Surgical curability of medullary thyroid cancer in multiple endocrine neoplasia 2B: a changing perspective

Multiple endocrine neoplasia 2B: Differential increase in enteric nerve subgroups in muscle and mucosa

Multiple endocrine neoplasia 2B (MEN2B) is a rare syndrome caused by an activating mutation of the RET gene, leading to enteric gangliomatosis. This child presented with constipation at 1-mo old, was diagnosed with MEN2B by rectal biopsy at 4 mo, had thyroidectomy at 9 mo and a colectomy at 4 years. We studied the extent of neuronal and nerve fibre proliferation and which classes of enteric nerves are affected by examining the colon with multiple neuronal antibodies. Resected transverse colon was fixed, frozen, sectioned and processed for fluorescence immunohistochemistry labelling with antibodies against TUJ1, Hu, ChAT, NOS, VIP, SP and CGRP and cKit. Control transverse colon was from the normal margin of Hirschsprung (HSCR) colon (4-year-old) and a child with familial adenomatous polyposis (FAP, 12 year). Myenteric ganglia were increased in size to as wide as the circular muscle. There was a large increase in nerve cells and nerve fibres. ChAT-, NOS-, VIP- and SP-immunoreactive nerve fibres all increased in the myenteric ganglia. NOS-IR nerves preferentially increased in the muscle, while VIP and SP increased in submucosal ganglia and mucosal nerve fibres. The density of ICC was normal. RET overactivation in MEN2B lead to a large increase in intrinsic nerve fibres in the myenteric and submucosal ganglia, with a relative increase in NOS-IR nerve fibres in the circular muscle and VIP and SP in the submucosal ganglia and mucosa. The changes were associated with severe constipation resulting in colectomy at 4 years.

Risk Profile of the RET A883F Germline Mutation: An International Collaborative Study

CONTEXT

The A883F germline mutation of the rearranged during transfection (RET) proto-oncogene causes multiple endocrine neoplasia 2B. In the revised American Thyroid Association (ATA) guidelines for the management of medullary thyroid carcinoma (MTC), the A883F mutation has been reclassified from the highest to the high-risk level, although no well-defined risk profile for this mutation exists.

OBJECTIVE

To create a risk profile for the A883F mutation for appropriate classification among the ATA risk levels.

DESIGN

Retrospective analysis.

SETTING

International collaboration.

PATIENTS

Included were 13 A883F carriers.

INTERVENTION

The intervention was thyroidectomy.

MAIN OUTCOME MEASURES

Earliest age of MTC, regional lymph node metastases, distant metastases, age-related penetrance of MTC and pheochromocytoma (PHEO), overall and disease-specific survival, and biochemical cure rate.

RESULTS

One and three carriers were diagnosed at age 7 to 9 years (median, 7.5 years) with a normal thyroid and C-cell hyperplasia, respectively. Nine carriers were diagnosed with MTC at age 10 to 39 years (median, 19 years). The earliest age of MTC, regional lymph node metastasis, and distant metastasis was 10, 20, and 20 years, respectively. Fifty percent penetrance of MTC and PHEO was achieved by age 19 and 34 years, respectively. Five- and 10-year survival rates (both overall and disease specific) were 88% and 88%, respectively. Biochemical cure for MTC at latest follow-up was achieved in 63% (five of eight carriers) with pertinent data.

CONCLUSIONS

MTC of A883F carriers seems to have a more indolent natural course compared with that of M918T carriers. Our results support the classification of the A883F mutation in the ATA high-risk level.

Is new American Thyroid Association risk classification for hereditary medullary thyroid carcinoma applicable to Chinese patients? A single-center study

Objective

The American Thyroid Association (ATA) proposed a new risk classification for hereditary medullary thyroid carcinoma (MTC) in 2015. This study aimed to assess whether the new guidelines are suitable for the Chinese population, and reported our experience on prophylactic thyroidectomy.

Methods

A total of 73 patients from 22 families were screened as rearranged during transfection (RET) mutation carriers from 2010 to 2016 in Cancer Hospital, Chinese Academy of Medical Science; the medical history for each patient was collected. Based on the initial treatment, we identified the risk factors for poor prognosis by univariate and multivariate logistic regression. Then, 4 RET mutation carriers were enrolled for prophylactic thyroidectomy, and their pathological data and follow-up outcomes were recorded.

