One hundred and seven family members with the rearranged during transfection V804M proto-oncogene mutation presenting with simultaneous medullary and papillary thyroid carcinomas, rare primary hyperparathyroidism, and no pheochromocytomas: Is this a new syndrome—MEN 2C?

The protean role of Val804Met RET mutation in thyroid neoplasms: An example of a "MEN2C" syndrome?

BACKGROUND

Val804Met RET is one of the most common genetic alterations in Multiple Endocrine Neoplasia 2 and is considered to confer only a moderate risk for familial medullary thyroid carcinoma (MTC). The associated phenotype can however be much more complex in some cases.

METHODS

A clinical, genetic, and pathological analysis was conducted on a family cluster of thyroid neoplasms associated with Val804Met RET mutation.

RESULTS

All the kindreds who are carriers of the mutated RET received total thyroidectomy + /- VI level dissection. The proband presented with a pT1bN0 MTC, her 29-yo brother showed a concomitant papillary thyroid carcinoma (PTC) and MTC, their father had a pT1a PTC plus a follicular adenoma, while the uncle of the proband showed C-cell hyperplasia. None had clinical or biochemical evidence of parathyroid disorders or pheochromocytoma.

CONCLUSIONS

In the presence of Val804Met RET several types of thyroid premalignant and malignant should be screened for, and without limiting to MTC.

Medullary thyroid cancer with RET V804M mutation: more indolent than expected?

BACKGROUND

Significant genotype-phenotype variability among multiple endocrine neoplasia type 2A patients with a RET V804M mutation has been reported.

METHODS

Patients with a RET V804M mutation treated at a single center were identified (January 1996-December 2020). The baseline characteristics, operative details, pathology, biochemical, and long-term data were analyzed.

RESULTS

There were 79 patients; none developed pheochromocytoma or hyperparathyroidism or died in the study period. The mean age was 41.5 years (range = 1.0-81.0 years); 46.8% were men. Of 68 surgical patients, 53 (77.9%) underwent total thyroidectomy and 15 (22.1%) underwent total thyroidectomy with central neck dissection with or without lateral neck dissection. Twenty-four patients had elevated preoperative calcitonin, of whom 12 underwent total thyroidectomy (median = 7.5; range = 5.0-237.0 pg/mL), 10 underwent total thyroidectomy + central neck dissection (median = 27.6; range = 5.1-147.0 pg/mL), and 2 underwent total thyroidectomy + central neck dissection + lateral neck dissection (median = 3182.0; range = 361.0-6003.0 pg/mL). Pathology was benign (27.9%), papillary thyroid cancer alone (1.5%), C-cell hyperplasia (23.5%), and medullary thyroid cancer (47.1%; median tumor size = 3.0 mm). Three patients had elevated calcitonin postoperatively (median follow-up time = 60.0 months). In adjusted modeling, a preoperative calcitonin >5 pg/mL was associated with having medullary thyroid cancer on final pathology (odds ratio = 13.3; 95% confidence interval, 3.2-56.3; P < .001).

CONCLUSION

In this large United States cohort of surgical patients with a RET V804M mutation, most had indolent disease and were without classic multiple endocrine neoplasia type 2A features. Calcitonin >5 pg/mL may serve as a meaningful value to guide surveillance and timing of surgery.

Controversy on the management of patients carrying RET p.V804M mutation

CONTEXT

RET p.V804M is classified as a moderate risk mutation for familial medullary thyroid cancer (FMTC). There is a significant controversy on the management of patients carrying this mutation. We describe a family incidentally discovered to have this mutation and review the literature on RET p.V804M mutation.

RESULTS

The proband was born to first-degree relative parents. He was noticed to have hypertrophy of some parts of the body and vascular skin changes. Whole-exome sequencing of DNA extracted from a skin biopsy showed a mutation in the PIK3CA (c.3132T>G, p.ASN1044LYS). This variant was not found in DNA extracted from blood. This confirmed the diagnosis of CLOVES syndrome (Congenital Lipomatous Overgrowth, Vascular malformations, Epidermal nevi and Scoliosis, skeletal or spinal anomalies). Another incidentally found mutation in the skin biopsy and blood sample was RET p.V804M. Although there was no family history of MTC or MEN 2 syndromes, family screening revealed RET p.V804M mutation and FMTC in the proband's father, paternal grandmother, one sister, and one aunt. There was significant interfamilial heterogeneity in the age of presentation and pathology. A review of literature showed that RET p.V804M mutation is a moderate risk mutation associated with late-onset FMTC, usually at middle to old age.

