Natural history, treatment, and long-term follow up of patients with multiple endocrine neoplasia type 2B: an international, multicentre, retrospective study

A New MEN2 Syndrome with Clinical Features of Both MEN2A and MEN2B Associated with a New RET Germline Deletion

Background

Multiple endocrine neoplasia type 2 (MEN2) is a hereditary cancer syndrome caused by RET proto-oncogene mutation. Two different clinical variants of MEN2 are known (MEN2A and MEN2B): medullary thyroid carcinoma (MTC) almost always present and associated with pheochromocytoma (Pheo), and primary hyperparathyroidism (HPTH) in MEN2A and with Pheo and other nonendocrine diseases in MEN2B. Case Report. A 7-year-old girl, previously treated for a pelvic plexiform neurofibroma, arrived at our observation with a peculiar MEN2B syndrome and with HPTH. The neck ultrasound showed bilateral thyroid nodules, local lymph node lesions, and a suspicious left hyperplastic parathyroid. The CT scan showed a megacolon and described the persistence of the pelvic tumor. A new RET germline deletion in exon 11 (c.1892_1899delCGAGCT; p.Glu632_Leu633del) was found. She underwent total thyroidectomy, central compartment and latero-cervical lymph node dissection, and neck exploration for primary HPTH. The histology confirmed bilateral MTC, multiple lymph node metastases, a hyperplastic parathyroid, and a parathyroid adenoma.

Conclusions

This is the first case of a complex syndrome characterized by peculiar features of MEN2B, without Pheo but with a pelvic plexiform neurofibroma and with HPTH, which is typical of MEN2A. A “de novo” new germline RET deletion located in exon 11 was found.

Clinical trial design in neurofibromatosis type 1 as a model for other tumor predisposition syndromes

Up to 10% of all pediatric cancer patients may have an underlying germline mutation which predisposed them to develop a malignancy. With more patients being tested for and diagnosed with genetic tumor predisposition syndromes, there has been improved characterization of their many nonmalignant manifestations. However, designing and implementing clinical trials to treat the nonmalignant tumor and non-tumor manifestations of these syndromes poses many unique challenges. Unlike trials for malignancies where tumor response and survival can be used as straightforward trial endpoints, the nonmalignant manifestations are often chronic, evolve more slowly over time, and may not be immediately life-threatening. Therefore, they will likely require a different approach to both testing and treatment with a focus on more functional and patient-reported outcome trial endpoints. The recent success of treatment trials for the benign tumors plexiform neurofibromas in the tumor predisposition syndrome neurofibromatosis type 1 (NF1) can be used as a model for the development of clinical trials in other tumor predisposition syndromes. In this article, we review the unique challenges associated with targeting the nonmalignant aspects of these conditions as well as some of the lessons learned from the NF1 experience which may be applied to other syndromes in the future.

Primary hyperparathyroidism as first manifestation in multiple endocrine neoplasia type 2A: an international multicenter study

OBJECTIVE

Multiple endocrine neoplasia type 2A (MEN 2A) is a rare syndrome caused by RET germline mutations and has been associated with primary hyperparathyroidism (PHPT) in up to 30% of cases. Recommendations on RET screening in patients with apparently sporadic PHPT are unclear. We aimed to estimate the prevalence of cases presenting with PHPT as first manifestation among MEN 2A index cases and to characterize the former cases.

DESIGN AND METHODS

An international retrospective multicenter study of 1085 MEN 2A index cases. Experts from MEN 2 centers all over the world were invited to participate. A total of 19 centers in 17 different countries provided registry data of index cases followed from 1974 to 2017.

RESULTS

Ten cases presented with PHPT as their first manifestation of MEN 2A, yielding a prevalence of 0.9% (95% CI: 0.4-1.6). 9/10 cases were diagnosed with medullary thyroid carcinoma (MTC) in relation to parathyroid surgery and 1/10 was diagnosed 15 years after parathyroid surgery. 7/9 cases with full TNM data were node-positive at MTC diagnosis.

CONCLUSIONS

Our data suggest that the prevalence of MEN 2A index cases that present with PHPT as their first manifestation is very low. The majority of index cases presenting with PHPT as first manifestation have synchronous MTC and are often node-positive. Thus, our observations suggest that not performing RET mutation analysis in patients with apparently sporadic PHPT would result in an extremely low false-negative rate, if no other MEN 2A component, specifically MTC, are found during work-up or resection of PHPT.

