RET gene mutations (genotype and phenotype) of multiple endocrine neoplasia type 2 and familial medullary thyroid carcinoma.

The rapid technical advances in molecular biology and accelerating improvements in genomic and proteomic diagnostics have led to increasingly personalized strategies for cancer therapy. Such an approach integrates the genomic, proteomic, and molecular information unique to the individual to provide an accurate genetic diagnosis, molecular risk assessment, informed family counseling, therapeutic profiling, and early preventative management that best fits the particular needs of each patient. The discovery of mutations in the RET proto-oncogene resulting in variable onset and severity of multiple endocrine neoplasia type 2 (MEN2) was the first step in developing direct genetic testing for at-risk individuals. Patients with germline RET mutations may undergo risk assessment and appropriate intervention based on specific mutations. Moreover, family members of affected individuals receive counseling based on understanding of the genetic transmission of the disease. Increasingly, clinicians are able to make therapeutic choices guided by an informative biomarker code. Improvements in detection and management of patients with MEN2 resulting from understanding of the RET proto-oncogene are evidence of the benefits of personalized cancer medicine. This review describes the discovery of the RET proto-oncogene, the association between genotype and phenotype, and the role of mutation analysis on diagnosis and treatment of MEN2.

Role of preoperative basal calcitonin levels in the timing of prophylactic thyroidectomy in patients with germline RET mutations.

BACKGROUND: The American Thyroid Association (ATA) published recommendations for the timing of prophylactic surgery for medullary thyroid carcinoma based on the specific mutation, patient age, family history, and serum calcitonin levels. The aim of this study was to assess the role of preoperative basal calcitonin (prebCt) levels in predicting the presence of medullary carcinoma of the thyroid in patients with RET mutations. METHODS: We conducted a retrospective study in two endocrine surgery departments. Between 1986 and 2012, a total of 32 patients with RET mutations underwent prophylactic thyroidectomy. The patients were stratified into four ATA risk levels: A, B, C, and D. RESULTS: All of the patients were biologically cured. Microcarcinoma was observed in the final pathology report for four of the 20 patients with normal prebCt (25 %) and for nine of the 12 patients with elevated prebCt (75 %). In the level A group, four patients with normal prebCt and one patient with elevated prebCt presented with microcarcinoma. In the level C group, one patient with normal prebCt and six of the seven patients with elevated prebCt (86 %) presented with microcarcinoma. CONCLUSIONS: PrebCt can predict the presence of microcarcinoma according to surgical pathological analysis. Patients with microcarcinoma can be biochemically and clinically cured using prophylactic thyroidectomy.

Hereditary medullary thyroid cancer: age-appropriate thyroidectomy improves disease-free survival.

BACKGROUND: Twenty-five percent of medullary thyroid cancer (MTC) cases are hereditary. The ideal age for prophylactic thyroidectomy is based on the specific RET mutation involved. The purpose of this study was to determine whether such age-appropriate prophylactic thyroidectomy results in improved disease-free survival. METHODS: Twenty-eight patients underwent thyroidectomy for hereditary MTC at our institution. Age-appropriate thyroidectomy was defined according to the North American Neuroendocrine Tumor Society (NANETS) guidelines. Patients who had age-appropriate surgery (group 1, n = 9) were compared to those who had thyroidectomy past the recommended age (group 2, n = 19). RESULTS: The mean age was 13 ± 2 years, and 61 % were female. Patients in group 1 were younger than in group 2 (4 ± 1 vs. 17 ± 2 years, p < 0.01). There were no significant differences in gender or RET mutation types between these two groups. Group 1 patients were cured with no disease recurrence compared with group 2 patients who had a 42 % recurrence rate (p = 0.05). Subanalysis of group 2 identified that patients who underwent surgery without evidence of disease did so at a shorter period following the guidelines compared with those who underwent therapeutic surgery (2 ± 2 vs. 16 ± 2 years, p = 0.01) and had longer disease-free survival (100 vs. 27 %, p = 0.005). CONCLUSIONS: Patients with hereditary MTC should undergo age-appropriate thyroidectomy based on RET mutational status to avoid recurrence. Patients who are past the recommended age should have surgery as early as possible to improve disease-free survival.

