Pulmonary Function in Patients With Multiple Endocrine Neoplasia 2B.

CONTEXT: Multiple endocrine neoplasia type 2B (MEN2B) is a rare cancer predisposition syndrome resulting from an autosomal-dominant germline mutation of the RET proto-oncogene. No prior studies have investigated pulmonary function in patients with MEN2B. OBJECTIVE: This study characterized the pulmonary function of patients with MEN2B. DESIGN: This is a retrospective analysis of pulmonary function tests (PFTs) and chest imaging of patients enrolled in the Natural History Study of Children and Adults with MEN2A or MEN2B at the National Institutes of Health. RESULTS: Thirty-six patients with MEN2B (18 males, 18 females) were selected based on the availability of PFTs; 27 patients underwent at least 2 PFTs and imaging studies. Diffusion abnormalities were observed in 94% (33/35) of the patients, with 63% (22/35) having moderate to severe defects. A declining trend in diffusion capacity was seen over time, with an estimated slope of -2.9% per year (P = 0.0001). Restrictive and obstructive abnormalities were observed in 57% (20/35) and 39% (14/36), respectively. Computed tomography imaging revealed pulmonary thin-walled cavities (lung cysts) in 28% (9/32) of patients and metastatic lung disease in 34% (11/32) of patients; patients with metastatic lung lesions also tended to have thin-walled cavities (P = 0.035). CONCLUSIONS: This study characterized pulmonary function within a MEN2B cohort. Diffusion, restrictive, and obstructive abnormalities were evident, and lung cysts were present in 28% of patients. Further research is required to determine the mechanism of the atypical pulmonary features observed in this cohort.

Hypervascularity is more frequent in medullary thyroid carcinoma: Compared with papillary thyroid carcinoma.

This study was designed to retrospectively compare the sonographic features of medullary thyroid carcinoma (MTC) and the features of papillary thyroid carcinoma (PTC).A total of 97 patients with 127 MTCs between January 2000 and January 2016 and 107 consecutive patients with 132 PTCs were included in this study. Two radiologists retrospectively determined the sonographic features and compared the findings of MTCs and PTCs.Compared with the patients with PTCs, the patients with MTCs were older (46.9 years vs 42.9 years, P = 0.016) and the male proportion was higher (53.6% vs 33.6%, P = 0.005). Most of the MTCs had an irregular shape (72.4%), a length/width ratio <1 (75.6%), an unclear boundary (63.8%), no peripheral halo ring (93.7%), hypoechogenicity (96.9%), heterogeneous echotexture (76.4%), no cystic change (78.7%), calcification (63.8%), and hypervascularity (72.4%). There was no significant difference in the boundary, peripheral halo ring, echogenicity, and calcification between the MTCs and PTCs. However, compared with the PTCs, a larger size (2.2 vs 1.2 cm, P <0.001), a regular shape (27.6% vs 7.6%, P <0.001), a length/width ratio <1 (75.6% vs 51.5%, P<0.001), heterogeneous echotexture (76.4% vs 54.5%, P <0.001), cystic change (21.3 vs 8.3%, P = 0.005), and hypervascularity (72.4% vs 47.7%, P <0.001) were more frequent in the MTCs.The sonographic features with a higher likelihood of malignancy are common in MTCs, including a shape taller than the width, irregular infiltrative margins, an absent halo, hypoechogenicity, the presence of microcalcifications, and increased intranodular vascularity. However, MTCs tend to possess these suspicious sonographic features less often than PTCs, with the exception of hypervascularity, which was more frequent in MTCs.

Molecular mechanisms of RET receptor-mediated oncogenesis in multiple endocrine neoplasia 2.

Multiple endocrine neoplasia type 2 is an inherited cancer syndrome characterized by tumors of thyroid and adrenal tissues. Germline mutations of the REarranged during Transfection (RET) proto-oncogene, leading to its unregulated activation, are the underlying cause of this disease. Multiple endocrine neoplasia type 2 has been a model in clinical cancer genetics, demonstrating how knowledge of the genetic basis can shape the diagnosis and treatment of the disease. Here, we discuss the nature and effects of the most common recurrent mutations of RET found in multiple endocrine neoplasia type 2. Current understanding of the molecular mechanisms of RET mutations and how they alter the structure and function of the RET protein leading to its aberrant activation, and the effects on RET localization and signaling are described.

