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

Chinese siblings with hereditary medullary thyroid carcinoma caused by RET mutation: implications for RET oncogene detection

BACKGROUND

Hereditary medullary thyroid carcinoma (MTC) is mainly caused by germline mutations in the RET proto-oncogene, which accounts for 20-30% of all MTC according to foreign studies. However, no English literatures have reported Chinese hereditary MTC. Here, we reported two Chinese brothers with MTC that caused by germline RET mutation.

CASE PRESENTATION

The younger brother was diagnosed with MTC at 29 years ago and suffered recurrence more than 10 years. For elder brother, the diagnosis of MTC was made by postoperative pathological examination at age 61. Both patients received total thyroidectomy and lymph node dissection. Since they had a significant family history for MTC, genetic detection was performed and identified a germline mutation in RET exon 10 (p.C620Y). This mutation was also detected in their offspring, indicating a moderate risk of MTC.

CONCLUSIONS

This is the first report presenting a Chinese family with hereditary MTC caused by the RET p.C620Y variant. This case series emphasize the importance of genetic detection of RET proto-oncogene for MTC patients, and bring out managements for individuals after detection of RET mutations.

Hereditary Syndromes in Neuroendocrine Tumors

OPINION STATEMENT

Oncologists should be able to discern the salient clinical features of the most common germline mutations that give rise to neuroendocrine tumors. Astute recognition of an index patient affected by a hereditary syndrome can lead to a "tip-of-the-iceberg" phenomenon whereby their entire kindred can then be proactively monitored and managed potentially with substantial reduction of morbidity and mortality. Through careful history-taking, as well as thoughtful assimilation of findings from the physical exam, biochemical laboratories, scans, and pathology reports, the clinician can spot phenotypic clues that distinguish these familial patterns from sporadic cases of tumorigenesis.

The role of hepatic trans-arterial chemoembolization in metastatic medullary thyroid carcinoma: a specialist center experience and review of the literature

BACKGROUND

Liver metastases are relatively common in patients with metastatic medullary thyroid carcinoma (MTC), carrying a negative impact on disease prognosis. The options for selective therapy of liver metastases in MTC patients are limited to catheter-guided procedures such as trans-arterial chemoembolization (TACE). Data regarding the effectiveness and safety of this procedure in MTC are limited.

AIM

To explore the clinical outcome, survival and safety profile of TACE for liver metastases in a group of MTC patients.

METHODS

Retrospective case series of patients treated at a single tertiary University Medical Center from 2005 to 2015.

RESULTS

Seven consecutive patients (mean age 64.5 ± 10.9 years, 5 females) with histologically confirmed MTC with liver metastases were included. Metastatic involvement of the liver was less than 50% of the liver volume in all patients. The median size of the largest liver lesion was 40 ± 6.9 mm. The patients underwent in total 20 sessions of TACE. Clinical improvement as well as tumor response (PR) were observed in all patients. The median time to tumor progression was 38 months (range 8-126). Three patients were still alive at the end of the follow-up period (a median overall survival rate of 57 ± 44 months).

CONCLUSION

TACE in MTC patients with hepatic metastases is usually well tolerated and induces both clinical improvement and tumor response for prolonged periods of time in the majority of patients. This therapeutic option should always be considered, irrespective of the presence of extrahepatic metastasis.

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.

Secondary or second primary malignancy in the thyroid? metastatic tumors suggested clinically: a differential diagnostic task

OBJECTIVE

To describe the algorithms employed to explore the suggestion or consideration of metastatic malignancy in the thyroid.

STUDY DESIGN

Thirty-seven cases with a history of malignancy (n = 21) and/or uncommon fine-needle aspiration biopsy (FNAB) findings (n = 37) were reviewed and reclassified according to The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC).