CONCLUSION

Despite the controversy and the heterogeneous presentation of patients with RET p.V804M mutation, our study and review of the literature suggest that this seemingly "low" risk mutation is associated with late-onset but potentially aggressive MTC. This indicates the need for follow-up and timely intervention based on calcitonin level elevation.

Case report of adrenocortical carcinoma associated with double germline mutations in MSH2 and RET

Adrenocortical carcinoma (ACC) is a rare aggressive malignancy that originates in the outer layer of the adrenal gland. Most ACCs are sporadic, but a small percentage of cases are due to hereditary cancer syndromes such as Li-Fraumeni syndrome (LFS), Lynch syndrome (LS), and familial adenomatous polyposis (FAP). Multiple endocrine neoplasia type 2A (MEN2A) is an inherited disorder that predisposes to medullary thyroid cancer, pheochromocytoma, and parathyroid hyperplasia. We present here a case of ACC with both LS and MEN2A; the family and medical history were consistent with Lynch. This is, to our knowledge, the first report of a patient with ACC associated with germline mutations in RET and MSH2, and no phenotypical characteristics of MEN2A.

Epidemiology of Simultaneous Medullary and Papillary Thyroid Carcinomas (MTC/PTC): An Italian Multicenter Study

Background: The concomitant presence of papillary thyroid cancer (PTC) and medullary TC (MTC) is rare. In this multicentric study, we documented the epidemiological characteristics, disease conditions and clinical outcome of patients with simultaneous MTC/PTC. Methods: We collected data of patients with concomitant MTC/PTC at 14 Italian referral centers. Results: In total, 183 patients were enrolled. Diagnosis was mostly based on cytological examination (n = 58, 32%). At diagnosis, in the majority of cases, both PTC (n = 142, 78%) and MTC (n = 100, 54%) were at stage I. However, more cases of stage II–IV were reported with MTC (stage IV: n = 27, 15%) compared with PTC (n = 9, 5%). Information on survival was available for 165 patients: 109 patients (66%) were disease-free for both PTC and MTC at the last follow-up. Six patients died from MTC. Median time to progression was 123 months (95% confidence interval (CI): 89.3–156.7 months). Overall, 45% of patients were disease-free after >10 years from diagnosis (125 months); this figure was 72.5% for PTC and 51.1% for MTC. Conclusions: When MTC and PTC are concurrent, the priority should be given to the management of MTC since this entity appears associated with the most severe impact on prognosis.

Medullary and papillary thyroid carcinomas in a patient with a C634Y mutation in the RET proto-oncogene: A case report

A 41 year old man presented with a familial history of multiple endocrine neoplasia type 2A (MEN2A) and severe hypertension. Rearranged during transfection (RET) gene sequencing confirmed a Cys634Tyr mutation of TGC to TAC. Total thyroidectomy and bilateral neck dissection were performed and the pathological assessment revealed a medullary thyroid carcinoma (MTC), 0.6 cm in size on the right side (number of lymph nodes: 0/2, 0/15, 0/12, and 0/8 in areas VI, II, III, and IV, respectively) and a papillary thyroid carcinoma (PTC), 0.2 cm in size on the left side (numbers of lymph nodes: 2/6, 0/3, 0/10, and 0/6 in areas VI, II, III, and IV, respectively). There were no pathological changes in the MTC observed in the thyroid tissues on the left side. We believe that the follow-up of patients with both MTC and PTC should utilize a combination of the respective principles for rational disease reassessment.

Familial MTC with RET exon 8 Gly533Cys mutation: origin and prevalence of second malignancy

INTRODUCTION

High prevalence of RET p.Gly533Cys (c.1597G > T) has been found in familial MTC in Greece (exon 8 fMTC). We studied their origin and compared clinical characteristics with non-exon 8 fMTC.

