Surgical Treatment of Hyperparathyroidism in Patients With Multiple Endocrine Neoplasia Type 1

Evaluation and Surgical Management of Multiple Endocrine Neoplasias

Multiple endocrine neoplasia (MEN) syndromes are rare autosomal dominant diseases that are associated with a mixture of both endocrine and non-endocrine tumors. Traditionally, there are 2 types of MEN that have unique clinical associations: MEN 1 (parathyroid hyperplasia, pancreatic neuroendocrine tumors, and pituitary tumors) and MEN 2 (medullary thyroid carcinoma and pheochromocytoma), which is further classified into MEN 2A (adds parathyroid adenomas) and 2B (adds ganglioneuromas and marfanoid habitus). Many of the endocrine tumors are resected surgically, and the pre, intra, and postoperative management strategies used must take into account the high recurrence rates asscioated with MEN tumors.

Molecular and Clinical Spectrum of Primary Hyperparathyroidism

Recent data suggest an increase in the overall incidence of parathyroid disorders, with primary hyperparathyroidism (PHPT) being the most prevalent parathyroid disorder. PHPT is associated with morbidities (fractures, kidney stones, chronic kidney disease) and increased risk of death. The symptoms of PHPT can be nonspecific, potentially delaying the diagnosis. Approximately 15% of patients with PHPT have an underlying heritable form of PHPT that may be associated with extraparathyroidal manifestations, requiring active surveillance for these manifestations as seen in multiple endocrine neoplasia type 1 and 2A. Genetic testing for heritable forms should be offered to patients with multiglandular disease, recurrent PHPT, young onset PHPT (age ≤40 years), and those with a family history of parathyroid tumors. However, the underlying genetic cause for the majority of patients with heritable forms of PHPT remains unknown. Distinction between sporadic and heritable forms of PHPT is useful in surgical planning for parathyroidectomy and has implications for the family. The genes currently known to be associated with heritable forms of PHPT account for approximately half of sporadic parathyroid tumors. But the genetic cause in approximately half of the sporadic parathyroid tumors remains unknown. Furthermore, there is no systemic therapy for parathyroid carcinoma, a rare but potentially fatal cause of PHPT. Improved understanding of the molecular characteristics of parathyroid tumors will allow us to identify biomarkers for diagnosis and novel targets for therapy.

Predicting multigland disease in primary hyperparathyroidism using ultrasound and clinical features

Background

The identification of multigland disease (MGD) in primary hyperparathyroidism (PHPT) patients is essential for minimally invasive surgical decision-making.

Objective

To develop a nomogram based on ultrasound (US) findings and clinical factors to predict MGD in PHPT patients.

Materials and methods

Patients with PHPT who had surgery between March 2021 and January 2022 were consecutively enrolled to this study. Biochemical and clinicopathological data were recorded. US images were analyzed to extract US features for prediction. Logistic regression analyses were used to identify MGD risk factors. A nomogram was constructed based on these factors and its performance evaluated by area under the receiver operating characteristic curve (AUC), calibration curve, Hosmer-Lemeshow tests, and decision curve analysis (DCA).

Results

A total of 102 PHPT patients were included; 82 (80.4%) had single-gland disease (SGD) and 20 (19.6%) had MGD. Using multivariate analyses, MGD was positively correlated with age (odds ratio (OR) = 1.033, 95% confidence interval (CI): 0.190-4.047), PTH levels (OR = 1.001, 95% CI: 1.000-1.002), multiple endocrine neoplasia type 1 (MEN1) (OR = 29.730, 95% CI: 3.089-836.785), US size (OR = 1.198, 95% CI: 0.647-2.088), and US texture (cystic-solid) (OR = 5.357, 95% CI: 0.499-62.912). MGD was negatively correlated with gender (OR = 0.985, 95% CI: 0.190-4.047), calcium levels (OR = 0.453, 95% CI: 0.070-2.448), and symptoms (yes) (OR = 0.935, 95% CI: 0.257-13.365). The nomogram showed good discrimination with an AUC = 0.77 (0.68-0.85) and good agreement in predicting MGD in PHPT patients. Also, 65 points was recommended as a cut-off value, with specificity = 0.94 and sensitivity = 0.50.

Conclusion

US was useful in evaluating MGD. Combining US and clinical features in a nomogram showed good diagnostic performance for predicting MGD.

Less Than Subtotal Parathyroidectomy for Multiple Endocrine Neoplasia Type 1 Primary Hyperparathyroidism: A Systematic Review and Meta-Analysis

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN1)-associated primary hyperparathyroidism (pHPT) is classically associated with an asymmetric and asynchronous parathyroid involvement. Subtotal parathyroidectomy (STP), which is currently the recommended surgical treatment, carries a high risk of permanent hypoparathyroidism. The results of less than subtotal parathyroidectomy (LSTP) are conflicting, and its place in this setting is still a matter of debate. The aim of this study was to identify the place of LSTP in the surgical management of patients with MEN-associated pHPT.

METHODS

A systematic literature review was conducted in accordance with PRISMA and MOOSE guidelines, for studies comparing STP and LSTP for MEN1-associated pHPT. The results of the two techniques, regarding permanent hypoparathyroidism, persistent hyperparathyroidism and recurrent hyperparathyroidism were computed using pairwise random-effect meta-analysis.

RESULTS

Twenty-five studies comparing STP and LSTP qualified for inclusion in the quantitative synthesis. In total, 947 patients with MEN1-associated pHPT were allocated to STP (n = 569) or LSTP (n = 378). LSTP reduces the risk of permanent hypoparathyroidism [odds ratio (OR) 0.29, confidence interval (CI) 95% 0.17-0.49)], but exposes to higher rates of persistent hyperparathyroidism [OR 4.60, 95% CI 2.66-7.97]. Rates of recurrent hyperparathyroidism were not significantly different between the two groups [OR 1.26, CI 95% 0.83-1.91].

CONCLUSIONS

LSTP should not be abandoned and should be considered as a suitable surgical option for selected patients with MEN1-associated pHPT. The increased risk of persistent hyperparathyroidism could improve with the emergence of more efficient preoperative localization imaging techniques and a more adequate patients selection.

Impact of parathyroidectomy on quality of life in multiple endocrine neoplasia type 1

BACKGROUND

Potential influences of parathyroidectomy (PTx) on the quality of life (QoL) in multiple endocrine neoplasia type 1-related primary hyperparathyroidism (HPT/MEN1) are unknown.