Changing clinical characteristics of thyroid carcinoma at a single center from Turkey: before and after the Chernobyl disaster.

AIM: The aim of the study was to determine the possible role of Chernobyl disaster on changing clinical features of thyroid carcinoma (TC) in a moderately iodine deficient region. METHODS: We retrospectively reviewed demographical features, presenting symptoms, tumor size, histopathological diagnosis and distant metastates in 160 patients with TC diagnosed between 1990-2007. We compared our findings with the database of 118 TC patients diagnosed between 1970-1990 in the same center. RESULTS: There were 123 female (76.9%) and 37 (23.1%) male patients with a mean age of 44.89±14.84. Sex distribution and age at diagnosis were similar between 1970-1990 and 1990-2007 (P=0.77 and P=0.42, respectively). Histopathological diagnoses were papillary in 114 (73.1%), follicular in 22 (14.1%), medullary in 9 (5.8%), hurthle cell in 7 (4.5%) and anaplastic TC in 4 (2.6%) patients. We observed a marked increase in papillary TC (P<0.001) and marked decreases in follicular (P<0.001) and anaplastic TC (P=0.01) compared to the period between 1970-1990. Thyroid microcarcinomas accounted for 27.1% and 37.1% of carcinomas in 1970-1990 and 1990-2007, respectively (P<0.05). CONCLUSION: We showed that incidence of papillary TC increased and incidences of follicular and anaplastic TC decreased in a period that might be affected by Chernobyl fallout in a moderately iodine deficient area. Presenting symptoms of TC have changed and microcarcinomas are diagnosed more frequently compared to past. Further large scale trials are needed to find out whether Chernobyl disaster has role on changing characteristic of TC in countries that are not very near but also not very far from Chernobyl such as Turkey.

Surgical management of medullary thyroid cancer.

Although thyroid cancer accounts for only 1.5% of all malignancies in the US it is the most rapidly increasing cancer in incidence and it is the most common endocrine malignancy that accounts for over 95% of the endocrine malignancies. Medullary thyroid cancer (MTC) originates from the parafollicular C cells and it represents 6-8% of all thyroid cancer cases. As many as 25% of the MTCs are familial and carry a specific germline mutation as compared to only than 10% familial inheritance in non-medullary thyroid cancers. While well-differentiated thyroid malignancies carry a very good prognosis, recurrence and survival rates of patients with MTC are significantly worse. The difference in cell origin and differentiation also results in different available adjunct therapy. The aim of this study is to review in detail the surgical management of patients with MTC.

[Prophylactic thyroidectomy in medullary thyroid cancer]. / La chirurgie prophylactique du cancer médullaire de la thyroïde.

Medullary thyroid cancer (MTC) is genetically determined in 30% to 35% of cases, notably through multiple mutations in the RET protooncogene located on chromosome 10, for which a genotype-phenotype relationship determines age of onset. There are three phenotypes: MEN 2 A and B, and isolated familial MTC. The type of mutation determines 3 levels of aggressiveness. Current guidelines recommend thyroidectomy during the first months of life for patients with very-high-risk (level 3) mutations and before 5 years of age for high-risk (level 2) mutations. There are no precise recommendations for lower-risk mutations, for which the surgical decision also depends on the calcitonin level and family history. We describe 18 patients who underwent prophylactic surgery. Regardless of the mutation, all patients with a normal preoperative calcitonin level were cured. However, surgery was performed later than recommended, for various reasons, including late genetic diagnosis and parents' opposition.

Greater vegetable and fruit intake is associated with a lower risk of breast cancer among Chinese women.