Results

In univariate and multivariate logistic regression analyses, age at initial surgery and risk classification were significant risk factors for stage III/IV hereditary MTC at initial diagnosis. The likelihood was increased by 11.6% per year of age at initial surgery [95% confidence interval (95% CI), 1.040–1.198; P=0.002). It was 7.888 times more likely to have III/IV stage disease for ATA highest risk patients, compared to ATA moderate risk individuals (95% CI, 1.607–38.717; P=0.003). Postoperative pathological results showed all 4 multiple endocrine neoplasia type 2A (MEN2A) patients had C-cell hyperplasia (CCH); multifocal malignancies were detected in 3 of them. All 4 patients were cured biochemically, and none developed permanent hypoparathyroidism.

Conclusions

In Chinese individuals, hereditary MTC aggressiveness is in line with the new ATA risk classification. Germline RET gene mutation carriers should undergo prophylactic thyroidectomy according to basal serum calcitonin levels.

Impact of central node dissection on postoperative morbidity in pediatric patients with suspected or proven thyroid cancer

BACKGROUND

Pediatric risk factors for postoperative morbidity after central node dissection are ill-defined.

METHODS

This outcome study aimed to evaluate operative morbidity in patients aged ≤18 years after total thyroidectomy with or without central node dissection for suspected or proven thyroid cancer.

RESULTS

Included were 102 patients with hereditary C-cell hyperplasia, 66 patients with medullary, 60 patients with papillary, and 2 patients with follicular thyroid cancer. In all 230 patients, 131 of whom underwent central node dissection, transient recurrent laryngeal nerve palsy was significantly associated only with central node dissection (100% vs 55%; P = .010). Transient and permanent hypoparathyroidism were significantly associated with age (means of 11.9 years versus 7.8 years, and 12.9 years versus 8.5 years; P ≤ .002); central node dissection (80% vs 50%, and 100% vs 54%; P ≤ .001); and the number of central lymph nodes cleared (means of 12.2 nodes versus 5.4 nodes, and 26.9 nodes versus 5.8 nodes, P < .001). These effects were stronger for permanent than transient hypoparathyroidism. Correlations between permanent hypoparathyroidism and the number of nodes cleared on central node dissection (r = 0.35) were closer than those between permanent hypoparathyroidism and age (r = 0.15), but similar for transient hypoparathyroidism (r = 0.22 and r = 0.25).

CONCLUSION

Owing to the incremental morbidity from central node dissection, the extent of a neck operation, in experienced hands, should be tailored to the extent of the underlying disease regardless of the child's age. The notion that the experience of the center and surgeons may be more important than the age of the child requires validation in independent series across different health care settings.

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.

Molecular diagnosis and comprehensive treatment of multiple endocrine neoplasia type 2 in Southeastern Chinese

Background

Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant inherited endocrine malignancy syndrome. Early and normative surgery is the only curative method for MEN 2-related medullary thyroid carcinoma (MTC). In patients with adrenal pheochromocytoma, cortical-sparing adrenalectomy (CSA) can be utilized to preserve adrenocortical function.

Methods

We present twenty-six of 33 MEN2 patients underwent prophylactic thyroidectomy with varying neck dissection and eight of 24 MEN2A patients with PHEO underwent adrenal-sparing surgery. Direct sequencing of entire RET exons was performed in all participants.

Results

The RET mutations (p.C634Y [n = 10], p.C634R [n = 9], p.C634F [n = 2], p.C618Y [n = 8], p.C618R [n = 3], and p.M918T [n = 1]) were confirmed in 20 symptomatic patients and identified in 13 at-risk relatives (RET carriers). Twenty-six of 33 MEN2 patients underwent thyroidectomies with neck dissections; the mean age at the time of the first thyroid surgery and the tumor diameter of the 6 RET carriers was decreased compared with 20 symptomatic patients (P < 0.001 and P = 0.007, respectively), while the disease-free survival was increased (80% vs.10%, P = 0.0001). Seven RET carriers who were declined surgery. One of 20 symptomatic patients with MTC bone metastases after surgery received vandetanib therapy for 20 months and responded well. Additionally, 8 of 24 MEN2A patients who initially had unilateral pheochromocytomas underwent CSA, 1 developed contralateral pheochromo cytomas 10 years later, then also accepted and also agreed to a CSA. None of the patients required steroid replacement therapy.

