Unilateral subtotal adrenalectomy for pheochromocytoma in multiple endocrine neoplasia type 2 patients: a feasible surgical strategy

Multiple endocrine neoplasia type 2: towards a risk-based approach integrating molecular and biomarker results

PURPOSE OF REVIEW

Significant advances have transformed our understanding of the molecular biology and natural history of multiple endocrine neoplasia type 2 (MEN2). This progress enacted a paradigm shift with regard to routine neck dissection for medullary thyroid cancer and total adrenalectomy for pheochromoytoma. The purpose of this review is to summarize key molecular and clinical data underpinning the current risk-based approach to MEN2 that integrates molecular and biomarker results.

RECENT FINDINGS

Early identification and biochemical monitoring of rearranged during transfection ( RET ) carriers yield important lead time. Within these ' windows of opportunity ', total thyroidectomy alone, avoiding incremental morbidity from node dissection; ' tissue-sparing ' subtotal adrenalectomy, balancing risks of steroid dependency with pheochromocytoma recurrence in adrenal remnants; and parathyroidectomy of enlarged glands only, weighing risks of postoperative hypoparathyroidism against hyperactive parathyroid glands left behind, are adequate therapies.

SUMMARY

All that is needed to determine a RET carriers' risk of medullary thyroid cancer, pheochromocytoma and/or primary hyperparathyroidism in the molecular era is patient age, underlying RET mutation, and biomarker levels. As broader testing begins to penetrate healthcare, the needle on population genomic screening and education needs to be moved forward to complete the transition from symptom-based to preventive healthcare.

Total adrenalectomy versus subtotal adrenalectomy for bilateral pheochromocytoma: meta-analysis

BACKGROUND

Bilateral pheochromocytomas are rare and often heritable. Total adrenalectomy leads to a definitive oncological cure, with subsequent definitive hypocortisolism. Subtotal adrenalectomy is a possible alternative. The aim of this study was to assess the effects of total adrenalectomy and subtotal adrenalectomy on bilateral pheochromocytoma in terms of post-surgical rate of recurrence, metastatic disease, and steroid dependence.

METHODS

Systematic searches in the bibliographic databases PubMed, Embase, and Europe PMC were performed for 1945 to 1 June 2023. PRISMA guidelines were followed and the PICO strategy was applied to English-language studies comparing subtotal adrenalectomy with total adrenalectomy. A random-effects model was used to assess the different outcomes for studies with high heterogeneity. The Newcastle-Ottawa scale and the Risk Of Bias In Non-randomized Studies of Interventions ('ROBINS-I') tool were used to assess quality and risk of bias.

RESULTS

From a total of 12 909 studies, 1202 patients (from 10 retrospective studies) were eligible for the meta-analysis. In six studies, including 1176 patients, the recurrence rate after subtotal adrenalectomy and total adrenalectomy was 14.1 versus 2.6 per cent respectively (OR 4.91, 95 per cent c.i. 1.30 to 18.54; P = 0.020; I2 72 per cent). In nine studies, including 1124 patients, the rate of post-surgical steroid dependence was 93.3 versus 11.6 per cent after total adrenalectomy and subtotal adrenalectomy respectively (OR 0.003, 95 per cent c.i. 0.0003 to 0.03; P < 0.00001; I2 66 per cent). Based on two studies, including 719 patients, no differences were evident regarding the occurrence of post-surgery metastatic disease.

CONCLUSION

Subtotal adrenalectomy leads to less post-surgical primary adrenal insufficiency, but leads to a higher postoperative recurrence rate. Future prospective randomized studies, with clear eligibility criteria, are needed to confirm these results.