Molecular mechanisms of RET receptor-mediated oncogenesis in multiple endocrine neoplasia 2

Multiple endocrine neoplasia type 2 is an inherited cancer syndrome characterized by tumors of thyroid and adrenal tissues. Germline mutations of the REarranged during Transfection (RET) proto-oncogene, leading to its unregulated activation, are the underlying cause of this disease. Multiple endocrine neoplasia type 2 has been a model in clinical cancer genetics, demonstrating how knowledge of the genetic basis can shape the diagnosis and treatment of the disease. Here, we discuss the nature and effects of the most common recurrent mutations of RET found in multiple endocrine neoplasia type 2. Current understanding of the molecular mechanisms of RET mutations and how they alter the structure and function of the RET protein leading to its aberrant activation, and the effects on RET localization and signaling are described.

Pheochromocytoma and medullary thyroid carcinoma in a pregnant multiple endocrine neoplasia-2A patient.

OBJECTIVE: We describe a rare combination of pheochromocytoma and medullary thyroid carcinoma (MTC) during pregnancy. METHODS: Twenty-three-years old lady, primigravida, was detected to be hypertensive at 12 weeks of gestation and was found to have left adrenal mass on routine obstetric scan. She had a goitre on examination which was proven to be MTC on fine needle aspiration cytology. Twenty-four hours urinary vanillyl mandelic acid and serum calcitonin levels were elevated. After adequate α and ß blockade she underwent left adrenalectomy during second trimester of gestation with no significant perioperative complications. Twelve days later she underwent total thyroidectomy. RESULTS: Adrenal mass was confirmed to be pheochromocytoma while MTC was confirmed in the thyroidectomy specimen. Post-operatively, she was normotensive and delivered a healthy female baby at term. Both mother and the baby tested positive for germline RET mutation (C634W) in exon 11. CONCLUSION: We describe a rare case of pregnant multiple endocrine neoplasia-2A patient with pheochromocytoma and MTC.

XL-184, a MET, VEGFR-2 and RET kinase inhibitor for the treatment of thyroid cancer, glioblastoma multiforme and NSCLC.

XL-184 (BMS-907351), under development by Exelixis Inc and Bristol-Myers Squibb Co, is a pan-tyrosine kinase inhibitor for the potential oral treatment of medullary thyroid cancer, glioblastoma multiforme and NSCLC. The prinicipal targets of XL-184 are MET, VEGFR-2 and RET, but the drug is also reported to display inhibitory activity against KIT, FLT3 and TEK. Preclinical studies demonstrated that XL-184 potently inhibited multiple receptor tyrosine kinases in various cancer cell lines and animal xenograft models, and that the drug exhibited significant oral bioavailability and blood-brain barrier penetration. A phase I clinical trial in patients with advanced solid malignancies indicated that XL-184 accumulated dose-dependently in the plasma and had a long terminal half-life. A phase II trial in patients with progressive or recurrent glioblastoma revealed modest but promising median progression-free survival. Toxicity and side effects for the drug have generally been of low-to-moderate severity. At the time of publication, three additional trials of XL-184 were recruiting patients, including a phase I trial in combination with standard of care in patients with glioblastoma, a phase I/II trial in combination with erlotinib in patients with NSCLC, and a phase III trial in patients with medullary thyroid cancer.

Beyond RET: potential therapeutic approaches for advanced and metastatic medullary thyroid carcinoma.

