Genetic testing for familial cancer. Consequences of RET proto-oncogene mutation analysis in multiple endocrine neoplasia, type 2

Natural History and Predictive Factors of Outcome in Medullary Thyroid Microcarcinoma

CONTEXT

Management of sporadic medullary thyroid microcarcinoma smaller than 1 cm (micro-MTC) is controversial because of conflicting reports of prognosis. As these cancers are often diagnosed incidentally, they pose a management challenge when deciding on further treatment and follow-up.

OBJECTIVE

We report the outcomes of surgically managed sporadic micro-MTC in a specialist endocrine surgery and endocrinology unit and identify associations for recurrence and disease-specific survival in this population.

METHODS

Micro-MTCs were identified from a prospectively maintained surgery database, and slides were reviewed to determine pathological grade. The primary end points were recurrence, time to recurrence and disease-specific survival. Prognostic factors assessed included size, grade, lymph node metastasis (LNM), and postoperative calcitonin.

RESULTS

From 1995 to 2022, 64 patients were diagnosed with micro-MTC with 22 excluded because of hereditary disease. The included patients had a median age of 60 years, tumor size of 4 mm, and 28 (67%) were female. The diagnosis was incidental in 36 (86%) with 4 (10%) being high grade, 5 (12%) having LNM and 9 (21%) having elevated postoperative calcitonin. Over a 6.6-year median follow-up, 5 (12%) developed recurrence and 3 (7%) died of MTC. High grade and LNM were associated with 10-year survival estimates of 75% vs 100% for low grade and no LNM (hazard ratio = 831; P < .01). High grade, LNM, and increased calcitonin were associated with recurrence (P < .01). Tumor size and type of surgery were not statistically significantly associated with recurrence or survival. No patients with low grade micro-MTC and normal postoperative calcitonin developed recurrence.

CONCLUSION

Most sporadic micro-MTCs are detected incidentally and are generally associated with good outcomes. Size is not significantly associated with outcomes. Using grade, LNM, and postoperative calcitonin allows for the identification of patients at risk of recurrence to personalize management.

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

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

Prophylactic thyroidectomy in children with multiple endocrine neoplasia type 2

BACKGROUND

In patients with multiple endocrine neoplasia type 2 (MEN2) syndrome, genetic testing offers early diagnosis, stratifies the risk of developing medullary thyroid cancer (MTC) and informs the timing of thyroidectomy. The efficacy of treatment, which depends on timely and safe surgery, is not well established.

METHODS

This was a retrospective review of diagnostic and clinicopathological outcomes of prophylactic thyroidectomy in children with MEN2 between 1995 and 2013 in the UK. American Thyroid Association (ATA) 2009 guidelines were used as a benchmark for adequate treatment.

RESULTS

Seventy-nine children from 16 centres underwent total thyroidectomy. Thirty-eight patients (48 per cent) underwent genetic testing and 36 (46 per cent) had an operation performed above the age recommended by the ATA 2009 guidelines; pathology showed MTC in 30 patients (38 per cent). Late surgery, above-normal preoperative calcitonin level and MTC on pathology correlated with late genetic testing. Twenty-five children had lymphadenectomy; these patients had more parathyroid glands excised (mean difference 0·61, 95 per cent c.i. 0·24 to 0·98; P = 0·001), and were more likely to have hypocalcaemia requiring medication (relative risk (RR) 3·12, 95 per cent c.i. 1·54 to 6·32; P = 0·002) and permanent hypoparathyroidism (RR 3·24, 1·29 to 8·11; P = 0·010) compared with those who underwent total thyroidectomy alone. Age did not influence the development of complications.

CONCLUSION

Late genetic testing may preclude age-appropriate surgery, increasing the risk of operating when MTC has already developed. Early genetic testing and age-appropriate surgery may help avoid unnecessary lymphadenectomy and improve outcomes.