Outcome of Partial Adrenalectomy in MEN2 Syndrome: Personal Experience and Systematic Review of Literature

Background: Partial adrenalectomy (PA) is an alternative option to total adrenalectomy for the treatment of hereditary pheochromocytoma (PHEO) to preserve cortical function and avoid life-long steroid replacement. The aim of this review is to summarize current evidence in terms of clinical outcome, recurrence, and corticosteroid therapy implementation after PA for MEN2-PHEOs. Material and Methods: From a total of 931 adrenalectomies (1997-2022), 16 of the 194 patients who underwent surgical treatment of PHEO had MEN2 syndrome. There were six patients scheduled for PA. MEDLINE^®, EMBASE^®, Web of Science, and Cochrane Library were searched for English studies from 1981 to 2022. Results: Among six patients who underwent PA for MEN2-related PHEO in our center, we reported two with bilateral synchronous disease and three with metachronous PHEOs. One recurrence was registered. Less than 20 mg/day Hydrocortison therapy was necessary in 50% of patients after bilateral procedures. Systematic review identified 83 PA for MEN2-PHEO. Bilateral synchronous PHEO, metachronous PHEO and disease recurrence were reported in 42%, 26%, and 4% of patients, respectively. Postoperative steroid implementation was necessary in 65% of patients who underwent bilateral procedures. Conclusions: PA seems to be a safe and valuable option for the treatment of MEN2-related PHEOs, balancing the risk of disease recurrence with the need for corticosteroid therapy.

Simultaneous bilateral laparoscopic cortical-sparing adrenalectomy for bilateral pheochromocytomas in multiple endocrine neoplasia type 2

Purpose

This study aimed to assess the feasibility of synchronous bilateral laparoscopic or open cortical-sparing adrenalectomy (SB-LCSA or SB-OCSA) for bilateral pheochromocytomas (bPHEOs) in multiple endocrine neoplasia type 2 (MEN2).

Methods

Altogether, 31 patients (54.8% were women) were diagnosed with MEN2-related bPHEOs, and 29 of them underwent varying specific adrenalectomies. We systematically analyzed and evaluated their clinical profiles, mutation types, tumor histopathological features, and follow-up records.

Results

All 31 patients with bPHEOs presented with RET-C634 (90.3%) and RET-M918T (9.7%) mutations, and the median age at initial presentation was 38 years (range, 23-78). bPHEOs were synchronous in 27 patients and metachronous in 4 (12.9%) patients. In total, 29 patients underwent initial cortical-sparing adrenalectomy (CSA) including 23 (79.3%) undergoing synchronous bilateral CSA (18 SB-LCSA and 5 SB-OCSA) and 6 (20.7%) undergoing metachronous CSA. SB-LCSA and synchronous surgery were associated with less bleeding volume and shorter length of hospital stay than SB-OCSA and metachronous surgery (all P's < 0.05). Corticosteroid replacement treatment was necessary for 14 patients (45.2%) after bilateral CSA. During a median follow-up period of 7 years (range, 1.8-23), three of these patients (10.3%) had a recurrent disease that required reoperation.

Conclusion

SB-LCSA is feasible for treating synchronous bPHEOs and should be recommended as a prioritized surgical approach.

Total versus partial adrenalectomy in bilateral pheochromocytoma - a systematic review and meta-analysis

BACKGROUND

In patients with bilateral pheochromocytoma, partial adrenalectomy offers the chance to preserve adrenal function and avoid the need for lifelong steroid supplementation. However, the risk of tumour recurrence raises questions about this procedure. The aim of our study was to compare partial and total adrenalectomy in bilateral pheochromocytoma through a systematic review with meta-analysis.

METHODS

A systematic search was carried out using databases (MEDLINE, EMBASE, Scopus, Web of Science, CENTRAL) and registers of clinical trials (ClinicalTrials.gov, European Trials Register, WHO International Trials Registry Platform). This meta-analysis included studies up to July 2022 without language restrictions. A random effects model meta-analysis was performed to assess the risk of tumor recurrence, steroid dependence and morbidity in these patients.

RESULTS

Twenty-five studies were included in the analysis involving 1444 patients. The relative risk (RR) of loss of adrenal hormone function during follow-up and the need for steroid therapy was 0.32 in patients after partial adrenalectomy: RR 0.32, 95% Confidence Interval (CI): 0.26-0.38, P < 0.00001, I2 = 21%. Patients undergoing partial adrenalectomy had a lower odds ratio (OR) for developing acute adrenal crisis: OR 0.3, 95% CI: 0.1-0.91, P=0.03, I2 = 0%. Partial adrenalectomy was associated with a higher risk of recurrence than total adrenalectomy: OR 3.72, 95% CI: 1.54-8.96, P=0.003, I2 = 28%.

