Medullary thyroid carcinoma: including MEN 2A and MEN 2B syndromes

Efficacy and Safety of RET-Specific Kinase Inhibitors in RET-Altered Cancers: A Systematic Review

RET proto-oncogene encodes receptor tyrosine kinase. Selpercatinib and pralsetinib are the only RET-specific tyrosine kinase inhibitors approved by FDA in RET-altered tumors. We searched PubMed, Embase, Cochrane, WOS, and Clinicaltrials.gov. Objective-response, complete-response, and partial-response were 60-89%, 0-11%, and 55-89%, respectively, with the use of RET-specific drugs. ≥Grade 3 adverse events were seen in 28-53% of the patients, with hypertension, change in ALT, QT prolongation, neutropenia, and pneumonitis among the common side effects. Hence, selpercatinib and pralsetinib were effective and well tolerated by most of the patients with RET-altered tumors.

Genetically engineered mouse models of head and neck cancers

The head and neck region is one of the anatomic sites commonly afflicted by cancer, with ~1.5 million new diagnoses reported worldwide in 2020 alone. Remarkable progress has been made in understanding the underlying disease mechanisms, personalizing care based on each tumor's individual molecular characteristics, and even therapeutically exploiting the inherent vulnerabilities of these neoplasms. In this regard, genetically engineered mouse models (GEMMs) have played an instrumental role. While progress in the development of GEMMs has been slower than in other major cancer types, several GEMMs are now available that recapitulate most of the heterogeneous characteristics of head and neck cancers such as the tumor microenvironment. Different approaches have been employed in GEMM development and implementation, though each can generally recapitulate only certain disease aspects. As a result, appropriate model selection is essential for addressing specific research questions. In this review, we present an overview of all currently available head and neck cancer GEMMs, encompassing models for head and neck squamous cell carcinoma, nasopharyngeal carcinoma, and salivary and thyroid gland carcinomas.

Psychosocial Characteristics and Experiences in Patients with Multiple Endocrine Neoplasia Type 2 (MEN2) and Medullary Thyroid Carcinoma (MTC)

Multiple Endocrine Neoplasia type 2 (MEN2) is a genetic cancer syndrome for which there are limited data pertaining to the quality of life and psychosocial experiences of persons affected. Medullary thyroid carcinoma (MTC) is a rare disease of the thyroid gland often associated with MEN2. MTC often progresses slowly and may present with a myriad of physical symptoms including hair loss, sleep disturbance, fatigue, weight changes, heart palpitations, and constipation or diarrhea. Like other cancers or rare, inheritable illnesses, patients with MEN2 and MTC may be at risk for psychosocial stressors. The current, cross-sectional study administered a structured psychosocial interview and The Distress Thermometer/Problem Checklist to 63 patients with MEN2 and MTC and their caregivers. Despite reports of overall good health, 46% of adults and 44% of youth reported that pain interferes with their daily life; 53% of adults and 59% of youth reported that pain interferes with their mood. Pediatric patients frequently reported experiencing attention challenges (50%) and difficulty concentrating (65%). Parents reported that mood shifts and becoming upset easily were the most prevalent concerns for their children. The most frequent need for services included education about MTC, treatment and research participation, and the opportunity to meet others with MTC.

Choroidal metastasis as initial presentation of aggressive medullary thyroid carcinoma with widespread mediastinal, brain, pituitary, bone, lung, and liver metastasis: Case report and literature review

INTRODUCTION

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor that originates from the parafollicular C cells of the thyroid gland. MTC can be due to sporadic or hereditary causes due to gain of function germ line mutations in the RET proto-oncogene. MTC presenting as ocular symptoms due to choroidal mass is rare with bad prognosis.

PRESENTATION OF CASE

A 38-year-old Sudanese male presented to Hamad General Hospital, complaining of sudden painless decrease of vision of the right eye of 3 weeks duration. After investigations using imaging methods, the patient was discovered to have metastatic MTC that presented as choroidal mass and metastasized to his lung, bone, brain, pituitary, liver and mediastinum.

DISCUSSION

In terms of investigations, serum levels of calcitonin have superior diagnostic accuracy. Our patient undertook diagnostic imaging including ultrasonography, fine needle aspiration and computerized tomography (CT) scan and/or MRI imaging. He undertook total thyroidectomy and left neck dissection followed by stereotactic radiosurgery for the right orbit and pituitary. He then received systemic anti-RET therapy (Selpercatinib). At 5 months follow up there was dramatic drop in CEA from 888 μg/L to 164 μg/L, and calcitonin from >585.2 pmol/L to 354 pmol/L.

CONCLUSION

Choroidal metastasis as initial presentation of MTC is extremely rare and challenging to diagnose. Surgeons need a high index of suspicion when ocular symptoms accompany a neck mass or thyroid-related symptoms. MTC has a progressive course with involvement of blood vessels and neck lymph nodes. Choroidal metastasis of MTC is challenging to manage.

Risk-reduction surgery in pediatric surgical oncology: A perspective

OBJECTIVE

A small percentage of pediatric solid cancers arise as a result of clearly identified inherited predisposition syndromes and nongenetic lesions. Evidence supports preemptive surgery for children with genetic [multiple endocrine neoplasia type 2 (MEN2), familial adenomatous polyposis syndrome (FAP), hereditary nonpolyposis colorectal cancer (HNPCC), and hereditary diffuse gastric cancer (HDGC) and nongenetic [thyroglossal duct cysts (TGDC), congenital pulmonary airway malformations (CPAM), alimentary tract duplication cysts (ATDC), and congenital choledochal cysts (CCC)] developmental anomalies. Our aim was to explore the utility of risk reduction surgery to treat and prevent cancer in children.