Advances in risk-oriented surgery for multiple endocrine neoplasia type 2

Genetic association studies hinge on definite clinical case definitions of the disease of interest. This is why more penetrant mutations were overrepresented in early multiple endocrine neoplasia type 2 (MEN2) studies, whereas less penetrant mutations went underrepresented. Enrichment of genetic association studies with advanced disease may produce a flawed understanding of disease evolution, precipitating far-reaching surgical strategies like bilateral total adrenalectomy and 4-gland parathyroidectomy in MEN2. The insight into the natural course of the disease gleaned over the past 25 years caused a paradigm shift in MEN2: from the removal of target organs at the expense of greater operative morbidity to close biochemical surveillance and targeted resection of adrenal tumors and hyperplastic parathyroid glands. The lead time provided by early identification of asymptomatic MEN2 carriers under biochemical surveillance delimits a 'window of opportunity', within which (i) pre-emptive total thyroidectomy alone is adequate, circumventing morbidity attendant to central node dissection; (ii) subtotal 'tissue-sparing' adrenalectomy is sufficient, trading the risk of steroid dependency for the risk of a second pheochromocytoma in the adrenal remnant and (iii) parathyroidectomy is limited to enlarged glands, trading the risk of postoperative hypoparathyroidism for the risk of leaving behind hyperactive parathyroid glands. Future research should delineate further the mutation-specific, age-dependent penetrance of pheochromocytoma and primary hyperparathyroidism to refine the risk-oriented approach to MEN2. The sweeping changes in the management of MEN2 since the new millenium hold the hope that death and major morbidity from this uncommon disease can be eliminated in our lifetime.

Long-term outcome of prophylactic thyroidectomy in children carrying RET germline mutations

Background

A comprehensive assessment has not been undertaken of long-term outcomes in children carrying germline RET mutations and undergoing prophylactic thyroidectomy with the aim of preventing medullary thyroid cancer (MTC).

Methods

A retrospective outcome study (1994–2017) of prophylactic thyroidectomy in children, with and without central node dissection, was performed at a tertiary surgical centre.

Results

Some 167 children underwent prophylactic thyroidectomy, 109 without and 58 with concomitant central node dissection. In the highest-risk mutational category, MTC was found in five of six children (83 per cent) aged 3 years or less. In the high-risk category, MTC was present in six of 20 children (30 per cent) aged 3 years or less, 16 of 36 (44 per cent) aged 4–6 years, and 11 of 16 (69 per cent) aged 7–12 years (P = 0·081). In the moderate-risk category, MTC was seen in one of nine children (11 per cent) aged 3 years or less, one of 26 (4 per cent) aged 4–6 years, three of 26 (12 per cent) aged 7–12 years, and seven of 16 (44 per cent) aged 13–18 years (P = 0·006). Postoperative hypoparathyroidism was more frequent in older children (32 per cent in the oldest age group versus 3 per cent in the youngest; P = 0·002), whether or not central node dissection was carried out. Three children developed recurrent laryngeal nerve palsy; all had undergone central node dissection (P = 0·040). All complications resolved within 6 months. Postoperative normalization of calcitonin serum levels was achieved in 114 (99·1 per cent) of 115 children with raised preoperative values. No residual structural disease or recurrence was observed.

Conclusion

Early prophylactic thyroidectomy is a viable surgical concept in experienced hands, sparing older children the postoperative morbidity associated with delayed neck surgery.

Essential genes in thyroid cancers: focus on fascin

Although thyroid cancers are not among common malignancies, they rank as the first prevalent endocrine cancers in human. According to the results of published studies it has been shown the gradual progress from normal to the neoplastic cell in the process of tumor formation is the result of sequential genetic events. Among them we may point the mutations and rearrangements occurred in a group of proto-oncogenes, transcription factors and metastasis elements such as P53, RAS,RET,BRAF, PPARγ and Fascin. In the present article,we reviewed the most important essential genes in thyroid cancers, the role of epithelial mesenchymal transition and Fascin has been highlighted in this paper.

