Mutations In RET Proto-oncogene Research Articles

Sentinel lymph node biopsy in medullary thyroid microcarcinomas.

The aim of this prospective study was to analyze accuracy of sentinel lymph node biopsy with methylene blue dye for intraoperative detection of lateral metastases in clinically N0M0 medullary microcarcinomas with calcitonin <1,000 pg/mL and selection of true-positive patients for one-time therapeutic lateral dissection. In addition to total thyroidectomy and central neck dissection, all patients had bilateral sentinel biopsy of jugulo-carotid regions after methylene blue injection to decide upon necessity for lateral dissection. If sentinels were benign on frozen section, additional non-sentinels were extirpated, with no further lateral dissection. If sentinels were malignant, one-time lateral dissection was performed. 20 patients were included in this study. Hereditary disease form was observed in 3/20 (15%) of patients with RET proto-oncogene mutation C634F; remaining 17/20 (85%) were negative for germline mutations. There were no allergic reactions to methylene blue and identification rate of sentinels was 100%. In total, 2/20 (10%) cN0 patients had lymphonodal metastases, thus were reclassified as pN1b. Remaining 18/20 (90%) were classified pN0 based on standard pathohistology. Frozen section findings on sentinels were 100% match with standard pathohistology, and there were no skip metastases in lateral compartments. Sensitivity, specificity and accuracy of sentinel biopsy method with methylene dye and frozen section were 100%. Dzodic's sentinel lymph node biopsy method can be used for intraoperative assessment of lateral compartments and optimization of initial surgery of medullary microcarcinomas with calcitonin <1,000 pg/mL. This way, cN0 patients with sentinel metastases can receive one-time lateral dissection, and those without benefit from less extensive surgery.

Coexistence of medullary carcinoma and papillary carcinoma of the thyroid in a 35 year old patient with RET protooncogene mutation

Coexistence of medullary carcinoma and papillary carcinoma of the thyroid in a 35 year old patient with RET protooncogene mutation

RET Proto-oncogene Gene Mutation Is Related to Cervical Lymph Node Metastasis in Medullary Thyroid Carcinoma.

RET proto-oncogene (RET) mutations were proved to be related to the development of medullary thyroid carcinoma (MTC). We aimed to analyze the role of RET mutations in cervical lymph node metastasis in patients with MTC. Forty-nine patients with preoperatively diagnosed MTC by fine-needle aspiration cytology (FNAC) who underwent bilateral total thyroidectomy with cervical lymphadenectomy were included. Postoperative RET gene test and pathological analysis were performed with the surgical specimens; serum calcitonin (Ctn) and carcinoembryonic antigen (CEA) levels were tested pre- and postoperatively, to evaluate the association between RET mutations and cervical lymph node metastasis in MTC. In these 49 patients, the RET mutation rates of Exon 11, Exon 10, Exon 11&13, Exon 13, and Exon 16 were 20.4%, 4.1%, 38.8%, 22.4%, and 0%, respectively. The lymph node metastasis rates of patients with RET mutation in the central and lateral compartments were 71.4% and 64.3%, respectively, versus 28.6% and 14.3% of patients without RET mutation. The preoperative basal serum levels of Ctn (234.8 ± 188.4 vs. 44.4 ± 27.5, p< 0.01) and postoperative Ctn (49.8 ± 86.4 vs. 3.7 ± 2.2, p= 0.001) in MTC patients with RET mutations were significantly higher than those in MTC patients without RET mutation. In addition, the preoperative (50.2 ± 76.7 vs. 7.4 ± 6.8, p= 0.001) and postoperative serum levels of CEA (13.2 ± 19.5 vs. 1.3 ± 1.6, p< 0.01) in MTC patients with RET mutations were significantly higher than those in MTC patients without RET mutation (p< 0.05). RET mutation was related to cervical lymph node metastasis in patients with MTC, especially the mutation in Exon 11&13. Patients with RET mutation in Exon 11&13 might be regarded as the predictor for prophylactic ipsilateral total cervical lymphadenectomy even without clear evidence of lateral cervical lymph node metastasis.

