The clinical manifestation of multiple endocrine neoplasia type 2 (MEN2) in terms of developing medullary thyroid cancer (MTC), pheochromocytoma (PCC), and/or primary hyperparathyroidism (PHPT) is related to the respective pathogenic variant of the RET proto-oncogene. The aim of this study is to retrospectively analyze the individual, genotype-dependent clinical manifestations of a large cohort of MEN2 patients. By comparing their clinical profile with currently existing evidence-based knowledge, an optimal therapy and prevention strategy in terms of prophylactic thyroidectomy and clinical follow-up could be ensured. This is a retrospective single-center study of 158 MEN2 patients who were diagnosed and/or surgically treated at a tertiary referral care center between 1990 and 2022. All participants were categorized according to their pathogenic variant of the RET proto-oncogene. Subsequently, the clinical manifestation of the disease and its time of occurrence was documented. Our analysis showed results in line with existing studies, except for a considerably lower-than-predicted occurrence of PCC in patients with V804M/L mutations. This study supports the current recommendation regarding the pathogenic variant-dependent management of this rare cancer-associated syndrome.

BACKGROUND: While primary tumor desmoplasia is a powerful biomarker of node metastases in sporadic medullary thyroid cancer (MTC), information for hereditary MTC is sparse.
METHODS: This proof-of-concept study, comprising 3 consecutive children with multiple endocrine neoplasia 2B, evaluated simultaneously the metastatic behavior of multiple primary thyroid tumors of disparate size and extent of desmoplasia within patients.
RESULTS: Altogether, MTC typically involved the ipsilateral central neck before spreading to the ipsilateral lateral and the contralateral neck. Medullary thyroid cancer in the upper thyroid lobe leaped the ipsilateral central neck to invade the ipsilateral lateral neck. Unlike the desmoplasia-positive 6-mm high-grade and 7-mm low-grade primary thyroid tumors, the desmoplasia-negative 8-, 11-, and 16-mm low-grade primary thyroid tumors did not spread to ipsilateral neck nodes. With extranodal growth, the extent of nodal desmoplasia was greater than with intranodal growth.
CONCLUSIONS: This proof-of-concept study suggests that primary tumor desmoplasia is an equally powerful biomarker of node metastasis in hereditary MTC.

Prophylactic and early thyroidectomy in RET germline mutation carriers allows the removal of the thyroid before medullary thyroid carcinoma (MTC) develops, or while it is still confined to the gland. This study was aimed to assess the clinicopathological features in RET carriers according to the age at surgery and the long-term outcomes after prophylactic and early thyroidectomy. A retrospective analysis of 63 operated asymptomatic RET carriers diagnosed after familial genetic screening was performed. Twenty-one RET carriers were operated at pediatric (<18 yrs) and 42 at adult (≥18 yrs) age. Serum preoperative calcitonin levels were significantly lower in pediatric compared to adult patients (p = 0.04); moreover, adult RET carriers had a greater frequency of microMTC at pathology (p = 0.009). Permanent postoperative morbidity occurred in 9.5% of patients, without differences between the two groups. Biochemical postoperative cure was achieved in all patients. At a median follow-up of 14 years, all C-cell hyperplasia patients are disease-free; conversely, biochemical, and structural recurrence of disease occurred in three adults and one pediatric patient with microMTC. The independent predictive factors of MTC were the age at surgery, the preoperative calcitonin level and the RET mutational risk profile (p < 0.02). In conclusion, prophylactic and early thyroidectomy are safe and effective procedures in achieving definitive cure in most RET carriers. However, since recurrences may occur at long-term in case of microMTC, thyroidectomy should be possibly performed earlier to prevent microMTC development.

Long-term data are scarce on large cohorts with sporadic (sMTC) and hereditary medullary thyroid carcinoma (hMTC).
To compare long-term disease-specific survival (DSS) and outcomes between sMTC and hMTC groups.
Retrospective analysis.
German tertiary referral center.
A total of 673 patients with MTC that underwent surgery from January 1974 to July 2019.
None (observational study).
Differences between sMTC and hMTC in long-term, stage-dependent survival and outcomes.
Surgery was performed at median ages of 49 years for sMTC (n = 477, 44% male) and 29 years for hMTC (n = 196, 43% male; P < 0.0001). The mean follow-up times were 9.2 ± 8.0 (sMTC) and 14.6 ± 10.3 years (hMTC). Age and tumor stage at diagnosis were significantly different between the 2 groups (P < 0.0001). The sMTC and hMTC groups had different overall DSS (log rank, P = 0.0183), but similar stage-dependent DSS (log rank, P = 0.1242-0.8981). In a multivariate analysis, sMTC and hMTC did not differ in DSS (hazard ratio [HR] = 1.56; 95% CI, 0.94-2.57), but in both groups, a worse DSS was significantly associated with age at diagnosis (HR = 1.04; 95% CI, 1.02-1.05), male sex (HR = 0.49; 95% CI, 0.32-0.76), and stages III and IV at diagnosis (HR = 20.00; 95% CI, 2.74-145.91 and HR = 97.47; 95% CI, 13.07-726.67, respectively). The groups had significantly different (P < 0.0001) outcomes (i.e., cured, minimal residual disease, structural detectable disease, and death), but similar stage-dependent outcomes (P = 0.9449-0.0511), except for stage III (P = 0.0489).
Patients with sMTC and hMTC had different ages of onset, but similar stage-dependent DSS and outcomes after the MTC diagnosis. This finding suggested that tumor behavior was similar in sMTC and hMTC.