METHOD

Short Form 36 Health Survey Questionnaire was prospectively applied to 30 HPT/MEN1 patients submitted to PTx (20, subtotal; 10, total with autograft) before, 6 and 12 months after surgery. Parameters that were analyzed included QoL, age, HPT-related symptoms, general pain, comorbidities, biochemical/hormonal response, PTx type and parathyroid volume.

RESULTS

Asymptomatic patients were younger (30 vs 38 years; P = 0.04) and presented higher QoL scores than symptomatic ones: Physical Component Summary score (PCS) 92.5 vs 61.2, P = 0.0051; Mental Component Summary score (MCS) 82.0 vs 56.0, P = 0.04. In both groups, QoL remained stable 1 year after PTx, independently of the number of comorbidities. Preoperative general pain was negatively correlated with PCS (r = -0.60, P = 0.0004) and MCS (r = -0.57, P = 0.0009). Also, moderate/intense pain was progressively (6/12 months) more frequent in cases developing hypoparathyroidism. The PTx type and hypoparathyroidism did not affect the QoL at 12 months although remnant parathyroid tissue volume did have a positive correlation (P = 0.0490; r = 0.3625) to PCS 12 months after surgery. Patients with one to two comorbidities had as pre-PTx PCS (P = 0.0015) as 12 months and post-PTx PCS (P = 0.0031) and MCS (P = 0.0365) better than patients with three to four comorbidities.

CONCLUSION

A variable QoL profile was underscored in HPT/MEN1 reflecting multiple factors associated with this complex disorder as comorbidities, advanced age at PTx and presence of preoperative symptoms or of general pain perception. Our data encourage the early indication of PTx in HPT/MEN1 by providing known metabolic benefits to target organs and avoiding potential negative impact on QoL.

Multiple Endocrine Neoplasia in Childhood: An Update on Diagnosis, Screening, Management and Treatment

Multiple endocrine neoplasia (MEN) is a group of heterogenous syndromes characterized by the occurrence of two or more endocrine gland tumors in a patient or related individuals in the same family. They are inherited in an autosomal dominant fashion and are highly penetrant. There are three types of MEN syndromes: MEN type 1 (MEN1), MEN type 2 (MEN2), and MEN type 4 (MEN4). MEN2 is further divided into MEN2A, MEN2B (formerly known MEN3), and familial medullary thyroid carcinoma (FMTC). Although MEN syndromes are rare, it is crucial to identify individuals at risk for potentially life-threatening neoplasias. This review article provides an update on each MEN syndrome, its genetics, diagnosis, and management in children.

[The clinical practice guidelines for primary hyperparathyroidism, short version]

Primary hyperparathyroidism (PHPT) is an endocrine disorder of parathyroid glands characterized by excessive secretion of parathyroid hormone (PTH) with an upper normal or elevated blood calcium level. Classical PHPT refers to a symptomatic, multi-system disorder, wich can lead to a significant decrease in the quality of life, disability of patients, and even an increased risk of premature death. Hypercalcemia and the catabolic effect of PTH on various cells are considered as the main pathogenetic mechanisms of the PHPT associated complications. In the last two decades, there has been an increase in the incidence of PHPT, mainly due to the mild forms of the disease, primarily due to the routine calcium screening in North America, Western Europe and, Asia. High prevalence of the disease, as well as the variety of clinical manifestations, cause the attention of different specialists - physicians, rheumatologists, urologists, nephrologists, cardiologists and other doctors. This review cover the main issues of Russian guidelines for the management of PHPT, approved in 2020, including laboratory and instrumental methods, differential diagnosis, surgical and conservative approach, short-term and long-term follow-up. This guidelines also include the recommendations for special groups of patients with hereditary forms of PHPT, parathyroid carcinoma, PHPT during pregnancy.

Optimal extent of initial parathyroid resection in patients with multiple endocrine neoplasia syndrome type 1: A meta-analysis

BACKGROUND

Hyperparathyroidism is an almost universal feature of multiple endocrine neoplasia type 1 syndrome. We present a systematic review and meta-analysis of the postoperative outcomes of patients undergoing initial operative treatment of primary hyperparathyroidism complicating multiple endocrine neoplasia 1.

METHODS

A comprehensive literature search was performed with a priori defined exclusion criteria for studies comparing total parathyroidectomy, subtotal parathyroidectomy, and less than subtotal parathyroidectomy.

RESULTS

Twenty-one studies incorporating 1,131 patients (272 undergoing total parathyroidectomy, 510 subtotal parathyroidectomy, and 349 less than subtotal parathyroidectomy) were identified. Pooled results revealed increased risk for long-term hypoparathyroidism in total parathyroidectomy patients (relative risk 1.61; 95% confidence interval, 1.12-2.31; P = .009) versus those undergoing subtotal parathyroidectomy. In the less than subtotal parathyroidectomy or subtotal parathyroidectomy comparison group, a greater risk for recurrence of hyperparathyroidism (relative risk 1.37; 95% confidence interval, 1.05-1.79; P = .02), persistence of hyperparathyroidism (relative risk 2.26; 95% confidence interval, 1.49-3.41; P = .0001), and reoperation for hyperparathyroidism (relative risk 2.48; 95% confidence interval, 1.65-3.73; P < .0001) was noted for less than subtotal parathyroidectomy patients, albeit with lesser risk for long-term for hypoparathyroidism (relative risk 0.47; 95% confidence interval, 0.29-0.75; P = .002).

CONCLUSION

Subtotal parathyroidectomy compares favorably to total parathyroidectomy, exhibiting similar recurrence and persistence rates with a decreased propensity for long-term postoperative hypoparathyroidism. The benefit of the decreased risk of hypoparathyroidism in less than subtotal parathyroidectomy is negated by the increase in the risk for recurrence, persistence, and reoperation. Future studies evaluating the performance of less than subtotal parathyroidectomy in specific multiple endocrine neoplasia 1 phenotypes should be pursued in an effort to delineate a patient-tailored, operative approach that optimizes long-term outcomes.

