Medullary thyroid carcinoma

Medullary thyroid carcinoma with micronodular lung metastases: a case report with an emphasis on the imaging findings

Medullary thyroid carcinoma is a rare malignancy that arises from calcitonin-producing C-cells and frequently metastasizes to lymph nodes in the neck. Distant metastases may involve bone, lung, and liver. The infrequent number of cases limits the clinical nature and ability to optimize diagnostic tools. Here, we present a case of a micronodular radiographic pattern in metastatic medullary thyroid cancer in order to enhance awareness of the disease process. A case discussion and relevant review of the literature are provided.

Percutaneous vertebroplasty for thyroid cancer metastases to the spine

BACKGROUND

Spinal metastases secondary to thyroid cancer of follicular and parafollicular cell origin are uncommon but may require stabilization of the compromised vertebrae to prevent fracture with spinal cord injury. Such treatment may also relieve pain and improve survival and quality of life.

SUMMARY

Percutaneous vertebroplasty (PV) is a minimally invasive, radiologically guided procedure whereby bone cement is injected into a structurally weakened vertebra to provide immediate stability. The authors present two cases of thyroid cancer with spinal metastases. Both patients successfully underwent PV. Following PV, the patients experienced significant pain relief with immediate reduction in analgesic requirements and improvement in other symptoms. Both were able to return to their daily activities.

CONCLUSION

PV is a minimally invasive spinal procedure and should be considered for patients with metastatic thyroid cancer with spinal metastases.

The rapamycin-derivative RAD001 (everolimus) inhibits cell viability and interacts with the Akt-mTOR-p70S6K pathway in human medullary thyroid carcinoma cells

Over-expression of the proto-oncogene Akt/PKB has been demonstrated in some neuroendocrine tumor models. Akt may activate downstream proteins such as mTOR and p70S6K, inducing tumor proliferation. The rapamycin-derivative RAD001, everolimus, interacts with this pathway by antagonizing mTOR, but its effects on neuroendocrine tumors are largely unknown. We explored the mechanism of action of RAD001 on cell proliferation, hormonal secretion and on Akt/mTOR/p70S6K pathway activation, in a human medullary thyroid carcinoma (MTC) cell-line (TT) and in cells derived from human MTCs. Treatment with RAD001 significantly inhibited cell viability in a dose- and time-dependent fashion, and diminished phosphorylation of Akt downstream targets, mTOR and p70S6K, in both TT cell-line and cultured human MTCs. Akt phosphorylation was not affected by RAD001. RAD001 induced cell-cycle arrest in the G(0)/G(1) phase in TT cells, but had no effect on apoptosis. Moreover, RAD001 did not affect calcitonin and carcinoembryonic antigen secretion in TT cells and in human MTCs. RAD001 seems to have potent anti-proliferative effect in human MTC cells, which suggest that clinical trials of this agent are of considerable interest.

Nodular disease and parafollicular C-cell distribution: results from a prospective and retrospective clinico-pathological study on the thyroid isthmus

OBJECTIVE

The isthmus represents a peculiar, as yet partially unexplored, thyroid gland area.

AIM OF THE STUDY

To assess i) the prevalence and clinico-pathological features of solitary thyroid isthmic nodules (STIN); ii) the frequency of medullary thyroid carcinoma (MTC) arising from the isthmus; and iii) the C-cell distribution in the isthmus of patients with MTC and benign nodular thyroid disease (NTD).

SUBJECTS AND METHODS

Patients referred from 2006 to 2008 for STIN were prospectively recruited, and underwent serum calcitonin (C(t)) measurement and fine needle aspiration cytology (FNAC). MTCs diagnosed from 1993 to 2005 were retrospectively searched. Immunohistochemistry was performed using anti-C(t) antibodies on lateral lobes and isthmi of 50 benign NTD and 50 MTC cases.

RESULTS

From 1993 to 2005, 150 patients underwent surgery for MTC. All patients had the neoplasm located in lateral thyroid lobes, none in the isthmus. In the 3 years following, 192 STIN patients (40 (21%) males, 152 (79%) females; mean age: 46.2+/-7.1 years; 6.4% of NTD subjects) were recruited. All had normal C(t) concentrations. FNAC was malignant or suspicious for malignancy in 14 (7.3%) patients. Histology found malignancy in 17 (9%) cases, MTC in none. C cells were disclosed in lateral thyroid lobes of 100% MTC and 77% benign NTD patients; isthmi were free of C cells in either group.

CONCLUSIONS

STINs are significantly less likely to be MTC in patients presenting with sporadic disease. Therefore, C(t) screening is not warranted in these subjects. Nonetheless, STINs are more likely to be neoplastic and deserve equal attention as those of the lateral lobes.