METHODS

A systematic review of the available peer-reviewed literature on PubMed was performed using a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) search strategy, where possible. Search items included "risk reduction surgery", "hereditary cancer predisposition syndrome", "multiple endocrine neoplasia type 2", "familial adenomatous polyposis", "hereditary nonpolyposis colorectal cancer", "hereditary diffuse gastric cancer", "thyroglossal duct cysts", congenital pulmonary airway malformations", "alimentary tract duplication cysts", "malignant transformation", and "guidelines".

RESULTS

We identified 67 articles that met the inclusion criteria describing the indications for prophylactic surgery in surgical oncology. For the genetic predisposition syndromes, 7 studies were related to professional endorsed guidelines, 7 were related to surgery for MEN2, 11 were related to colectomy for FAP, 6 were related to colectomy for HNPCC, and 12 related to gastrectomy for HDGC. Articles for the nongenetic lesions included 5 for techniques related to TGDC resection, 9 for surgery for CPAMs, and 10 for resection of ATDCs. Guidelines and strategies varied significantly especially related to the extent and timing of surgical intervention; the exception was for the timing of thyroidectomy in children with MEN2.

CONCLUSION

Current evidence supporting prophylactic surgery in the management of pediatric cancer predisposition syndromes and nongenetic lesions is best delineated for thyroidectomy to prevent medullary thyroid cancer in children with MEN2 (Strength of Recommendation Grade B/C). Despite the lack of pediatric specific evidence-based recommendations regarding the appropriate extent and timing for risk-reduction surgery for FAP, HNPCC, HDGC and nongenetic anomalies, our review represents an opportunity towards understanding the postgenomic development of these lesions and provides current indications and techniques for preemptive cancer prevention surgery in children.

A multicenter phase 2 trial of pazopanib in metastatic and progressive medullary thyroid carcinoma: MC057H

CONTEXT

Pazopanib is a small molecule inhibitor of kinases principally including vascular endothelial growth factor receptors-1, -2, and -3; platelet-derived growth factor receptors-α and -β; and c-Kit. We previously reported a tumor response rate of 49% in patients with advanced differentiated thyroid cancer and 0% in patients with advanced anaplastic thyroid cancer. The present report details results of pazopanib therapy in advanced medullary thyroid cancer (MTC). OBJECTIVE, DESIGN, SETTING, PATIENTS, INTERVENTION, AND OUTCOME MEASURES: Having noted preclinical activity of pazopanib in MTC, patients with advanced MTC who had disease progression within the preceding 6 months were accrued to this multiinstitutional phase II clinical trial to assess tumor response rate (by Response Evaluation Criteria In Solid Tumors criteria) and safety of pazopanib given orally once daily at 800 mg until disease progression or intolerability.

RESULTS

From September 22, 2008, to December 11, 2011, 35 individuals (80% males, median age 60 y) were enrolled. All patients have been followed up until treatment discontinuation or for a minimum of four cycles. Eight patients (23%) are still on the study treatment. The median number of therapy cycles was eight. Five patients attained partial Response Evaluation Criteria In Solid Tumors responses (14.3%; 90% confidence interval 5.8%-27.7%), with a median progression-free survival and overall survival of 9.4 and 19.9 months, respectively. Side effects included treatment-requiring (new) hypertension (33%), fatigue (14%), diarrhea (9%), and abnormal liver tests (6%); 3 of 35 patients (8.6%) discontinued therapy due to adverse events. There was one death of a study patient after withdrawal from the trial deemed potentially treatment related.

CONCLUSIONS

Pazopanib has promising clinical activity in metastatic MTC with overall manageable toxicities.

(111)In-octreotide scintigraphy for identification of metastatic medullary thyroid carcinoma in children and adolescents

CONTEXT

Most medullary thyroid cancers (MTC) express somatostatin receptors; therefore, (111)In-octreotide somatostatin receptor scintigraphy (SRS) may be useful in detecting sites of metastases in children with MTC.

OBJECTIVE

The aim of the study was to evaluate tumor metastases in children and adolescents with MTC using SRS in comparison to conventional imaging.

DESIGN AND SETTING

A case series was conducted as part of baseline evaluation for cancer treatment protocol at the National Institutes of Health Clinical Center.

PATIENTS

Eleven patients with a median age of 15 (range, 9-17) yr participated in the study, 10 with histologically proven, metastatic MTC due to the M918T mutation of the RET protooncogene, and one with a known RET polymorphism.

INTERVENTION

After receiving 0.086 mCi/kg (111)Indium-pentreotide, patients were examined with a single photon emission computed tomography scan 4 and 24 h after injection. Baseline conventional imaging, including computed tomography (neck, chest, abdomen, ± pelvis, adrenals), magnetic resonance imaging (neck), and bone scan, was performed on all patients.

MAIN OUTCOME MEASURES

SRS results were compared with conventional imaging.

RESULTS

Five of the 11 patients had abnormal findings on SRS. Of the 53 total target lesions present in the patients, only 24.5% were accurately identified through SRS.

CONCLUSIONS

SRS appears to be less sensitive than conventional imaging at detecting the full extent of metastatic disease in children and adolescents with hereditary MTC. SRS incompletely identified sites of tumor and failed to visualize small sites of tumor or liver and lung metastases, and it has a limited role in the evaluation of metastatic disease in pediatric MTC patients.