[Hereditary syndromal and nonsyndromal forms of primary hyperparathyroidism]

Primary hyperparathyroidism is a common disorder of mineral homeostasis, characterized by overproduction of parathyroid hormone and upper normal or elevated calcium levels due to hyperplasia or a tumor of parathyroid gland. 90&minus;95% of cases of primary hyperparathyroidism are sporadic, while hereditary genetic forms occur in 5&ndash;10% of all cases. Primary hyperparathyroidism as the component of hereditary syndromes can present in various clinical forms (asymptomatic, symptomatic), can be associated with other endocrine or non-endocrine diseases, and require special approaches to treatment. Given that primary hyperparathyroidism is one of the most common components of these syndromes, it can be used as an important diagnostic tool in identifying affected families. This review is devoted to modern ideas about the clinical course and genetic characteristics of hereditary variants of primary hyperparathyroidism and the diagnostic and treatment algorithms recommended today. The review considers primary hyperparathyroidism as a component of hereditary syndromes including multiple endocrine neoplasias types 1, 2A and 4 and syndrome of hyperparathyroidism with a jaw tumor. Also non-syndromic hereditary forms are descripted, such as familial isolated hyperparathyroidism, familial hypocalciuric hypercalcemia, and severe neonatal primary hyperparathyroidism.

Concomitant Thyroid Cancer in Patients with Multiple Endocrine Neoplasia Type 1 Undergoing Surgery for Primary Hyperparathyroidism

BACKGROUND

Compared to those with sporadic primary hyperparathyroidism (SPHP), multiple endocrine neoplasia type 1 (MEN1) patients with primary hyperparathyroidism (MPHP) typically require more extensive dissection and have higher recurrence rates. Little is known about the risk of concomitant thyroid cancer in either setting. This study aimed to determine the rates and characteristics of thyroid cancer for MPHP versus SPHP patients undergoing parathyroidectomy.

METHODS

Patients with MPHP (diagnosed by clinical and/or genetic criteria) or SPHP who had initial or reoperative parathyroid exploration from 1967 to 2014 were identified via a prospective database. The thyroid cancer-specific data for MPHP patients (n = 29) were compared to a selected 2:1 age- and sex-matched SPHP cohort (n = 58) who all had concurrent thyroidectomy for any reason. Clinically significant thyroid cancer was defined as >1 cm in diameter.

RESULTS

In the MPHP group, 24/29 (83%) thyroidectomies were preoperatively unplanned versus 20/58 (34%) in the SPHP matched cohort (p < 0.01), and in this setting there was no difference in the rate of histologic thyroid cancer (3/24 [13%] vs. 5/20 [25%], p = 0.44). Histologic thyroid cancer was identified in 8/29 (28%) MPHP versus 27/58 (47%) SPHP patients (p = 0.11). Despite observed differences in the time period and extent of thyroidectomy, MPHP patients did not have an increased likelihood of thyroid cancer (surgery before 2005: odds ratio [OR] = 2.57, p = 0.09; total thyroidectomy: OR = 5.47, p < 0.01; MPHP: OR = 1.14, p = 0.83). All MPHP thyroid cancers were characterized as conventional papillary thyroid cancer (PTC), while thyroid cancers in SPHP patients included both PTC (66%) and follicular-variant PTC (34%). No MPHP patient had clinically significant thyroid cancer compared to an incidence of 15/58 (26%) in SPHP patients (p < 0.01).

CONCLUSIONS

Although patients with MEN1 have a substantial incidence of thyroid cancer (28%) and undergo more unplanned thyroidectomies during parathyroidectomy than do patients with SPHP, clinically significant thyroid cancer is proportionally uncommon.

Impact of "Tailored" Parathyroidectomy for Treatment of Primary Hyperparathyroidism in Patients with Multiple Endocrine Neoplasia Type 1

BACKGROUND

Whether total parathyroidectomy (TPTX) or subtotal parathyroidectomy (SPTX) should be performed for primary hyperparathyroidism (PHPT) in patients with multiple endocrine neoplasia type 1 (MEN1) is controversial. At our institution, the parathyroidectomy strategy is based on the number of enlarged intraoperative parathyroid glands. We retrospectively analyzed our parathyroidectomy procedures.

METHODS

Data of PHPT treatment in patients with MEN1 who underwent parathyroidectomy from 1982 to 2012 at our department were retrospectively collected. The data were grouped according to the surgical procedure: TPTX, SPTX, and less than SPTX (LPTX). TPTX or SPTX was selected based on the preoperative examination findings and number of enlarged intraoperative parathyroid glands. The outcomes were the disease-free survival (DFS) rate and postoperative calcium replacement rate based on Kaplan-Meier analysis for each type of surgical procedure.

RESULTS

Forty-five patients were analyzed. The overall 5- and 10-year DFS was 91.7 and 55.8%, respectively. The 5- and 10-year DFS in each subgroup was 100.0 and 85.7% in the TPTX group, 89.4 and 57.3% in the SPTX group, and 91.6 and 57.3% in the LPTX group, respectively. The postoperative calcium replacement rate at 1 and 12 months was 91.7 and 58.3% in the TPTX group, 21.1 and 7.0% in the SPTX group, and 30.0 and 0.0% in the LPTX group, respectively.

CONCLUSIONS

Although LPTX was not satisfactory as a standard procedure, both SPTX and TPTX are effective treatment methods for PHPT in patients with MEN1. The parathyroidectomy strategy should be based on intraoperative evaluation of the parathyroid glands.

Intraoperative Decision-Making and Technical Aspects of Parathyroidectomy in Young Patients With MEN1 Related Hyperparathyroidism

One in 5,000 to 1 in 50,000 births have multiple endocrine neoplasia type 1 (MEN1). MEN1 is a hereditary syndrome clinically defined by the presence of two of the following endocrine tumors in the same patient: parathyroid adenomas, entero-pancreatic endocrine tumors and pituitary tumors. Most commonly, patients with MEN1 manifest primarily with signs and symptoms linked to primary hyperparathyroidism. By age 50, it is estimated that 100% of patients with MEN1 will have been diagnosed with primary hyperparathyroidism. These patients will need to undergo resection of their hyperfunctioning glands, however there is no clear consensus on which procedure to perform and when to perform it in these patients. In this original study we describe and explain the rational of our peri-operative approach and management at MD Anderson Cancer Center of MEN1 patients with hyperparathyroidism. This protocol includes preoperative evaluation, intraoperative decision-making and detailed surgical technique adopted for these patients' care. Additionally we review follow-up and disease management in instances of recurrent primary hyperparathyroidism in patients with MEN1 syndrome.