Current surgical management in RET mutation carriers [Aktualne postępowanie chirurgiczne u nosicieli mutacji proto-onkogenu RET

Medullary thyroid carcinoma (MTC) still remains a rare endocrine tumor. 20-25% of MTC cases are genetically determined. The detection of the RET proto-oncogene mutation in 1993 allowed to understand the unique genotype-phenotype relationships in hereditary medullary thyroid carcinoma (HMTC) and formed the basis for therapeutic decisions based on the molecular results. Currently, prophylactic thyroidectomy is a commonly adopted and accepted therapeutic method. The decision on the time and extent of surgery should be made based on the results of molecular examination, the assessment of calcitonin (Ct) concentration and family history. Treatment of patients with HMTC requires the cooperation of a multidisciplinary team of experts and should be done in specialized centers only. The study is a review of the current guidelines for surgical management in the MEN2 syndrome.

MON-392 Bilateral Pheocromocytoma With A Ret Proto-oncogene Mutation

Introduction: Pheochromocytoma is a rare neoplasm, occurring in less than 0.2% percent of patients with hypertension. We present a case of bilateral pheochromocytoma with a RET proto-oncogene mutation. Clinical case: 47 year old male with history of multiple hypertensive crises, 10 kg weight loss in a 3 month period and atrial fibrillation with rapid ventricular rate; heavy tobacco use; and family history of cerebrovascular disease. He presents to the emergency department with fever, right flank ecchymosis, abdominal pain, and blood pressure of 210/110 mmHg (n <120/90 mmHg); thyroid and pulmonary examination were normal. Abdominal CT scan revealed bilateral growth of adrenal glands, which prompted his hospital admission. Total plasma catecholamines were 12159 pg/ml (n <504 pg/ml), predominately epinephrine; 24 hour urine catecholamines measured 1254 µg (n <100 µg), and 24 hour urine metanephrines measured 22485 µg (n <900 µg). Abdominal MRI showed bilateral adrenal tumors; right adrenal gland measuring 3.5 x 4 cm and left adrenal gland 6 x 5 cm; heterogeneous, with cystic features and hyperintensity on T2 weighted images. Patient underwent bilateral adrenalectomy. The pathology report showed bilateral pheochromocytoma without capsular or vascular invasion. Peripheral leukocyte DNA analysis showed a RET proto-oncogene TGC-TAC mutation in codon 634 of exon 11. Postoperative testing showed normal catecholamine and metanephrine levels. Patient presented complete clinical remission. Conclusion: There are several familial disorders associated with adrenal pheochromocytoma, all of which have autosomal dominant inheritance: von Hippel-Lindau syndrome, multiple endocrine neoplasia type 2 and, less commonly, neurofibromatosis type 1. Multiple endocrine neoplasia type 2 is associated with mutations in the RET proto-oncogene. If a patient presents with bilateral adrenal pheochromocytoma but without a history of medullary thyroid cancer or goiter, tests for mutations in the following genes should be ordered sequentially: VHL, RET, SDHx, TMEM127, and MAX. This particular case presented with bilateral pheochromocytoma and a RET proto-oncogene mutation, but no other neoplasms. The definite treatment is laparoscopic adrenalectomy by an experienced endocrine surgeon with preoperative alpha-adrenergic blockade. Because of the identification of the RET proto-oncogene mutation a prophylactic thyroidectomy is recommended.