Alternative surgical strategies in patients with sporadic medullary thyroid carcinoma: Long-term follow-up

The extent of surgical resection in patients with sporadic medullary thyroid carcinoma (SMTC) remains controversial. The aim of the present study was to discuss the prognosis of sporadic medullary thyroid carcinoma with different surgical treatments. Of 73 patients with SMTC (mean age of 43.78 years at diagnosis), 70 patients were followed up for 12.0-169.0 months (median 90.0). Having given their informed consent, 12 patients underwent total thyroidectomy with bilateral central neck dissection (group A), 40 underwent subtotal thyroidectomy preserving contralateral thyroid tissue on the entrance point of the recurrent laryngeal nerve into the larynx with ipsilateral modified radical neck dissection (group B), and 18 patients underwent subtotal thyroidectomy preserving contralateral thyroid tissue on the entrance point of the recurrent laryngeal nerve into the larynx with bilateral modified radical neck dissection (group C). The diagnosis was confirmed by a pathology examination. The incidences of hypoparathyroidism and recurrent laryngeal nerve injury, the cancer recurrence rates and survival time were investigated post-operatively. Significant differences were found between groups A, B and C in the incidence of hypoparathyroidism (χ(2)=40.9, P<0.01), as well as that of recurrent laryngeal nerve injury (χ(2)=32.9, P<0.01). The cancer recurrence rates in groups A, B and C were 75.0% (9/12), 2.5% (1/40) and 44.4% (8/18) respectively, (χ(2)=31.1, P<0.01) and the cure rates were 25, 97.5 and 55.6% respectively (χ(2)=31.1, P<0.01). The mean survival times in groups A, B and C were 77.8, 106.1 and 111.0 months respectively, but significant difference was noted (χ(2)=3.2, P>0.05). In conclusion, compared to total thyroidectomy with bilateral central neck dissection, subtotal thyroidectomy with ipsilateral/bilateral modified radical neck dissection showed a lower incidence of hypoparathyroidism, recurrent laryngeal nerve injury and lower rates of recurrence, along with a similar cumulative survival.

Disparity between tissue and serum calcitonin and carcinoembryonic antigen in a patient with medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor of parafollicular or C-cells of thyroid that comprises 5-10% of all thyroid cancers [1, 2]. The neoplastic cells secrete calcitonin, carcinoembryonic antigen (CEA), and chromogranin A. Typically, increased serum levels of these tumor markers permit them to be used for initial diagnosis and long-term disease status surveillance. This article reports a case of sporadic MTC (pT2N0M0) in a young patient with normal serum tumor markers. A 16-year-old woman presented with MTC without evidence for this to be a familial case due to the absence of germline mutations in the RET proto-oncogene and negative family history. Surprisingly, there were normal preoperative serum levels of calcitonin, CEA, and chromogranin A, despite the immunohistochemistry showing strong and diffuse positive staining for these markers. This disparity between serum levels and tumor expression of calcitonin and CEA in MTC is quite rare. The relevant features of this case are discussed in consideration of the published experiences. This case may represent an unique subgroup of MTC with abnormal secretory capacity that requires reliance upon radiological evaluation for evidence of recurrent or disseminated disease, without the diagnostic benefit of serum tumor markers.

Resveratrol induces Notch2-mediated apoptosis and suppression of neuroendocrine markers in medullary thyroid cancer

BACKGROUND

Currently, complete surgical resection is the only curative option for medullary thyroid cancer (MTC). Previous work has shown the Notch pathway is a potent tumor suppressor in MTC and that resveratrol activates the Notch pathway in carcinoid cancer, a related neuroedocrine malignancy. In this study, we hypothesized that the effects observed on carcinoid cells could be extended to MTC.

METHODS

MTC cells treated with varying doses of resveratrol were assayed for viability by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. Western blot analysis for achaete-scute complex-like 1 (ASCL1), chromogranin A (CgA), full-length and cleaved caspase 3, and poly-ADP ribose polymerase (PARP) was performed. Quantitative real-time polymerase chain reaction (qPCR) was used to measure relative mRNA expression.

RESULTS

Treatment with resveratrol resulted in growth suppression and an increase in the cleavage of caspase-3 and PARP. A dose-dependent inhibition of ASCL1, a neuroedocrine transcription factor, was observed at the protein and mRNA levels. Protein levels of CgA, a marker of hormone secretion, were also reduced after treatment with resveratrol. A dose-dependent induction of Notch2 mRNA was observed by qPCR.

CONCLUSIONS

Resveratrol suppresses in vitro growth, likely through apoptosis, as demonstrated by cleavage of caspase-3 and PARP. Furthermore, resveratrol decreased neuroedocrine markers ASCL1 and chromogranin A. Induction of Notch2 mRNA suggests that this pathway may be central in the anti-MTC effects observed.

Role of RET codonic mutations in the surgical management of medullary thyroid carcinoma in pediatric age multiple endocrine neoplasm type 2 syndromes

PURPOSE

Hereditary medullary thyroid carcinoma (MTC) therapy is surgical resection. Because the genetic screening was available, the early diagnosis of the disease has been possible. The purpose of this study was to evaluate the role of the genetic test in the management of these children and to draw some information about the surgical timing.

METHODS

Thirteen patients underwent total thyroidectomy at our institute between 1995 and 2007. Seven patients underwent a curative thyroidectomy, and 6 patients underwent a prophylactic thyroidectomy. Two patients were operated with a minimally invasive video-assisted technique. We studied the following parameters: age, risk level associated to the RET gene mutations, aim of surgery (curative or prophylactic), tumor histopathologic features, lymph node involvement, and distal metastases.

RESULTS

We found a statistical association between cancer maximum diameter and some parameters analyzed: age of patients, aim of surgery, single or multifocal MTC, and number of organs involved by distal metastases. Cancer diameter at the moment of diagnosis seems to increase according to the aggressiveness of RET gene mutation found.

CONCLUSIONS

The best strategy to cure MTC is to prevent it. Genetic screening could be a fundamental tool in the management of multiple endocrine neoplasm type 2 children. An improvement of scientific knowledge regarding RET gene alterations and an early and appropriate use of genetic tests could allow a better understanding of the correct surgical timing and a wider use of less aggressive surgical procedures.