Medullary Thyroid Cancer - Feature Review and Update on Systemic Treatment

Medullary thyroid carcinoma (MTC) is a rare malignancy that originates from parafollicular (C cells) of the thyroid and accounts for 2-4% of all thyroid malignancies. MTC may be sporadic or inherited, the latter as part of the MEN 2 syndromes. Germline mutations in the RET proto-oncogene (REarranged during Transfection) are driver mutations in hereditary MTC, whereas somatic RET mutations and, less frequently, RAS mutations, have been described in tumor tissues of sporadic MTC. Genetic screening for germline mutations in RET proto-oncogene identifies gene carriers of germline mutations. That enables primary prevention (the avoidance of disease onset by total prophylactic thyroidectomy), or at least secondary prevention (early detection) of the disease. Radical surgery with complete tumor resection is still pivotal in attaining cure for MTC. Despite recent advances, the treatment of advanced, metastatic, and progressive MTC remains challenging. Metastatic MTC can have an indolent clinical course; therefore, it is necessary to assess which patient to cure and when to initiate the treatment. Multidisciplinary boards of various specialists involved in the diagnostics and therapy of the patients with MTC in highly specialized centers with a high volume of patients provide optimal patient management. Multikinase inhibitors (MKI) vandetanib and cabozantinib were approved for the treatment of progressive or symptomatic metastatic/unresectable MTC. Although these treatments have been shown to improve progression-free survival (PFS) with higher overall response rates (ORR) compared with placebo, no MKI has been shown to increase the overall survival (OS) yet, except in the subgroup of patients with RETM918T-mutations on cabozantinib therapy. As these drugs are nonselective, significant off-target toxicities may occur. Recently, next-generation small-molecule tyrosine kinase inhibitors (TKIs) have been developed. These highly selective RET-inhibitors are specifically designed for highly potent and selective targeting of oncogenic RET alterations, making them promising drugs for the treatment of advanced MTC. The selective RET-inhibitor selpercatinib has been very recently registered for the treatment of RET-mutated thyroid cancer.

Revisiting the genotype-phenotype correlation in children with medullary thyroid carcinoma: A report from the GPOH-MET registry

BACKGROUND

Medullary thyroid carcinomas (MTC) account for 3% to 5% of all thyroid cancers. In most cases, MTC is hereditary and occurs as part of the multiple endocrine neoplasia (MEN) type 2A and 2B syndromes. There is a strong genotype-phenotype correlation associated with the respective RET mutations, making risk-adapted management possible.

PROCEDURE

We report the prospectively collected data on children and adolescents of the multicenter nonrandomized German GPOH-MET registry. Children and adolescents with MTC and C-cell hyperplasia (CCH) were included.

RESULTS

From 1997 to June 2019, a total of 57 patients with MTC and 17 with CCH were reported. In patients with MTC, median follow-up was five years (range, 0-19) and median age at diagnosis 10 years (range, 0-17). Overall survival and event-free survival (EFS) were 87% and 52%, respectively. In total 96.4% of patients were affected by MEN2 syndromes, which was in 37/42 MEN2A and 3/28 MEN2B (M918T mutation) inherited. EFS in MEN2A was 78%, and in MEN2B 38% (P < 0.001). In multivariate analyses, lymph node (LN) status and postoperatively elevated calcitonin were significant prognostic factors for EFS. Notably, modest-risk mutation carriers presented with MTC at a rather young age, without raised calcitonin, and LN metastases.

CONCLUSIONS

Identification of children carrying de novo RET M918T mutations by means of the characteristic phenotype is crucial to detect MTC at an early stage, which will be associated with improved survival. As calcitonin levels may be false-negative and modest-risk mutation carriers present with a variable phenotype, particular attention should be paid to these children.

Multiple endocrine neoplasia type 2B: Frequency of physical stigmata-Results of the GPOH-MET registry

BACKGROUND

Multiple endocrine neoplasia (MEN) 2B is characterized by early development of aggressive medullary thyroid carcinoma (MTC), visible physical stigmata, and associated symptoms. In most cases, de novo mutations are revealed. There are premonitory symptoms and stigmata that enable early diagnosis, before an inoperable MTC develops. The German Society for Paediatric Oncology and Haematology (GPOH)-Malignant Endocrine Tumours (MET) registry maintains records of children with MTC in Germany since 1997.