The effect of vegetable and fruit consumption on breast cancer risk is controversial. We examined the association between vegetable and fruit intake and breast cancer risk in a hospital-based case-control study conducted in Guangdong, China. Four hundred and thirty-eight cases were frequency matched to 438 controls by age (5-year interval) and residence (rural/urban). Dietary intake was assessed by face-to-face interviews using a validated food frequency questionnaire. Multivariate logistic regression was used to estimate the odds ratios (ORs) and 95% confidence interval (CI) after adjusting for various potential confounders. Total vegetable and fruit intake was found to be inversely associated with breast cancer risk. The ORs of the highest quartile relative to the lowest quartile of total vegetable and fruit intake were 0.28 (95% CI 0.18-0.43) and 0.53 (95% CI 0.34-0.82), respectively. Consumption of individual vegetable and fruit groups such as dark green leafy vegetables, cruciferous vegetables, carrots and tomatoes, banana, watermelon/papaya/cantaloupe were all inversely and significantly related with breast cancer risk. An inverse association was also observed for vitamin A, carotene, vitamin C, vitamin E, and fiber intake. These data indicate that greater intake of vegetables and fruits is associated with a decreased risk of breast cancer among Chinese women residing in Guangdong.

Prophylactic thyroidectomy in ethnic Chinese patients with multiple endocrine neoplasia type 2A syndrome after the introduction of genetic testing.

OBJECTIVE: To evaluate the impact of genetic testing in the management of familial multiple endocrine neoplasia 2A patients. DESIGN: Retrospective study. SETTING: University teaching hospital, Hong Kong. PATIENTS: Twenty-two patients from eight multiple endocrine neoplasia 2A families underwent prophylactic total thyroidectomy based on a positive RET mutation genetic testing. All mutations were located at codon 634 of exon 11. Nineteen patients had preoperative basal serum calcitonin measured, and the 12 with normal levels had pentagastrin stimulation tests. Preoperative thyroid ultrasound examination was performed for 17 patients. RESULTS: There were 13 females and 9 males with a median age of 25.1 (range, 6.1-71.9) years. Histopathology revealed medullary thyroid carcinoma in 17 (77%), C-cell hyperplasia in four (18%), and normal pathology in one (5%) of the patients. Five patients with either C-cell hyperplasia or normal pathology were among the youngest (age range, 6-9 years). The youngest patient with medullary thyroid carcinoma was nearly 9 years old. The median size of medullary thyroid carcinomas was 8.3 (range, 0.1-18) mm, but there were no lymph node metastases. Of 15 patients with normal basal calcitonin levels, 10 had medullary thyroid carcinoma, though two tested negative with the pentagastrin-stimulated calcitonin assay. Five of six patients with normal preoperative ultrasonographic examinations had medullary thyroid carcinoma. Three (14%) of the patients were prescribed long-term calcium and vitamin D supplementation. After a median follow-up of 49 (range, 13-128) months, no patient had recurrence of medullary thyroid carcinoma. CONCLUSIONS: Genetic testing has replaced conventional biochemical and radiological modalities to identifying multiple endocrine neoplasia 2A carriers, in order to offer them prophylactic thyroidectomy. Chinese multiple endocrine neoplasia 2A patients with codon 634 mutation seem to have less aggressive forms of medullary thyroid carcinoma, for whom prophylactic thyroidectomy can be considered at the age of 8 years.

Genotype-phenotype relationship in multiple endocrine neoplasia type 2. Implications for clinical management.

Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant tumour syndrome caused by germline activating mutations of the RET proto-oncogene. It has a strong penetrance of medullary thyroid carcinoma (MTC) and can be associated with bilateral pheochromocytoma and primary hyperparathyroidism (MEN2A) within a single patient or family. Based on the phenotype three distinct clinical forms have been described: (1) classical MEN2A, (2) MEN2B, an association of MTC, pheochromocytoma and mucosal neuroma and (3) familial MTC (FMTC), which is associated with a very low incidence of other endocrinopathies. Each variant of MEN2 results from a different RET gene mutation, with a good genotype-phenotype correlation with regard to aggressiveness of MTC, time of onset of MTC and the presence or absence of other endocrine tumours. Recommendations on the timing of prophylactic thyroidectomy and extent of surgery are based on a classification of RET mutations into three risk levels using the genotype-phenotype correlations. MEN2 provides a unique model for early prevention and cure of cancer and for stratified roles of mutation-based diagnosis of carriers.