Molecular diagnosis of primary hyperparathyroidism in familial cancer syndromes

In the last few years, causative genes have been identified for most of the familial hyperparathyroidism conditions. Germline mutations in the tumour suppressors multiple endocrine neoplasia type 1 (MEN1) and hyperparathyroidism 2 (HRPT2) provide a molecular diagnosis of multiple endocrine neoplasia type 1 and hyperparathyroidism jaw tumour syndrome, respectively. Germline mutations in the proto-oncogene RET (rearranged during transfection) provide a molecular diagnosis of multiple endocrine neoplasia type 2. Germline mutations of both MEN1 and, less frequently HRPT2, have been found in familial isolated hyperparathyroidism. A molecular diagnosis can now be incorporated into the management of patients with these conditions, however, the ease of diagnostics and value of genetic information in the context of clinical screening and early surgical intervention varies between these disorders. This review focuses on familial hyperparathyroidism and its known causative genes in the setting of neoplastic syndromes, with particular discussion of recent developments in the molecular diagnosis of parathyroid carcinoma.

Thyroid nodules in pediatrics: which ones can be left alone, which ones must be investigated, when and how

Thyroid nodules are less frequent in childhood than in adulthood, but are more often malignant. Recent estimates suggest that up to 25% of thyroid nodules in children are malignant, therefore, a more aggressive approach is recommended. In this review, we suggest an approach based on a first-step clinical, laboratory, and sonographic evaluation. A history of irradiation of the neck, cranium or upper thorax, previous thyroid diseases or thyroid neoplasms in the family should alert clinicians as being associated with a greater likelihood of malignant nodules. Signs or symptoms of hyperthyroidism and dysmorphic features should be carefully considered during the physical examination. Palpable firm lymph nodes, found in some 70% of cases, are the most significant clinical finding in children with malignant nodules. Although the routine determination of calcitonin levels is not uniformly practiced, it can help recognize sporadic or familial medullary thyroid neoplasms. Blood thyroid stimulating hormone, free thyroxine, and free triiodothyronine determinations (the latter in case of symptoms of hyperthyroidism) are aimed at identifying the few hyperthyroid patients, for whom the next step should be scintiscan. Hyperthyroid patients usually disclose an increased uptake, and a diagnosis of toxic adenoma is commonly made. Cases with normal thyroid function or hypothyroidism (which is usually subclinical) should be evaluated by fine-needle aspiration biopsy (FNAB). In eu/hypo-thyroid patients, scintiscan provides poor diagnostic information and should not be routinely employed. Thyroid ultrasonography is used to select cases for FNAB. Although ultrasound cannot reliably discriminate between benign and malignant lesions, it does provide an index of suspicion. Sonographic features that increase the likelihood of malignancy are microcalcifications, lymph node alterations, nodule growth under levothyroxine treatment, and increased intranodular vascularization demonstrated by color Doppler. There is growing evidence that elastography may provide further information on nodule characteristics. FNAB is indicated in all cases with a likelihood of malignancy. FNAB has a diagnostic accuracy of approximately 90% and is used in selection of patients which require surgery. Recently, histological markers and elastography have been introduced to increase the specificity of FNAB and ultrasound, respectively. The pitfall in FNAB cytology is the follicular cytology, in which it is not possible to distinguish between adenoma and carcinoma and therefore thyroidectomy is advised.

Pediatric ethics guidelines for hereditary medullary thyroid cancer

Hereditary medullary thyroid cancer is an aggressive cancer for which there is no standard effective systemic therapy, but which can be prevented through genetic screening and prophylactic thyroidectomy. Although this cancer accounts for roughly 17% of all pediatric thyroid cancers, a significant percentage of affected families do not "accept" screening, while many gene carriers delay or refuse prophylactic thyroid surgery for their children. Current genetic screening practices in medullary thyroid cancer are inadequate; more than 50% of index patients with hereditary medullary thyroid cancer present with a thyroid mass; up to 75% have distant metastasis. These proposed pediatric ethics guidelines focus on two ethical issues that affect at-risk children: (1) how do we identify at-risk children whose RET-positive relative refuses to disclose that they carry the mutation? (2) How do we protect RET-positive children whose parents refuse prophylactic thyroidectomy?

Surgical approaches to thyroid tumors

This article includes discussions of the surgical approach to benign and malignant disease and the role of prophylactic thyroidectomy and nodal dissection for medullary thyroid cancer. The controversy regarding the extent of dissection for differentiated thyroid cancer and the role of lymph node dissection are reviewed also. A description of the authors' surgical technique for thyroidectomy is detailed. Finally, several emerging technologies are introduced.