Medullary thyroid carcinoma (MTC) is a rare calcitonin-producing neuroendocrine tumour that originates from the parafollicular C-cells of the thyroid gland. The RET proto-oncogene encodes the RET receptor tyrosine kinase, which has essential roles in cell survival, differentiation and proliferation. Activating mutations of RET are associated with the pathogenesis of MTC and have been demonstrated in nearly all hereditary and in 30-50% of sporadic MTC cases, making this receptor an excellent target for small-molecule inhibitors for this tumour. Clinical trials of small organic inhibitors of tyrosine kinase receptors (TKIs) targeting the RET receptor have shown efficacy for treatment of metastatic MTC with 30-50% of patients responding to these agents. Despite the importance of the RET receptor in MTC, it is clear that other signal transduction pathways, tyrosine kinase receptors, and tumour suppressor genes are involved in MTC tumourigenesis and progression. A better understanding of molecular cross-talk between these signal pathways and the RET receptor may lead to combinatorial therapy that will improve outcomes beyond what is currently possible with RET-directed TKIs. Finally, there is evidence that immunological-based therapy using dendritic cell vaccination strategies have been effective for reducing tumour mass in a small number of patients. The identification of additional MTC-specific tumour antigens and a better understanding of specific epitopes in these tumour antigens may lead to improvement of response rates.

Regulation of cell-cell contact molecules and the metastatic phenotype of medullary thyroid carcinoma by the Raf-1/MEK/ERK pathway.

BACKGROUND: Medullary thyroid carcinoma (MTC) is highly metastatic. We have recently reported that activation of the Raf-1/MEK/ERK signaling pathway in MTC cells results in morphologic changes. We hypothesized that Raf-1-induced morphologic changes could be associated with alterations in cell-cell contact molecules, thereby affecting the metastatic potential of MTC cells. METHODS: An estradiol (E(2))-inducible Raf-1 MTC cell line (TT-raf) was utilized in this study. Western blot analysis was used to confirm the Raf-1/MEK/ERK pathway activation and to measure levels of essential cell-cell contact molecules. Assays for cell adhesion and migration were performed to investigate the cell motility. RESULTS: E(2) treatment of TT-raf cells resulted in the Raf-1/MEK/ERK pathway activation as evidenced by increased levels of phospho-MEK1/2 and -ERK1/2. This resulted in significant reductions in levels of essential cell-cell contact molecules including E-cadherin, beta-catenin, and occludin. Importantly, activation of the Raf-1/ MEK/ERK pathway and the associated decrease in essential cell-cell contact molecules dramatically inhibited the abilities of adhesion and migration in MTC cells. Furthermore, treatment of Raf-1-activated cells with U0126, a specific inhibitor of MEK, abrogated these Raf-1-induced effects indicating that the suppression of the metastatic phenotype in MTC cells is a MEK-dependent pathway. CONCLUSION: These data suggest that the Raf-1/MEK/ERK pathway regulates essential cell-cell contact molecules and metastatic phenotype of MTC cells. Thus, these findings provide further insight into the key steps in the metastatic progression of MTC.

Carcinoma medular da mama: correlação anátomo-radiológica / Medullary breast carcinoma: anatomo-radiological correlation", "_i": "en

OBJETIVO: Avaliar as características radiológicas do câncer de mama medular em pacientes submetidas atratamento cirúrgico no Instituto Nacional de Câncer (INCA) û Ministério da Saúde, Rio de Janeiro, RJ, correlacionando os achados com estudo histopatológico. MATERIAIS E MÉTODOS: Foi realizado estudo descritivo retrospectivo de mulheres submetidas a tratamento cirúrgico no INCA, no período de janeiro de 1997 adezembro de 2006, para identificação das pacientes com carcinoma medular e análise dos achados radiológicos.RESULTADOS: Foram identificadas 21.287 pacientes com diagnóstico de carcinoma neste período, sendo 76 pacientes com diagnóstico de carcinoma medular típico (0,357%). Nessas pacientes selecionadas, a idade média foi de 51,9 anos (32 a 81 anos). Dezenove pacientes apresentavam lesão na mamografia, sendo 17 (89,5%) nódulos e 2 assimetrias focais (10,5%). Entre as pacientes com nódulo, 15 (88,1%) apresentavam alta densidade e 2 eram isodensos (11,9%). Doze pacientes apresentavam achados ultra-sonográficos e, destas, 11 (91,6%) apresentavam nódulos hipoecóicos. Foi observada uma paciente com nóduloanecóico com áreas de degeneração cística. CONCLUSÃO: O nódulo foi o achado radiológico dominante (89,5%), dos quais 88,1% apresentaram nódulos com alta densidade e margens circunscritas. Apesar das características radiológicas de benignidade, um nódulo com alta densidade, sólido, margens circunscritas e crescimento rápido deve ser investigado para confirmar o diagnóstico.