METHODS

Children with a diagnosis of MTC in MEN 2B recorded in the GPOH-MET study were analyzed retrospectively. Stigmata and symptoms associated with MEN 2B were examined.

RESULTS

From inception through 2017, 24 patients aged 0.2-17.3 years were included. Symptoms affecting the oral/dental (88.0%), musculoskeletal (79.2%), and gastrointestinal (70.8%) systems were recognized most frequently. Gastrointestinal and musculoskeletal symptoms preceded symptoms of MTC. Twelve patients had short stature. Regarding the prevalence of single symptoms, neuromas of the lips and the oral cavity were mentioned most frequently. Five patients died from MTC. Patients diagnosed by tumor symptoms showed more advanced disease than those with disease detected by other means. Children diagnosed via associated stigmata and symptoms or positive family history had significantly improved overall survival (OS) compared to children diagnosed via symptoms of MTC (OS 100% vs 53.3%).

CONCLUSIONS

In children with MEN 2B, oral/dental, musculoskeletal, and gastrointestinal symptoms are most common. If children are diagnosed via associated symptoms and stigmata, OS is improved. Most of the children were diagnosed with growth disturbances; this finding requires verification and ranging in other patient cohorts.

5P Strategies for Management of Multiple Endocrine Neoplasia Type 2: A Paradigm of Precision Medicine

Multiple endocrine neoplasia type 2 (MEN2) is a neuroendocrine cancer syndrome characterized by medullary thyroid carcinoma, in combination or not with pheochromocytoma, hyperparathyroidism, and extra-endocrine features. MEN2 syndrome includes two clinically distinct forms subtyped as MEN2A and MEN2B. Nearly all MEN2 cases are caused by germline mutations of the RET proto-oncogene. In this review, we propose "5P" strategies for management of MEN2: prevention, prediction, personalization, psychological support, and participation, which could effectively improve clinical outcomes of patients. Based on RET mutations, MEN2 could be prevented through prenatal diagnosis or preimplantation genetic testing. Identification of pathogenic mutations in RET can enable early diagnosis of MEN2. Combining RET mutation testing with measurement of serum calcitonin, plasma or urinary metanephrine/normetanephrine, and serum parathyroid hormone levels could allow risk stratification and accurately prediction of MEN2 progression, thus facilitating implementation of personalized precision treatments to increase disease-free survival and overall survival. Furthermore, increased awareness of MEN2 is needed, which requires participation of physicians, patients, family members, and related organizations. Psychological support is also important for patients with MEN2 to promote comprehensive management of MEN2 symptoms. The "5P" strategies for management of MEN2 represent a typical clinical example of precision medicine. These strategies could effectively improve the health of MEN2 patient, and avoid adverse outcomes, including death and major morbidity, from MEN2.

Update on Fundamental Mechanisms of Thyroid Cancer

The incidence of thyroid cancer (TC) has increased worldwide over the past four decades. TC is divided into three main histological types: differentiated (papillary and follicular TC), undifferentiated (poorly differentiated and anaplastic TC), and medullary TC, arising from TC cells. This review discusses the molecular mechanisms associated to the pathogenesis of different types of TC and their clinical relevance. In the last years, progresses in the genetic characterization of TC have provided molecular markers for diagnosis, risk stratification, and treatment targets. Recently, papillary TC, the most frequent form of TC, has been reclassified into two molecular subtypes, named BRAF-like and RAS-like, associated to a different range of cancer risks. Similarly, the genetic characterization of follicular TC has been proposed to complement the new histopathological classification in order to estimate the prognosis. New analyses characterized a comprehensive molecular profile of medullary TC, raising the role of RET mutations. More recent evidences suggested that immune microenvironment associated to TC may play a critical role in tumor invasion, with potential immunotherapeutic implications in advanced and metastatic TC. Several types of ancillary approaches have been developed to improve the diagnostic value of fine needle aspiration biopsies in indeterminate thyroid nodules. Finally, liquid biopsy, as a non-invasive diagnostic tool for body fluid genotyping, brings a new prospective of disease and therapy monitoring. Despite all these novelties, much work remains to be done to fully understand the pathogenesis and biological behaviors of the different types of TC and to transfer this knowledge in clinical practice.