METHODS

102 fMTC (FMTC and MEN2A) patients (31.4% males) were followed for 2.9-37 years (median 6 years). Fifty-one carried the RET exon 8 mutation; the remaining were non-exon 8 fMTC (exons 10, 11, 13, 14). Pre-, post-operative calcitonin, disease extent at diagnosis and follow-up and families' place of origin were recorded.

RESULTS

Exon 8 fMTC were older (42.3 ± 13.3 vs 30.8 ± 17.8 years, P < 0.001), including index cases (P = 0.016). In index cases, the stage at diagnosis was more favorable in exon 8 fMTC compared to non-exon 8 fMTC (stage I and II: 65% vs 23.8%, stage III: 25% vs 57.1%, stage IV: 10% vs 19%, P = 0.025). More favorable outcome was noted in exon 8 fMTCs (remission: 72.5% vs 45.8%, stable disease: 27.5% vs 41.7%, progression: 0.0% vs 12.5%, P = 0.001). Exon 8 fMTC patients carried more frequently a second malignancy (25.5% vs 6.3%, P = 0.009); 69% of these were PTCs. Exon 8 fMTC patients were significantly older at diagnosis compared to non-exon 8 moderate-risk RET carriers and presented more favorable clinical outcome (remission: 72.5% vs 50%, stable disease: 27.5% vs 41.7%, progression: 0.0% vs 8.3%, P = 0.021). This difference remained when only index cases were analyzed. 'Hot spots' in the origin of exon 8 fMTCs families were recognized. No phenotype or outcome differences were found between the exon 8 families from the various regions.

CONCLUSIONS

In exon 8 fMTCs' older age, favorable disease stage at diagnosis and favorable outcome suggest slow disease progression compared to non-exon 8 fMTC. Compared with moderate-risk RET mutation carriers, exon 8 fMTC patients have a more favorable clinical outcome. The higher prevalence of second malignancies, especially PTC, not previously reported, merits further investigation. Increased awareness for inherited disease is required for patients with apparently sporadic MTC originating from recognized 'hot spots', as the age at presentation is usually delayed.

Classical point mutations of RET, BRAF and RAS oncogenes are not shared in papillary and medullary thyroid cancer occurring simultaneously in the same gland

BACKGROUND

Papillary (PTC) and medullary (MTC) thyroid carcinomas represent two distinct entities, but quite frequently, they may occur simultaneously.

AIM

To provide genetic analysis of PTC and MTC occurring in the same patient (PTC/MTC) to elucidate their origin.

METHODS

Sequencing analysis of RAS, BRAF and RET oncogenes hot spots mutations in tumoral and normal tissues of 24 PTC/MTC patients.

RESULTS

Two of 24 patients (8.3 %) were affected by familial MTC (FMTC) harboring RET germline mutations in all tissues. Eight of 22 (36.4 %) sporadic cases did not show any somatic mutation in the three tissue components. Considering the MTC component, 10/22 (45.4 %) patients did not show any somatic mutation, 7 of 22 (31.8 %) harbored the M918T RET somatic mutation and 4/22 (18.2 %) presented mutations in the H-RAS gene. In an additional case (1/22, 4.6 %), H-RAS and RET mutations were simultaneously present. Considering the PTC component, 1 of 24 (4.2 %) patients harbored the V600E BRAF mutation, 1 of 24 (4.2 %) the T58A H-RAS mutation and 1 of 24 (4.2 %) the M1T K-RAS mutation, while the remaining PTC cases did not show any somatic mutation. In one case, the MTC harbored a RET mutation and the PTC a BRAF mutation. None of the mutations found were present in both tumors.

CONCLUSIONS

To our knowledge, this is the first study analyzing a possible involvement of RET, BRAF and RAS oncogene mutations in PTC/MTC. These data clearly suggest that the classical activating mutations of the oncogenes commonly involved in the pathogenesis of PTC and MTC may not be responsible for their simultaneous occurrence.

How to Assess the Clinical Relevance of Novel RET Missense Variants in the Absence of Functional Studies?

INTRODUCTION AND BACKGROUND

Familial medullary thyroid cancer (FMTC) is caused by gain of function mutations in the proto-oncogene RET (rearranged during transfection). Missense mutations within exon 14 including p.Val804Met are known to cause FMTC and multiple endocrine neoplasia type 2a/b. The clinical significance of other novel missense variants within this hotspot region of exon 14 is not delineated.