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.

Prophylactic thyroidectomy in multiple endocrine neoplasia type 2A.

BACKGROUND: Medullary thyroid carcinoma is the most common cause of death in patients with multiple endocrine neoplasia (MEN) type 2A (MEN-2A) or type 2B or familial medullary thyroid carcinoma. We sought to determine whether total thyroidectomy in asymptomatic young members of kindreds with MEN-2A who had a mutated allele of the RET proto-oncogene could prevent or cure medullary thyroid carcinoma. METHODS: A total of 50 patients 19 years of age or younger who were consecutively identified through a genetic screening program as carriers of a RET mutation characteristic of MEN-2A underwent total thyroidectomy. Five to 10 years after the surgery, each patient was evaluated by physical examination and by determination of plasma calcitonin levels after stimulation with provocative agents. RESULTS: In 44 of the 50 patients, basal and stimulated plasma calcitonin levels were at or below the limits of detection of the assay (proportion, 0.88; 95 percent confidence interval, 0.76 to 0.95). Two patients had basal and stimulated plasma calcitonin levels above the normal range. Stimulated plasma calcitonin levels had increased but remained within the normal range in four patients. The data suggest that there was a lower incidence of persistent or recurrent disease in children who underwent total thyroidectomy before eight years of age and in children in whom there were no metastases to cervical lymph nodes. CONCLUSIONS: In this study, young patients identified by direct DNA analysis as carriers of a RET mutation characteristic of MEN-2A had no evidence of persistent or recurrent medullary thyroid carcinoma five or more years after total thyroidectomy. A longer period of evaluation will be necessary to confirm that they are cured.

[Is immediate prophylactic thyroidectomy indispensable in familiar medullary thyroid carcinoma?]. / Es imprescindible la tiroidectomía profiláctica inmediata en el carcinoma medular de tiroides familiar?

PURPOSE: To emphasize the importance of genetic studies in family members and early prophylactic thyroidectomy in oncogene mutation carriers in the management of familiar medullary thyroid carcinoma. METHODS: A retrospective review of families with familiar medullary thyroid carcinoma treated at our center in the last 7 years was performed. We identified a total of 7 families who has isolated prevalences with thyroid malignancies. Forty members of the 7 families were screened for gene RET mutations. Prophylactic total thyroidectomy was performed in every RET mutation gene carriers. RESULTS: In all families the index case were patients with medullary thyroid carcinoma presenting at a mean age of 37.25 years (range 23-42). The RET oncogen mutation was in codon 634 in exon 11 (multiple endocrine neoplasia type 2A) in all these patients. Fourteen gene carriers were identified with a mean age of 20 years (range 7-37), eleven of whom had medullary thyroid carcinoma at the time of surgery. Five of the gene carriers were children, with a mean age of 11 years (range 7-16), four of whom had microcarcinoma and one had metastatic carcinoma at the time of surgery. After surgery no hypoparathyroidism or recurrent nerve paralysis were documented. No pediatric patient has presented with phaeochromocytoma or hypoparathyroidism to date Four of the five children have normal calcitonin levels (< 2 pg/ml) and they are free of disease. The one who presented metastatic carcinoma has recurrent disease and is awaiting surgical treatment. CONCLUSIONS: Genetic studies of family members related to patients with familiar medullary thyroid carcinoma and RET mutations is indispensable. The RET mutation in codon 634 exon 11 was found to be the most frequent association. Prophylactic thyroidectomy is the only curative treatment and has minimal complications when performed by expert surgeons. Early thyroidectomy is recommended since distant metastatic spread can occur at early age.

Inactivation of glycogen synthase kinase-3beta, a downstream target of the raf-1 pathway, is associated with growth suppression in medullary thyroid cancer cells.