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.

Thyroid cancer in children

In 1996, the authors were asked to review the subject of thyroid cancer in children. Over the subsequent decade, much has been learned about the treatment and outcome of these uncommon tumors. We now recognize quantitative and perhaps qualitative differences in genetic mutations and growth factor expression patterns in childhood thyroid cancers compared with those of adults. We also know that thyroid cancers induce a robust immune response in children that might contribute to their longevity. Patients under 10 years of age probably represent a unique subset of children at particularly high risk for persistent or recurrent disease; the management of these patients is under evaluation. We remain limited in our knowledge of how to stratify children into low- and high-risk categories for appropriate long-term follow-up and in our knowledge of how to treat children who have detectable serum thyroglobulin but negative imaging studies. In this article, the authors update our understanding of thyroid cancers in children with special emphasis on how these data relate to the current guidelines for management of thyroid cancer developed by the American Thyroid Association Taskforce. The limited data regarding management of children who have detectable serum thyroglobulin but negative whole-body scans are also reviewed.

Self-Surveillance for Genetic Predisposition to Cancer: Behaviors and Emotions

PURPOSE/OBJECTIVES

To describe the kinds of self-monitoring activities and the emotional responses associated with those activities in patients with a genetic predisposition to multiple endocrine neoplasia type 2a (MEN2a) or familial adenomatous polyposis (FAP).

RESEARCH APPROACH

Thematic analysis of the transcripts of patient interviews conducted for two previous grounded theory investigations of participation in lifelong surveillance for patients with cancer predisposition syndromes and their family members.

SETTING

In the original studies, participants were recruited through a high-risk gastrointestinal cancer clinic (for FAP) and pediatric and adult endocrinology clinics (for MEN2a) at two eastern U.S. medical centers and by patient referral.

PARTICIPANTS

58 transcripts of interviews with 29 patients; 17 diagnosed with FAP or the variants of Gardner syndrome and attenuated FAP and 12 patients diagnosed with MEN2a.

METHODOLOGIC APPROACH

Informants participated in two hour-long, in-depth interviews and completed a self-administered sociodemographic questionnaire.

MAIN RESEARCH VARIABLES

Types of self-surveillance activities.

FINDINGS

Patients engage in an elaborate set of self-surveillance activities that are grouped into five categories of behavior: Medication Appraisal, Phenotype Tracking, Intake and Output Monitoring, Laboratory and Treatment Recording, and Tracking of Visits. Self-surveillance behaviors are grouped independent of type of syndrome, penetrance, age, or gender of the patient. Each category comprises a variety of behaviors that correspond with treatment recommendations and understanding of the disorder.

CONCLUSIONS

Self-surveillance may be driven by a combination of anticipation and the need for control and understanding.

INTERPRETATION

Findings from the study could be used to create an assessment tool to evaluate the extent to which patients are involved in day-to-day self-monitoring. Clinicians may use the categories to better understand patients' knowledge deficits and the emotional impact of enhanced vigilance. Self-surveillance activities performed by patients with MEN2a and FAP also may be performed by patients with other cancer predisposition syndromes.

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.

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.

Evaluation of the thyroid nodule

BACKGROUND

Thyroid nodules are common, yet treatment modalities range from observation to surgical resection. Because thyroid nodules are frequently found incidentally during routine physical examination or imaging performed for another reason, physicians from a diverse range of specialties encounter thyroid nodules. Clinical decision making depends on proper evaluation of the thyroid nodule.

METHODS

The current literature was reviewed and synthesized.

RESULTS

Current evidence allows the formulation of recommendations and a general algorithm for evaluating the incidental thyroid nodule.

CONCLUSIONS

Only a small percentage of thyroid nodules require surgical management. Diagnosis and treatment selection require a risk stratification by history, physical examination, and ancillary tests. Nodules causing airway compression or those at high risk for carcinoma should prompt evaluation for surgical treatment. In nodules larger than 1 cm, fine-needle aspiration biopsy is central to the evaluation as it is accurate, low risk, and cost effective. Subcentimeter nodules, often found incidentally on imaging obtained for another purpose, can usually be evaluated by ultrasonography. Other laboratory and imaging evaluations have specific and more limited roles. An algorithm for the evaluation of the thyroid nodule is presented.