CASE DESCRIPTION

A three-generation pedigree of FMTC is presented with the co-occurrence of two missense variants within exon 14 of the RET gene, the known variant p.Val804Met and the novel variant p.Val826Met. The female index patient developed medullary thyroid cancer at the age of 42 years and was heterozygous for both missense variants. Her younger sister was also tested to be compound heterozygous for both mutations, and five further relatives were heterozygous for only one of both sequence variants. Prophylactic thyroidectomy was recommended for the two carriers of the RET mutation p.Val804Met, revealing a C-cell hyperplasia for one of them at the age of 19 years. Medical surveillance of 6 heterozygous carriers including repeated neck ultrasound examination as well as basal and calcium (pentagastrin)-stimulated calcitonin levels were recommended.

CONCLUSION

Our data emphasize the importance of an interdisciplinary approach to assess the functional and clinical significance of novel RET variants. In the absence of functional studies, the plausibility of the pathologic significance of a detected endocrine genetic variant can be estimated by in silico methods such as computational analysis of protein structure and biophysical differences or comparative database search for evolutionary conservation.

Papillary thyroid carcinoma and multiple endocrine neoplasia type 2

INTRODUCTION

Papillary thyroid carcinoma (PTC) is exceptional in MEN 2.

RESULTS

The analysis in 135 patients revealed two PTC, without C-cell pathology; both being positive for V804M mutation (RET proto-oncogene).

CONCLUSIONS

Few data are available about PTC in MEN 2, and without C-cell pathology is even less common. More studies are needed to correlate genetics and histology, and even for assessing PTC as only manifestation of MEN 2.

Characterization of V804M-mutated RET proto-oncogene associated with familial medullary thyroid cancer, report of the largest Turkish family

PURPOSE

Analysis of the RET proto-oncogen is very important for diagnosis and prognosis of medullary thyroid cancer (MTC). Genotype-phenotype correlation is also well known. Here we report features of the largest known family in Turkey with the V804M-mutated RET proto-oncogene.

METHODS

Thirty members from three generations were evaluated. A RET proto-oncogen mutation, calcitonin (Ct) measurement and thyroid ultrasound were performed on all individuals. Seventeen members had V804M mutation. Fourteen of these patients underwent total thyroidectomy and additional central lymph node dissection for five subjects.

RESULTS

The mean age of patients with MTC was 46.5 (30-61) years. The mean calcitonin level of RET positive members was 13.27 pg/mL (1-49.8 pg/mL). Three had a basal Ct level above normal limits. Seven of the 14 patients were diagnosed with MTC, and two were diagnosed with papillary thyroid cancer without MTC. One patient had central neck metastasis. Hyperparathyroidism or pheochromocytoma was not detected in any case. Patients who were RET negative, had normal Ct levels and no suspected nodule on ultrasound examination.

CONCLUSIONS

Our study revealed a relatively good prognosis in patients with V804M mutation. Despite the surgery was performed in older age no advance disease was observed.

Prevalence by age and predictors of medullary thyroid cancer in patients with lower risk germline RET proto-oncogene mutations

BACKGROUND

Age-related risk of medullary thyroid carcinoma (MTC) development in presymptomatic carriers of lower risk germline RET mutations is uncertain; such data may aid counseling patients regarding timing of thyroidectomy.

METHODS

From an institutional database and an exhaustive literature review, we identified 679 patients with American Thyroid Association (ATA) level A or B mutations who were identified because of family screening (index cases of MTC were excluded to minimize selection bias). We evaluated age at thyroidectomy or last evaluation if no thyroidectomy, preoperative calcitonin level (elevated or not), the mutated codon, and outcome (MTC vs. no MTC after thyroidectomy or no clinical evidence of MTC if thyroid intact). Data were used to estimate the cumulative prevalence of MTC and/or assess likelihood of MTC stratified by codon. After exclusion of cases with missing data or small representation, 503 patients with mutations in codons 533, 609, 611, 618, 620, 791, and 804 were analyzed.