SAT-585 Presence of Metastatic Medullary Thyroid Cancer without a Distinct Thyroid Nodule: A Diagnostic Challenge

Introduction Neuroendocrine tumors originate from the GI tract, lungs or endocrine glands. Diagnosis can be done by different imaging modalities including Octreoscan, MIBG scan, FDG PET/CT and Ga-Dotatate PET/CT. Case 52 year old female with past history of hypertension, presented to an outside facility with complaint of a right lower neck mass, hoarseness and cough. Thyroid ultrasound identified a 0.3 cm right lobe calcific density with no discrete nodules. Neck CT showed right thyroid calcification and a 2.5 cm right supraclavicular mass. A core needle biopsy of the mass was consistent with metastatic low grade neuroendocrine carcinoma. Immunostains were positive for EP-CAM, TTF-1, synaptophysin, CD56 and CK7. Metastatic pulmonary carcinoma was suspected. She was seen at our institution for a multidisciplinary team evaluation. Pathology slides for additional stains were unavailable. Whole body CT showed low suspicion mediastinal lymph nodes. FDG PET/CT showed a 2.6 cm right neck hypermetabolic mass and a tiny calcified density in the right thyroid lobe, but no metastatic disease elsewhere. Endoscopic ultrasound-guided transbronchial biopsy of the mediastinal nodes was negative for cancer. An Octreotide scan showed only right neck mass hypermetabolism. Gallium-68 Dotatate scan had just become available and was able to identify increased uptake in the right supraclavicular region and an additional focus of uptake within the superior aspect of the right thyroid lobe. Fine-needle aspiration of the right thyroid focus was consistent with medullary thyroid carcinoma. Calcitonin was 1268 pg/ml, CEA 1.7 ng/ml and RET proto-oncogene was positive (p.C609Y). She had normal parathyroid hormone, calcium and plasma metanephrines. Total thyroidectomy was performed. Pathology was consistent with right neck metastatic medullary thyroid carcinoma with 18/27 lymph nodes involved. Multifocal medullary thyroid carcinoma from 0.2-0.6 cm was found in the right lobe. The left lobe had a 0.2 cm focus of medullary thyroid carcinoma with 1/2 lymph nodes involved. Her most recent neck ultrasound showed a persistent, stable hypoechoic 0.5 cm right lateral neck lesion. Most recent neck CT was unremarkable. PET/CT done 2 months ago showed only mildly prominent mediastinal lymph nodes that are stable compared with 2 years ago. Calcitonin decreased initially from 1268 pg/ml to 321 pg/ml and has now plateaued in the low 500s. CEA and other biomarkers are normal. Patient's daughter and son tested positive for the RET proto-oncogene mutation. Conclusion Metastatic medullary thyroid carcinoma without a discrete thyroid nodule is an uncommon presentation. Our patient presented with a metastatic neuroendocrine neck mass and conventional imaging modalities failed to identify the primary site, leading to delay in proper treatment. Ga-Dotatate PET/CT may improve management of patients with neuroendocrine tumors.

A review on the RET proto-oncogene mutation in medullary thyroid carcinoma

Medullary thyroid carcinoma（MTC） is a special type of neuroendocrine tumor originated from C-cells of the thyroid gland, MTC can be divided into sporadic(70%-80%)and hereditary(20%-30%), about 98% of the hereditary MTC patients have RET proto-oncogene germline mutation in exon 10, 11, 13, 14, 15, 16. The mutation of RET proto oncogene is closely related to the pathogenesis of MTC, and different mutation of RET proto oncogene exon may lead to different MTC phenotypes.More than 100 kinds of mutations in the RET gene were reported. This paper reviews the research progress of RET proto-oncogene mutation in MTC.

Study of RET proto-oncogene mutations in two pedigrees affected with multiple endocrine neoplasia type 2A

To study the pattern of RET proto-oncogene mutations in two pedigrees affected with multiple endocrine neoplasia type 2A (MEN2A). Peripheral blood samples were collected from members of the two pedigrees, with total genomic DNA extracted for polymerase chain reaction (PCR). PCR products of 7 exons of the RET proto-oncogene (including exons 8, 10, 11, 13, 14, 15, 16) which have higher mutation rates were purified and subjected to direct sequencing. Suspected mutations in the 2 probands were verified in other members of the pedigrees. To exclude other mutations, PCR products of remaining 14 exons were sequenced in the proband from pedigree 1. A novel heterozygous mutation, 1893-1895delCGA, was detected in exon 11 of the RET proto-oncogene among 3 patients and 2 unaffected members from pedigree 1, while a heterozygous mutation, Cys634Arg, was detected in exon 11 among 2 patients and 1 unaffected family member from pedigree 2. The heterozygous 1893-1895delCGA and Cys634Arg mutations of the RET proto-oncogene probably underlie the disease in the two pedigrees. Above discovery has enriched the human gene mutation database.