Glycogen synthase kinase-3beta (GSK-3beta) is an important regulator of cell proliferation and survival. Conflicting observations have been reported regarding the regulation of GSK-3beta and extracellular signal-regulated kinase (ERK1/2) in cancer cells. In this study, we found that raf-1 activation in human medullary thyroid cancer cells, TT cells, resulted in phosphorylation of GSK-3beta. Inactivation of GSK-3beta in TT cells with well-known GSK-3beta inhibitors such as lithium chloride (LiCl) and SB216763 is associated with both growth suppression and a significant decrease in neuroendocrine markers such as human achaete-scute complex-like 1 and chromogranin A. Growth inhibition by GSK-3beta inactivation was found to be associated with cell cycle arrest due to an increase in the levels of cyclin-dependent kinase inhibitors such as p21, p27, and p15. Additionally, LiCl-treated TT xenograft mice had a significant reduction in tumor volume compared with those treated with control. For the first time, we show that GSK-3beta is a key downstream target of the raf-1 pathway in TT cells. Also, our results show that inactivation of GSK-3beta alone is sufficient to inhibit the growth of TT cells both in vitro and in vivo.

Early malignant progression of hereditary medullary thyroid cancer.

BACKGROUND: An age-related progression from C-cell hyperplasia to medullary thyroid carcinoma is associated with various germ-line mutations in the rearranged during transfection (RET) proto-oncogene that could be used to identify the optimal time for prophylactic surgery. METHODS: In this European multicenter study conducted from July 1993 to February 2001, we enrolled patients who had a RET point mutation in the germ line, were 20 years of age or younger, were asymptomatic, and had undergone total thyroidectomy after confirmation of the RET mutation. Exclusion criteria were medullary thyroid carcinomas of more than 10 mm in greatest dimension and distant metastasis. RESULTS: Altogether, 207 patients from 145 families were identified. There was a significant age-related progression from C-cell hyperplasia to medullary thyroid carcinoma and, ultimately, nodal metastasis in patients whose RET mutations were grouped according to the extracellular- and intracellular-domain codons affected and in those with the codon 634 genotype. No lymph-node metastases were noted in patients younger than 14 years of age. The age-related penetrance was unaffected by the type of amino acid substitution encoded by the various codon 634 mutations. The codon-specific differences in the age at presentation of cancer and the familial rates of concomitant adrenal and parathyroid involvement suggest that the risk of progression was based on the transforming potential of the individual RET mutation. CONCLUSIONS: These data provide initial guidelines for the timing of prophylactic thyroidectomy in asymptomatic carriers of RET gene mutations.

Mutation analysis of the RET proto-oncogene and early thyroidectomy: results of a Portuguese cancer centre.

BACKGROUND: Evidence that germline mutations in the RET proto-oncogene are the underlying cause of the familial form of medullary thyroid carcinoma (MTC) made it possible to identify gene carriers with a very high degree of accuracy. Aiming to define the mutational profile observed in our patients and to assess gene carriers' compliance with an early surgery, we reviewed results of molecular analysis of RET performed at our institution since 1994. METHODS: One hundred fifty-eight individuals were screened for germline mutations of the RET proto-oncogene. Seventy-seven patients had apparently sporadic MTC; 8 patients had both MTC and pheochromocytoma or MTC and clinical features of multiple endocrine neoplasia type 2B despite a negative family history; 8 patients were known to belong to affected kindreds; and 65 individuals were at-risk individuals to develop MTC. RESULTS: A germline mutation in RET was identified in 4% of apparently sporadic MTC patients, in 100% of patients with MTC and pheochromocytoma or MTC and clinical features of multiple endocrine neoplasia type 2B, and in 100% of probands of clinically established kindreds. The most affected codon was 634 (58%) followed by codon 804 (16%). Among at-risk individuals, 49% were identified as gene carriers. Seven individuals were submitted to prophylactic thyroidectomy (mean age, 17.7 +/- 12.5 years; range: 3-42 years), and all but 1 had MTC. CONCLUSIONS: RET mutational spectrum observed in the present population disclosed a higher frequency of codon 804 mutations than expected. Compliance with an early prophylactic surgery seemed to be influenced not only by medical advice and cultural factors but also by the aggressiveness of disease in gene carriers' families.