The future: medical advances in MEN1 therapeutic approaches and management strategies

Multiple endocrine neoplasia type 1 is a rare autosomal inherited disorder associated with a high risk for patients to simultaneously develop tumors of the parathyroid glands, duodenopancreatic neuroendocrine tumors and tumors of the anterior pituitary gland. Early identification of MEN1 in patients enables presymptomatic screening of manifestations, which makes timely interventions possible with the intention to prevent morbidity and mortality. Causes of death nowadays have shifted toward local or metastatic progression of malignant neuroendocrine tumors. In early cohorts, complications like peptic ulcers in gastrinoma, renal failure in hyperparathyroidism, hypoglycemia and acute hypercalcemia were the primary causes of early mortality. Improved medical treatments of these complications led to a significantly improved life expectancy. The MEN1 landscape is still evolving, considering the finding of breast cancer as a new MEN1-related manifestation and ongoing publications on follow-up and medical care for patients with MEN1. This review aims at summarizing the most recent insights into the follow-up and medical care for patients with MEN1 and identifying the gaps for future research.

Hereditary hyperparathyroidism--a consensus report of the European Society of Endocrine Surgeons (ESES)

BACKGROUND

Hereditary hyperparathyroidism has been reported to occur in 5-10 % of cases of primary hyperparathyroidism in the context of multiple endocrine neoplasia (MEN) types 1, 2A and 4; hyperparathyroidism-jaw tumour (HPT-JT); familial isolated hyperparathyroidism (FIHPT); familial hypocalciuric hypercalcaemia (FHH); neonatal severe hyperparathyroidism (NSHPT) and autosomal dominant moderate hyperparathyroidism (ADMH). This paper aims to review the controversies in the main genetic, clinical and pathological features and surgical management of hereditary hyperparathyroidism.

METHODS

A peer review literature analysis on hereditary hyperparathyroidism was carried out and analyzed in an evidence-based perspective. Results were discussed at the 2015 Workshop of the European Society of Endocrine Surgeons devoted to hyperparathyroidism due to multiple gland disease.

RESULTS

Literature reports scarcity of prospective randomized studies; thus, a low level of evidence may be achieved.

CONCLUSIONS

Hereditary hyperparathyroidism typically presents at an earlier age than the sporadic variants. Gene penetrance and expressivity varies. Parathyroid multiple gland involvement is common, but in some variants, it may occur metachronously often with long disease-free intervals, simulating a single-gland involvement. Bilateral neck exploration with subtotal parathyroidectomy or total parathyroidectomy + autotransplantation should be performed, especially in MEN 1, in order to decrease the persistent and recurrent hyperparathyroidism rates; in some variants (MEN 2A, HPT-JT), limited parathyroidectomy can achieve long-term normocalcemia. In FHH, surgery is contraindicated; in NSHPT, urgent total parathyroidectomy is required. In FIHPT, MEN 4 and ADMH, a tailored case-specific approach is recommended.

Value of Prophylactic Cervical Thymectomy in Parathyroid Hyperplasia

BACKGROUND

In parathyroid hyperplasia (HPT), parathyroid glands within the cervical thymus are a cause for recurrence. As a result of differences in pathophysiology, variable practice patterns exist regarding performing bilateral cervical thymectomy (BCT) in primary hyperplasia versus hyperplasia from renal failure or familial disease. The objective of this study was to capture patients where thymic tissue was found with subtotal parathyroidectomy (PTX) and intended BCT, identify number of thymic supernumerary glands (SNGs), and determine overall cure rate.

METHODS

Retrospective review of patients with four-gland exploration and intended BCT for HPT from 2000 to 2013 was performed. Identification of thymic tissue and SNGs were determined by operative/pathology reports. Univariate analysis identified differences in cure rate for patients undergoing subtotal PTX with or without BCT.

RESULTS

Thymic tissue was found in 52 % of 328 primary HPT (19 % unilateral, 33 % bilateral), 77 % of 128 renal HPT (28 % unilateral, 49 % bilateral), and 100 % of familial HPT (24 % unilateral, 76 % bilateral) patients. Nine percent of primary, 18 % of renal, and 10 % of familial HPT patients had SNGs within thymectomy specimens. Cure rates of primary HPT patients with BCT were 99 % compared to 94 % in subtotal PTX alone. Renal HPT cure rates were 94 % with BCT compared to 89 % without BCT.

CONCLUSIONS

Renal HPT patients benefited most in cure when thymectomy was performed. Although the rate of SNGs found in primary HPT was lower than renal HPT, the cure rate mimicked the pattern in renal disease. Furthermore, the incidences of SNGs in primary and familial HPT were similar. On the basis of these data, we advocate that BCT be considered in primary HPT when thymic tissue is readily identified.

Familial syndromes associated with neuroendocrine tumours

Neuroendocrine tumours may be associated with familial syndromes. At least eight inherited syndromes predisposing to endocrine neoplasia have been identified. Two of these are considered to be major factors predisposing to benign and malignant endocrine tumours, designated multiple endocrine neoplasia type 1 and type 2 (MEN1 and MEN2). Five other autosomal dominant diseases show more heterogeneous clinical patterns, such as the Carney complex, hyperparathyroidism-jaw tumour syndrome, Von Hippel-Lindau syndrome (VHL), neurofibromatosis type 1 (NF1) and tuberous sclerosis. The molecular and cellular interactions underlying the development of most endocrine cells and related organs represent one of the more complex pathways not yet to be deciphered. Almost all endocrine cells are derived from the endoderm and neuroectoderm. It is suggested that within the first few weeks of human development there are complex interactions between, firstly, the major genes involved in the initiation of progenitor-cell differentiation, secondly, factors secreted by the surrounding mesenchyme, and thirdly, a series of genes controlling cell differentiation, proliferation and migration. Together these represent a formula for the harmonious development of endocrine glands and tissue.

Outcomes after subtotal parathyroidectomy for primary hyperparathyroidism due to hyperplasia: significance of whole vs. partial gland remnant

INTRODUCTION

Primary hyperparathyroidism (PHPT) due to multigland hyperplasia is managed by subtotal parathyroidectomy (sPTX), with a partial gland left in situ. However, smaller, hyperplastic glands may be encountered intraoperatively, and it is unclear if leaving an intact gland is an equivalent alternative. This study evaluates the rates of permanent hypoparathyroidism and cure of PHPT patients with four-gland hyperplasia that were left with either a whole gland remnant (WGR) or a partial gland remnant (PGR) after sPTX.

METHODS

We reviewed the outcomes of PHPT patients with hyperplasia who underwent sPTX at an academic institution. Surgeon intraoperative judgment determined remnant size (a WGR vs. a PGR).