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.

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.

FDG PET imaging in hereditary thyroid cancer

AIM

To report the role of different imaging methods in staging individuals with multiple endocrine neoplasia 2A (MEN2A) or familial medullary thyroid carcinoma (FMTC).

MATERIAL AND METHODS

Fourteen newly diagnosed gene carriers underwent cervical ultrasound scanning (US), cervical and mediastinal CT, MRI and whole-body meta-[131I]iodobenzylguanidine (MIBG) scintigraphy and [18F]fluorodeoxyglucose (FDG) PET scanning.

RESULTS

US identified seven true primary cancer. CT and MRI located only tumors > or =5 mm in diameter. MIBG scintigraphy and FDG PET could not identify MTC foci within the thyroid. Whole-body FDG PET identified two true-positive and one false-positive lymph node metastases. MIBG scintigraphy did not identify lymph node metastases. Total thyroidectomy was performed in 12 cases, and subtotal thyroidectomy in two subjects.

CONCLUSIONS

Whole-body FDG PET and cervical US help stage individuals carrying mutant genes verifying MEN2A or FMTC.

Bringing threat to the fore: participating in lifelong surveillance for genetic risk of cancer

PURPOSE/OBJECTIVES

To explain how patients with multiple endocrine neoplasia type 2a (MEN2a) and family members conceptualize participation in lifelong surveillance in genetic cancer care.

DESIGN

Qualitative naturalistic inquiry.

SETTING

Northeastern United States. Data were collected during interviews in informants' homes.

SAMPLE

12 adult patients and 9 family members were recruited purposively through endocrinology clinics at two East Coast medical centers.

METHODS

A grounded theory design was used. Subjects completed a demographic questionnaire and were interviewed on two occasions. In-depth interviews were audiotaped. The core concept and process variables emerged through three levels of narrative content analysis, theoretical sampling, and constant comparison. The generated theory was presented to the participants for validation.

MAIN RESEARCH VARIABLES

The basic psychological issue associated with participation in lifelong surveillance and the psychosocial processes used by individuals to deal with the issues.

FINDINGS

MEN2a patients and family members experience surveillance as a (Re)Minding of a threat to health. Once threat is brought to the fore, participants interpret the meaning and negotiate control of the impact of the diagnosis, related events, and consequences. Meaningful information from surveillance activities is incorporated into participants' self-image and daily lives through a process of (Re)Integration. The genetic nature of MEN2a did not emerge as a significant subcategory in relation to the core variable.

CONCLUSIONS

Finding meaning in the outcomes of surveillance events is a psychosocial process that is central to participation in lifelong surveillance. Genetic predisposition to cancer was a peripheral concern to subjects as they dealt with surveillance issues.

IMPLICATIONS FOR NURSING

This investigation provides a model for the development of a grounded theory for understanding how people with other genetic cancer syndromes participate in lifelong surveillance.

Prophylactic thyroidectomy in multiple endocrine neoplasia: the impact of molecular mechanisms of RET proto-oncogene

BACKGROUND

Multiple endocrine neoplasia (MEN) type 2, a cancer syndrome inherited in the dominant fashion, is defined by the occurrence of medullary thyroid carcinoma (MTC), either as a singular lesion (familial medullary thyroid carcinoma, FMTC) or with the variable expression of pheochromocytoma, hyperparathyroidism (MEN 2A), ganglioneuromas, buccal neuromas and Marfanoid-like phenotype (MEN 2B).

DISCUSSION

Germline mutations of the RET proto-oncogene, localized on chromosome 10q11.2, have been identified as the underlying genetic cause of the disorder. In the majority of patients with MEN 2A/FMTC missense mutations at exon 10 or exon 11 are identifiable. Cysteine to arginine exchange at codon 634 is the mutation most frequently found. In MEN 2B approximately 95% of patients present with a mutation at codon 918 (exon 16). Additionally, less frequent mutations in other codons have been found in both syndromes. The DNA-based genotype analysis enables the identification of gene carriers at risk of developing MTC and offer them prophylactic thyroidectomy prior to development of any thyroid pathologies. Prophylactic surgery is generally recommended for MEN 2A/FMTC gene carriers at the age of 4-6 years. Due to the aggressiveness of the MEN 2B syndrome gene carriers should be operated by the age of 1 year. Presumably some less virulent mutations allow postponement of the prophylactic treatment to the second to fourth decade of life.