CONCLUSION

Partial adrenalectomy for bilateral pheochromocytoma is a treatment that offers a chance of preserving adrenal hormonal function, but is associated with a higher risk of local tumor recurrence. There was no difference for the risk of metastasis and in overall mortality among the group with bilateral pheochromocytomas undergoing total or partial adrenalectomy. This study is in line with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and AMSTAR (A Measurement Tool to Assess Systematic Reviews) Guidelines (10, 11).

SYSTEMATIC REVIEW REGISTRATION

https://osf.io/zx3se.

Laparoscopic resection of aortocaval paraganglioma diagnosed by serial increase in urinary metanephrines after bilateral adrenalectomy in a patient with multiple endocrine neoplasia type 2A

INTRODUCTION

Although bilateral pheochromocytoma is prevalent in patients with multiple endocrine neoplasia type 2, extra-adrenal tumors rarely occur in the aortocaval area.

CASE PRESENTATION

A 35-year-old man with multiple endocrine neoplasia type 2A (RET codon Cys634Arg mutation) underwent bilateral adrenalectomy for metachronous pheochromocytoma. After bilateral adrenalectomy, urinary metanephrines decreased below the measurement sensitivity. The levels of urinary metanephrines were serially elevating to a peak of 187 ng/mgCr during the 11-year follow-up period; however, urinary normetanephrine levels remained almost stable. 123I-metaiodobenzylguanidine single-photon emission computed tomography revealed abnormal accumulation with a mass of 25 × 18 mm in diameter in the aortocaval space cranially to the renal vessels. The extra-adrenal paraganglioma was successfully resected using transperitoneal laparoscopic surgery.

CONCLUSION

The serial increase in urinary metanephrine levels was useful for the detection of the recurrent tumor in a patient who had undergone bilateral adrenalectomy.

Phaeochromocytoma recurrence in a patient with multiple endocrine neoplasia type 2A

Multiple endocrine neoplasia type 2A (MEN2A) is a hereditary syndrome associated with tumours of the endocrine system. Principally, it is characterized by medullary thyroid carcinoma (MTC) with some individuals also developing phaeochromocytoma and hyperparathyroidism. Patients with fewer than two clinical features require either an identification of a germline rearranged in transfection mutation, or MEN2A characteristics in first-degree relatives, to establish a diagnosis of MEN2A. We present the case of a 54-year-old female with MEN2A, diagnosed by genetic screening, due to a substantial history of the disease in her ancestry. This case outlines the successful treatment of recurrent phaeochromocytoma, through the medium of radioactive iobenguane as an adjunct to surgical management. The report focuses particularly on the significance of innovative treatment strategies and forthcoming approaches to improve patient care in treating phaeochromocytoma in MEN2A.

Adrenal-sparing surgery: current concepts on a theme from the past

Adrenal insufficiency represents a debilitating condition which mandates lifelong steroid replacement and which is associated with significant long-term morbidity, due to either inadequate or excessive replacement. The concept of preserving healthy cortical tissue by means of partial adrenalectomy has evolved as a means of avoiding the detrimental consequences of adrenal insufficiency. The advent of advanced technology in adrenal surgery has greatly facilitated the performance of partial adrenalectomy, enabling utilization of this method in an increasing number of endocrine diseases. Hereditary pheochromocytoma, Conn's syndrome, Cushing's syndrome, and non-functional adrenal masses represent the current indications for partial adrenalectomy, although the specific circumstances under which adrenal-sparing surgery should be proposed are still debatable. Partial adrenalectomy can be achieved by all types of minimally invasive surgery. In the absence of randomized, prospective, controlled studies designed to compare laparoscopic, retroperitoneoscopic, and robot-assisted partial adrenalectomy, none of these techniques has as yet been proven to be the gold standard for adrenal-sparing surgery. Apart from indications for surgery, results of surgery, and different types of partial adrenalectomy, controversial topics addressed in this review article include technical aspects such as the volume of residual adrenal tissue needed, ligation of adrenal vein, and means of tumor identification. Discussion of these controversial topics represents an attempt to define the role of partial adrenalectomy in modern adrenal surgery.