RESULTS

Between 2002 and 2013, 172 patients underwent sPTX for PHPT. There were 108 patients (62.8%) who had a WGR. Another 64 patients (37.2%) had a PGR. Mean age was 60 ± 14 years. There were 82.6% female patients. Cases with positive family history for PHPT were more likely to have a PGR (12.5 vs. 3.7%; p = 0.03). Patients had similar preoperative and postoperative laboratories. Individuals with a PGR tended to have larger glands encountered by surgeons intraoperatively (525 ± 1,308 vs. 280 ± 341 mg; p = 0.02). One patient with a WGR developed permanent hypocalcemia. Overall, the cure rate was 97.1%. A mean of 29 ± 28.7 months follow-up revealed a recurrence rate of 5.2%. Disease persistence and recurrence rates were similar in patients.

CONCLUSION

PHPT due to hyperplasia is managed by sPTX, leaving WGR without increased rates of disease persistence/recurrence. Patients without family history for hyperparathyroidism and those with smaller glands may be the best candidates for this approach.

GEP-NETS update: a review on surgery of gastro-entero-pancreatic neuroendocrine tumors

The incidence of neuroendocrine tumors (NETs) has increased in the last decades. Surgical treatment encompasses a panel of approaches ranging from conservative procedures to extended surgical resection. Tumor size and localization usually represent the main drivers in the choice of the most appropriate surgical resection. In the presence of small (<2 cm) and asymptomatic nonfunctioning NETs, a conservative treatment is usually recommended. For localized NETs measuring above 2 cm, surgical resection represents the cornerstone in the management of these tumors. As they are relatively biologically indolent, an extended resection is often justified also in the presence of advanced NETs. Surgical options for NET liver metastases range from limited resection up to liver transplantation. Surgical choices for metastatic NETs need to consider the extent of disease, the grade of tumor, and the presence of extra-abdominal disease. Any surgical procedures should always be balanced with the benefit of survival or relieving symptoms and patients' comorbidities.

Preoperative multiple endocrine neoplasia type 1 diagnosis improves the surgical outcomes of pediatric patients with primary hyperparathyroidism

BACKGROUND

Primary hyperparathyroidism (PHPT) is uncommon in children. The surgical management of PHPT in children has evolved over the past two decades.

METHODS

A retrospective study of patients who underwent parathyroidectomy for PHPT diagnosed at age < 18 years and managed at a tertiary referral center for endocrine and familial disorders.

RESULTS

Thirty-eight patients met eligibility criteria (1981-2012). Median age at PHPT diagnosis was 15 years. Two-thirds of patients were symptomatic (68%, n=26), most commonly from nephrolithiasis. Twenty-six (68%) patients underwent a standard cervical exploration while 32% underwent a focused unilateral parathyroidectomy. Multiple endocrine neoplasia type 1 (MEN1) was diagnosed preoperatively in 22/26 patients. Patients with a preoperative diagnosis of MEN1 were more likely to undergo a complete initial operation (≥ 3 gland parathyroidectomy with transcervical thymectomy, 13/22, 59% vs. 0/4, 0%; P=0.03) and less likely to have recurrent disease (10/22, 45% vs. 3/4, 75%; P<0.001) during follow up than patients diagnosed postoperatively.

CONCLUSIONS

Children with PHPT should raise suspicion for MEN1. Preoperative MEN1 evaluation helped guide the extent of initial parathyroidectomy and was associated with lower rates of recurrence in sporadic and familial PHPT in pediatric patients. Management should occur at a high volume center with experienced clinicians and genetic counseling services.

Recovery of parathyroid hormone secretion and function in postoperative hypoparathyroidism: a case series

CONTEXT

Transient and permanent postoperative hypoparathyroidism are recognized complications of neck surgery. Postoperative hypoparathyroidism is usually considered permanent when it persists for 6 months; in rare cases, recovery of hypoparathyroidism through 1 year has been described. Recovery of hypoparathyroidism years after diagnosis has not previously been reported.

OBJECTIVE

We report four patients being treated with PTH(1-84) in a research protocol who recovered from postoperative hypoparathyroidism many years after onset.

METHODS

Recovery from hypoparathyroidism was established by: 1) serum calcium and PTH levels within the normal range off PTH(1-84) treatment for at least 1 week; 2) requirement for daily calcium supplementation reduced to ≤1 g; and 3) no supplemental active vitamin D therapy.

RESULTS

Hypoparathyroidism developed in three subjects after repeated neck surgery for primary hyperparathyroidism and in one subject after total thyroidectomy for Graves' disease. Parathyroid tissue autotransplant was performed in two of the four subjects. Two had undetectable PTH levels at study entry, whereas the other two subjects had detectable, although low, PTH levels. Hypoparathyroidism had been present for at least 8 years, and in one case for 16 years. The recovery of parathyroid function followed treatment with PTH(1-84) for 36 to 63 months.

CONCLUSIONS

Although it remains relatively rare, this report documents recovery of long-term postoperative hypoparathyroidism many years after the initial diagnosis. A potential role for exogenous PTH is intriguing with several plausible mechanisms.

Differences between sporadic and MEN related primary hyperparathyroidism; clinical expression, preoperative workup, operative strategy and follow-up

Background

Primary hyperparathyroidism (PHPT) is most commonly sporadic (sPHPT). However, sometimes PHPT develops as part of multiple endocrine neoplasia (MEN) type 1 or 2A. In all, parathyroidectomy is the only curative treatment. Nevertheless, there are important differences in clinical expression and treatment.

Methods

We analyzed a consecutive cohort of patients treated for sporadic, MEN1-related, and MEN2A-related PHPT and compared them regarding clinical and biochemical parameters, differences in preoperative workup, operative strategies, findings, and outcome.

Results

A total of 467 patients with sPHPT, 52 with MEN1- and 16 with MEN2A-related PHPT were analyzed. Patients with sPHPT were older, more often female and had higher preoperative calcium and parathyroid hormone levels, when compared with MEN1 and MEN2A patients. Minimally invasive parathyroidectomy (MIP) was performed in 367 of 467 sPHPT patients (79%). One abnormal parathyroid was found in 426 patients (91%). Two or more in 35 patients (7%). In six patients (1%) no abnormal parathyroid gland was retrieved. Of 52 MEN1 patients, eight (15%) underwent a MIP and 44 patients (85%) underwent conventional neck exploration (CNE); with resection of fewer than 3½ enlarged glands in 21 patients (40%), subtotal parathyroidectomy (SPTX, 3-3½ glands) in seventeen (33%) and total parathyroidectomy with autotransplantation (TPTX) in six (12%). Eleven patients (21%) had persistent disease, 29 (56%) recurrent PHPT and nine (17%) permanent hypoparathyroidism, mostly after TPTX. Of 16 MEN2A patients, six (38%) underwent MIP, four (25%) CNE and six (38%) selective resection of the enlarged gland(s) during total thyroidectomy. Three patients (19%) suffered from persistent PHPT and two (13%) developed recurrent disease.

