining 3. Three of the 18 RET positive patients had also pheochromocytoma. Primary hyperparathyroidism was present in only one patient. The mean age of diagnosis of medullary cancer was between 25-50 yr and mean age of death was between 35-95 yr in affected members of the family. The family had many other affected members in other cities in Turkey and in other countries throughout the world from Australia to the Netherlands. So this family is perhaps one of the most extended families with MEN-2A.

Adrenalectomy for familial pheochromocytoma in the laparoscopic era

OBJECTIVE

To report the results of treatment of patients with familial pheochromocytomas in the laparoscopic era.

SUMMARY BACKGROUND DATA

The optimal surgical management of pheochromocytomas that arise in familial neoplasia syndromes may be complicated by bilateral involvement and associated endocrinopathies.

METHODS

Twenty-one patients with familial pheochromocytomas (15 with multiple endocrine neoplasia [MEN] 2A, 4 with MEN 2B, 1 each with von Hippel-Lindau and neurofibromatosis type 1) underwent adrenalectomy between December 1993 and July 2001. Clinical, biochemical, and pathologic data were obtained by retrospective review of perioperative medical records, postoperative biochemical testing, and patient questionnaire.

RESULTS

Mean age at diagnosis was 37 +/- 11 years. Twenty of the 21 patients had elevated urine catecholamines, and all had radiographic evidence of an adrenal tumor or tumors. Pheochromocytoma-related symptoms were present in 11 patients (52%). One patient with MEN 2B underwent open adrenalectomy due to previous adrenal surgery and megacolon. Laparoscopic adrenalectomy was attempted in the remaining 20 patients (9 right, 11 left, 2 bilateral). Two patients (9.1%) were converted to open adrenalectomy. Intraoperative hypertensive episodes occurred in 15 patients (71%) and were easily controlled medically. Mean operative time was 216 +/- 57 minutes, mean postoperative length of stay was 3.1 +/- 1.3 days, and mean tumor size was 3.1 +/- 1.0 cm. Minor complications occurred in three patients (14.3%) and major complications in two patients (9.5%). During a mean follow-up of 57 months, a contralateral pheochromocytoma developed in four patients with MEN 2 (33%); three of them underwent adrenalectomy. There have been no long-term complications related to hypertension or adrenalectomy.

CONCLUSIONS

This study is the largest series of patients with familial pheochromocytoma undergoing adrenalectomy during the laparoscopic era. The results suggest that the laparoscopic approach is safe and effective for managing unilateral or bilateral adrenal medullary disease in this population.

Familial medullary thyroid carcinoma: clinical variability and low aggressiveness associated with RET mutation at codon 804

Sixty-one heterozygotes harboring the germline V804L mutation of the RET protooncogene were identified in five independent families. A total of 31 subjects underwent surgery. Histology identified C cell hyperplasia in 30 cases, isolated in 12 and associated with medullary thyroid carcinoma (MTC) in 18. Six patients with MTC had lymph node metastases. Among the 14 patients with basal detectable calcitonin (CT) level, 12 had MTC and 2 had isolated C cell hyperplasia. In most individuals carrying 804 RET mutation, C cell disease displayed late onset and an indolent course; a pentagastrin test was negative in the majority of heterozygotes during the first 2 decades and was positive in only half of them during the third and fourth decades of life. Interestingly, concomitant somatic M918T was detected in a 12-yr-old girl with MTC and was likely to be responsible for both the early clinical appearance and the aggressiveness of the disease. Our data show that in these gene carriers, surgery may be postponed to the fourth decade of life or until the pentagastrin stimulation test becomes positive. Indeed, our data should be confirmed on a larger series of V804L carriers, but may offer a balanced strategy to keep under control and prevent development of the full disease phenotype.

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

BACKGROUND

Multiple endocrine neoplasia type 2 (MEN 2) is an inherited disease caused by germline mutations in the RET proto-oncogene, and is responsible for the development of endocrine neoplasia. Its prognosis is dependent on the appearance and spread of medullary thyroid carcinoma (MTC). Relatives at risk can be identified before clinical or biochemical signs of the disease become evident.