CONCLUSIONS

Compared to standard presymptomatic biochemical screening, genetic testing and consecutive prophylactic treatment contribute to better outcome of individuals at risk for MTC.

Prolonged survival of a patient with multiple endocrine neoplasia type 2b and stage IV medullary thyroid carcinoma

OBJECTIVE

To present a case of multiple endocrine neoplasia type 2B (MEN2B) with a prolonged course.

METHODS

We describe the clinical, laboratory, and radiologic findings in a patient with MEN2B and review the various interventions during a period of approximately 3 decades.

RESULTS

In 1962, a 19-year-old man with a marfanoid body habitus presented with multiple thyroid nodules and neurofibromas of the tongue. Total thyroidectomy demonstrated multicentric medullary thyroid carcinoma with cervical lymph node metastatic involvement. At the time of the first description of the MEN2B syndrome, the patient was enrolled in a surveillance program. An increase in urinary metanephrines resulted in bilateral adrenalectomy for multinodular pheochromocytoma in 1972. Increased serum calcitonin levels and the appearance of cervical lymphadenopathy led to modified radical neck dissection 12 years after the initial diagnosis of medullary thyroid carcinoma. In 1975, angiography revealed extensive hepatic lesions metastatic from the medullary thyroid carcinoma; this finding was confirmed by open liver biopsy in 1988. The patient lived 16 years after the initial diagnosis of liver metastatic disease and died 29 years after the initial examination.

CONCLUSION

The 3-decade course of this patient not only represents a classic case of MEN2B but also allows us to present the history of this disease from its discovery to the current era of genetic testing and exemplifies the possibility of long-term survival in a patient with liver metastatic involvement from medullary thyroid carcinoma.

Presurgical assessment of the tumor burden of familial medullary thyroid carcinoma by calcitonin testing

BACKGROUND

Early diagnosis of familial medullary thyroid carcinoma (MTC) is currently done by genetic analysis. These techniques have replaced calcitonin stimulation testing, which was previously used for this purpose. Some studies suggest a relationship between MTC spread and calcitonin levels. The aim of this study was to assess whether the tumor burden of MTC associated with multiple endocrine neoplasia type 2A (MEN 2A) syndrome can be estimated from the plasma calcitonin values before surgery.

STUDY DESIGN

We retrospectively studied the relationship of basal and peak calcitonin values before thyroidectomy with histopathologic findings in 53 patients with MEN 2A syndrome from 14 families. The MTC was classified according to TNM staging. Analysis of variance was used for statistical analysis complemented with equality contrasts for pairs of means by the least significant difference method with a Student's t-test and with the Bonferroni's adjustment.

RESULTS

A positive association was found between tumor stage and basal and peak calcitonin levels. There were significant differences between the following: mean basal concentrations of patients with C cell hyperplasia (CCH) (34.3 pg/mL) and TNM stage II (1,097.4 pg/mL), p < 0.01; CCH and TNM stage III (2,940.8 pg/mL), p < 0.001; TNM stage I (165.3 pg/mL) and stage II (1,097.4 pg/mL), p < 0.01, and between TNM stages I and III, p < 0.001. Poststimulation mean concentrations were different between CCH (48.7 pg/mL) and TNM I (514.2 pg/mL), p < 0.001.

CONCLUSIONS

Preoperative calcitonin testing may be useful for assessing tumor spread and should be considered when deciding the extent of surgery for MEN 2A 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.

Ethical issues in genetic testing. The experiences of one family diagnosed with an inherited cancer syndrome

This article describes selected ethical issues faced by members of a family with genetic predisposition to the cancer syndrome multiple endocrine neoplasia type 2a. The bioethical principles of autonomy, nonmaleficence, beneficence, and justice are the moral guides for nurses and other health professionals, who may apply them to help patients, family members and peers resolve ethical issues and moral dilemmas. Sometimes, however, issues that are morally problematic cannot be settled by simply referring to standards of practice and bioethical norms. In these cases all stakeholders must struggle together to resolve the conflict.