RESULTS

236 patients had MTC. Cumulative prevalence and median time to MTC varied by codon and within ATA risk levels (p<0.0001). Patients with a codon 620 mutation were 2.8-6.9 times more likely to have MTC than other level B mutation carriers, and 5.1-21.7 times more likely than level A mutation carriers included in our focus population. The youngest median time to MTC was 19 years for codon 620 and the oldest was 56 years for codon 611. Cumulative prevalence of MTC by age 20 was 10% or lower for codons 533, 609, 611, 791, and 804. By age 50, it ranged from 18% for codon 791 to 95% for codon 620. An elevated preoperative calcitonin level strongly predicted MTC on final pathology, though false-negative rates varied by codon (p<0.0001). Positive predictive values ranged from 76% to 100% by codon with an overall positive predictive value of 87% across codons.

CONCLUSIONS

This study offers a better understanding of the age-related development of MTC in lower risk RET mutation carriers, provides evidence of further distinctions between lower risk mutations within ATA subgroups, and clarifies the clinical significance of codon 791 mutations. The data support individualized "codon-based" management approaches coupled with clinical data such as calcitonin levels.

Ponatinib is a potent inhibitor of wild-type and drug-resistant gatekeeper mutant RET kinase

RET kinase is aberrantly activated in thyroid cancers and in rare cases of lung and colon cancer, and has been validated as a molecular target in these tumors. Vandetanib was recently approved for the treatment of medullary thyroid cancer. However, vandetanib is ineffective in vitro against RET mutants carrying bulky aminoacids at position 804, the gatekeeper residue, similarly to drug-resistant BCR-ABL mutants in chronic myeloid leukemia. Ponatinib is a multi-target kinase inhibitor that was recently approved for treatment-refractory Philadelphia-positive leukemia. We show here potent inhibition of oncogenic RET by ponatinib, including the drug-insensitive V804M/L mutants. Ponatinib inhibited the growth of RET+ and BCR-ABL+ cells with similar potency, while not affecting RET-negative cells. Both in biochemical and in cellular assays ponatinib compared favorably with known RET inhibitors, such as vandetanib, cabozantinib, sorafenib, sunitinib and motesanib, used as reference compounds. We suggest that ponatinib should be considered for the treatment of RET+ tumors, in particular those expressing vandetanib-resistant V804M/L mutations.

A Case of medullary thyroid carcinoma with de novo V804M RET germline mutation

Many cases of RET proto-oncogene mutations of hereditary medullary thyroid carcinoma (MTC) have been reported in Korea. However, MTC with V804M RET proto-oncogene germline mutations have not been reported in Korea. A 33-yr-old man was diagnosed with a 0.7-cm sized thyroid nodule. Laboratory testing revealed serum calcitonin was elevated. The patient underwent total thyroidectomy with central compartment neck dissection for the thyroid tumor. RET gene analysis was performed in both the index patient and his family. There were no V804M RET mutation and abnormal laboratory findings within his family except the index patient. Therefore, this patient was a de novo V804M RET germline mutation.

Simultaneous medullary and differentiated thyroid cancer: a population-level analysis of an increasingly common entity

BACKGROUND

Simultaneous medullary thyroid carcinoma (MTC) and differentiated thyroid carcinoma (DTC) is a rare entity. This is the first population-level analysis of the characteristics and outcomes of simultaneous MTC/DTC.

METHODS

In the Surveillance, Epidemiology, and End Results (SEER) database (1988-2008), patients with simultaneous MTC/DTC were retrospectively compared with those with MTC alone using χ(2), ANOVA, log-rank tests, Cox multivariate regression, and Kaplan-Meier analyses.

RESULTS

A total of 162 patients had simultaneous MTC/DTC; 1,699 had MTC alone. MTC was diagnosed first in 67.9 % of simultaneous MTC/DTC cases. Simultaneous MTC/DTC increased from 2.7 % of all MTCs in 1988-1997 to 12.3 % in 2003-2008. Compared with MTC alone, simultaneous MTC/DTC had smaller mean MTC tumor size (2.9 vs. 2.2 cm; p = 0.005) and lower rates of MTC extrathyroidal extension (25.4 vs. 16.8 %; p = 0.015) and distant metastases (15.7 vs. 9.3 %; p = 0.032). Patients diagnosed with DTC first had smaller mean MTC tumor sizes (p = 0.01), whereas patients diagnosed with MTC first had tumor sizes similar to those of MTC alone. Compared with MTC alone, patients with simultaneous MTC/DTC were more likely to receive thyroidectomy (84.7 vs. 93.2 %; p = 0.003) and radioisotopes (4.4 vs. 25 %; p < 0.001). On Kaplan-Meier analysis, disease-specific survival rates were higher for simultaneous MTC/DTC than for MTC alone (10-year survival rates 87 vs. 81 %; p = 0.056).