METHODS

Twenty-one families with MEN 2 (16 families with MEN 2A and 5 families with MEN 2B) were studied. Peripheral blood DNA was amplified by polymerase chain reaction. DNA sequence or restriction enzyme analysis was performed to detect mutations of RET proto-oncogene exons 10, 11, and 16. Molecular analysis was carried out in all index patients as well as in 98 relatives of MEN 2A patients (60 juveniles, ages 6 months to 21 years, and 38 adults, ages 22 to 81 years) and in 13 relatives (6 juveniles ages 10 to 21 years, and 7 adults ages 41 to 66 years) from MEN 2B families.

RESULTS

Molecular studies showed a mutation at codon 634, exon 11 in all MEN 2A patients. All MEN 2B patients showed an ATG to ACG (Met918Thr) mutation. In MEN 2A families, 42 out of 98 relatives were affected. Total thyroidectomy was performed in 18 juvenile carriers ages 17 months to 21 years. Histopathologic studies of the glands revealed parafollicular cell (C-cell) hyperplasia in all of these carriers, medullary thyroid carcinoma in 15 carriers, and only one carrier with lymph node metastases.

CONCLUSIONS

The consistent finding of C-cell disease in all the juvenile carriers who underwent preventive thyroidectomy emphasizes the relevance of early screening in children at risk of developing MTC. The presence of MTC in the specimen of prophylactic thyroidectomy from a 17 month old girl highlights the importance of thyroidectomy as soon as the molecular diagnosis is confirmed.

The finding of a somaticdeletion in RET exon 15 clarified the sporadic nature of amedullary thyroid carcinoma suspected to be familial

Medullary thyroid carcinoma (MTC) occurs both sporadically and in the autosomal dominantly inherited multiple endocrine neoplasia (MEN) type 2 syndromes. The distinction between both is important for future clinical management. We report a family initially described as a familial MTC by pentagastrin stimulation test and clinical outcome, in which we found a 12 bp deletion within the catalytic domain of the protooncogene RET in the index case tumor alone. Linkage study suggests that it is a sporadic MTC. Therefore, in view of these results, in kindred with just one MTC case, borderline pentagastrin test values must be carefully assessed. In addition, this and other mutations can help us to understand some features about domains that play an important role in the normal function of this tyrosine kinase receptor and involved in MTC.

Multiple endocrine neoplasia type 2a (MEN2a): a call for psycho-social research

This paper summarizes what is known about the diagnosis, treatment, and follow-care of people with the inherited disorder multiple endocrine neoplasia type 2a (MEN2a). Several databases were searched throughout the year 2000, including MEDLINE, CINAHL, CancerLit, PsychINFO, and Dissertation Abstracts International. MEN2a is a complex disease involving cancer care and control by surgery, health maintenance, and life-long observation of gene mutation carriers. Genetic testing is the standard of care, prophylactic surgery is recommended during directive counseling, and life-long surveillance is encouraged for people with MEN2a. A substantial body of scientific literature describes morbidity and mortality outcomes of disease treatment, and the monitoring of multiple organ systems. Research is scant concerning the psychological consequences and social impact of the MEN2a diagnosis, treatment, and follow-up. Nearly all that is known from a psycho-social perspective comes from data in The Netherlands. Little is known of the psychological responses to and social consequences of genetic predisposition testing, prophylactic and curative surgery, and life-long surveillance. Psycho-social research is essential to provide comprehensive care for patients and family members with this disorder and it is necessary to guide the development of risk management strategies for patients with this inherited cancer syndrome. Since MEN2a has been labeled a prototype for medical genetics, information on MEN2a patient experiences may be relevant to the care of individuals with other inherited cancer syndromes.