100-Year evolution of precision medicine and surgery for multiple endocrine neoplasia type 2A

PURPOSE

To determine whether published disease penetrance estimates of 50% for pheochromocytoma and 20-30% for primary hyperparathyroidism in multiple endocrine neoplasia (MEN 2A), conceivably reflecting overrepresentation of index patients with completely developed MEN 2A, may be too high.

METHODS

Cross-sectional study of carriers at high risk of MEN 2A from a tertiary referral center.

RESULTS

There were 213 carriers of RET mutations in codon 634, born between 1922 and 2014. Median age of thyroidectomy was 17 years, with MTC being present in 76.5%; pheochromocytoma in 31.0% at a median of 34 years in the first, and in 18.8% at a median of 35 years in the second adrenal; and primary hyperparathyroidism in 10.8% at a median of 39 years. MTC, pheochromocytoma and primary hyperparathyroidism, stratified by year of birth, were diagnosed earlier over time: for MTC from 51 to 4 years; for pheochromocytoma from 51 to 22.5 years in the first, and from 51 to 29.5 years in the second adrenal, and for primary hyperparathyroidism from 46 to 12 years (P ≤ 0.008). This decline in age was paralleled by diminishing tumor diameters, more strongly in the thyroid (from 20 to 1.8 mm; P < 0.001) than in the adrenals (from 43 to 30 mm in the first, and from 20-57.5 to 30.5 mm in the second adrenal; statistically nonsignificant).

CONCLUSIONS

The lower disease penetrance estimates and sluggish decline of adrenal tumor diameters call for more widespread adoption of adrenal-sparing and parathyroid preservation surgery based on early and regular biochemical screening.

5P Strategies for Management of Multiple Endocrine Neoplasia Type 2: A Paradigm of Precision Medicine

Multiple endocrine neoplasia type 2 (MEN2) is a neuroendocrine cancer syndrome characterized by medullary thyroid carcinoma, in combination or not with pheochromocytoma, hyperparathyroidism, and extra-endocrine features. MEN2 syndrome includes two clinically distinct forms subtyped as MEN2A and MEN2B. Nearly all MEN2 cases are caused by germline mutations of the RET proto-oncogene. In this review, we propose "5P" strategies for management of MEN2: prevention, prediction, personalization, psychological support, and participation, which could effectively improve clinical outcomes of patients. Based on RET mutations, MEN2 could be prevented through prenatal diagnosis or preimplantation genetic testing. Identification of pathogenic mutations in RET can enable early diagnosis of MEN2. Combining RET mutation testing with measurement of serum calcitonin, plasma or urinary metanephrine/normetanephrine, and serum parathyroid hormone levels could allow risk stratification and accurately prediction of MEN2 progression, thus facilitating implementation of personalized precision treatments to increase disease-free survival and overall survival. Furthermore, increased awareness of MEN2 is needed, which requires participation of physicians, patients, family members, and related organizations. Psychological support is also important for patients with MEN2 to promote comprehensive management of MEN2 symptoms. The "5P" strategies for management of MEN2 represent a typical clinical example of precision medicine. These strategies could effectively improve the health of MEN2 patient, and avoid adverse outcomes, including death and major morbidity, from MEN2.

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.

Advances in the management of MEN2: from improved surgical and medical treatment to novel kinase inhibitors

Medullary thyroid carcinoma (MTC), a tumor derived from the neural crest, occurs either sporadically or as the dominant component of the type 2 multiple endocrine neoplasia (MEN) syndromes, MEN2A and MEN2B. The discovery that mutations in the RET protooncogene cause hereditary MTC was of great importance, since it led to the development of novel methods of diagnosis and treatment. For example, the detection of a mutated RET allele in family members at risk for inheriting MEN2A or MEN2B signaled that they would develop MTC, and possibly other components of the syndromes. Furthermore, the detection of a mutated allele created the opportunity, especially in young children, to remove the thyroid before MTC developed, or while it was confined to the gland. The discovery also led to the development of molecular targeted therapeutics (MTTs), mainly tyrosine kinase inhibitors, which were effective in the treatment of patients with locally advanced or metastatic MTC. While responses to MTTs are often dramatic, they are highly variable, and almost always transient, because the tumor cells become resistant to the drugs. Clinical investigators and the pharmaceutical industry are focusing on the development of the next generation of MTTs, which have minimal toxicity and greater specificity for mutated RET.