OBJECTIVE: To evaluate radiological findings in patients submitted to surgical treatment for medullary breast cancer at Instituto Nacional de Câncer (INCA), Rio de Janeiro, RJ, Brazil, correlating them with histological results. MATERIALS AND METHODS: A retrospective descriptive study was developed with patients submitted to surgery at INCA, in the period from January 1997 to December 2006, for identifying the presence of medullary breast carcinoma and analyzing radiological findings. RESULTS: Among 21,287 patients diagnosed with carcinoma, 76 (0.357%) had typical medullary breast carcinoma. The age range of these patients was 32û81 years (mean = 59.1 years). Mammography demonstrated lesions in 19 of these patients, 17 (89.5%) of them with masses, and 2 with focal asymmetry. Among the patients with masses, 15 (88.1%) presented with high density and 2 (11.9%) with isodensity. Twelve patients presented sonographic findings, 11 (91.6%) of them with hypoechoic masses, and one with an anechoic mass with areas of cystic degeneration. CONCLUSION: Nodular mass was the predominant radiological finding (89.5%), 88.1% of them corresponding to masses with high density and circumscribed margins. Despite the radiological characteristics of benignity, a solid, fastgrowing, highly dense mass with circumscribed margins should be further investigated to confirm the diagnosis.

Valproic acid activates Notch1 signaling and induces apoptosis in medullary thyroid cancer cells.

OBJECTIVE: To examine the effects of valproic acid (VPA) on Notch1 expression and cancer cell proliferation in medullary thyroid cancer (MTC) cells. BACKGROUND: Other than surgery, there are no effective treatments for MTC, a neuroendocrine malignancy that frequently metastasizes. We have previously shown that over-expression of Notch1 in MTC cells inhibits cell growth and hormone production. VPA, a drug long used for the treatment of epilepsy, has recently been identified as a potential Notch1 activator. We hypothesized that VPA might activate Notch1 signaling in MTC cells, with antiproliferative effects. METHODS: Human MTC cells were treated with VPA (0-5 mM) and Western blotting was performed to measure levels of Notch1 pathway proteins and neuroendocrine tumor markers. After confirming that VPA is a Notch1 activator in MTC cells, we performed cell proliferation assay. Finally, to determine the mechanism of growth inhibition, we measured protein levels of various markers of apoptosis. RESULTS: Notch1 was absent in MTC cells at baseline. VPA treatment resulted in an increase in both full-length and active Notch1 protein. Notch1 activation with VPA suppressed 2 neuroendocrine tumor markers, ASCL1 and chromogranin A. Importantly, VPA inhibited the growth of MTC cells in a dose-dependent manner. Immunoblot analysis demonstrated caspase activation and poly(ADP-ribose) polymerase cleavage, indicating the induction of apoptosis. CONCLUSIONS: VPA activates Notch1 signaling in MTC cells and inhibits their growth by inducing apoptosis. As the safety of VPA in human beings is well established, a clinical trial using this drug to treat patients with advanced MTC could be initiated in the near future.

¿Es imprescindible la tiroidectomía profiláctica inmediata en el carcinoma medular de tiroides familiar? / Is immediate prophylactic thyroidectomy indispensable in familiar medullaty thyroid carcinoma?