RESULTS

The group was heterogeneous in terms of the final histopathology results: the suggested metastasis was confirmed in only half of the cases (11/21; 52.4%). Primary thyroid malignancies were mostly nondifferentiated, medullary, or rare. However, 3 papillary carcinomas (the less common variants) were also found. Finally, 5 out of 37 cases were surprisingly benign upon histopathological investigation (uncommon repair and fibrotizing Hashimoto thyroiditis).

CONCLUSIONS

The metastatic nature of thyroid gland nodule(s) must be considered in cases of generalization of malignancy and/or uncommon FNAB findings. We must be as open-minded as possible from the outset. Additional techniques are helpful if available - cytoblock and immunocytochemistry can contribute substantially. Morphological comparisons with the previous malignancy are recommended whenever possible. To avoid overtreatment, cases without precise typing should not be classified as TBSRTC diagnostic category VI - malignant, but should remain in TBSRTC diagnostic category V - suspicious for malignancy. Repeated FNAB to enable additional techniques may be suggested.

Personalized medicine: caught between hope, hype and the real world

Genomic and personalized medicine have become buzz phrases that pervade all fields of medicine. Rapid advances in "-omics" fields of research (chief of which are genomics, proteinomics, and epigenomics) over the last few years have allowed us to dissect the molecular signatures and functional pathways that underlie disease initiation and progression and to identify molecular profiles that help the classification of tumor subtypes and determine their natural course, prognosis, and responsiveness to therapies. Genomic medicine implements the use of traditional genetic information, as well as modern pangenomic information, with the aim of individualizing risk assessment, prevention, diagnosis, and treatment of cancers and other diseases. It is of note that personalizing medical treatment based on genetic information is not the revolution of the 21st century. Indeed, the use of genetic information, such as human leukocyte antigen-matching for solid organ transplantation or blood transfusion based on ABO blood group antigens, has been standard of care for several decades. However, in recent years rapid technical advances have allowed us to perform high-throughput, high-density molecular analyses to depict the genomic, proteinomic, and epigenomic make-up of an individual at a reasonable cost. Hence, the so-called genomic revolution is more or less the logical evolution from years of bench-based research and bench-to-bedside translational medicine.

Medullary thyroid cancer: management guidelines of the American Thyroid Association

BACKGROUND

Inherited and sporadic medullary thyroid cancer (MTC) is an uncommon and challenging malignancy. The American Thyroid association (ATA) chose to create specific MTC Clinical Guidelines that would bring together and update the diverse MTC literature and combine it with evidence-based medicine and the knowledge and experience of a panel of expert clinicians.

METHODS

Relevant articles were identified using a systematic PubMed search and supplemented with additional published materials. Evidence-based recommendations were created and then categorized using criteria adapted from the United States Preventive Services Task Force, Agency for Healthcare Research and Quality.

RESULTS

Clinical topics addressed in this scholarly dialog included: initial diagnosis and therapy of preclinical disease (including RET oncogene testing and the timing of prophylactic thyroidectomy), initial diagnosis and therapy of clinically apparent disease (including preoperative testing and imaging, extent of surgery, and handling of devascularized parathyroid glands), initial evaluation and treatment of postoperative patients (including the role of completion thyroidectomy), management of persistent or recurrent MTC (including the role of tumor marker doubling times, and treatment of patients with distant metastases and hormonally active metastases), long-term follow-up and management (including the frequency of follow-up and imaging), and directions for future research.

CONCLUSIONS

One hundred twenty-two evidence-based recommendations were created to assist in the clinical care of MTC patients and to share what we believe is current, rational, and optimal medical practice.

New presentation of familial medullary thyroid carcinoma in 87-year-old patient with high-riskRETproto-oncogene codon 620 mutation

Objective:

We report a case of familial medullary thyroid carcinoma in an 87-year-old woman, despite the patient having a high-risk codon 620 mutation.

Method:

Medline and PubMed were searched for cases and literature reviews relating to the following keywords: ‘codon 620’, ‘medullary thyroid carcinoma’, ‘multiple endocrine neoplasia’ and ‘RET proto-oncogene’.