Video-assisted central compartment lymphadenectomy in a patient with a positive RET oncogene: initial experience.

BACKGROUND: Prophylactic surgery for patients carrying a positive RET proto-oncogene proved to be highly effective in curing those likely to experience the development of a medullary carcinoma. Video-assisted procedures have been proved feasible for central compartment dissection. METHODS: A total of 15 patients (7 men and 8 women) with a positive RET proto-oncogene underwent total thyroidectomy and central compartment lymphadenectomy via a video-assisted approach. The mean age of the patients was 32.5 years. The echographically estimated mean volume was 10.3 ml, and the mean diameter of the main nodule was 8.8 mm. Preoperative ultrasound showed an absence of lateral neck lymph node involvement in all cases. No drain was used. Direct laryngoscopy was performed in all cases 1 month after surgery. RESULTS: The mean operative time was 67.3 min. A transient hypoparathyroidism occurred in one patient, and a permanent hypoparathyroidism occurred in another patient. No laryngeal nerve palsy was present. All the patients were discharged on postoperative day 1. Histology showed a medullary carcinoma in 10 patients and diffuse C-cell hyperplasia in 5 patients. The mean number of lymph nodes removed was 5.1. None of these nodes proved to be metastatic. Calcitonin levels were undetectable in all six patients who had a follow-up period longer than 1 year. CONCLUSION: Video-assisted central compartment lymphadenectomy was proved to be effective and safe. The procedure demonstrated a complication rate comparable with that for the conventional procedure, a better cosmetic outcome, and less postoperative pain. Although the video-assisted access proved to be a valid option for the treatment of patients carrying a positive RET proto-oncogene, a greater number of cases with a longer follow-up period is necessary to estimate the impact of the video-assisted approach on central neck lymphadenectomy.

[Diagnostic value of positron emission tomography/computed tomography with fluorine-18 fluordeoxyglucose in patients with differentiated thyroid gland carcinoma, high thyroglobulin serum levels and negative iodine whole body scan]. / Valor diagnóstico da tomografia por emissão de pósitrons/tomografia computadorizada (PET-CT) com flúor-18 fluordeoxiglicose (FDG-18F) em pacientes com carcinoma diferenciado da tireóide, níveis séricos de tireoglobulina elevados e pesquisa de corpo inteiro com iodo negativa.

PURPOSE: To evaluate the role of PET-CT with FDG-18F in the detection of recurrence and/or metastasis of differentiated thyroid carcinoma (DTC) in patients with elevated levels of thyroglobulin (TG) and negative whole body scan (WBS). PATIENTS AND METHOD: PET-CT findings of 25 patients were compared to histopathology evaluation and conventional imaging (CI). RESULTS: PET-CT scan was positive in 16 patients finding 14 true-positive and 2 false-positive cases (positive predictive value 87.5%). Nine patients had negative PET-CT; two had decrease of TG to undetectable levels. One patient had residual disease detected by post-therapeutic WBS. Six patients had no evidence of tumor during follow-up (mean time 16 months). PET-CT was concordant with CI in 52%, partially concordant in 12% and discordant in 36% (6 false-negatives and 3 false-positive of CI). We observed a tendency of increasing proportion of positive PET-CT with increasing TG. CONCLUSION: PET-CT scan with FDG-18F is useful in the detection of recurrence and/or metastases of DTC with high TG levels but negative WBS. It presents elevated positive predictive value and is superior to CI being more effective as higher the serum TG levels.

Dual inhibition of RET and FGFR4 restrains medullary thyroid cancer cell growth.