1828P - Role of SPECT-CT somatostatin-receptor scintigraphy in the management of medullary thyroid cancer (MTC)

Background: The MTC arises from the parafollicular, calcitonin-secreting malignant transformed thyroid C-cells who express on the surface somatostatin SSTR receptors. The most of aggressive locally advanced/metastatic MTC tumors, found to be positive for RET proto-oncogene mutation, are treated with Vandetanib. SPECT-CT somatostatin-receptor scintigraphy with 99mTc-Tektrotyd should be considered for MTC imaging before and after therapy for exact staging and follow-up of the disease due to its highly sensitivity and specificity for detection of neuroendocrine tumors, expressed SSTR. The aim of this study was to evaluate clinical role of SPECT-CT scintigraphy with 99mTc-Tektrotyd in the management of patients with MTC. Methods: 25pts (7M;18F) with MTC were studied; whole body somatostatin scintigraphy followed by target SPECT-CT studies were performed 2-4 hrs post i.v.inj. of 740 MBq 99mTc-Tektrotyd (Polatom). SPECT-CT camera Symbia T2, Siemens was used. Three of them were studied for initial pre-operative N/M-staging, 17 were follow-up after surgery. In 5 patients with metastatic disease SPECT-CT with 99mTc-Tektrotyd were performed before and after target therapy with Caprelsa (Vandetanib), 300mg/d orally. Results: Initial pre-operative staging showed 3 positive results for the primary tumor and metastatic lymph nodes and 2 false negative imaging of small 1-4 mm lung metastases. True negative results were obtained in 5 cases after thyroidectomy. True positive results were obtained in 17 cases with local recurrence in the thyroid bed, lymphadenopathy, osteolytic bone metastases, lung and subcutaneous lesions. False positive result was in 1 case with benign ovary cyst. Plasma levels of calcitonin vary from 94 to 5496 pg/ml in all 17 patients with local recurrence and/or metastatic lesions. In 5/17 cases SPECT-CT studies were used to evaluate effect of target therapy, respectively: partial response – in 2 cases, stable disease – in 2 cases and progressive disease – in 1 cases. Conclusions: SPECT-CT somatostatin-receptor scintigraphy with 99mTc-Tektrotyd is very useful functional imaging modality in patients with MTC in order to determinate personalized therapeutic disease approach. Legal entity responsible for the study: Sonya Sergieva. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest.

Over-diagnosis of potential malignant behavior in MEN 2A-associated pheochromocytomas using the PASS and GAPP algorithms

PurposePheochromocytomas (PCCs) exhibit malignant potential, but current histological modalities for the proper detection of aggressive behavior are debated. The two most widespread algorithms are the “Pheochromocytoma of the Adrenal Gland Scaled Score” (PASS) and the “Grading System for Adrenal Pheochromocytoma and Paraganglioma” (GAPP), both which mostly rely on histological parameters to identify PCC patients at risk of disseminated disease. Since the algorithms are derived from studies using predominantly sporadic PCCs, little is known whether the PASS or GAPP scores can predict malignant potential in hereditary cases.MethodsPASS and GAPP were applied on 41 PCCs; 13 PCCs were diagnosed in ten multiple endocrine neoplasia type 2A (MEN 2A) patients carrying established germline RET proto-oncogene mutations, as well as 28 assumed sporadic PCCs.ResultsSix out of thirteen MEN 2A tumors (46%) exhibited PASS scores ≥ 4, indicative of a potential for aggressive behavior. In addition, 7/13 tumors (54%) exhibited GAPP scores ≥ 3, indicative of a “moderately differentiated type” with risk of future recurrence. All MEN 2A PCCs with an elevated PASS score also displayed an elevated GAPP score. In contrast, 4/28 (14%) sporadic PCCs demonstrated PASS scores ≥ 4, and 9/28 (32%) displayed GAPP scores ≥ 3. Follow-up found all cases in the study are free of metastatic or recurrent disease.ConclusionsWe conclude that the PASS and GAPP scoring systems might be suboptimal for determining true malignant potential in PCCs with constitutional RET mutations and advocate restrictive use of these scores in MEN 2A cases until the results are reproduced in larger numbers.