Objetivo. Demostrar la importancia de la realización de estudios genéticos a familiares y de la tiroidectomía profiláctica precoz en el manejo del carcinoma medular de tiroides familiar. Material y métodos. Estudio retrospectivo y realización de árboles genealógicos de las familias afectadas de carcinoma medular de tiroides familiar tratadas en nuestro hospital en los últimos años. Estudiamos un total de 7 familias con antecedentes de patología tiroidea maligna sin filiar realizando la detección de la mutación del gen RET en un total de 40 familiares. Se realizó una tiroidectomía total con resección de la cápsula posterior asociada a resección radical modificada de las cadenas ganglionares adyacentes de manera profiláctica en todos los casos en los que se halló la mutación del gen RET Resultados. En todas las familias el caso índice es un paciente con carcinoma medular de tiroides de edad media 37,25 años (rango 23-42).En todos ellos se halló una mutación de exón 11, codón 634 del oncogén RET (MEN 2 A).La mutación del gen fue positiva en 14 de los familiares estudiados, con una edad media de 20 años (rango 7-37). 11 de ellos presentaron ya carcinoma medular de tiroides en el análisis patológico de la pieza quirúrgica. Cinco de los familiares con la mutación positiva eran niños, con una edad media de 11 años (rango7-16), 4 de ellos presentaron áreas demicrocarcinoma en la pieza quirúrgica de la tiroidectomía profilácticay el otro un carcinoma manifiesto con metástasis a distancia. Tras la intervención no se hallaron lesiones del nervio recurrenteni hipoparatiroidismo. Ningún paciente de edad pediátrica asoció feocromocitomaso hiperparatiroidismo hasta el momento. Los niveles de calcitonina permanecen indetectables (<2 pg/ml) en los4 primeros niños, que se encuentran libres de enfermedad. La paciente que presentaba carcinoma medular avanzado se encuentra viva, aunque pendiente de una segunda intervención por persistencia de la enfermedad. Conclusiones. Es imprescindible el estudio genético de los familiares de pacientes con carcinoma medular de tiroides y mutaciones del oncogén RET. La mutación más frecuentemente encontrada se halla en el exón 11,codón 634.La tiroidectomía profiláctica es el único tratamiento curativo y presenta escasas complicaciones en manos de un equipo quirúrgico experto. Dicha tiroidectomía debe realizarse de forma precoz debido a la presencia de lesiones malignas, incluso a edades muy tempranas (AU)

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 hypoparathiroidism or recurrent nerve paralysis were documented. No pediatric patient has presented with phaeochromocytoma or hypoparathiroidism 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 (AU)

Suberoyl bis-hydroxamic acid activates Notch-1 signaling and induces apoptosis in medullary thyroid carcinoma cells.

Medullary thyroid carcinoma (MTC) is a neuroendocrine (NE) malignancy that frequently metastasizes and has limited treatments. We recently reported that ectopic expression of Notch-1 in human MTC cells suppresses growth. The objective of this study was to evaluate the ability of suberoyl bis-hydroxamic acid (SBHA) to modulate Notch-1 signaling in MTC cells. At baseline, no active Notch-1 protein was present in MTC cells. Treatment with SBHA resulted in a dose-dependent induction of the Notch-1 intracellular domain, the active form of the protein. Furthermore, with Notch-1 activation there was a concomitant decrease in achaete-scute complex-like 1 (ASCL-1), a downstream target of Notch-1 signaling, as well as the NE tumor marker chromogranin A (CgA). Transfection of Notch-1 small-interfering RNA into MTC cells blocked the effects of SBHA on Notch-1 activation, ASCL-1, and CgA. Importantly, SBHA treatment resulted in a dose-dependent decrease in cell viability. Treated cells had an increase in protein levels of cleaved caspase-3 and poly ADP-ribose polymerase, and changes in the expression of apoptotic mediators including Bcl-X(L) and Bad, indicating that the growth inhibition was a result of apoptosis. These results demonstrate that SBHA activates Notch-1 signaling, which is associated with the antiproliferative and apoptotic effects in MTC cells. Therefore, Notch-1 activation with SBHA is an attractive new strategy for the treatment of patients with MTC.

Expression and role of estrogen receptor alpha and beta in medullary thyroid carcinoma: different roles in cancer growth and apoptosis.