Conclusions

Sporadic PHPT, MEN1- and MEN2A-related PHPT are three distinct entities as is reflected preoperatively by differences in gender, age at diagnosis and calcium and PTH levels.

MEN2A patients are very similar to sPHPT with respect to operative approach and findings. MIP is the treatment of choice for both. MIP has low rates of persistent and recurrent PHPT and a low complication rate. The percentage of multiglandular disease and recurrences are significantly higher in MEN1 patients, demonstrating the need for a different approach. We advocate treating these patients with CNE and SPTX.

Preoperative localizing studies for initial parathyroidectomy in MEN1 syndrome: is there any benefit?

BACKGROUND

The objective of the present study was to evaluate the utility of preoperative localizing studies in patients with MEN1 undergoing initial bilateral neck exploration (BNE) and parathyroidectomy for pHPT.

METHODS

We performed a retrospective analysis of patients diagnosed with MEN1 who underwent initial parathyroidectomy between December 1993 and December 2010. Results of preoperative localizing studies were compared with intraoperative findings and outcome.

RESULTS

Sixty patients with MEN1 (32 females and 28 males) underwent initial subtotal parathyroidectomy. The median age at the time of surgery was 33 years (range: 13-78 years). Fifty-three patients had one or more positive localizing study results. Neck ultrasonography, sestamibi scan, parathyroid protocol computed tomography scan, and neck and mediastinum magnetic resonance imaging were performed in 93, 91, 32, and 19% of patients, respectively. Fifty-three patients (88%) had cervical thymectomy. Twenty patients had 24 ectopic parathyroid glands; 18 glands were in the thymus (75%). Preoperative localizing studies identified 9 of 24 ectopic parathyroid glands (38%), including 4 ectopic glands outside the thymus in 4 patients (7%); 3 were detected by ultrasonography. There were no supernumerary glands identified on preoperative localizing studies.

CONCLUSIONS

In patients with MEN1, preoperative localizing studies identified a subset of ectopic glands (38%). Preoperative localizing studies may alter the operative approach in 7% of patients. Ultrasonography can detect most ectopic parathyroid glands outside thymus. This suggests that routine preoperative localizing studies to identify ectopic and supernumerary enlarged parathyroid glands is not useful in the majority of patients with MEN1 undergoing bilateral neck exploration and subtotal parathyroidectomy with cervical thymectomy.

Clinical practice guidelines for multiple endocrine neoplasia type 1 (MEN1)

OBJECTIVE

The aim was to provide guidelines for evaluation, treatment, and genetic testing for multiple endocrine neoplasia type 1 (MEN1).

PARTICIPANTS

The group, which comprised 10 experts, including physicians, surgeons, and geneticists from international centers, received no corporate funding or remuneration.

PROCESS

Guidelines were developed by reviews of peer-reviewed publications; a draft was prepared, reviewed, and rigorously revised at several stages; and agreed-upon revisions were incorporated.

CONCLUSIONS

MEN1 is an autosomal dominant disorder that is due to mutations in the tumor suppressor gene MEN1, which encodes a 610-amino acid protein, menin. Thus, the finding of MEN1 in a patient has important implications for family members because first-degree relatives have a 50% risk of developing the disease and can often be identified by MEN1 mutational analysis. MEN1 is characterized by the occurrence of parathyroid, pancreatic islet, and anterior pituitary tumors. Some patients may also develop carcinoid tumors, adrenocortical tumors, meningiomas, facial angiofibromas, collagenomas, and lipomas. Patients with MEN1 have a decreased life expectancy, and the outcomes of current treatments, which are generally similar to those for the respective tumors occurring in non-MEN1 patients, are not as successful because of multiple tumors, which may be larger, more aggressive, and resistant to treatment, and the concurrence of metastases. The prognosis for MEN1 patients might be improved by presymptomatic tumor detection and undertaking treatment specific for MEN1 tumors. Thus, it is recommended that MEN1 patients and their families should be cared for by multidisciplinary teams comprising relevant specialists with experience in the diagnosis and treatment of patients with endocrine tumors.

Total parathyroidectomy in a large cohort of cases with hyperparathyroidism associated with multiple endocrine neoplasia type 1: experience from a single academic center

Most cases of sporadic primary hyperparathyroidism present disturbances in a single parathyroid gland and the surgery of choice is adenomectomy. Conversely, hyperparathyroidism associated with multiple endocrine neoplasia type 1 (hyperparathyroidism/multiple endocrine neoplasia type 1) is an asynchronic, asymmetrical multiglandular disease and it is surgically approached by either subtotal parathyroidectomy or total parathyroidectomy followed by parathyroid auto-implant to the forearm. In skilful hands, the efficacy of both approaches is similar and both should be complemented by prophylactic thymectomy. In a single academic center, 83 cases of hyperparathyroidism/ multiple endocrine neoplasia type 1 were operated on from 1987 to 2010 and our first surgical choice was total parathyroidectomy followed by parathyroid auto-implant to the non-dominant forearm and, since 1997, associated transcervical thymectomy to prevent thymic carcinoid. Overall, 40% of patients were given calcium replacement (mean intake 1.6 g/day) during the first months after surgery, and this fell to 28% in patients with longer follow-up. These findings indicate that several months may be needed in order to achieve a proper secretion by the parathyroid auto-implant. Hyperparathyroidism recurrence was observed in up to 15% of cases several years after the initial surgery. Thus, long-term follow-up is recommended for such cases. We conclude that, despite a tendency to subtotal parathyroidectomy worldwide, total parathyroidectomy followed by parathyroid auto-implant is a valid surgical option to treat hyperparathyroidism/multiple endocrine neoplasia type 1. Larger comparative systematic studies are needed to define the best surgical approach to hyperparathyroidism/multiple endocrine neoplasia type 1.

Bilateral neck exploration in primary hyperparathyroidism--when is it selected and how is it performed?

BACKGROUND

Although most patients with primary hyperparathyroidism (PHPT) are ideal candidates for minimally invasive parathyroidectomy, some will have more than one enlarged gland and require bilateral neck exploration to achieve biochemical cure. We evaluated the clinical evidence for when to choose bilateral neck exploration for patients with PHPT.