Composite paraganglioma-ganglioneuroma concomitant with adrenal metastasis of medullary thyroid carcinoma in a patient with multiple endocrine neoplasia type 2B: A case report

Multiple endocrine neoplasia type 2 (MEN2) is an autosomal-dominant cancer syndrome with major components of medullary thyroid carcinoma, pheochromocytoma, and hyperparathyroidism. MEN2B is the most aggressive and rarest of the MEN2 variants. Pheochromocytoma in MEN2 is virtually always located in the adrenal medulla, but MEN2-associated extra-adrenal pheochromocytomas (paraganglioma) are rare. A 59-year-old man who has been diagnosed with MEN2B consulted our hospital for surgical treatment of a 10-mm left adrenal mass and a 30-mm retroperitoneal mass. He had paroxysmal elevations in blood pressure and in urinary metanephrine and vanillylmandelic acid values. Laparoscopic excision of the left adrenal gland and retroperitoneal mass was performed. We experienced an extremely rare case of composite paraganglioma-ganglioneuroma concomitant with adrenal metastasis of medullary thyroid carcinoma in a patient with MEN2B.

MANAGEMENT OF ENDOCRINE DISEASE: Recurrence or new tumors after complete resection of pheochromocytomas and paragangliomas: a systematic review and meta-analysis

OBJECTIVES

To systematically review the incidence and factors associated with recurrences or new tumors after apparent complete resection of pheochromocytoma or thoraco-abdomino-pelvic paraganglioma.

DESIGN

A systematic review and meta-analysis of published literature was performed.

METHODS

Pubmed and Embase from 1980 to 2012 were searched for studies published in English on patients with non-metastatic pheochromocytoma or thoraco-abdomino-pelvic paraganglioma, complete tumor resection, postoperative follow-up exceeding 1 month, and recurrence or new tumor documented by pathology, hormonal dosages, or imaging tests. Incidence rates of new events after curative surgery were calculated for each study that had sufficient information and pooled using random-effect meta-analysis.

RESULTS

In total, 38 studies were selected from 3518 references, of which 36 reported retrospective cohorts from the USA, Europe, and Asia. Patient follow-up was neither standardized nor exhaustive in the included studies. A clear description of patient retrieval methods was available for nine studies and the follow-up protocol and patient flow for four studies. Only two studies used multivariable methods to assess potential predictors of postoperative events.The overall rate of recurrent disease from 34 studies was 0.98 events/100 person-years (95% confidence interval 0.71, 1.25). Syndromic diseases and paragangliomas were consistently associated with a higher risk of a new event in individual studies and in meta-regression analysis.

CONCLUSIONS

The risk of recurrent disease after complete resection of pheochromocytoma may be lower than that previously estimated, corresponding to five events for 100 patients followed up for 5 years after complete resection. Risk stratification is required to tailor the follow-up protocol after complete resection of a pheochromocytoma or paraganglioma. Large multicenter studies are needed to this end.

Multiple Endocrine Neoplasia: Genetics and Clinical Management

Early diagnosis of multiple endocrine neoplasia (MEN) syndromes is critical for optimal clinical outcomes; before the MEN syndromes can be diagnosed, they must be suspected. Genetic testing for germline alterations in both the MEN type 1 (MEN1) gene and RET proto-oncogene is crucial to identifying those at risk in affected kindreds and directing timely surveillance and surgical therapy to those at greatest risk of potentially life-threatening neoplasia. Pancreatic, thymic, and bronchial neuroendocrine tumors are the leading cause of death in patients with MEN1 and should be aggressively considered by at least biannual computed tomography imaging.