Multiple endocrine neoplasia-2B presenting with orthodontic relapse

The multiple endocrine neoplasia (MEN) syndromes are a relatively uncommon group of genetic disorders characterized by the development of tumors in various endocrine organs. MEN type 2B is of particular interest to the dental profession because of its oral manifestations, which are often some of the earliest clinically detectable signs of the disorder. Early identification of this syndrome is critical because affected patients often develop a characteristic malignancy, medullary carcinoma of the thyroid, at a very early age. We describe a 17-year-old male whose initial diagnosis of MEN-2B was triggered by his orthodontist's request for an oral and maxillofacial pathology consultation to evaluate the patient's oral abnormalities.

Phase II study of safety and efficacy of motesanib in patients with progressive or symptomatic, advanced or metastatic medullary thyroid cancer

PURPOSE

This phase II study investigated the efficacy and tolerability of motesanib, an investigational, highly selective inhibitor of vascular endothelial growth factor receptors 1, 2, and 3; platelet-derived growth factor receptor; and Kit in advanced medullary thyroid cancer (MTC).

PATIENTS AND METHODS

Patients with locally advanced or metastatic, progressive or symptomatic MTC received motesanib 125 mg/d orally for up to 48 weeks or until unacceptable toxicity or disease progression. The primary end point was objective response by independent review. Other end points included duration of response, progression-free survival, safety, pharmacokinetics, and changes in tumor markers.

RESULTS

Of 91 enrolled patients who received motesanib, two (2%) achieved objective response (95% CI, 0.3% to 7.7%); their duration of response was 32 weeks (censored) and 21 weeks (disease progressed). Eighty-one percent of patients had stable disease (48% had durable stable disease > or = 24 weeks), 8% had disease progression as best response, and 9% were not evaluated; 76% experienced a decrease from baseline in target lesion measurement. Median progression-free survival was 48 weeks (95% CI, 43 to 56 weeks). Among patients with tumor marker analysis, 69 (83%) of 83 and 63 (75%) of 84 had decreased serum calcitonin and carcinoembryonic antigen during treatment, respectively, compared with baseline. The most common treatment-related adverse events were diarrhea (41%), fatigue (41%), hypothyroidism (29%), hypertension (27%), and anorexia (27%). In pharmacokinetic analyses, motesanib trough concentrations were lower compared with differentiated thyroid cancer patients from the same study.

CONCLUSION

Although the objective response rate was low, a significant proportion of MTC patients (81%) achieved stable disease while receiving motesanib.

Thyroid cancer in young adults

The incidence of thyroid cancer in young adults is rising. Differentiated carcinoma (ie, papillary, follicular, and their variants) and medullary thyroid carcinoma (MTC) represent the two most common subtypes, with differing etiologies, prognoses, and management strategies. Ultrasound (US)-guided fine needle aspiration (FNA) is the best initial test for evaluating a nodule or mass suspicious for malignancy. Tumor histology, in addition to radiographic findings and clinical presentation, guides surgical management, the need for adjuvant therapies, and the optimal approach to long-term follow-up. Radioactive iodine (RAI) is used to reduce recurrence and improve survival for differentiated thyroid carcinomas (DTCs). Emerging systemic therapies provide options for patients with progressive metastatic MTC or radio-resistant DTC. Overall, the prognosis for the most common thyroid malignancy, papillary thyroid carcinoma (PTC), is excellent. The treatment of young adult thyroid cancer patients occurs optimally as part of a multidisciplinary coordination of care.

Modeling thyroid cancer in the mouse

Thyroid carcinomas, the most common endocrine tumors in humans, have an increasing incidence in the U.S. and worldwide. There are four major types of thyroid cancers: papillary, follicular, anaplastic, and medullary carcinomas. In recent years, significant progress has been made in the identification of genetic alterations in thyroid carcinomas, particularly, papillary and medullary thyroid cancers. Mouse models of thyroid cancer are valuable tools in elucidating molecular genetic changes underlying thyroid carcinogenesis and in identifying potential molecular targets for therapeutic intervention. Representative mouse models of papillary, follicular, and medullary carcinomas are reviewed here with particular emphasis on those for follicular thyroid carcinomas. Challenges for further development in the modeling of thyroid cancer will also be discussed.

Postoperative radiotherapy for advanced medullary thyroid cancer--local disease control in the modern era

BACKGROUND

The purpose of this study is to catalog modern-era postoperative radiotherapy (external beam radiotherapy [EBRT]) outcomes for advanced medullary thyroid cancer.

METHODS

Thirty-four consecutive patients with stage IVa-c disease were evaluated. Ten patients had recurrent disease, 16 had mediastinal involvement, and 10 had distant metastasis. Positive surgical margins were present in 12 cases. Median pre-EBRT serum calcitonin was 556. All patients received conformal EBRT or intensity-modulated radiotherapy. Median EBRT dose was 60 Gy and median follow-up was 46.5 months.

RESULTS

Kaplan-Meier estimates of locoregional relapse-free survival, disease-specific survival, and overall survival at 5 years were 87%, 62%, and 56%, respectively. Disease in 3 patients with gross residual disease was controlled locoregionally. Distant disease at the time of EBRT did not predict survival. Two (9%) patients reported symptomatic chronic morbidity.

CONCLUSION

Surgery followed by EBRT provided durable locoregional disease control with limited morbidity. Postoperative EBRT merits consideration in cases of advanced disease at high risk for locoregional recurrence.