Medullary thyroid carcinoma (MTC) originates from parafollicular C cells. Estrogen receptor beta(ERbeta) expressionwas detected in normal parafollicular C cells and MTC tumor tissue, but ERalpha expression in MTC tumors still remains undetermined. The appearance and loss of ERalpha or ERbeta expression has been known to play a role in the development and progression of many human cancers. We performed immunohistochemical studies of ERalpha, ERbeta, and Ki67, a mitotic index, in 11 human MTC tissue samples. ERalpha was detected in 10 cases (91%), and ERbeta expression was observed in 8 cases (72.7%). A majority (8/10) of ERalpha-positive tumors showing ERbeta Ki67 expression was detected in three cases (27.3%). Neither clinical parameters nor tumor node metastasis (TNM) tumor staging was correlated with the positivity for ERs or Ki67. To investigate the biological role of each ER, we used ER-negative MTC TT cells and adenoviral vectors carrying ERalpha (Ad-ERalpha), ERbeta (Ad-ERbeta), estrogen response element (ERE)-Luc (Ad-ERE-Luc), and activator protein 1 (AP1)-Luc (Ad-AP1-Luc). Estrogen stimulated and anti-estrogen, ICI 182 780, suppressed ERE reporter activity in TT cells expressing ERalpha or ERbeta, suggesting that both ERs use the same classical ERE-mediated pathway. Ad-ERalpha infection stimulated TT cell growth; in contrast, Ad-ERbeta infection suppressed their growth. Apoptosis was detected in Ad-ERbeta-infected TT cells. Estrogen and anti-estrogen suppressed AP1 activity in Ad-ERalpha-infected cells, whereas upon Ad-ERbeta infection estrogen further stimulated AP1 activity which in turn is suppressed by anti-estrogen, suggesting that each ER acts differently through a non-ERE-mediated pathway. Our results suggest that ERalpha and ERbeta may play different roles in MTC tumor growth and progression.

Simultaneous occurrence of medullary carcinoma and papillary microcarcinoma of thyroid in a patient with MEN 2A syndrome. report of a case.

We report a case of simultaneous multifocal medullary carcinoma and papillary microcarcinoma in a patient with several distinctive features of MEN 2A. The patient underwent total thyroidectomy and central lymph node dissection. The extreme rarity and pathological features of this occurrence are discussed. There is no known common cause of these 2 different tumor types; it may be a stochastic exception. However, several other possibilities such as a common precursor cell or a common tumorigenic stimulus offer interesting perspectives for speculation.

Mechanisms of Disease: cancer targeting and the impact of oncogenic RET for medullary thyroid carcinoma therapy.

Growing evidence supports the concept of oncogene dependence for cancer development; inhibition of the initiating oncogene can result in revertion of the neoplastic phenotype. The outstanding role of the RET proto-oncogene in the development of medullary thyroid carcinoma (MTC) is well established. With the emerging knowledge concerning the signal transduction pathways leading to subsequent neoplastic transformation, oncogenic activated RET becomes a highly attractive target for selective cancer therapy. A variety of novel approaches that target RET directly or indirectly have recently emerged and an increasing number are currently being assessed in clinical trials. In view of these findings, it becomes strikingly obvious that inhibition of RET oncogene function can be a viable option for the treatment of MTC. We summarize the current evidence for RET involvement in the etiology of MTC, and the therapeutic targeting of this process in preclinical and clinical studies.

Isthmus-preserving total bilobectomy: an adequate operation for C-cell hyperplasia.