Study on the overexpression of succinate dehydrogenase B and MIB-1 in pheochromocytoma/paraganglioma tissue

Objective We aimed to investigate the overexpression of succinic dehydrogenase (SDH)B and MIB-1 in patients with pheochromocytoma/paraganglioma(PHEO/PGLs) and its significance for predicting the clinical malignant behavior. Methods From August 2008 to April 2016, the clinical characteristics of 93 patients with PHEO/PGLs were analyzed retrospectively. There were 57 males and 36 females. with an average of 34 years, ranging 8-73 years old. There were 68 cases of adrenal pheochromocytoma and 25 cases of paraganglioma. There were 79 cases with hypertension and 14 cases of adrenal accidental tumors. Sixty-six cases with typical hyper-catecholamine secretion symptoms and 27 cases with non-functional PHEO/PGL. Benign PHEO/PGLs were 77 cases and malignant 16 cases. The tumor was located on the left side in 39 cases, on the right side in 32 cases and multiple lesions in 22 cases. The diameter of the PHEO/PGL tumor was (6.8±2.7) cm. The 24 h urine catecholamine was measured before operation, which showed epinephrine was(42.6±5.1)μg/24 h, norepinephrine was(167.5±13.5)μg/24h and dopamine was (246.4±71.2)μg/24h. Six cases wihtout hereditary diseases of urinary system were selected as normal control group. SDHB, SDHAF2, SDHC, SDHD, VHL and RET gene mutations were detected in all patients. Immunohistochemical panel has been performed to detect the expression of SDHB, MIB-1, EPAS1, VEGF-1 receptor (VEGF-1R), and chromain A (CgA) in 93 specimens of PHEO/PGL tissue. The positive granular cytoplasm staining >50% was strongly positive (+ + + ), 11% to 50% was moderately positive (+ + ), 1% to 10% was weak positive (+ ) and the negative was compared with the known positive internal reference, that is, there was less than 1% or no stain completely. Results SDHB, SDHAF2, SDHC, SDHD, VHL and RET gene mutations in 27 cases (29.5%). Nine patients with SDHB gene mutation (9.7%). RET proto-oncogene mutations in 8 cases (8.6%). 3 cases had VHL mutation (3.2%). Immunohistochemical staining showed that MIB-1 positive expression was found in 7 of 9 patients with SDHB gene mutation. Six cases in the control group were negative for gene detection and MIB-1, EPAS1, CgA and VEGF-1R immunohistochemical results. EPAS1 showed moderately positive in patients with PHEO/PGL and strong positive in patients with malignant PHEO/PGL. In 9 cases with SDHM mutation, EPAS1 was noticed positive in seven cases, which showed the relationship with CgA, MIB-1 and VEGF-1R. Conclusions The SDHB gene mutation is usually shown as a paraganglioma focus outside the adrenal gland. And 9.8% of the paragangliomas were associated with a mutation of the SDHB gene with an increase in malignant risk. The SDHB mutation caused over-expression of MIB-1 and the positive expression of EPAS1 and VEGF-1R in PHEO/PGL tissues, which was associated with invasion and metastasis of malignant PHEO/PGL. Key words: Pheochromocytoma; Paraganglioma; Succinate dehydrogenase B