Inheritable forms of medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) arises from parafollicular or C cells of the thyroid that produce calcitonin. It accounts for 5-10% of all thyroid cancers. Hereditary MTC represents 20-30% of all MTCs. It can be transmitted with an autosomal dominant pattern, either as a single entity, familial MTC, or it can arise as part of a multiple endocrine neoplasia (MEN) syndrome type 2A or 2B. The identification of hereditary MTC has been facilitated in recent years by the direct analysis of the ret proto-oncogene.

Neuroendocrine tumor markers

Tumor markers used in the diagnosis and follow-up of patients with neuroendocrine tumors are in most instances not specific for a given tumor and circulate under normal conditions in the serum, making their use as an early diagnostic tool difficult (low sensitivity). By combining hormone measurements with tissue responsiveness, demonstrations of inappropriate secretions of PTH, insulin, and gastrin during hypercalcemia, hypoglycemia, and hyperacidity, respectively, become highly sensitive and specific diagnostic tests. The application of polyclonal antibodies in RIAs of hormones, such as ACTH, insulin, and gastrin, increase the diagnostic level of hormone measurements in patients with neuroendocrine tumors. Other markers, such as chromogranin A, neuron-specific enolase, and alpha-subunit, as well as peptide receptor visualization, are of increasing importance in the diagnosis and follow-up of neuroendocrine and non-neuroendocrine tumors.

Acute dyspnoea resulting from pulmonary oedema as the first sign of a phaeochromocytoma

The day after undergoing neck dissection, a 42-year-old woman developed acute dyspnoea due to pulmonary oedema. Measurements with a Swan-Ganz catheter revealed not only cardiac depression but also a greatly increased peripheral vascular resistance: 5,400 dyn x s x cm(-5)/m2. A phaeochromocytoma with acute cardiac failure leading to pulmonary oedema was considered. Treatment with alpha- and beta-blockers was complicated by severe hypotension and later ventricular fibrillation. Mechanical ventilation was required for 6 days following resuscitation. Investigation of the urine subsequently showed greatly increased catecholamine concentrations, while imaging revealed bilateral adrenal tumours. Our case history shows that acute pulmonary oedema may be the presenting manifestation of a phaeochromocytoma. The pulmonary oedema resulted partly from backward failure following tachycardia, myocyte necrosis and the greatly increased peripheral vascular resistance, and partly from increased permeability of the capillary network in the lungs.

Germline RET 634 mutation positive MEN 2A-related C-cell hyperplasias have genetic features consistent with intraepithelial neoplasia

C-cell hyperplasias are normally multifocal in multiple endocrine neoplasia type 2A. We compared clonality, microsatellite pattern of tumor suppressor genes, and cellular kinetics of C-cell hyperplasia foci in each thyroid lobe. We selected 11 females from multiple endocrine neoplasia type 2A kindred treated with thyroidectomy due to hypercalcitoninemia. C-cell hyperplasia foci were microdissected for DNA extraction to analyze the methylation pattern of androgen receptor alleles and microsatellite regions (TP53, RB1, WT1, and NF1). Consecutive sections were selected for MIB-1, pRB1, p53, Mdm-2, and p21WAF1 immunostaining, DNA content analysis, and in situ end labeling. Appropriate tissue controls were run. Only two patients had medullary thyroid carcinoma foci. Nine informative C-cell hyperplasia patients showed germline point mutation in RET, eight of them with the same androgen receptor allele preferentially methylated in both lobes. C-cell hyperplasia foci showed heterogeneous DNA deletions revealed by loss of heterozygosity of TP53 (12 of 20), RB1 (6 of 14), and WT1 (4 of 20) and hypodiploid G0/G1 cells (14 of 20), low cellular turnover (MIB-1 index 4.5%, in situ end labeling index 0.03%), and significantly high nuclear area to DNA index ratio. MEN 2A (germline point mutation in RET codon 634) C-cell hyperplasias are monoclonal and genetically heterogeneous and show down-regulated apoptosis, findings consistent with an intraepithelial neoplasia. Concordant X-chromosome inactivation and interstitial gene deletions suggest clone expansions of precursors occurring at a point in embryonic development before divergence of each thyroid lobe and may represent a paradigm for other germline mutations.