Variability in Medullary Thyroid Carcinoma in RET L790F Carriers: A Case Comparison Study of Index Patients

Background: Previous studies have suggested that the variability in age of onset and aggressiveness of medullary thyroid carcinoma (MTC) in patients with multiple endocrine neoplasia type 2A (MEN 2A) carrying the same REarranged during Transfection (RET) mutation may be caused by additional RET germline variants or somatic variants. Methods: This study was a retrospective case comparison study of all MEN 2A index patients (n = 2) with the RET L790F germline mutation in Denmark. Whole blood and MTC tissue were analyzed for RET germline variants and other somatic variants (>500), respectively. Results: Patient 1 presented with MTC (T1aN1bM0) at age 14 years, while patient 2 presented with MTC (T1bN0M0) at age 70 years. No germline RET germline variants nor other variants were found to explain this MTC variability. Conclusions: We could not confirm the previously reported finding of a somatic RET variant as likely responsible for the early onset and aggressiveness of MTC in a RET germline mutation carrier. Also, we found no RET germline variants that could explain the MTC variability among our index patients. We did, however, identify a somatic FLT3 R387Q variant with an unknown potential as genetic modifier. Further large-scale studies are needed to investigate genetic modifiers in RET L790F carriers.

Thyroid nodules in children and adolescents

PURPOSE OF REVIEW

Compared with adults, there is a two-fold to three-fold increased risk of malignancy for a pediatric patient undergoing evaluation of a thyroid nodule. In 2015, the American Thyroid Association published guidelines on the evaluation and management of pediatric patients with thyroid nodules and differentiated thyroid cancer. The goal of this clinical update is to review recent additions to the literature and propose opportunities how to best incorporate these findings into clinical practice.

RECENT FINDINGS

Recent additions to the literature include assessment of ultrasound-based scoring systems to improve selection of patients for fine needle aspiration, defining the pediatric-specific risk of malignancy within The Bethesda System for Reporting Thyroid Cytopathology, and broadening our knowledge of the oncogene landscape that supports incorporation of adjunct oncogene testing to rule-in malignancy of nodules with indeterminate cytology.

SUMMARY

There have been significant additions to the literature on the evaluation and management of children and adolescents with thyroid nodules since publication of the 2015 American Thyroid Association guidelines. Incorporating these changes into clinical care, within the setting of multidisciplinary, pediatric-specific, regional centers, will maximize ongoing efforts to improve the care of children and adolescents with thyroid nodules.

Long-Term Outcomes and Aggressiveness of Hereditary Medullary Thyroid Carcinoma: 40 Years of Experience at One Center

CONTEXT

Recent data on long-term outcomes and aggressiveness of medullary thyroid carcinoma (MTC) are lacking for patients with multiple endocrine neoplasia type 2 (MEN2).

OBJECTIVES

To analyze the long-term outcomes in MEN2 and compare MTC aggressiveness in three defined RET mutation-risk categories: moderate risk (MOD), high risk (H), and highest risk (HST).

DESIGN, SETTING

Retrospective study of 263 operated patients with MEN2 from one German tertiary referral center from 1979 to 2017 comparing demographic, biochemical, genetic, and outcome parameters.

INTERVENTION

None (observational study).

MAIN OUTCOME MEASURE

Long-term survival and outcomes in three risk groups.

RESULTS

Surgery was performed at a mean age of 35.3 ± 18.8 (MOD, n = 122), 23.0 ± 15.7 years (H, n = 120), and 14.9 ± 9.3 (HST, n = 21) years (P < 0.05). The mean follow-up was 12.9 ± 9.8 years. Age and tumor stage at diagnosis differed among the three risk groups (P < 0.0001). Multivariate analysis of disease-specific survival (DSS) showed that increasing age [hazard ratio (HR), 1.06; 95% CI, 1.02 to 1.09], stage III/IV at diagnosis (HR, 7.39; 95% CI, 2.39 to 22.8), and HST group (HR, 14.4; 95% CI, 3.32 to 62.6) were significantly associated with worse DSS; the H group was not (P = 0.175). The DSS rates and outcomes were not different between the MOD and H groups (P = 0.179 and P = 0.893, respectively) but were significantly inferior in the HST group (P < 0.0008 and P < 0.0001, respectively).