Multiple endocrine neoplasia 2 in Cyprus: evidence for a founder effect

PurposeMultiple endocrine neoplasia type 2 (MEN2) affects patients with RET proto-oncogene mutations. This cohort study refers to patients who were diagnosed with familial medullary thyroid carcinoma (MTC) and underwent RET genetic testing in Cyprus between years 2002 and 2017.Methods and patientsForty patients underwent RET testing by Sanger sequencing of exons 10–11 and 13–16. Genotyping with STR genetic markers flanking the RET gene along with Y-chromosome genotyping and haplogroup assignment was also performed.ResultsRET mutations were identified in 40 patients from 11 apparently unrelated Cypriot families and two non-familial sporadic cases. Nine probands (69.2%) were heterozygous for p.Cys618Arg, one (7.7%) for p.Cys634Phe, one (7.7%) for the somatic delE632-L633 and two (15.4%) for p.Met918Thr mutations. The mean age at MTC diagnosis of patients carrying p.Cys618Arg was 36.8 ± 14.2 years. The age of pheo diagnosis ranged from 26 to 43 years and appeared simultaneously with MTC in 5/36 (13.9%) cases. The high frequency of the p.Cys618Arg mutation suggested a possible ancestral mutational event. Haplotype analysis was performed in families with and without p.Cys618Arg. Six microsatellite markers covering the RET gene and neighboring regions identified one core haplotype associated with all patients carrying p.Cys618Arg mutation.ConclusionsThe mutation p.Cys618Arg is by far the most prevalent mutation in Cyprus followed by other reported mutations of variable clinical significance. The provided molecular evidence speculates p.Cys618Arg mutation as an ancestral mutation that has spread in Cyprus due to a possible founder effect.

Prophylactic thyroidectomies in MEN2 syndrome: Management and outcomes

Aim of the studyThe aim of the study was to evaluate the outcomes of prophylactic thyroidectomies performed in an academic setting in the context of multiple endocrine neoplasia type 2 (MEN2) syndrome. MethodsA chart review of patients <18years old who underwent prophylactic thyroidectomy for a MEN2 syndrome at a children's hospital between 2006 and 2015 was performed. Main resultsThe study included 21 patients (57% female) with a mean age of 6.2±2.5years. All patients were asymptomatic at first evaluation. Nineteen had MEN2A syndrome with RET proto-oncogene mutations identified. The remaining two were RET-negative with familial medullary thyroid cancer (FMTC). One patient had a concomitant Hirschsprung disease. Of the 11 patients who had RET proto-oncogene mutations ranked as Moderate Risk for medullary thyroid cancer (MTC) (American Thyroid Association), one had a microcarcinoma on the resected specimen, and the others had C-Cell Hyperplasia. Among the 8 patients who had RET proto-oncogene mutations ranked as High Risk level for MTC, all had microcarcinoma. Of the nine patients with microcarcinoma, three underwent surgery after 5years of age. No microcarcinoma exceeded 6mm. There were no permanent complications. Six patients experienced transient hypocalcemia, of which only one was symptomatic. No patients had lymph node involvement, and no recurrence was noted during the follow-up period. ConclusionsOf 21 children with familial thyroid cancer syndrome who underwent a prophylactic thyroidectomy, nine had microcarcinoma. This study highlights the need for a complete familial history, including FMTC history and mandatory preventive surgical approach. Level of evidenceIII