Results:

We report the case of an 87-year-old woman who presented with a goitre, later identified as medullary thyroid carcinoma. Genetic analysis revealed aRETproto-oncogene codon 620 mutation. Genetic testing has revolutionised the management of medullary thyroid carcinoma. The genetic basis of hereditary medullary thyroid carcinoma lies with theRETproto-oncogene. Several disease-causing mutations of this gene have been identified and their clinical prognosis described. The penetrance of these mutations is high; as such, carriers progress to develop medullary thyroid carcinoma at a young age. Mutations at the codon 620 position are classified as high-risk for early development of medullary thyroid carcinoma; thus, the current recommendation is for prophylactic thyroidectomy at five years of age.

Conclusions:

In this case, the progress of hereditary medullary thyroid carcinoma was unique, considering the late presentation of medullary thyroid carcinoma despite the presence of the high-riskRETproto-oncogene codon 620 mutation. The authors wish to highlight the importance of this case, as it may present a counter-argument to the current recommendations for early, prophylactic thyroidectomy in codon 620 mutation carriers in order to prevent early development of medullary thyroid carcinoma.

Analysis of selected genes in neuroendocrine tumours: insulinomas and phaeochromocytomas

Insulinomas and phaeochromocytomas are neuroendocrine tumours that may be either sporadic or manifestation of a familial cancer syndromes and are both derived from the neural crest. In the present study, gene components of different signalling pathways were investigated in sporadic human insulinomas and phaeochromocytomas to identify the responsible candidates. Ret and k-ras were tested for activating point mutations, and NF1, p53, BRCA1, nm23-H1, SDHB and SDHD for loss of heterozygosity (LOH). Twenty-two sporadic insulinomas and 15 phaeochromocytomas were analysed by the polymerase chain reaction using restriction fragment length polymorphism or dinucleotide repeat polymorphism methods. The results of our analysis demonstrate that the most frequent changes were point mutations of k-ras: 23% of insulinomas and 62% of phaeochromocytomas harboured k-ras mutations. The analysis also showed two phaeochromocytomas with point mutations of the ret oncogene. Only one insulinoma showed LOH of NF1, and another showed LOH of p53. Allelic loss of BRCA1 was detected in two insulinomas, and of nm23-H1 in another insulinoma. Allelic losses of the SDHB gene were present in two phaeochromocytoma and one insulinoma cases and allelic losses of SDHD were present in one phaeochromocytoma case. The changes observed in phaeochromocytomas were more homogenous and confined to k-ras and ret oncogenes, whereas insulinomas showed more heterogenic situation. Our findings may contribute to a better understanding of the genetic profile of neuroendocrine tumours.

Oral manifestations of internal malignancy and paraneoplastic syndromes

Malignant tumors of visceral organs are a fundamental feature of familial cancer and paraneoplastic syndromes. In many instances, the presence of an internal and often occult malignancy may be forewarned by various external manifestations. Several of these findings are preferentially localized to the head and neck region, including the oral cavity proper. This places the dental practitioner in a unique position to detect these "markers" of occult neoplastic involvement. Because these markers may present before an established syndrome or cancer diagnosis, even representing the first expression of disease in some cases, early recognition by a dentist may lead to timely diagnosis and management of these cancer-associated syndromes.

Prophylactic thyroidectomy in pediatric carriers of multiple endocrine neoplasia type 2A or familial medullary thyroid carcinoma: mutation in C620 is associated with Hirschsprung's disease

PURPOSE

Prophylactic total thyroidectomy is now recommended after having confirmed RET mutations in children of parents with multiple endocrine neoplasia type 2 or familial medullary thyroid carcinoma. We reviewed our experience to determine the incidence of medullary thyroid carcinoma with respect to age at surgery, the location of the mutation, and its association with Hirschsprung's disease (HD).