Revised American Thyroid Association guidelines for the management of medullary thyroid carcinoma

INTRODUCTION

The American Thyroid Association appointed a Task Force of experts to revise the original Medullary Thyroid Carcinoma: Management Guidelines of the American Thyroid Association.

METHODS

The Task Force identified relevant articles using a systematic PubMed search, supplemented with additional published materials, and then created evidence-based recommendations, which were set in categories using criteria adapted from the United States Preventive Services Task Force Agency for Healthcare Research and Quality. The original guidelines provided abundant source material and an excellent organizational structure that served as the basis for the current revised document.

RESULTS

The revised guidelines are focused primarily on the diagnosis and treatment of patients with sporadic medullary thyroid carcinoma (MTC) and hereditary MTC.

CONCLUSIONS

The Task Force developed 67 evidence-based recommendations to assist clinicians in the care of patients with MTC. The Task Force considers the recommendations to represent current, rational, and optimal medical practice.

Molecular diagnosis and comprehensive treatment of multiple endocrine neoplasia type 2 in Southeastern Chinese

Background

Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant inherited endocrine malignancy syndrome. Early and normative surgery is the only curative method for MEN 2-related medullary thyroid carcinoma (MTC). In patients with adrenal pheochromocytoma, cortical-sparing adrenalectomy (CSA) can be utilized to preserve adrenocortical function.

Methods

We present twenty-six of 33 MEN2 patients underwent prophylactic thyroidectomy with varying neck dissection and eight of 24 MEN2A patients with PHEO underwent adrenal-sparing surgery. Direct sequencing of entire RET exons was performed in all participants.

Results

The RET mutations (p.C634Y [n = 10], p.C634R [n = 9], p.C634F [n = 2], p.C618Y [n = 8], p.C618R [n = 3], and p.M918T [n = 1]) were confirmed in 20 symptomatic patients and identified in 13 at-risk relatives (RET carriers). Twenty-six of 33 MEN2 patients underwent thyroidectomies with neck dissections; the mean age at the time of the first thyroid surgery and the tumor diameter of the 6 RET carriers was decreased compared with 20 symptomatic patients (P < 0.001 and P = 0.007, respectively), while the disease-free survival was increased (80% vs.10%, P = 0.0001). Seven RET carriers who were declined surgery. One of 20 symptomatic patients with MTC bone metastases after surgery received vandetanib therapy for 20 months and responded well. Additionally, 8 of 24 MEN2A patients who initially had unilateral pheochromocytomas underwent CSA, 1 developed contralateral pheochromo cytomas 10 years later, then also accepted and also agreed to a CSA. None of the patients required steroid replacement therapy.

Conclusions

Based on our results, integrated RET screening and the pre-operative calcitonin level is an excellent strategy to ensure earlier diagnosis and standard thyroidectomy. CSA can be utilized to preserve adrenocortical function in patients with pheochromocytomas.

Electronic supplementary material

The online version of this article (doi:10.1186/s13053-015-0026-1) contains supplementary material, which is available to authorized users.

Hereditary Medullary Thyroid Cancer Genotype-Phenotype Correlation

During the last two decades, there has been a marked expansion of our knowledge of both the basic and clinical aspects of multiple endocrine neoplasia type 2 (MEN2). There are two clinically distinct types of MEN2 syndrome, termed MEN2A and MEN2B. Within MEN2A, there are four variants: (i) classical MEN2A, represented by the uniform presence of MTC and the less frequent occurrence of pheochromocytoma, or primary hyperparathyroidism, or both; (ii) MEN2A with cutaneous lichen amyloidosis; (iii) MEN2A with Hirschsprung's disease; and (iv) familial medullary thyroid carcinoma (FMTC), i.e., families or individuals with only MTC. MEN2B is associated with MTC, pheochromocytoma, and mucosal neuromas. Hereditary MTC is caused by autosomal dominant gain of function mutations in the RET proto-oncogene. Specific RET mutations may suggest a predilection toward a particular phenotype and clinical course with a strong genotype-phenotype correlation. Based upon these genotype-phenotype correlations, RET mutations are now stratified into three risk levels, i.e., highest, high, and moderate risk, based on the penetrance and aggressiveness of the MTC. Children in the highest risk category should undergo thyroidectomy in their first year of life, and perhaps even in their first months of life. Children in the high-risk category should have ultrasound of the neck and calcitonin (CTN) measurement performed prior to thyroidectomy. Thyroidectomy should typically be performed at the age of 5 or earlier, depending on the presence of elevated serum CTN levels. However, heterogeneity in disease expression and progression within these groups varies considerably. To personalize disease management, the decision regarding the age of prophylactic thyroidectomy is no longer based upon genotype alone but is currently driven by additional clinical data, the most important being serum CTN levels; specifically, the decision to perform thyroidectomy should err on the safe side if the CTN level is elevated but below 30 pg/ml, especially in the moderate risk group. Personalized management also includes decisions about the best age to begin biochemical screening for pheochromocytoma and primary hyperparathyroidism.