TP53 and RET may serve as biomarkers of prognostic evaluation and targeted therapy in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the most common malignancy of the liver. Genomic analysis is conducted to identify genetic alterations in driver genes which are all druggable targets for cancer therapy. In the present study, we performed an exome sequencing of 45 driver genes in 100 paired samples from HCC patients including tumors and matched adjacent normal tissues using Illumina HiSeq 2000 platform. Non-synonymous mutations were ascertained using the iPLEX MassARRAY system and Sanger sequencing. Clinicopathological relevance with genetic variations was assessed using SPSS software. The prognostic analyses of patients with gene mutation status were summarized using Kaplan-Meier curves. Sixty-one non-synonymous somatic mutations were identified in 43% of the HCC patients. The most frequent mutations were: TP53 (20%), RET (6%), PLCE1 (5%), PTEN (4%) and VEGFR2 (3%). Patients with mutations in TP53 had a lower overall survival (OS) (P=0.002) than those without mutations. Recurrent mutations in the Ret proto-oncogene (RET) were associated with poor outcomes for both disease-free survival (DFS) (P=0.028) and OS (P=0.001) in HCC patients. The mutational status of sorafenib-targeted genes were associated with decreased DFS (P=0.039), and decreased OS (P=0.15) without statistical significance. Mutual exclusion of TP53 and RET mutations were observed in the present study. In conclusion, patients with TP53 mutations, RET mutations and sorafenib-targeted gene mutations were demonstrated to be associated with poor HCC prognosis, which suggests that both TP53 and RET may serve as biomarkers of prognostic evaluation and targeted therapy in HCC.

Clinical features and mutations of RET proto-oncogene in a pedigree affected with type 2A multiple endocrine neoplasia

To investigate the clinical features and mutations of RET proto-oncogene in a pedigree affected with multiple endocrine neoplasia type 2A (MEN2A). Clinical data of the family members was collected. Genomic DNA from peripheral blood leukocytes were extracted and subjected to PCR amplification. Exons 8, 10, 11, 13, 14, 15, 16 of the RET gene was sequenced. A missense mutation p.C634W was detected in 8 members from the family. Among them, 3 were diagnosed with pheochromocytoma, 1 with medullary thyroid carcinoma, 1 with medullary thyroid carcinoma and pheochromocytoma, 1 with medullary thyroid carcinoma and hyperparathyroidism. One member was found with thyroid enlargement but refused further examination, and another one was identified as carrier of the RET gene mutation. A p.C634W mutation has been detected in a family affected with MEN2A, in which most carriers have developed clinical symptoms. RET mutation detection should be routinely performed for families affected with MEN2A.

Three RET germ-line mutations in a family with multiple endocrine neoplasia type 2A syndrome

Multiple mutations in RET proto-oncogene are not common findings in patients with multiple endocrine neoplasia type 2A syndrome (MEN2A). Screening for RET mutation in MEN2A family members is usually limited by the known affected exon. However the second unrevealed mutation in RET proto-oncogene can coexist and modify the phenotype of MEN2 patients, including age of onset of medullary thyroid carcinoma, penetrance of pheochromocytoma etc. We here describe a family with MEN 2A syndrome with combination of three different germ-line RET mutations in its members (RET codon C634R, C634R+I852M, I852M+Y791F, Y791F). The earliest onset of medullary thyroid carcinoma was in a patient harboring the C634R+I852M double mutation at age 24 years. A 49-y.o.patient with C634R mutation has persistent medullary thyroid carcinoma after thyroidectomy at 35 years old. A carrier of Y791F mutation had no clinical evidence of disease at age of 28 years. In a child with compound I852M+Y791F mutation preventive thyroidectomy revealed C-cell hyperplasia at age of 4 years. The clinical significance of double RET mutation in the described family is not clear. Literature data of multiple germ-line RET mutations in patients with multiple endocrine neoplasia type 2A syndrome are presented.

RET pro-oncogene and medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) originats from the parafollicular C cells of the thyroid, which is one of the most aggressive forms of thyroid malignancy with the poor prognosis. Hereditary MTC has multiple endocrine neoplasia types 1, 2A and 2B. The mutation of RET proto-oncogene has been identified as the main cause of MTC, and all mutations locate among the exons 5, 8, 10, 11, 13, 14, 15, and 16. Mutation analysis of the RET may provide a theoretical basis for the prevention, diagnosis and treatment of MTC.

