Karin Frank-Raue

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.

Prophylactic Thyroidectomy in 75 Children and Adolescents with Hereditary Medullary Thyroid Carcinoma: German and Austrian Experience

Abstract. When mutations of theRETproto-oncogene were found in 1993 to account for hereditary medullary thyroid carcinoma (MTC), surgeons obtained the opportunity to operate on patients prophylactically (i.e., at a clinically asymptomatic stage). Whether this approach is justified, and, if so, when and to which extent surgery should be performed remained to be clarified. A questionnaire was sent to all surgical departments in Germany and Austria. All of the patients who fulfilled the following criteria were enrolled: (1) preoperatively proved RET mutation; (2) age ≤ 20 years, (3) clinically asymptomatic thyroid C cell disease; and (4) TNM classification pT0–1/pNX/pN0–1/M0. Seventy-five patients were identified, and fifteen mutations were detected in six codons. Two adolescents had unilateral pheochromocytomas as part of the multiple endocrine neoplasia II (MEN-II) syndrome. No hyperparathyroidism was noted. All patients underwent total thyroidectomy, and 57 patients went on to have lymph node dissection. Parathyroid glands were removed in 34 patients and autografted in 11. Histopathology revealed MTC in 46 patients (61%, youngest 4 years); C cell hyperplasia (CCH) only was detected in the other 29 patients. Three patients had lymph node metastases (LNMs) the youngest being age 14 years. Calcitonin levels were not useful for differentiating between CCH and MTC, but in all patients with LNMs at least the stimulated calcitonin levels were assayed. After surgery, five patients (6.7%) sustained permanent hypoparathyroidism, and one patient (1.3%) had a permanent unilateral recurrent nerve palsy. All but three patients (96%) were biochemically cured. In conclusion, prophylactic total thyroidectomy can be performed safely in experienced centers. We recommend prophylactic total thyroidectomy at age 6. Cervicocentral lymph node dissection should be included when calcitonin levels are elevated or if patients are older than 10 years. Bilateral lymph node dissection should be performed if LNMs are suspected or when patients with elevated calcitonin are older than 15 years.

Update multiple endocrine neoplasia type 2.

Multiple endocrine neoplasia type 2 (MEN2) is a autosomal dominat inherited tumour-syndrome caused by germline activating mutations of the RET proto-oncogene on chromosome 10. It is clinically characterized by the presence of medullary thyroid carcinoma (MTC), bilateral pheochromocytoma and primary hyperparathyroidism (MEN2A) within a single patient. Three distinct clinical forms have been described depending on the phenotype: the classical MEN 2A, MEN 2B, an association of MTC, pheochromocytoma and mucosal neuroma, (FMTC) familial MTC with a low incidence of other endocrinopathies. Each variant of MEN2 results from different RET gene mutation, with a good genotype phenotype correlation. Genetic testing detects nearly 100% of mutation carriers and is considered the standard of care for all first degree relatives of patients with newly diagnosed MTC. Recommendations on the timing of prophylactic thyroidectomy and extent of surgery are based on a classification into four risk levels utilizing the genotype-phenotype correlations. MEN 2 gives a unique model for early prevention and cure of cancer and for stratified roles of mutation-based diagnosis of carriers.

Efficacy of imatinib mesylate in advanced medullary thyroid carcinoma

OBJECTIVE Medullary thyroid carcinoma (MTC) is often associated with gain-of-function mutations in the RET proto-oncogene, which is found in all hereditary cases and most sporadic cases. The activated RET receptor tyrosine kinase can be inhibited by tyrosine kinase inhibitors in vitro. We evaluated the efficacy of treatment with imatinib mesylate, a tyrosine kinase inhibitor, in patients with advanced MTC. DESIGN AND PATIENTS In this open-label clinical trial, nine patients, eight with sporadic and one with hereditary MTC, with unresectable, measurable, progressive metastases were treated with imatinib mesylate 600 mg daily. The tumour response to imatinib was evaluated after 3, 6 and 12 months by computed tomography and after 1 month by (18)F-fluoro-2-deoxy D-glucose position-emission tomographic scanning. The median duration of therapy was 8 months. RESULTS Overall, stable disease occurred in five patients for up to 6 months and in one patient for up to 12 months, with a median duration of progression-free survival of 6 months. Four patients had progressive disease after 12 months. One patient stopped therapy after 2 weeks because of worsening of diarrhoea. Therapy was well tolerated, although transient mild-to-moderate nausea (n = 3), oedema (n = 3), diarrhoea (n = 2) and skin rash (n = 2) were observed. CONCLUSION Imatinib mesylate is well tolerated, no tumour remission was observed, only transient stable disease was achieved in some patients with advanced MTC.

Age-related penetrance of endocrine tumours in multiple endocrine neoplasia type 1 (MEN1): a multicentre study of 258 gene carriers

Objective  In multiple endocrine neoplasia type 1 (MEN1), age‐related tumour penetrance according to the type of MEN1 germline mutation has not been investigated in‐depth. This study was conducted to examine whether carriers of out‐of‐frame/truncating and in‐frame MEN1 mutations differ in age‐related tumour penetrance.