Conclusions

Based on our results, integrated RET screening and the pre-operative calcitonin level is an excellent strategy to ensure earlier diagnosis and standard thyroidectomy. CSA can be utilized to preserve adrenocortical function in patients with pheochromocytomas.

Electronic supplementary material

The online version of this article (doi:10.1186/s13053-015-0026-1) contains supplementary material, which is available to authorized users.

Hereditary Medullary Thyroid Cancer Genotype-Phenotype Correlation

During the last two decades, there has been a marked expansion of our knowledge of both the basic and clinical aspects of multiple endocrine neoplasia type 2 (MEN2). There are two clinically distinct types of MEN2 syndrome, termed MEN2A and MEN2B. Within MEN2A, there are four variants: (i) classical MEN2A, represented by the uniform presence of MTC and the less frequent occurrence of pheochromocytoma, or primary hyperparathyroidism, or both; (ii) MEN2A with cutaneous lichen amyloidosis; (iii) MEN2A with Hirschsprung's disease; and (iv) familial medullary thyroid carcinoma (FMTC), i.e., families or individuals with only MTC. MEN2B is associated with MTC, pheochromocytoma, and mucosal neuromas. Hereditary MTC is caused by autosomal dominant gain of function mutations in the RET proto-oncogene. Specific RET mutations may suggest a predilection toward a particular phenotype and clinical course with a strong genotype-phenotype correlation. Based upon these genotype-phenotype correlations, RET mutations are now stratified into three risk levels, i.e., highest, high, and moderate risk, based on the penetrance and aggressiveness of the MTC. Children in the highest risk category should undergo thyroidectomy in their first year of life, and perhaps even in their first months of life. Children in the high-risk category should have ultrasound of the neck and calcitonin (CTN) measurement performed prior to thyroidectomy. Thyroidectomy should typically be performed at the age of 5 or earlier, depending on the presence of elevated serum CTN levels. However, heterogeneity in disease expression and progression within these groups varies considerably. To personalize disease management, the decision regarding the age of prophylactic thyroidectomy is no longer based upon genotype alone but is currently driven by additional clinical data, the most important being serum CTN levels; specifically, the decision to perform thyroidectomy should err on the safe side if the CTN level is elevated but below 30 pg/ml, especially in the moderate risk group. Personalized management also includes decisions about the best age to begin biochemical screening for pheochromocytoma and primary hyperparathyroidism.

Surgical Treatment of Medullary Thyroid Cancer

Medullary thyroid cancer (MTC) can vary in tumor biology and progression. The most important indicator of distant metastases, determining clinical outcome, is lymph node metastasis to the neck and mediastinum. Surgical cure is within reach in node-negative tumors or node-positive tumors with fewer than 10 lymph node metastases. From a surgical point of view, compartment-oriented lymph node dissection, clearing gross, and occult metastases are important for locoregional tumor control. The discovery of missense germline mutations in the RET proto-oncogene and the close genotype-phenotype correlation in hereditary MTC promoted the worldwide breakthrough of prophylactic thyroidectomy. The best approach to hereditary MTC affords the DNA-based/biochemical concept, which is geared at limiting prophylactic surgery to total thyroidectomy at minimal surgical morbidity before the tumor can spread beyond the thyroid capsule. To improve outcome, routine calcitonin screening in nodular thyroid disease and DNA-based screening of the offspring in RET families are effective interventions.

RET revisited: expanding the oncogenic portfolio

The RET receptor tyrosine kinase is crucial for normal development but also contributes to pathologies that reflect both the loss and the gain of RET function. Activation of RET occurs via oncogenic mutations in familial and sporadic cancers - most notably, those of the thyroid and the lung. RET has also recently been implicated in the progression of breast and pancreatic tumours, among others, which makes it an attractive target for small-molecule kinase inhibitors as therapeutics. However, the complex roles of RET in homeostasis and survival of neural lineages and in tumour-associated inflammation might also suggest potential long-term pitfalls of broadly targeting RET.