METHODS

A retrospective review from 1996 to 2005 revealed 20 children with genetic screening for multiple endocrine neoplasia type 2A or familial medullary thyroid carcinoma who underwent a prophylactic total thyroidectomy with parathyroid gland preservation.

RESULTS

The median age of the 20 patients (9 boys and 11 girls) included in this study was 8.2 years (range, 3.7-16.9 years) at the time of their surgery. Final pathology revealed normal thyroid tissue (n = 3; median age, 5.9 years), C-cell hyperplasia (n = 13; median age, 10 years), or medullary thyroid carcinoma (n = 4; median age, 8 years). Four children, all with mutations in C620, had a previous diagnosis of HD. At a median follow-up of 3.7 years (range, 1 month to 8.4 years), all patients were well and cancer free.

CONCLUSIONS

There is no correlation between histologic findings and median age at surgery. Hirschsprung's disease was found in 50% of the patients with the RET mutation in C620. In children of C620 parents, symptoms of HD should be actively sought, and if such are found, rectal biopsies should be performed even if mutation results are not yet available. Based on the age of the earliest cancer and the safety of total thyroidectomy, children should promptly undergo surgery after genetic screening and before their fifth year of life.

Hereditary medullary thyroid cancer in Slovenia – genotype-phenotype correlations

BACKGROUND

Medullary thyroid cancer (MTC) is a rare endocrine tumor that may be sporadic or inherited in settings of MEN2A, MEN2B and FMTC. Germline point mutations in the RET proto-oncogene are responsible for tumor occurrence, inheritance and great clinical variability. The aim of this study was to correlate the genotype and phenotype of patients with hereditary MTC (age at diagnosis, sex, TNM classification and clinical features).

PATIENTS

Between 1997 and 2003 genetic testing was performed in 69 out of 98 patients with "sporadic" MTC. Carriage of mutation was found in 14 (20.2%) patients (index patients) and in 16 out of 31 (51.6%) of their relatives. One patient with MEN2B and codon 918 mutation was excluded from further analysis.

METHODS

Genomic DNA was isolated from peripheral blood leukocytes. Exons 10, 11, 13, 14, 15 and 16 of the RET proto-oncogene were amplified in polymerase chain reactions. Point mutations of the RET gene were detected with single-strand conformation analysis and DNA sequencing. Detected mutations were confirmed with restriction enzyme analysis.

RESULTS

Codon 634 mutations were detected in 15 patients (50%; aged 18-76 years; 6 families), codon 618 in nine patients (30%; aged 12-65 years; 4 families) and codon 790 in five patients (16.6%; aged 16-74 years; 3 families). The median age at diagnosis was 31 +/- 17.3, 33 +/- 15.9 and 36 +/- 23.8 years for patients with codon 618, 634 and 790 mutations. Selected by sex, females with codon mutations 618 and 634 versus 790 had median age at diagnosis of 34.5 +/- 15.6 years and 43.5 +/- 22.9 years, whereas the inverse result was observed in males (26.5 +/- 18.0 versus 16 years). The male/female ratio was 1:2 for patients with codon 618 and 634 mutations and 1:4 for patients with codon 790 mutations. Some of the data suggested correlation between specific genotypes, tumor size, stage of MTC and age at diagnosis. Pheochromocytoma (12 out of 15 patients) and primary hyperparathyroidism (6 out of 15 patients) were diagnosed solely in patients with codon 634 mutations. One patient with FMTC and Hirschprung disease was found in a family with codon 618 mutations.

CONCLUSION

Correlation between tumor size, stage of MTC at diagnosis in view of patient's age, and specific genotype were indicated in our limited series and were more evident in female patients with codon 790 mutations. Later onset and a probably less aggressive course of MTC in these patients than in patients with other mutations should be considered in planning prophylactic thyroid surgery. MEN2A syndrome was related solely to codon 634 mutations.

[Pre-symptomatic diagnosis of severe hereditary diseases with late onset in Lebanon: a choice or a necessity?]