Four patients with cutaneous metastases from medullary thyroid cancer

Cutaneous metastasis from thyroid cancer, especially medullary thyroid cancer (MTC) is rare. We report four patients with cutaneous metastases from sporadic MTC, three women and one man, aged 50 to 69 years. They presented different cutaneous lesions phenotypes. The first patient had a remote history of MTC and initial presentation of the recurrence was a rapidly progressing cutaneous lesion; on subsequent disease staging, widely metastatic disease was discovered. The other three patients developed cutaneous metastases in the presence of known distant metastases, indicating systemic spread of thyroid cancer. Definitive diagnosis of cutaneous metastases of MTC was made on biopsy of the lesions with cells that stained positive for neuroendocrine markers. Accurate diagnosis of cutaneous metastasis from MTC is important because it is a negative prognostic factor indicative of multisystemic disease. Thus, MTC metastases should be included in the differential diagnosis of erythematous maculopapular eruptions and nodular lesions of the skin, especially when these metastases occur in the upper part of the body and if the patient has a history of MTC. The appearing of cutaneous metastasis is a negative prognostic factor since all the patients here described died within one year from the diagnosis of cutaneous metastases.

Surgical approach to medullary thyroid cancer

Medullary thyroid cancer (MTC) compromises 3-5% of all thyroid cancers and arises from parafollicular or calcitonin-producing C cells. It may be sporadic (75% of cases), or may occur as a manifestation of either the hereditary syndrome Multiple Endocrine Neoplasia type 2 (MEN 2A or MEN 2B) (25% of cases), or rarely as an isolated familial syndrome (FMTC). Complete surgical resection comprising in most cases total thyroidectomy with central lymph node dissection at an early stage of the disease is the only potential cure for MTC. The familial form of the disease, MEN-2A occupies a unique place in surgical history, having been the first disease where surgical removal of an affected organ was undertaken before the development of malignancy, solely on the basis of genetic testing. Total thyroidectomy prior to the development of invasive cancer completely avoids an otherwise lethal malignancy. Timing of prophylactic surgery is based on models that utilise genotype-phenotype correlations, which have now been stratified into three risk groups based on the specific codon involved. MTC should be followed with postoperative serial serum calcitonin levels to survey for persistent or recurrent disease as indicated by detectable levels. The challenge however, if calcitonin levels are increased, is to find the source of its production. The first localisation technique recommended would be ultrasound of the neck, since there is a high frequency of local recurrence and cervical node metastasis, followed by a total body CT scan and bone scintigraphy.

Multiple endocrine neoplasia

MEN1 and MEN2 are autosomal dominant cancer syndromes with the potential for considerable morbidity and mortality. Better understanding of the molecular pathogenesis in MEN1 and MEN2 has fostered the development of specific DNA screening. Knowing the genetic status of patients is valuable for making decisions regarding surveillance and interventions, such as prophylactic thyroidectomy for medullary thyroid cancer. Identifying new RET pathways has provided molecular targets for therapies that currently are being tested in clinical trials for locally advanced, metastatic, and recurrent medullary thyroid cancer.

RET oncogene in MEN2, MEN2B, MTC and other forms of thyroid cancer

Hereditary medullary thyroid carcinoma (MTC) is caused by specific autosomal dominant gain-of-function mutations in the RET proto-oncogene. Genotype-phenotype correlations exist that help predict the presence of other associated endocrine neoplasms as well as the timing of thyroid cancer development. MTC represents a promising model for targeted cancer therapy, as the oncogenic event responsible for initiating malignancy has been well characterized. The RET proto-oncogene has become the target for molecularly designed drug therapy. Tyrosine kinase inhibitors targeting activated RET are currently in clinical trials for the treatment of patients with MTC. This review will provide a brief overview of MTC and the associated RET oncogenic mutations, and will summarize the therapies designed to strategically interfere with the pathologic activation of the RET oncogene.

Long-term clinical and biochemical follow-up in medullary thyroid carcinoma: a single institution's experience over 20 years

OBJECTIVE

Many patients with medullary thyroid carcinomas (MTC) have reoperative surgery in different hospitals, which makes their follow-up difficult. To comprehend these complex courses and to find relevant prognostic factors we report a 20-year single center experience of 289 patients with MTC or precursor C-cell-hyperplasias.

PATIENTS AND METHODS

Between April 1986 and May 2006, 289 consecutive patients with MTC or MEN2 gene carriers were treated at the Department of Surgery at the University Hospital Düsseldorf. Tumor stages were documented according to the classification of the International Union against Cancer 5th edition, 1997 (Schott. Endocr Relat Cancer. 2006;13:779-795). A system to easily comprehend operative procedures is suggested.

RESULTS

There were 159 female and 130 male patients (f/m ratio 1.22). Mean age at time of diagnosis was 32 years (4-77) in the familial cases and 53 years (23-84) years in the sporadic cases. Sixty-six patients (23%) had multifocal disease. Twelve MEN2-patients had only C-cell-hyperplasia (pT0). Tumor stage was pT1 in 86 patients, pT2 in 106 patients, pT3 in 25 patients, pT4 in 52 patients and unclear in 8 patients. In the 289 patients 648 operations were performed. One hundred seventy patients had more than 1 operation (59%). Ninety-nine patients (34%) are calcitonin-negative and 91 patients (31%) live with elevated calcitonin. Median follow-up time of the surviving 211 patients was 8.9 years (range, 0.3-30.7 years). The 5- and 10-year survival of all tumor patients was 86% and 68%, respectively.

CONCLUSION

The chance to achieve biochemical cure in MTC is clearly dependent on the primary tumor size. The chance for long-term biochemical cure in a pT4-tumor is almost nil even after multiple and extended reoperations, whereas a pT1 tumor can be cured in up to 67% of the patients. Long-term survival, however, can be achieved even in pT4 tumor patients in almost 50%.