A germline RET proto-oncogene mutation in multiple members of an Arab family with variable onset of MEN type 2A-associated clinical manifestations

BackgroundMultiple endocrine neoplasia type 2A (MEN2A) is a rare cancer associated-syndrome, inherited in an autosomal dominant fashion and caused by germline mutation in RET proto-oncogene. Clinical diagnosis depends on the manifestation of two or more certain endocrine tumors in an individual, such as medullary thyroid carcinoma, pheochromocytoma, and parathyroid adenoma or hyperplasia. Prophylactic total thyroidectomy with central neck lymph node dissection is mandatory for mutation carriers, with periodic monitoring of the other concerned organs. Subjects and methodsWe have screened 27 individuals from a large Arab family with multiple affected members. Mutational screening involved the hotspot regions in the most commonly implicated exons 10 and 11 of RET proto-oncogene using PCR amplification of the coding and the flanking intronic regions followed by the Sanger sequencing. We aimed for confirmation of the clinical diagnosis and identification of at-risk asymptomatic mutation carriers. ResultsA pathogenic variant c.1901G>T (p.Cys634Phe), in exon 11 of RET proto-oncogene was identified in 15 members of different ages. ConclusionGenetic counseling plays a key role in the management of such high-risk families and hence helps in avoiding or reducing disease recurrence in their future generations.

Erratum to: PI3K/Akt/mTOR signaling in medullary thyroid cancer: a promising molecular target for cancer therapy.

The phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway is a central hub for the regulation of cell proliferation, apoptosis, cell cycle, metabolism, and angiogenesis. Several studies have recently suggested that the PI3K/Akt/mTOR signaling pathway is implicated in the pathogenesis and progression of neuroendocrine tumors. Medullary thyroid cancer (MTC) is a neuroendocrine tumor developing from the C cells of the thyroid. Mutations in the RET proto-oncogene are involved in the pathogenesis of several forms of MTC. The deregulation of the PI3K/Akt/mTOR pathway seems to contribute to the tumorigenic activity of RET proto-oncogene mutations. Targeting this pathway through specific inhibitors at simple or multiple sites may represent an attractive potential therapeutic approach for patients with advanced MTCs. The aim of this review is to examine the role of the PI3K/Akt/mTOR pathway in the development and progression of MTC and the new therapeutic options that target this signaling pathway.

Prognostic markers and response to vandetanib therapy in sporadic medullary thyroid cancer patients.

Medullary thyroid carcinoma (MTC) occurs sporadically in 75% of patients. Metastatic disease is associated with significantly poorer survival. The aim of this study was to identify prognostic markers for progressive MTC and oncogenic factors associated with response to vandetanib therapy. Clinical courses of 32 patients with sporadic MTC (n=10 pN0cM0, n=8 pN1cM0, n=14 pN1cM1) were compared with genetic profiles of the patients' primary tumour tissue. Analysis for RET proto-oncogene mutations was performed by Sanger sequencing and next-generation sequencing (NGS). The mRNA expression (mRNA count) of 33 targets was measured by nCounter NanoString analysis. Somatic RET mutations occurred in 21/32 patients. The RET918 mutation was found in 8/14 pN1cM1 patients. BRAF (P=0.019), FGFR2 (P=0.007), FGFR3 (P=0.044) and VEGFC (P=0.042) mRNA expression was significantly lower in pN1cM0/pN1cM1 compared with pN0cM0 patients, whereas PDGFRA (P=0.026) mRNA expression was significantly higher in pN1cM0/pN1cM1 when compared with pN0cM0 patients. Among the 10/32 vandetanib-treated patients, 5 showed partial response (PR), all harbouring the RET918 mutation. mRNA expression of FLT1 (P=0.039), FLT4 (P=0.025) and VEGFB (P=0.042) was significantly higher in therapy responders. In this study, we identified molecular markers in primary tumour tissue of sporadic MTC associated with the development of metastasis (both lymph node and organ metastasis) as well as response to vandetanib therapy.