Medullary thyroid cancer is frequently an aggressive form of carcinoma for which there are currently no effective forms of systemic therapy. These carcinomas arise as a result of activating mutations in the RET proto-oncogene transmembrane tyrosine kinase receptor. We, therefore, examined the potential efficacy of the tyrosine kinase inhibitor STI571 on the growth of human TT medullary cancer cells in vitro and in xenografted severe combined immunodeficiency mice. Treatment with STI571 resulted in inhibition of RET phosphorylation, cell proliferation, tumor growth and invasiveness. Based on the profile of expression of fibroblast growth factor receptors (FGFR), we examined the effects of FGFR tyrosine kinase inhibition using the small molecule FGFR inhibitor PD173074. This inhibitor resulted in abrogation of fibroblast growth factor-1-mediated FGFR4 phosphorylation in TT cells, an effect that was accompanied by significant arrest of cell proliferation and tumor growth in vivo. Moreover, the combination of STI571 and PD173074 resulted in greater suppression of cell proliferation in vitro and tumor control in vivo than that achieved with either agent alone. These data highlight RET and FGFR4 as therapeutic targets and suggest a potential role for the combined use of tyrosine kinase inhibitors in the management of inoperable medullary thyroid cancers.

[Prophylactic thyroid surgery]. / Prophylaktische Chirurgie der Schilddrüse.

Early diagnosis for thyroid carcinoma, potentially before neoplastic transformation has taken place, would allow preventive and thus curative surgical intervention. Identifying and characterizing the RET proto-oncogene as the disease-causing gene for hereditary medullary thyroid carcinoma and then establishing a genotype-phenotype correlation served as the prerequisite for the risk-adapted prophylactic surgical approach practised today. Carriers of RET mutations associated with very aggressive tumour behaviour should be subjected to prophylactic thyroidectomy within the 1st year of life. For individuals harbouring less virulent types of mutations, prophylactic intervention is recommended at 5-20 years. Although genetic research on hereditary nonmedullary thyroid cancer is still in progress, initial results indicate the need of prophylactic surgical treatment also for this subgroup of thyroid neoplasia.

[Prophylactic thyroidectomy in children who are carriers of a multiple endocrine neoplasia type 2 mutation: description of 20 cases and recommendations based on the literature]. / Profylactische thyreoïdectomie bij kinderen die drager zijn van een mutatie van multipele endocriene neoplasie type 2: beschrijving van 20 casussen en aanbevelingen op grond van de literatuur.

OBJECTIVE: Evaluation of treatment of children who are proven carriers of a multiple endocrine neoplasia type 2 (MEN 2)-associated rearranged during transfection (RET) gene mutation. DESIGN: Retrospective case study and review of the literature. METHOD: Between 1976 and 2005, 6 boys and 14 girls with a proven RET mutation or biochemical indication of MEN 2 had thyroid surgery at the University Medical Center, Groningen, The Netherlands. The median age was 10 years (range: 0-08). Preoperative assessment, surgical procedure, pathological findings, postoperative complications and treatment results were studied and compared with data from the literature. RESULTS: All 20 children underwent total thyroidectomy. In 17 children with preoperatively abnormal basal or stimulated calcitonin levels, total thyroidectomy was combined with tracheo-oesophageal exploration (n = 6) or central compartment dissection (n = 11). C-cell hyperplasia was found in 19 cases (95%) and medullary thyroid carcinoma in 14 (70%; aged 3-18 years). Lymph-node metastases were found in 3 children (15%), all over the age of 10. They underwent additional selective lateral neck dissection, unilateral in 2 cases and bilateral in 1. Two children developed hypoparathyroidism postoperatively, no recurrent laryngeal-nerve palsy was observed. All patients are clinically free of disease after a median follow-up of 9 years (range: 0.6-27). The patients with node metastases still have biochemical evidence of disease. The literature indicates that the progression of the malignant transformation to medullary thyroid carcinoma is connected to the type of RET-mutation. The treatment plan depends on the type of mutation. CONCLUSION: Medullary thyroid cancer occurs at a very young age in carriers ofgermline RET mutations. In patients with high-risk mutations prophylactic thyroidectomy is likely to be recommended before the child reaches the age of 2. Elective central lymph-node dissection can be omitted in this instance. After this age, however, the risk of lymph-node metastases increases and, for cases with increased basal or stimulated calcitonin levels, total thyroidectomy with central compartment dissection is indicated.