Cancer médullaire de la thyroïde

Medullary thyroid carcinoma (MTC) is developed from thyroid C cells that secrete calcitonin (CT). MTC represents 5-10% of thyroid cancers with a 1-2% incidence in nodular thyroid diseases. Diagnosis is usually made by a solitary nodule often associated to nodal metastasis and confirmed by a high basal CT level which represents its biological marker. MTC may present as a sporadic form and in about 30% of case as a familial form as a part of multiple endocrine neoplasia syndrome, an hereditary dominant inherited disease related to germline mutation of the proto-oncogene RET. Both biological (CT) and genetic (RET) markers allows the optimal diagnosis and treatment of MTC; the former allows screening and early diagnosis of MTC by routinely CT measurements in nodular thyroid diseases that make the adequate and complete surgery required to be performed. The former leads to diagnose familial MTC and to identify at risk subjects in whom early or prophylactic surgery may be performed. Treatment of MTC is based on the complete surgical resection: total thyroidectomy associated to central and laterocervical nodal dissection. For locally advanced or metastatic MTC, complete cervical surgery is required and needs to be associated to other systemic treatments: as chemotherapy is not very efficient, radioimmunotherapy and RET target gene therapy (mainly tyrosine kinase inhibitors) appears as possible valuable therapeutic options for the future. Prognosis of MTC is mainly related to both the stage of the disease and the extend of the initial surgery. Ten-year survival is about 80% when the patients are not surgically cured and reaches 95% when the biological marker CT is normalized after surgery.

Evidence-based approach to the management of sporadic medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a rare malignancy of the thyroid C cells. It occurs in hereditary (25% of cases) and sporadic (75%) forms. Sporadic MTCs frequently metastasize to cervical lymph nodes. Thorough surgical extirpation of the primary tumor and nodal metastases by compartment-oriented resection has been the mainstay of treatment (level IV evidence). Surgical resection of residual and recurrent disease is effective in reducing calcitonin levels and controlling complications of central neck disease (level IV evidence). Radioactive iodine, external beam radiation therapy, and conventional chemotherapy have not been effective. Newer systemic treatments, with agents that target abnormal RET proteins hold promise and are being tested in clinical trials for patients with metastatic disease.

[Multiple endocrine neoplasia type 2]

Multiple endocrine neoplasia type 2 (MEN2) is an hereditary disease with a prevalence of 1/5000. Three phenotypic variants have been identified: MEN2A associates medullary thyroid carcinoma (MTC) to pheochromocytoma in about 20-50% of cases and to primary hyperparathyroidism in 5-20% of cases; MEN2B associates MTC to pheochromocytoma in 50% of cases, to marphanoid habitus and to mucosal and digestive ganglioneuromatosis whereas in familial isolated medullary thyroid carcinoma (FMTC), the other components of the disease are absent. In MEN2, natural history of the disease and a common embryologic origin (neural crest) may explain the phenotypes observed in the organ involved, beginning from the stage of hyperplasia to adenoma and cancer. MEN2 is an inherited autosomal dominant disease with a complete penetrance, related to germline mutation in the proto-oncogene RET. MTC represent the most frequent circumstance of diagnosis. Pheochromocytoma and HPT may reveal the disease unfrequently and are systematically associated to undiagnosed MTC which is present yet. Analysis of the RET gene allows to confirm the diagnosis of MEN2 by identifying the causal germline mutation. Management of MEN2 patients include thyroidectomy associated to cervical central and bilateral lymph nodes dissection for MTC, unilateral adrenalectomy for unilateral pheochromocytoma or bilateral adrenalectomy when both glands are involved, and selective resection of pathologic parathyroid glands for HPT. Familial genetic screening detects at risk subjects who will develop the disease and allows to manage them at the earliest stage of the disease by perform early or prophylactic thyroidectomy such giving them the best chance of cure. Prognosis of MEN2 is mainly related to the stage-dependant prognosis of MTC, thus pointing the necessity of a complete thyroid surgery for index cases with MTC and the earliest thyroidectomy for screened at risk subjects.

Medullary Thyroid Carcinoma

Medullary thyroid carcinoma is a neuroendocrine tumor derived from the C cells of the thyroid gland and accounts for approximately 5% of all thyroid carcinomas. Approximately 30% of the cases are associated with an autosomal dominant syndrome called multiple endocrine neoplasia type 2, and the identification of these individuals is important because affected family members may benefit from an early diagnosis. The treatment of this disease is predominantly surgical, and the impact of radiotherapy and chemotherapy is limited. The identification of the associated molecular events has lead to the development of specific molecular targeted agents that may change the way this disease is treated in the near future.

Somatostatin receptor scintigraphy using 99mTc-EDDA/HYNIC-TOC in patients with medullary thyroid carcinoma

PURPOSE

Several new somatostatin analogues have been developed for the diagnosis and therapy of different tumours. Since somatostatin receptors are often over-expressed in medullary thyroid carcinoma (MTC), the aim of our study was to evaluate the utility of scintigraphy with the somatostatin analogue (99m)Tc-EDDA/HYNIC-TOC in MTC in comparison with other diagnostic techniques.

METHODS

Forty-five patients with MTC, aged 14-83 years, were investigated. Scintigraphy using (99m)Tc-EDDA/HYNIC-TOC (Tektrotyd) was performed 2 and 4 h post injection of 740 MBq (20 mCi) of the tracer. Other imaging techniques were also applied and analysed in individual cases (ultrasonography, computed tomography, (99m)Tc(V)-DMSA, (131)I-MIBG, (99m)Tc-MDP, (111)In-DTPA-octreotide and (18)F-FDG-PET) and compared with (99m)Tc-EDDA/HYNIC-TOC.