Genetic cancer syndromes and large-scale gene expression analysis: applications in surgical oncology

The last decade of the 20th century was characterized by an explosion in genetic discoveries. The Human Genome Project and technical advances have made it possible to unravel many genetic abnormalities underlying cancer. Many genes responsible for inherited cancer syndromes have been identified and diagnostic tests are readily available. The clinical implications of these tests are currently under debate. Large-scale gene expression analysis enables simultaneous monitoring of expression of thousands of genes, in vitro and in vivo. The identification of high risk patients and drug responsiveness, can be studied within the framework of complex molecular networks. This article will focus on the possibilities for surgical oncology.

Multiple endocrine neoplasia type 2B — genetic basis and clinical expression

Multiple endocrine neoplasia (MEN) type 2B is a heritable endocrine disorder characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, multiple mucosal neuromas, and a marfanoid habitus. Intestinal ganglioneuromatosis, corneal nerve thickening and skeletal abnormalities are also often present. The disease is inherited in an autosomal dominant fashion and is caused by a single mutation in the RET proto-oncogene, with a methionine to threonine substitution at codon 918. The MTC in MEN 2B presents at an earlier age and tends to be more aggressive than the MTC in MEN 2A. It is multicentric and bilateral and occurs as young as age 3, with early lymph node metastases. Pheochromocytoma is also often bilateral but is rarely malignant. If pheochromocytoma is detected, adrenalectomy should precede thyroidectomy to avoid intraoperative catecholamine crisis. Patients at risk for MEN 2B should undergo genetic screening in infancy. Total thyroidectomy should be performed on all patients positive for RET mutations even prior to the onset of clinical symptoms.

RET proto-oncogene mutations in thyroid carcinomas: clinical relevance

Different forms of RET mutations are found in papillary and medullary thyroid carcinomas. Rearrangements with other genes (RET/PTC oncogene) play a causative role in a significant proportion of papillary thyroid carcinomas. In this case, several factors influence the frequency and the type of RET/PTC, such as exposure to radiation, age and histological variant of the papillary tumor. On the other hand, the presence of the mutation does not seem to influence the biological behavior of the tumor or its response to conventional treatment modalities. In the setting of medullary thyroid cancer, germline RET point-mutations are implicated in the pathogenesis of virtually all hereditary forms and somatic point-mutations in nearly half of the sporadic forms. The clinical impact of this finding is that family members at-risk of hereditary MTC may be screened by genetic analysis, to distinguish those carrying or not-carrying the mutation. The last can be reassured on their status and relieved from further follow-up. Those with the mutation may be treated at a pre-clinical stage of the disease or even before the disease is started. The present review is focused on the clinical implication of RET gene mutations in thyroid cancer patients.

Spiraling out of control: one case of pathologic anxiety as a response to a genetic risk of cancer

The threat of cancer can result in an existential crisis characterized by feelings of uncertainty and fear. Anxiety, the most common response to the threat of cancer, may be expressed in ways as varied as individual personalities and circumstances. It is a normal response to the threat of cancer, but in some it may deteriorate to pathologic anxiety and manifest somatic or avoidant patterns. Members of families diagnosed with genetic mutations that predispose to cancer are unique in that they experience a complex chain of life events. People affected with genetic mutations that increase the risk for the development of cancer may be at greater risk of manifesting abnormal anxiety. Little research exists that can guide the health professional in meeting the needs of these individuals, which leads health practitioners to approach their needs on the basis of combined theoretical assumptions about the needs of people with cancer, people who have family members with cancer, and people with recurrent cancer. Some factors may be assessed by the health professional as an aid in identifying an individual at increased risk of developing a psychopathology. These factors include age and developmental level, existence of a previous psychologic disorder, and family integrity. Advanced practice nurses may effectively intervene in the care of these patients by (a) accurately assessing the risk for and extent of the anxiety reaction in individuals and family members; (b) developing management plans that include ongoing support, education, psychotherapy, and pharmacotherapeutics for the individual; and (c) support and psychotherapy for the family. In this article, the pathologic anxiety experienced by one adolescent girl diagnosed with a genetic mutation that caused multiple endocrine neoplasia 2a is addressed, along with the treatment of her avoidant anxiety disorder--trichotillomania.