CONCLUSIONS

Simultaneous MTC/DTC is diagnosed earlier in tumor development than MTC alone, with a trend toward better prognosis. This entity likely represents a primary tumor with an incidental pathologic finding of a second malignancy. Each malignancy should be treated according to its respective stage and current guidelines.

Simultaneous medullary and papillary thyroid cancer: a novel entity?

BACKGROUND

The causes underlying the phenomenon of simultaneous medullary (MTC) and papillary thyroid cancer (PTC) are unclear.

METHODS

This study of 26 patients with simultaneous MTC and PTC aimed at clarifying clinical and histopathologic characteristics and trends of this unusual condition among MTC and PTC patients who were operated on at a tertiary referral center in Germany.

RESULTS

A total of 26 patients revealed simultaneous MTC and PTC, yielding the following rates: 2.6% (26 patients) among all 1019 PTC patients, 2.6% (6 patients) among all 235 hereditary MTC patients, 4.1% (20 patients) among all 492 sporadic MTC patients, and 3.6% (26 patients) among all 727 MTC patients. Simultaneous MTC and PTC were consistently smaller than nonsimultaneous MTC (6 vs. 13 mm for hereditary MTC, P = .16; 12 vs. 23 mm for sporadic MTC, P = .009; and 11 vs. 20 mm for any MTC, P = .008) and PTC (8 vs. 20 mm, P < .001). Simultaneous MTC and PTC increased among MTC and PTC patients over time: from 0% to 4.3% (PTC), from 0% to 4.6% (hereditary MTC), from 0% to 8.1% (sporadic MTC), and from 0% to 7.0% (any MTC). For sporadic MTC, these rates virtually doubled every 5 years. Of 6 patients with simultaneous hereditary MTC and PTC, 5 revealed late-onset REarranged during Transfection (RET) mutations (1 L790F carrier; 2 V804L and 2 S891A carriers).

CONCLUSIONS

Greater pathologic scrutiny, in addition to environmental changes, explains the surge of simultaneous MTC and PTC in Germany. More data are needed from additional geographic areas and populations to delineate individual contributions of these factors.

RET genetic screening of sporadic medullary thyroid cancer (MTC) allows the preclinical diagnosis of unsuspected gene carriers and the identification of a relevant percentage of hidden familial MTC (FMTC)

OBJECTIVE

This study was aimed to demonstrate the clinical benefits of rearranged during transfection (RET) genetic screening in patients with apparently sporadic medullary thyroid cancer (MTC) not only to identify the hereditary nature of the disease in the index case but also to discover family members harbouring the same germline mutations (i.e. gene carriers) who are unaware of their condition.

CONTEXT

RET genetic screening allowed the identification of germline RET mutations in apparently sporadic MTC resulting in their re-classification as hereditary forms.

PATIENTS AND MEASUREMENTS

RET genetic screening was performed in 729 apparently sporadic MTC patients by direct sequencing RET exons 5, 8, 10, 11 and 13-16. Clinical and biochemical evaluation of gene carriers was also performed.

RESULTS

We discovered an unsuspected germline RET mutation in 47 of 729 (6·5%) apparently sporadic MTC who were re-classified as hereditary. We found 60 of 146 (41·1%) gene carriers, 35 of whom had biochemical or clinical evidence of MTC. Thirty gene carriers underwent total thyroidectomy and 27 of 30 (90%) were persistently cured after a mean follow-up of 6·0 years. As a further result of RET genetic screening, we observed a significantly higher prevalence of familial medullary thyroid cancer (FMTC) in our series with respect to the largest series of the International RET Consortium (P = 0·0002).

CONCLUSIONS

RET genetic screening of patients with apparently sporadic MTC represents a major tool for the preclinical diagnosis and early treatment of unsuspected affected family members and allows the identification of a relevant percentage of hidden FMTC.