RESULTS

In group 1 (eight patients before thyroidectomy), uptake of the tracer was found in the primary tumours. In group 2 (six patients with remission), a false positive result was found in one patient; in the remaining five patients, no pathological foci were visualised. In group 3 (31 patients with post-surgical hypercalcitoninaemia), scintigraphy was true positive in 23 patients (74.2%): uptake in the thyroid bed was found in five patients, in the lymph nodes in 18 and in bone metastases in four. Using (99m)Tc-EDDA/HYNIC-TOC scintigraphy, the overall sensitivity was 79.5%, specificity 83.3%, accuracy 80.0%, positive predictive value 96.9% and negative predictive value 38.5%.

CONCLUSION

(99m)Tc-EDDA/HYNIC-TOC is clinically useful for scintigraphy in the follow-up of patients with MTC. It can be used in clinical practice for preoperative evaluation, for localisation of local recurrence or distant metastases and particularly for therapy decision making.

Genetic alterations in thyroid cancer: the role of mouse models

Thyroid carcinomas are the most common endocrine neoplasms in humans, with a globally increasing incidence. Thyroid follicular cells and neuroendocrine (parafollicular) C cells are each susceptible to neoplastic transformation, resulting in thyroid cancers of differing phenotypes with unique associated genetic mutations and clinical outcomes. Over the past 15 years, several sophisticated genetically engineered mouse models of thyroid cancer have been created to further our understanding of the genetic events leading to thyroid carcinogenesis in vivo. The most significant mouse models of papillary, follicular, anaplastic, and medullary thyroid carcinoma are highlighted, with particular emphasis on the relationship between the relevant oncogenes in these models and genetic events in the naturally occurring human disease. Limitations of each model are presented, and the need for additional models to better recapitulate certain aspects of the human disease is discussed.

Role of FNA cytology and immunochemistry in the diagnosis and management of medullary thyroid carcinoma: Report of six cases and review of the literature

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine thyroid malignancy. This study retrospectively reviewed 10 fine-needle aspiration samples from six MTC patients. Aspirated specimens were from thyroid (3), cervical lymph nodes (5), left lung (1), and anterior chest wall (1). Cytomorphology consisted predominantly of plasmacytoid cells (3 cases), spindle cells (2 cases), and epithelioid cells (1 case). However, all specimens had a mixture of other cell types and "salt and pepper" chromatin. Only one specimen showed Congo-red-positive amyloid. Calcitonin was expressed in 7/7 specimens. Four patients underwent surgical excision and MTC was confirmed in all four. Follow-up studies included serum calcitonin (3/6 cases) and imaging (2/6 cases). One patient had MTC associated with multiple endocrine neoplasia IIA syndrome and one had familial MTC with a history of MTC in mother. In conclusion, the cytomorphology of MTC is typical and calcitonin immunostain is a reliable method for confirming primary or metastatic MTC. Early cytological diagnosis of MTC positively impacted patient management. Follow-up with serum calcitonin and imaging is helpful in the early detection of recurrences.

Current approaches to medullary thyroid carcinoma, sporadic and familial

Medullary thyroid carcinoma (MTC) is a rare malignancy of the thyroid C cells. It occurs in hereditary (25% of cases) and sporadic forms, and aggressiveness is related to the clinical presentation (hereditary vs. sporadic) and the type of RET mutation present. In hereditary cases, early diagnosis makes preventative surgery possible. In established cases, thorough surgical extirpation of the primary tumor and nodal metastases has been the mainstay of treatment. Radioactive iodine, external beam radiation therapy (EBRT), and conventional chemotherapy have not been effective. Newer systemic treatments, with agents that target abnormal RET proteins, hold promise and are being tested in clinical trials for patients with metastatic disease.

Molecular mechanisms of RET receptor-mediated oncogenesis in multiple endocrine neoplasia 2B

Multiple endocrine neoplasia 2B (MEN 2B) is an inherited syndrome of early onset endocrine tumors and developmental anomalies. The disease is caused primarily by a methionine to threonine substitution of residue 918 in the kinase domain of the RET receptor (2B-RET); however, the molecular mechanisms that lead to the disease phenotype are unclear. In this study, we show that the M918T mutation causes a 10-fold increase in ATP binding affinity and leads to a more stable receptor-ATP complex, relative to the wild-type receptor. Further, the M918T mutation alters local protein conformation, correlating with a partial loss of RET kinase autoinhibition. Finally, we show that 2B-RET can dimerize and become autophosphorylated in the absence of ligand stimulation. Our data suggest that multiple distinct but complementary molecular mechanisms underlie the MEN 2B phenotype and provide potential targets for effective therapeutics for this disease.

Mechanisms of Disease: cancer targeting and the impact of oncogenic RET for medullary thyroid carcinoma therapy

Growing evidence supports the concept of oncogene dependence for cancer development; inhibition of the initiating oncogene can result in revertion of the neoplastic phenotype. The outstanding role of the RET proto-oncogene in the development of medullary thyroid carcinoma (MTC) is well established. With the emerging knowledge concerning the signal transduction pathways leading to subsequent neoplastic transformation, oncogenic activated RET becomes a highly attractive target for selective cancer therapy. A variety of novel approaches that target RET directly or indirectly have recently emerged and an increasing number are currently being assessed in clinical trials. In view of these findings, it becomes strikingly obvious that inhibition of RET oncogene function can be a viable option for the treatment of MTC. We summarize the current evidence for RET involvement in the etiology of MTC, and the therapeutic targeting of this process in preclinical and clinical studies.