Aspectos moleculares do câncer tiroideano

A proliferação da célula tiroideana normal é regulada por fatores de crescimento estimuladores e inibidores, que atuam através de seus receptores de membrana e, subseqüentemente, através de transdutores citoplasmáticos. Na glândula normal adulta, o equilíbrio de sinais é tal que a proliferação é mínima, enquanto nas neoplasias o crescimento resulta de um distúrbio irreversível desse equilíbrio. Apesar do número de moléculas envolvidas nesse processo ser grande, apenas um pequeno subgrupo parece estar envolvido na tumorigênese tiroideana. Tais proteínas são codificadas pelos genes RAS, RET, NTRK1 e TP53. O transdutor de sinais ras é ativado por mutações em ponto e constitui uma alteração genética precoce nos tumores com histologia folicular. Os genes dos receptores de crescimento RET e NTRK1 são alterados por rearranjos cromossômicos do tipo translocação ou inversão nos carcinomas papilares e por mutações em ponto nos medulares. As alterações do gene TP53, por sua vez, têm sido observadas em carcinomas tiroideanos pobremente diferenciados e na maioria dos indiferenciados, o que sugere sua participação na progressão dessas lesões. O modelo molecular da carcinogênese tiroideana, embora ainda incompleto, pode fornecer instrumentos importantes para o diagnóstico diferencial e para o desenvolvimento de novas técnicas terapêuticas nesse grupo de neoplasias.

Normal thyroid pathology in patients undergoing thyroidectomy for finding a RETgene germline mutation: a report of three cases and review of the literature

Genetic screening for germline RET proto-oncogene mutation in hereditary medullary thyroid cancer (MTC) is accurate and allows for preventive total thyroidectomy to be performed early in patients who are gene carriers. We report 3 children who underwent preventive total thyroidectomy based on the finding of a RETgene germline mutation, but who had no evidence of MTC or C-cell hyperplasia on permanent histology, even after calcitonin immunostaining. Review of the English literature of patients undergoing preventive thyroidectomy for a positive RETgene germline mutation, shows that 3.4% of these patients (a total of 209 patients) had normal thyroid glands. Also, 8.6% of patients undergoing preventive total thyroidectomy with prophylactic central neck node dissection had cervical node metastases. We conclude that preventive thyroidectomy in patients screened early for germline RETgene mutation allows for earlier diagnosis and treatment of patients, sometimes even before any hyperplasia or neoplasia can be demonstrated because cervical node metastases can occur early and be demonstrated even with small tumors (< 1 cm), we recommend prophylactic central neck node dissection at the time of preventive thyroidectomy.

The molecular genetics of endocrine tumours

The molecular genetics of endocrine tumours is an area of great interest, due to the heterogeneity of endocrine tumour types, the association of hormone over-production in some cases, and the wide variation in tumour behaviour. Genes implicated fall into functional categories such as oncogenes, in which mutations tend to cause activation, and tumour suppressor genes, in which mutations lead to loss of function. Oncogenes include the receptor tyrosine kinases such as RET, signal transduction proteins and other molecules such as cell cycle regulators and nuclear proteins. Tumour suppressor genes include cell cycle regulators such as p53 and other molecules such as the MEN 1 gene. Loss of heterozygosity studies help in the initial localisation of the latter. Endocrine tumours, as with other tumours, develop as a result of a combination of genetic events, and in the paediatric age group they often occur in the setting of familial cancer syndromes. In this review we analyse the main genetic lesions which have been described in endocrine tumours. There has been an explosion of knowledge in the last 5 years including the identification of the causative genes for MEN 2 and most recently for MEN 1. Characterisation of such genes also aids in the study of somatic mutations in sporadic versions of the same tumour types as occur in the familial syndromes. Identification of a genetic predisposition to a certain tumour has management implications that are still to be clarified in most cases, although in the case of MEN 2 the guidelines for prophylactic thyroidectomy are generally well accepted.