Genetic analysis for germline mutations of RET proto-oncogene has provided a basis for individual management of medullary thyroid carcinoma (MTC) and pheochromocytoma. Most of compound mutations have more aggressive phenotypes than single point mutations, but the compound C634Y/V292M variant in MTC has never been reported. Thus, we retrospectively investigated synergistic effect of C634Y and V292M RET germline mutations in family members with multiple endocrine neoplasia type 2A. Nine of 14 family members in a northern Chinese family underwent RET mutation screening using next-generation sequencing and PCR followed by direct bidirectional DNA sequencing. Clinical features of nine individuals were retrospectively carefully reviewed. In vitro, the scratch-wound assay was used to investigate the difference between the cells carrying different mutations. We find no patients died of MTC. All 3 carriers of the V292M variant were asymptomatic and did not have biochemical or structural evidence of disease (age: 82, 62 and 58). Among 4 C634Y mutation carriers, 2 patients had elevated calcitonin with the highest (156 pg/mL) in an 87-year-old male. Two carriers of compound C634Y/V292M trans variant had bilateral MTC with pheochromocytoma or lymph node metastasis (age: 54 and 41 years, respectively). Further, the compound C634Y/V292M variant had a faster migration rate than either single point mutation in vitro (P < .05). In conclusion, the V292M RET variant could be classified as \'likely benign\' according to ACMG (2015). The compound variant V292M/C634Y was associated with both more aggressive clinical phenotype and faster cell growth in vitro than was either single mutation.

Thirty-two cases of hereditary medullary thyroid carcinoma (HMTC) and 95 sporadic HMTC (SHMTC), 44 familial papillary TC (FPTC), and 172 sporadic cases were comparatively analyzed to improve the diagnosis and treatment of familial thyroid cancer. A hundred and one DNA samples from patients with MTC and their relatives were examined. BRAF and RET/PTC gene mutations were investigated in 6 patients with FPTC. The frequencies of familial TC, HNTC, and FPTC were 6 6, 26.5, and 4.3%, respectively. The mean age of patients with HMTC and SHMTC was 30.J±13.6 and 46.3±J3.1 years, respectively (p < 0.0001); tumor multicentricity was 87.5 and 36.8% (p < 0 0001) and bilaterality was 87.5 and 0%, respectively (p < 0.001). Inheritable RET mutations were detected in 16 families. Eight asymptomatic carriers of RET mutations were revealed; 3 of them underwent preventive thyroidectomy. There was the commonest (63.6%) codon 634 mutation in which the earliest manifestation and aggressive course of the disease were observed. The efficiency of screening for type 2 multiple endocrine neoplasia syndrome Increased by 1.8 times (from 31.2 to 51.2%). In the mother and daughter with FPTC, silent mutation was found in codon 891 of RET gene exon 15. Genetic examination of the relatives of patients with HMTC made it possible to diagnose the disease at its early stage and to perform preventive surgical treatment. The aggressiveness of HMTC makes it necessary to make total thyroidectomy. The absence of differences in the clinical course of familial and sporadic PTC predetermines uniform treatment policy.
С целью улучшить диагностику и лечение семейного рака щитовидной железы проведен сравнительный анализ 32 случаев наследственного медуллярного рака щитовидной железы (НМРЩЖ) и 95 спорадических МРЩЖ (СпМРЩЖ), 44 семейных папиллярных РЩЖ (СПРЩЖ) и 172 спорадических. Изучен 101 образец ДНК больных МРЩЖ и их родственников. У 6 больных СПРЩЖ проведен поиск мутаций в генах BRAF и RET/PTC. Частота семейного РЩЖ составила 6,6%, НМРЩЖ- 26,5%, СПРЩЖ- 4,3%. Средний возраст больных НМРЩЖ и СпМРЩЖ- 30,1 ± 13,6 и 46,3 ± 13,1 года (р < 0,0001), мультицентричность - 87,5 и 36,8% (р < 0,0001) и билатеральность - 87,5 и 0% (р < 0,0001) соответственно. Наследственные RET-мутации обнаружены в 16 семьях. Выявлено 8 бессимптомных носителей RET-мутации, у 3 из них выполнена превентивная тиреоидэктомия. Наиболее частая мутация - в 634-м кодоне (63,6% случаев), при которой выявлены наиболее ранняя манифестация и агрессивное течение заболевания. Скрининг синдрома МЭН 2 в 1,8 раза (с 31,2 до 51,2%) эффективнее. У матери и дочери с СПРЩЖ обнаружена \"молчащая\"мутация в 891-м кодоне 15-го экзона гена RET. ПРОБЛЕМЫ ЭНДОКРИНОЛОГИИ, 2007. Т. 53, № 4. Генетическое обследование родственников бoльных НМРЩЖ позволило диагностировать заболевание на ранней стадии и провести превентивное хирургическое лечение. Агрессивность НМРЩЖ обусловливает необходимость выполнения тотальной тиреоидэктомии. Отсутствие различий в клиническом течении семейного и спорадического ПРЩЖ предопределяет единую лечебную тактику.