METHODS

We searched PubMed for English-language studies published from 1996 to 2008. The level of clinical evidence was determined according to the criteria proposed by Sackett (Chest 95[2 Suppl]:2S, 1989), and the grade of recommendation was established according to the criteria proposed by Heinrich et al. (Ann Surg 243:154, 2006).

RESULTS

Level III-IV evidence shows that patients with multiple endocrine neoplasia (MEN) 1 and PHPT should have a bilateral neck exploration (grade C recommendation). Only level IV evidence indicates that patients with familial PHPT should do so (no recommendation). Although most patients with MEN 2A have single-gland disease, bilateral neck exploration is still indicated, because they will have either a therapeutic or prophylactic total thyroidectomy for medullary thyroid cancer. A history of head and neck irradiation is associated with PHPT, but the risk of multi-gland parathyroid disease is apparently no higher than in sporadic cases (level IV evidence, no recommendation). Previous or current lithium therapy confers a higher risk of multi-gland disease (25%-45%; level IV-V evidence), which may require bilateral neck exploration. Preoperative localizing studies reliably identify most patients with single-gland but not multi-gland disease (level II-IV evidence). Negative localizing studies confer an approximately 50% risk of multi-gland disease and indicate that bilateral neck exploration is necessary. If two localizing studies are concordant, few patients will require bilateral neck exploration (level IV, no recommendation).

CONCLUSIONS

No level I or II evidence reliably identifies preoperative clinical risk factors for determining which patients should have routine bilateral neck exploration for multi-gland disease or for intraoperative decision making to convert to bilateral neck exploration. Imaging studies are positive in most patients (level II). No randomized studies exist to determine when a bilateral neck exploration is indicated based on clinical risk factors or imaging studies that may suggest multi-gland disease.

Causes and treatment of recurrent hyperparathyroidism after subtotal parathyroidectomy in the presence of multiple endocrine neoplasia 1

BACKGROUND

Subtotal parathyroidectomy (SPTX) is the treatment of choice for hyperparathyroidism in a patient with multiple endocrine neoplasia type 1 (HPT-MEN-1). There are scarce data on the causes, timing, and appropriate surgical treatment of patients with recurrent HPT-MEN-1. The aim of this study was to investigate the timing, causes, site of recurrence, and surgical treatment of recurrent HPT-MEN-1 in patients who underwent SPTX.

METHODS

The study was a retrospective review of prospectively collected data on patients with HPT-MEN-1 with SPTX at two referral institutions. The data collected included the following: demographics, duration of follow-up, weight of resected parathyroid tissue, type of remnant, time to reoperation, cause/site of recurrence, and surgical treatment. We studied prognostic factors of recurrence.

RESULTS

A total of 69 patients underwent SPTX and were followed for a mean of 75.3 months. After the surgery, 15 patients were left with a single "normal" gland and 54 with a 50- to 70-mg remnant of a partially excised abnormal gland. Nine patients (13%) had a recurrence within a mean of 85 months (12-144 months). Patients with a recurrence had been followed longer (115 vs. 66 months; p = 0.005). Five recurrences occurred in a parathyroid remnant, 3 in a previously "normal" gland; the fifth recurrence was in both a hyperplastic remnant and a fifth gland. Remedial surgery included five subtotal resections and four immediate parathyroid autotransplantations. Two patients had a second recurrence due to a supernumerary gland. Factors related with recurrence are the follow-up time (p < 0.01) and thymectomy (p < 0.003).

CONCLUSIONS

Recurrence of HPTP-MEN-1 usually is located in preserved parathyroid tissue with no preference for a previously normal gland or a remnant. A second recurrence is most likely seen in a supernumerary gland. Recurrence is associated with the follow-up time and thymectomy.

Multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal-dominant inherited tumor syndrome characterized by hyperplasia and/or tumors in the parathyroid glands, the pancreatic islets, the anterior pituitary and adrenal glands, as well as neuroendocrine tumors in the thymus, lungs and stomach, and tumors in nonendocrine tissues. In 1997, the responsible MEN1 gene was identified as a tumor-suppressor gene and its product was named menin. In this review, guidelines for early diagnosis, including MEN1 gene mutation analysis, and treatment, including periodic clinical monitoring, have been formulated, enabling improvement of life expectancy and quality of life. Identification of menin-interacting proteins has provided new insights into the function of menin, notably involving regulation of gene transcription related to proliferation and apoptosis, genome stability and DNA repair, and endocrine/metabolic homeostasis. In the near future, target-directed intervention may prevent or delay the onset of MEN 1-related tumors.

The utility of routine transcervical thymectomy for multiple endocrine neoplasia 1-related hyperparathyroidism

BACKGROUND

Operation for multiple endocrine neoplasia (MEN)1-related hyperparathyroidism (HPT) includes a neck exploration with resection of 3.5 or 4 parathyroid glands and transcervical thymectomy (TCT). We reviewed our experience with initial operation for primary HPT to determine the outcome and utility of routine TCT.

METHODS

All patients with MEN1 who underwent initial neck exploration from 1993 to 2007 under an institutional review board-approved protocol were reviewed.

RESULTS

We identified 66 patients with initial operation for HPT in MEN1. In 34 patients, 4 glands were found; in 32 patients, <4 glands were found. In 2 of the 34 (6%) and 17 of the 32 (53%), intrathymic parathyroid tissue was found on permanent pathology. No thymic carcinoid tissue was found in any specimen.

CONCLUSION

These data highlight the importance of performing TCT when <4 entopic parathyroid glands are found at first operation.

Multiple endocrine neoplasia syndromes

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

Prospective study of surgery for primary hyperparathyroidism (HPT) in multiple endocrine neoplasia-type 1 and Zollinger-Ellison syndrome: long-term outcome of a more virulent form of HPT

BACKGROUND

Primary hyperparathyroidism (HPT) in multiple endocrine neoplasia type 1 (MEN1) patients with Zollinger-Ellison syndrome (ZES) is caused by parathyroid hyperplasia. Surgery for parathyroid hyperplasia is tricky and difficult. Long-term outcome in ZES/MEN1/HPT is not well known.

METHODS

Eighty-four consecutive patients (49 F/35 M) with ZES/MEN1/HPT underwent initial parathyroidectomy (PTX) and were followed at 1- to 3-year intervals.