Risk Profiles and Penetrance Estimations in Multiple Endocrine Neoplasia Type 2A Caused by Germline RET Mutations Located in Exon 10

Multiple endocrine neoplasia type 2 is characterized by germline mutations in RET. For exon 10, comprehensive molecular and corresponding phenotypic data are scarce. The International RET Exon 10 Consortium, comprising 27 centers from 15 countries, analyzed patients with RET exon 10 mutations for clinical‐risk profiles. Presentation, age‐dependent penetrance, and stage at presentation of medullary thyroid carcinoma (MTC), pheochromocytoma, and hyperparathyroidism were studied. A total of 340 subjects from 103 families, age 4–86, were registered. There were 21 distinct single nucleotide germline mutations located in codons 609 (45 subjects), 611 (50), 618 (94), and 620 (151). MTC was present in 263 registrants, pheochromocytoma in 54, and hyperparathyroidism in 8 subjects. Of the patients with MTC, 53% were detected when asymptomatic, and among those with pheochromocytoma, 54%. Penetrance for MTC was 4% by age 10, 25% by 25, and 80% by 50. Codon‐associated penetrance by age 50 ranged from 60% (codon 611) to 86% (620). More advanced stage and increasing risk of metastases correlated with mutation in codon position (609→620) near the juxtamembrane domain. Our data provide rigorous bases for timing of premorbid diagnosis and personalized treatment/prophylactic procedure decisions depending on specific RET exon 10 codons affected. Hum Mutat 31:1–8, 2010.

Molecular genetics and phenomics of RET mutations: Impact on prognosis of MTC.

Multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominant hereditary cancer syndrome caused by missense gain-of-function mutations of the RET proto-oncogene. Three distinct clinical subtypes of MEN 2 have been characterized: MEN 2A, MEN 2B, and familial medullary thyroid carcinoma (FMTC). The specific RET mutation may suggest a predilection toward a particular phenotype and clinical course, with strong genotype-phenotype correlations. Recommendations on the timing of prophylactic thyroidectomy and extent of surgery are based on classification of RET mutations into risk levels according to genotype-phenotype correlations. The excellent prognosis for MTC diagnosed at its earliest stage underscores the importance of prospective screening (calcitonin screening) for sporadic MTC and early diagnosis by RET-mutation analysis for hereditary MTC. MEN 2 provides a unique model for early prevention and cure of cancer and for the roles of stratified mutation-based diagnosis and therapy of carriers.

Novel Inactivating Mutations of the Calcium-Sensing Receptor: The Calcimimetic NPS R-568 Improves Signal Transduction of Mutant Receptors

CONTEXT AND OBJECTIVE Inactivating mutations in the calcium-sensing receptor (CaSR) gene cause neonatal severe hyperparathyroidism and familial hypocalciuric hypercalcemia (FHH). The aims of the present study were the functional characterization of novel mutations of the CaSR found in FHH patients, the comparison of in vitro receptor function with clinical parameters, and the effect of the allosteric calcimimetic NPS R-568 on the signaling of mutant receptors. METHODS Wild-type and mutant CaSRs (W530G, C568Y, W718X, M734R, L849P, Q926R, and D1005N) were expressed in human embryonic kidney 293 cells. Receptor signaling was studied by measuring intracellular free calcium in response to different concentrations of extracellular calcium ([Ca(2+)](o)). RESULTS Four CaSR mutations (C568Y, W718X, M734R, and L849P) demonstrated a complete lack of a [Ca(2+)](o)-induced cytosolic Ca(2+) response up to 30 mm [Ca(2+)](o), whereas the CaSR mutants W530G, Q926R, and D1005N retained some sensitivity to [Ca(2+)](o). There was no significant relation between the in vitro calcium sensitivity, serum calcium, and intact PTH levels in the patients. Patients with C-terminal CaSR mutations had a calcium to creatine ratio above the established diagnostic threshold of 0.01 for FHH. The calcimimetic NPS R-568 enhanced the responsiveness to [Ca(2+)](o) in CaSR mutants of the extracellular domain (W530G and C568Y) as well as the intracellular C-terminal domain (Q926R and D1005N). CONCLUSION Therefore, calcimimetics might offer medical treatment for symptomatic FHH patients, and more important, for patients with neonatal severe hyperparathyroidism that harbor calcimimetic-sensitive CaSR mutants.

Somatostatin receptor imaging in persistent medullary thyroid carcinoma.

OBJECTIVE Somatostatin is secreted from thyroid C‐cells and seems to play an Important part In the regulation of calcitonin secretion. We therefore evaluated the usefulness of somatostatin receptor scintigraphy in the localization of tumour tissue in patients with persistent medullary thyroid carcinoma.

Multiple endocrine neoplasia type 2: 2007 update.

Background: Multiple endocrine neoplasia type 2 (MEN-2) is an autosomal dominant tumour syndrome caused by germline-activating mutations of the RET proto-oncogene. It is clinically characterised by the presence of medullary thyroid carcinoma (MTC), bilateral pheochromocytoma and primary hyperparathyroidism (MEN-2A) within a single patient. Three distinct clinical forms have been described depending on the phenotype: (1) classic MEN-2A, (2) MEN-2B, an association of MTC, pheochromocytoma and mucosal neuroma and (3) familial MTC (FMTC), which is associated with a low incidence of other endocrinopathies. Each variant of MEN-2 results from a different RET gene mutation, with a good genotype-phenotype correlation. Detection and Treatment: Genetic testing detects nearly 100% of mutation carriers and is considered the standard of care for all first-degree relatives of patients with newly diagnosed MTC. Recommendations on the timing of prophylactic thyroidectomy and extent of surgery are based on a three risk-level classification using the genotype-phenotype correlations. Conclusions: MEN-2 provides a unique model for early prevention and cure of cancer and for stratified roles of mutation-based diagnosis of carriers.