CONCLUSION

MTC in patients with MEN2 showed a clearly different age of onset in the different risk groups. DSS and outcomes after MTC diagnosis were similar in the MOD and H groups, suggesting similar tumor behavior. The HST group had inferior outcomes and survival vs the MOD and or H groups.

Long-term outcome after DNA-based prophylactic neck surgery in children at risk of hereditary medullary thyroid cancer

Advances in sequencing technology, providing unprecedented insights into cancer progression, have shifted the treatment paradigm towards precision medicine for hereditary medullary thyroid cancer (MTC), away from the 'one-size-fits-all' approach predicated on genetic risk alone. The DNA-based/biochemical concept, factoring serum calcitonin into the benefit-risk equation, optimizes biochemical cure while minimizing extent of prophylactic surgery and operative morbidity in children at risk. The transformative effect that has taking effect on medical practice has been impressive: Increasingly earlier molecular diagnosis and more limited prophylactic neck operations yielded excellent clinical outcomes at expert facilities 7-16 years postoperatively: biochemical cure rates approximating 100%; absence of residual structural disease or recurrence; and rarely any permanent operative morbidity. These excellent results, contingent on proper health care funding and pediatric surgical specialization, make a case for early prophylactic thyroidectomy in experienced hands once calcitonin serum levels exceed the upper normal limit of the assay in young gene carriers.

Unique association of multiple endocrine neoplasia 2A and congenital anomalies of the kidney and urinary tract in a child with a RET mutation

Pathogenic variants in the RET gene can cause isolated and multi-system diseases. We report a patient diagnosed prenatally with unilateral multicystic dysplastic kidney and genitourinary abnormality whose mother had multiple endocrine neoplasia type 2A (MEN2A). Targeted RET sequencing found the same pathogenic variant p.C618S in the child as her mother. The child is followed by paediatric nephrology for congenital anomalies of the kidney and urinary tract (CAKUT) and by endocrine oncology for surveillance for MEN2A-related endocrine tumours. While implicated in each of these conditions individually, RET variants have never been reported to cause MEN2A and CAKUT together. This child’s family history prompted RET sequencing, resulting in presymptomatic, personalised care for MEN2A. However, this case supports the idea that genetic screening of RET (and many other genes) in patients with CAKUT may lead to molecular diagnoses that potentially improve their health through precision care.

Analysis of Short-term Blood Pressure Variability in Pheochromocytoma/Paraganglioma Patients

Data on short-term blood pressure variability (BPV), which is a well-established cardiovascular prognostic tool, in pheochromocytoma and paraganglioma (PPGL) patients is still lack and conflicting. We retrospectively evaluated 23 PPGL patients referred to our unit from 2010 to 2019 to analyze 24 h ambulatory blood pressure monitoring (24-h ABPM)-derived markers of short-term BPV, before and after surgical treatment. PPGL diagnosis was assessed according to guidelines and confirmed by histologic examination. The 24-h ABPM-derived markers of short-term BPV included: circadian pressure rhythm; standard deviation (SD) and weighted SD (wSD) of 24-h, daytime, and night-time systolic and diastolic blood pressure (BP); average real variability (ARV) of 24-h, daytime, and night-time systolic and diastolic BP. 7 males and 16 females of 53 ± 18 years old were evaluated. After surgical resection of PPGL we found a significant decrease in 24-h systolic BP ARV (8.8 ± 1.6 vs. 7.6 ± 1.3 mmHg, p < 0.001), in 24-h diastolic BP ARV (7.5 ± 1.6 vs. 6.9 ± 1.4 mmHg, p = 0.031), and in wSD of 24-h diastolic BP (9.7 ± 2.0 vs 8.8 ± 2.1 mmHg, p = 0.050) comparing to baseline measurements. Moreover, baseline 24-h urinary metanephrines significantly correlated with wSD of both 24-h systolic and diastolic BP. Our study highlights as PPGL patients, after proper treatment, show a significant decrease in some short-term BPV markers, which might represent a further cardiovascular risk factor.