RESULTS

Age at PTX was 36 +/- 2 years. Mean follow-up was 17 +/- 1 years. Before PTX, mean Ca = 2.8 mmol/L (normal level (nl <2.5), PTH i = 243 pg/mL (nl <65), and gastrin = 6950 pg/mL (nl < 100). Sixty-one percent had nephrolithiasis. Each patient had parathyroid hyperplasia. Fifty-eight percent of patients had 4 parathyroid glands identified. Nine of 84 (11%) had 4 glands removed with immediate autograft, 40/84 (47%) 3 to 3.5 glands, whereas 35/84 (42%) <3 glands removed. Persistent/recurrent HPT occurred in 42%/48% of patients with <3 glands, 12%/44% with 3 to 3.5 glands, and 0%/55% with 4 glands removed. Hypoparathyroidism occurred in 3%, 10%, and 22%, respectively. The disease-free interval after surgery was significantly longer if >3 glands were removed. After surgery to correct the HPT, each biochemical parameter of ZES was improved and 20% of patients no longer had laboratory evidence of ZES.

CONCLUSIONS

HPT/MEN1/ZES is a severe form of parathyroid hyperplasia with a high rate of nephrolithiasis, persistent and recurrent HPT. Surgery to correct the hypercalcemia significantly ameliorates the ZES. Removal of less than 3.5 glands has an unacceptably high incidence of persistent HPT (42%), whereas 4-gland resection and transplant has a high rate of permanent hypoparathyroidism (22%). More than 3-gland resection has a longer disease-free interval. The surgical procedure of choice for patients with HPT/MEN1/ZES is 3.5-gland parathyroidectomy. Careful long-term follow-up is necessary as a significant proportion will develop recurrent HPT.

Surgical approach to the patient with familial hyperparathyroidism

Familial hyperparathyroidism encompasses the diagnoses of multiple endocrine neoplasia (MEN) type 1, MEN type 2A, and familial isolated primary hyperparathyroidism. All patients should undergo bilateral neck exploration and identification of all four or more parathyroid glands to evaluate for gross abnormalities. MEN-1 patients should have subtotal parathyroidectomy and cervical thymectomy because this operation achieves an appropriate balance between optimizing the potential for cure yet minimizing the risk of permanent hypocalcemia. However, MEN-2A patients may best be treated by selective resection of abnormal parathyroid glands, although some experts recommend a total parathyroidectomy and autotransplantation in the forearm. Familial isolated hyperparathyroidism is a rare disorder, and authors have described success in treatment with subtotal parathyroidectomy or limited adenoma resections. Some patients with familial isolated hyperparathyroidism also have jaw tumors, and members of these families are more likely to have parathyroid carcinoma. Concurrent cryopreservation of parathyroid tissue for all of these disorders is recommended if there is any concern for possible permanent hypoparathyroidism.

Indications for operative intervention in patients with asymptomatic primary hyperparathyroidism: Practice patterns of endocrine surgery

BACKGROUND

Currently, many patients with primary hyperparathyroidism (PHPT) are diagnosed when they are considered to be "asymptomatic." The need for parathyroidectomy in these patients has been questioned. A consensus statement drafted after the National Institutes of Health (NIH) 2002 Workshop on Asymptomatic PHPT provided guidelines for management of such patients but has been criticized for being too conservative. The purpose of this survey was to determine the impact of these guidelines on practice patterns of endocrine surgeons.

METHODS

Members of the American Association of Endocrine Surgeons (AAES) were surveyed to determine whether previously published consensus guidelines for management of asymptomatic patients with PHPT are used to base the decision of whether to offer parathyroidectomy and to ascertain what parameters are considered indicators to proceed with operative intervention. AAES members were asked about the management of patients with asymptomatic PHPT, specialty characteristics, and demographics.

RESULTS

Of 257 AAES members, 96 (37%) responded to the survey. Although the majority of the respondents were aware of and followed the NIH consensus conference guidelines, the majority of surgeons (80%) would operate on a patient with PHPT who did not meet these criteria but had other nonspecific symptoms. Surgeons favored operative intervention when preoperative localization studies were positive, even if the criteria of the NIH guidelines were not fulfilled. Most of the responders who would operate on all patients with PHPT, regardless of objective parameters, were surgeons with a high-volume practice (>30 parathyroidectomies per year). The presence of multiple endocrine neoplasia (MEN) syndromes did not alter the decision to operate on asymptomatic patients.

CONCLUSIONS

Endocrine surgeons do not base the decision to intervene operatively in patients with PHPT solely on objective criteria. Most high-volume, experienced endocrine surgeons believe that subjective complaints warrant operative intervention.

Familial neuroendocrine tumor syndromes: from genetics to clinical practice

Thanks to recent developments in molecular biology and cancer genetics, genetic testing has become widely available and useful in several kinds of familial tumor syndrome. However, the impact of genetic testing on medical management is not always straightforward. Clinicians have to consider the psychological impact and ethical complexities of communicating hereditary cancer risk information to families. This review notes some points on genetic counseling before and after genetic testing for familial neuroendocrine tumor syndromes.

Génétique des tumeurs endocrines

Major advances have been made in the understanding of the genetic mechanisms underlying endocrine tumorigenesis, through the study of several syndromes of genetic predisposition and the identification of the genes involved. The syndrome of type 1 multiple endocrine neoplasia (MEN-1) is one of the best known; this autosomal dominant hereditary syndrome predisposes to the development of endocrine tumors of the pituitary, the parathyroids, the foregut and the adrenals. The responsible gene, known as MEN-1, encodes an original protein, menin, involved in several major cellular functions, such as the control of cell proliferation and differentiation. Type 2 multiple endocrine neoplasia (MEN-2) is an autosomal dominant hereditary syndrome associated with the development of medullary carcinomas of the thyroid, pheochromocytomas and hyperparathyroidism; the corresponding gene, RET, encodes a transmembrane receptor with tyrosine kinase activity. Endocrine tumors are also associated with non Hippel-Lindau disease and with phacomatoses, such as type 1 neurofibromatosis and tuberous sclerosis. Finally, isolated familial syndromes of endocrine tumors have been described: isolated familial hyperparathyroidism type II (HRPT2), associated with alterations in a gene coding for an original protein, parafibromin, or isolated familial syndromes of pheochromocytomas and paragangliomas (PRG) associated with mutations in the genes SDHB, SDHC or SDHD, which encode succinate-dehydrogenase subunits. The understanding of the genetic mechanisms underlying these syndromes of predisposition is essential for the diagnosis and management of these patients and their family; it also gives insight on the molecular mechanisms of endocrine tumorigenesis.