Progress achieved in the field of molecular genetics has opened the door to pre-symptomatic diagnosis tests of several severe hereditary disease, a majority of which are dominant and appear later in life. Given the importance of diagnosis in some of the cases where medical supervision and prevention are possible, there are a number of ethical dilemmas with regards to most of these diseases that, unfortunately, do not have a cure or any preventive treatment available. Above and beyond the capacity for medical care provision, there is a very high level of pressure and anxiety felt by every member of a family who has someone affected by one of these diseases in that they might be a carrier of a mutated gene which could be the cause or source of illness. They carry the burden of uncertainty that they may have already transmitted this gene or could give it to any of their children, and often there is also a significant level of guilt when one is the carrier but not to be affected by the disease itself. More and more frequently in these types of cases, there is a strong desire to know--in order to better organise and plan one's life and that of one's potential future family in the instance where one wishes to found one. This article discusses these problems based upon the consideration of four examples of such diseases with late onset: Huntington's disease, the common forms of thyroid cancer, the familiar forms of a predisposition to breast and ovarian cancer, and von Hippel-Lindau syndrome. However, regardless of the type of disease, the decision to take a genetic test is solely the choice of the individual in question, and the person should be accompanied and guided in his or her reflection by a multi-disciplinary team who can advise him or her and initiate useful deliberations on the various possibilities, their advantages and their disadvantages.

Gene-expression profiling in differentiated thyroid cancer – a viable strategy for the practice of genomic medicine?

Thyroid neoplasias have been largely ignored as an active field of investigation due to the overall favorable prognosis of differentiated nonmedullary thyroid cancers. However, differentiated thyroid cancers have the highest estimated annual percentage increase in incidence amongst all cancer sites. Furthermore, no significant progress has been made to improve survival, especially for advanced disease. Compounding the problem, there remains a lack of highly accurate preoperative markers or molecular-based predictive models to differentiate benign from malignant follicular neoplasias, thus we continue to rely upon surgery for diagnostic purposes in this subset of patients. Therefore, new approaches are necessary to identify potential novel diagnostic, prognostic and therapeutic algorithms, which would not only allow accurate early diagnosis but also personalized patient management, with clinical management and surveillance tailored according to the genetic signature of the patient. The advent of modern genomic technologies, such as global gene-expression profiling, may begin to provide the data required for the evidence-based practice of genomic medicine as it relates to thyroid neoplasia. However, it is already clear that genomic technology alone is insufficient to fully achieve this vision.

Surgical Prevention of Cancer

There have been many recent advances in cancer prevention, including improved understanding of cancer biology, better characterization of premalignant disease, significant advances in cancer surveillance, and identification of effective chemoprevention regimens. Despite this, surgery remains the best option for many individuals at high risk of cancer. Like all prevention modalities, surgical prevention involves balancing the factors governing cancer risk with the benefits and risks of treatment. The issues governing decision making for surgical prevention vary widely among different cancer types, and include consideration of the age and level of cancer risk of the individual, the effectiveness of cancer surveillance for the particular organ at risk, the aggressiveness of the cancer once present, and the morbidity of surgery. This article briefly reviews the use of surgery to prevent some of the most common epithelial malignancies, as well as some of the genetic cancer syndromes for which surgery plays an important role in improving survival.

Molecular biology of primary hyperparathyroidism

As molecular biology and genetic mapping receive wider application to human disease, genetic alterations have been identified with increased frequency in some patients with primary hyperparathyroidism(HPT). These alterations have been found in molecules related to cellular signaling and growth (RET proto-oncogene)and in tumor suppressors that control cell cycle progression and gene transcription (cyclin D1 and the MEN1 gene product. Although primary HPT can usually be treated surgically without knowledge of which specific genetic alteration has occurred, this information may assist clinicians in identifying which patients will go on to develop multiglandular or recurrent disease. In addition,such an approach would facilitate more appropriate postoperative surveillance, as well as counseling and screening of family members who may be at high risk for HPT.