BACKGROUND: Autopsy studies show that C cells deriving from the ultimobranchial body and migrating into the thyroid do not reach the isthmus region and are distributed along the vertical axes of thyroid lobes. This was confirmed in a surgical series of 58 patients (34 with preoperatively normal and 24 with elevated serum calcitonin) where no calcitonin-positive cells were demonstrable immunohistochemically within separately investigated isthmi. Consequently, isthmus-preserving total bilateral lobectomy (IPTB) may be regarded as an adequate surgical procedure for C-cell hyperplasia (CCH). PATIENTS AND METHODS: IPTB was performed from October 2001 to December 2004 in 64 patients, 59 patients with nodular goiter and slightly to moderately elevated serum calcitonin (stimulated under 500 pg/ml) (group A, apparently sporadic cases) and in 5 patients undergoing prophylactic surgery for hereditary medullary thyroid carcinoma (MTC) with intermediate- or low-risk RET mutations (non-634) (group B). The surgical procedure focused on meticulous total extracapsular resection of both thyroid lobes, preservation of an isthmus remnant of about 3 ml (smaller in children), and histologic workup of the border zones of resection in addition to that of the completely removed lobes. When malignancy could be proven intraoperatively (7 patients) or when the isthmus turned out to contain nodular lesions (4 patients), completion total thyroidectomy (plus lymphadenectomy) was performed as a one-stage procedure. Second-stage total thyroidectomy was performed in 3 cases. Thus, IPTB was the definitive surgical procedure in 50 patients (45 of group A and all 5 of group B). RESULTS: In all of the 50 definite IPTB cases, postoperative serum calcitonin was below the measurable limit (2 pg/ml); stimulated calcitonin was below the measurable limit in 47 (including all of group B) and was measurable in 3 sporadic cases in a lower-normal range between 2.4 and 3.5 pg/ml. Genetic screening of the apparently sporadic cases with CCH was positive in one (codon 791). The risk of recurrent laryngeal nerve paralysis seems not to be elevated (0% permanent); permanent hypocalcemia occurred in 1 patient (2%). Follow-up data of 37 patients, median 18 (6-36) months, showed continuously nonmeasurable serum calcitonin with one exception, where it was in the normal range after 18 months. All IPTB patients are still under substitution therapy with L-thyroxine (median 125 mug/day) with decreasing tendency in all 3 children after prophylactic operation, the latter also showing an increasing volume of well-vascularized isthmi (from 1.5 to 2.5 ml). CONCLUSION: IPTB reliably removes all C cells. There may not be need for total thyroidectomy (TTx) in cases with CCH. When necessary, completion TTx can be performed easily without additional risk. IPTB leaves a functionally relevant remnant, corresponding to that of a subtotal resection. This might be of importance especially for prophylactic surgery in children where the isthmus can compensate for the loss of thyroid function with time.

Somatic VHL gene alterations in MEN2-associated medullary thyroid carcinoma.

BACKGROUND: Germline mutations in RET are responsible for multiple endocrine neoplasia type 2 (MEN2), an autosomal dominantly inherited cancer syndrome that is characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, and parathyroid hyperplasia/adenoma. Recent studies suggest a "second hit" mechanism resulting in amplification of mutant RET. Somatic VHL gene alterations are implicated in the pathogenesis of MEN2 pheochromocytomas. We hypothesized that somatic VHL gene alterations are also important in the pathogenesis of MEN2-associated MTC. METHODS: We analyzed 6 MTCs and 1 C-cell hyperplasia (CCH) specimen from 7 patients with MEN2A and RET germline mutations in codons 609, 618, 620, or 634, using microdissection, microsatellite analysis, phosphorimage densitometry, and VHL mutation analysis. RESULTS: First, we searched for allelic imbalance between mutant and wild-type RET by using the polymorphic markers D10S677, D10S1239, and RET on thyroid tissue from these patients. Evidence for RET amplification by this technique could be demonstrated in 3 of 6 MTCs. We then performed LOH analysis using D3S1038 and D3S1110 which map to the VHL gene locus at 3p25/26. VHL gene deletion was present in 3 MTCs. These 3 MTCs also had an allelic imbalance between mutant and wild-type RET. Mutation analysis of the VHL gene showed a somatic frameshift mutation in 1 MTC that also demonstrated LOH at 3p25/26. In the 2 other MTCs with allelic imbalance of RET and somatic VHL gene deletion, no somatic VHL mutation could be detected. The CCH specimen did neither reveal RET imbalance nor somatic VHL gene alterations. CONCLUSION: These data suggest that a RET germline mutation is necessary for development of CCH, that allelic imbalance between mutant and wild-type RET may set off tumorigenesis, and that somatic VHL gene alterations may not play a major role in tumorigenesis of MEN2A-associated MTC.