Diagnosis and preoperative imaging of multiple endocrine neoplasia type 2: current status and future directions

Multiple endocrine neoplasia type 2 (MEN2) is a rare autosomal dominant syndrome caused by mutations in the RET protooncogene and is characterized by a strong penetrance of medullary thyroid carcinoma (all subtypes) and is often accompanied by pheochromocytoma (MEN2A/2B) and primary hyperparathyroidism (MEN2A). The evaluation and management of MEN2-related tumours is often different from that of sporadic counterparts. This review article provides an overview of clinical manifestations, diagnosis and surgical management of MEN2 patients. This review also presents applications of the most up-to-date imaging modalities to MEN2 patients that are tightly linked to the clinical management and aims to guide physicians towards a rationale for the use of imaging prior to prophylactic thyroidectomy, initial surgery and reoperations for persistent/recurrent disease. This review also concludes that, in the near future, it is expected that these patients will indeed benefit from newly developed positron emission tomography approaches which will target peptide receptors and protein kinases. Identification of MEN2-specific radiopharmaceuticals will also soon arise from molecular profiling studies. Furthermore, subtotal (cortical-sparing) adrenalectomy, which is a valid option in MEN2 for avoiding long-term steroid replacement, will benefit from an accurate estimation through imaging of differential adrenocortical function.

Multiplicity of hormone-secreting tumors: common themes about cause, expression, and management

CONTEXT

Multiplicity of hormone-secreting tumors occurs in a substantial portion of hormone-excess states. Multiplicity increases the difficulty of management and drives the selection of special strategies.

EVIDENCE ACQUISITION

This is a synthesis from publications about tumor development and expression, and also about types of clinical strategy for hormone-secreting tumors.

EVIDENCE SYNTHESIS

Comparisons were made between patient groups with solitary tumors vs those with multiple tumors. Major themes with clinical relevance emerged. Usually, tumor multiplicity develops from a genetic susceptibility in all cells of a tissue. This applies to hormone-secreting tumors that begin as either polyclonal (such as in the parathyroids of familial hypocalciuric hypercalcemia) or monoclonal tumors (such as in the parathyroids of multiple endocrine neoplasia type 1 [MEN1]). High penetrance of a hereditary tumor frequently results in bilaterality and in several other types of multiplicity. Managements are better for the hormone excess than for the associated cancers. Management strategies can be categorized broadly as ablation that is total, subtotal, or zero. Examples are discussed for each category, and 1 example of each category is named here: 1) total ablation of the entire tissue with effort to replace ablated functions (for example, in C-cell neoplasia of multiple endocrine neoplasia type 2); 2) subtotal ablation with increased likelihood of persistent disease or recurrent disease (for example, in the parathyroid tumors of MEN1); or 3) no ablation of tissue with or without the use of pharmacotherapy (for example, with blockers for secretion of stomach acid in gastrinomas of MEN1).

CONCLUSIONS

Tumor multiplicity usually arises from defects in all cells of the precursor tissue. Even the optimized managements involve compromises. Still, an understanding of pathophysiology and of therapeutic options should guide optimized management.

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

CONTEXT

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

EVIDENCE ACQUISITION

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

EVIDENCE SYNTHESIS

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

CONCLUSIONS

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