BACKGROUND: Serum calcitonin is often elevated in medulla thyroid carcinoma (MTC) and thus serves as an indicator of primary and recurrent disease. However, there are MTC patients with normal Serum calcitonin and the underlying mechanisms are largely unknown.
METHODS: A 48-year-old female patient presenting with a right anterior cervical mass was diagnosed with medullary carcinoma. She had elevated carcinoembryonic antigen (CEA) but normal Serum calcitonin levels. Next generation sequencing (NGS) of paired tumor and peripheral blood revealed a germline pathogenic RET mutation, indicating the hereditary nature of MTC in this patient. Two somatic loss-of-function mutations in DICER1 gene were also found, which we postulated to account for the normal calcitonin levels found in this patient. To our knowledge, this is the first report of a hereditary MTC case displaying a normal Serum calcitonin.
CONCLUSIONS: The case suggests NGS can be used in the diagnosis of hereditary MTC and exploring the reasons of normal Serum calcitonin in these patients.

Recent studies have shown a significant increase in the temporal trend of medullary thyroid carcinoma (MTC) incidence. However, it remains unknown to which extent sporadic medullary thyroid carcinoma (SMTC) and hereditary MTC (HMTC) affect the MTC incidence over time. We conducted a nationwide retrospective study using previously described RET and MTC cohorts combined with review of medical records, pedigree comparison and relevant nationwide registries. The study included 474 MTC patients diagnosed in Denmark between 1960 and 2014. In the nationwide period from 1997 to 2014, we recorded a mean age-standardized incidence of all MTC, SMTC and HMTC of 0.19, 0.13 and 0.06 per 100,000 per year, respectively. The average annual percentage change in incidence for all MTC, SMTC and HMTC were 1.0 (P = 0.542), 2.8 (P = 0.125) and -3.1 (P = 0.324), respectively. The corresponding figures for point prevalence at January 1, 2015 were 3.8, 2.5 and 1.3 per 100,000, respectively. The average annual percentage change in prevalence from 1998 to 2015 for all MTC, SMTC and HMTC was 2.8 (P < 0.001), 3.8 (P < 0.001) and 1.5 (P = 0.010), respectively. We found no significant change in the incidence of all MTC, SMTC and HMTC possibly due to our small sample size. However, due to an increasing trend in the incidence of all MTC and opposing trends of SMTC (increasing) and HMTC (decreasing) incidence, it seems plausible that an increase for all MTC seen by others may be driven by the SMTC group rather than the HMTC group.

BACKGROUND: Hereditary medullary thyroid carcinoma (HMTC) is thought to be associated with germline mutations of the RET proto-oncogene.
METHODS: We detected RET proto-oncogene germline mutations from a pedigree with HMTC in the east of China and investigated the characteristics of these mutations in this pedigree and their correlation with HMTC by direct sequencing of all 21 exons in the RET gene of all 46 subjects.
CONCLUSIONS: (1) Thirteen types of RET gene variants were detected in this pedigree. Of these, p.F285S in exon 4, c.854_855CA in exon 4, and p.D707E in exon 11 are reported for the first time in our study. (2) Both linkage disequilibrium analysis and logistic regression analysis showed a significant correlation between the p.D707E variant and HMTC (LOD = 3.69, OR = 4.413, p = 0.000167), indicating that this variant is a risk factor for medullary thyroid carcinoma (MTC). (3) The single-nucleotide polymorphisms (SNP) G691S in exon 11 (rs1799939), S904S in exon 15 (rs1800863), and rs2075912 and rs2565200 in the 3\'-untranslated region of the RET proto-oncogene are in complete linkage disequilibrium (D\' = 1, r2 = 1); no correlation of these SNP and MTC was observed in this pedigree. (4) No hot-spot mutation of the RET proto-oncogene was detected in this pedigree. We drew the conclusion that the heterozygous nonsynonymous variant p.D707E in the RET proto-oncogene is rare, but it is a risk factor for hereditary MTC.

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.