An introduction to managing medullary thyroid cancer

MTC is a rare neuroendocrine thyroid tumour accounting for 3% to 10% of all thyroid malignancies. It can occur in a sporadic and a hereditary clinical setting. Hereditary MTC may either occur alone (familial MTC, FMTC) or as part of multiple endocrine neoplasia (MEN) type 2A, or MEN 2B. These disorders are due to germline mutations in the RET (REarranged during Transfection) gene. In carriers of MEN 2B-associated RET mutations, prophylactic thyroidectomy is indicated before the first year of life. In the case of MEN 2A-associated germline RET mutations with a high-risk profile, total thyroidectomy is warranted before the age of 2 years and certainly before the age of 4 years. At that age the risk of invasive MTC and metastases is acceptably low. Depending on the type of RET mutation, thyroidectomy can take place at an older age in patients with a lower risk profile. In case of elevated basal or stimulated serum calcitonin, preventive surgery including total thyroidectomy and central compartment dissection should be performed regardless of age. When MTC presents as a palpable tumour, total thyroidectomy should be combined with extensive lymph node dissection of levels II-V on both sides and level VI to prevent locoregional recurrences.

Thyroid carcinoma

PURPOSE OF REVIEW

Diagnostic methods and treatment options for differentiated and medullary thyroid carcinoma are continuously influenced by new trends and techniques. Our review therefore displays the most recent clinical practices for diagnosis and operative treatment of differentiated and medullary thyroid carcinoma.

RECENT FINDINGS

Among the new diagnostic methods, high-resolution ultrasonography plays an important role for both the evaluation of thyroid nodules and the detection of enlarged suspicious cervical lymph nodes. The results of ultrasound will definitely influence operative decisions. A second step to diagnose medullary thyroid carcinoma is calcitonin measurement before surgery, which is sensitive and specific enough to detect medullary thyroid carcinoma in patients with thyroid nodules. Surgical treatment for differentiated or medullary thyroid carcinoma mostly consists of total or near-total thyroidectomy. An additional central or lateral modified-radical neck dissection might help to reduce local recurrence, especially in medullary carcinoma, but still does not influence significantly the survival rates. Monitoring of the recurrent laryngeal nerve during surgery is used increasingly. According to the newest literature, however, compared with visual identification of the laryngeal nerve, it cannot be considered as superior.

SUMMARY

Diagnosis and treatment of thyroid carcinoma are still subjected to changes and the different options of surgical treatment in particular will be continuously discussed in the future.

Analysis of inherited genetic variants in ret proto-oncogene of Brazilian patients with apparently sporadic medullary thyroid carcinoma

Mutations in different exons of ret proto-oncogene are responsible for the development of medullary thyroid carcinoma (MTC). The mutations can occur as sporadic or as part of multiple endocrine neoplasia (MEN) type 2 hereditary syndromes. Here we report the first focused study of sporadic MTC in Brazilian patients regarding clinical and molecular analysis of ret proto-oncogene. Our study seeks to estimate the risk of hereditary MTC cases among apparently sporadic cases in a Brazilian population and describe ret genetic variants in their germinative lineage. Germinative sequence variants were screened by DNA sequencing and denaturing gradient gel electrophoresis (DGGE) analysis of exons 10, 11, 13, 14, 15, and 16 of 24 Brazilian patients with apparently sporadic MTC. We identified 1 inherited case of 24 (4%) patients with apparently sporadic MTC. Polymorphisms for the ret proto-oncogene coding region were identified in codon 769 of exon 13 (LeuCTT--> LeuCTG) at a frequency of 13% (3/24) and in codon 904 of exon 15 (SerTCC--> SerTCG) at a frequency of 16.6% (4/24). The observed frequency (4%) of inherited disease among apparent sporadic MTC strengthens routine application of ret proto-oncogene germinative DNA screening in all cases of apparently sporadic MTC ascertained at Brazilian cancer hospitals.

Multiple endocrine neoplasia: paediatric perspective

Neuroendocrine tumours constitute a heterogeneous association of neoplasms, originated from a common precursor cell population. They include endocrine glands, such as the pituitary, the parathyroids, the cells of the neuroendocrine adrenals, endocrine islets within glandular tissue (thyroid, pancreas) and dispersed cells (diffuse endocrine system). Neuroendocrine tumours can occur sporadically or in a familial context, such as multiple endocrine neoplasia (MEN) syndromes. These are inherited autosomal dominant cancer syndromes, transmitted with 100% penetrance. They are categorized into MEN type 1 and type 2. The dream of each physician who treats cancer is to develop a strategy that will have a significantly favourable impact on morbidity and mortality associated with malignant tumours. This has been achieved as a result of improved screening and early treatment strategies in MEN. MEN 2 and medullary thyroid carcinoma (MTC) are of special relevance in childhood, because they require urgent and early diagnosis and treatment. The explication of the genetic basis of MTC has revolutionised management of the familial forms of this tumour.

A Drosophila model of multiple endocrine neoplasia type 2

Dominant mutations in the Ret receptor tyrosine kinase lead to the familial cancer syndrome multiple endocrine neoplasia type 2 (MEN2). Mammalian tissue culture studies suggest that RetMEN2 mutations significantly alter Ret-signaling properties, but the precise mechanisms by which RetMEN2 promotes tumorigenesis remain poorly understood. To determine the signal transduction pathways required for RetMEN2 activity, we analyzed analogous mutations in the Drosophila Ret ortholog dRet. Overexpressed dRetMEN2 isoforms targeted to the developing retina led to aberrant cell proliferation, inappropriate cell fate specification, and excessive Ras pathway activation. Genetic analysis indicated that dRetMEN2 acts through the Ras-ERK, Src, and Jun kinase pathways. A genetic screen for mutations that dominantly suppress or enhance dRetMEN2 phenotypes identified new genes that are required for the phenotypic outcomes of dRetMEN2 activity. Finally, we identified human orthologs for many of these genes and examined their status in human tumors. Two of these loci showed loss of heterozygosity (LOH) within both sporadic and MEN2-associated pheochromocytomas, suggesting that they may contribute to Ret-dependent oncogenesis.