Medullary thyroid cancer: RET testing of an archival material

Medullary thyroid carcinoma (MTC) might be sporadic (75%) or hereditary (25%). Until the mid nineties the diagnosis of hereditary MTC was based on family history, clinical evaluation, histological detection of C-cell hyperplasia and tumor multifocality. Patients and families with hereditary MTC might be missed? Today mutation analysis of the RET proto-oncogene is routinely performed on DNA. Departments of pathology often store tissue specimens from performed surgical procedures. The purpose of this study was to examine if analysis of DNA extracted from formalin fixed archival tissue might be a possible method to identify not previously known cases of hereditary MTC. In 23 cases, tissue analysis was performed, and in 2 patients (9%) a mutation was identified, but in both cases the most likely explanation was contamination with tumor tissue. The ability to detect RET mutations was confirmed by testing of non-tumor tissue from patients with known hereditary MTC. This study shows that genetic testing of archival MTC material is technically possible and might be a way of identifying patients with previously not recognized hereditary MTC.

Mutational spectrum of multiple endocrine neoplasia type 2 and sporadic medullary thyroid carcinoma in taiwan

BACKGROUND/PURPOSE

Multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominant cancer predisposition syndrome, and > 95% of MEN 2 patients carry rearranged during transfection (RET) protooncogene mutants. We aimed to elucidate the genotype and phenotype relationship of RET proto-oncogene mutations in Taiwanese subjects with medullary thyroid cancer (MTC).

METHODS

We genotyped the MEN-2-associated germ-line mutations by PCR-based sequencing of the RET gene. DNA was extracted from a total of 69 members from eight unrelated families with individuals affected by MTC, and from seven sporadic cases of MTC.

RESULTS

RET mutations were found in four MEN 2A families, all at codon 634 (one with C>R, two with C>F, and one with C>W). One MEN 2A patient carried a de novo mutation at codon 634 (C>R). In two families of MEN 2B, all carried the mutation at codon 918 (M>T). These two cases of MEN 2B were all de novo mutations. One family of familial MTC or unclassified MEN 2 carried the codon 620 (C>F) mutation. Among the seven sporadic cases of MTC, none was found to carry any mutation in hotspot exons. Only two non-synonymous variants (T278N/exon 4 and D489N/exon 7) were found in two cases. However, these two variants were not uncommon in our elderly population.

CONCLUSION

We found that all eight MTC patients with a family history or with the other phenotypes of MEN 2 had RET mutations, whereas no significant RET mutation was found in seven patients with isolated MTC without family history and other endocrine diseases. Molecular scanning of the RET gene in MEN 2 and MTC in Taiwanese patients probably should be limited to exons 10, 11 and 16, initially to be cost-effective.

F-18 FDG PET detection of a medullary thyroid carcinoma in a patient with metastatic colonic cancer; literature review

OBJECTIVE

We report a case of a medullary thyroid carcinoma discovered by F-18 fluorodeoxyglucose-positron emission tomography (F-18 FDG PET).

PATIENT AND METHODS

A 73-year-old man with a history of surgical removal of sigmoid colon cancer underwent F-18 FDG PET to search for distant metastases and / or local recurrence because of elevated CEA level and new episode of occlusion. F-18 FDG PET images showed increased focal FDG uptake in the right lobe of the thyroid. Thyroid ultrasound showed one thyroid nodule in each lobe.

RESULTS

The fine needle aspiration result was suspicious and calcitonin level was elevated. The subject underwent thyroidectomy without lymph node dissection. The pathology showed a 14 mm medullary thyroid carcinoma. There was no germline mutation of RET.

CONCLUSIONS

F-18 FDG PET can detect primitive or secondary malignant thyroid tumors. Thus, thyroid incidentaloma revealed by 18 FDG PET uptake always necessitates careful evaluation.

Phase II study of safety and efficacy of motesanib in patients with progressive or symptomatic, advanced or metastatic medullary thyroid cancer

PURPOSE

This phase II study investigated the efficacy and tolerability of motesanib, an investigational, highly selective inhibitor of vascular endothelial growth factor receptors 1, 2, and 3; platelet-derived growth factor receptor; and Kit in advanced medullary thyroid cancer (MTC).

PATIENTS AND METHODS

Patients with locally advanced or metastatic, progressive or symptomatic MTC received motesanib 125 mg/d orally for up to 48 weeks or until unacceptable toxicity or disease progression. The primary end point was objective response by independent review. Other end points included duration of response, progression-free survival, safety, pharmacokinetics, and changes in tumor markers.

RESULTS

Of 91 enrolled patients who received motesanib, two (2%) achieved objective response (95% CI, 0.3% to 7.7%); their duration of response was 32 weeks (censored) and 21 weeks (disease progressed). Eighty-one percent of patients had stable disease (48% had durable stable disease > or = 24 weeks), 8% had disease progression as best response, and 9% were not evaluated; 76% experienced a decrease from baseline in target lesion measurement. Median progression-free survival was 48 weeks (95% CI, 43 to 56 weeks). Among patients with tumor marker analysis, 69 (83%) of 83 and 63 (75%) of 84 had decreased serum calcitonin and carcinoembryonic antigen during treatment, respectively, compared with baseline. The most common treatment-related adverse events were diarrhea (41%), fatigue (41%), hypothyroidism (29%), hypertension (27%), and anorexia (27%). In pharmacokinetic analyses, motesanib trough concentrations were lower compared with differentiated thyroid cancer patients from the same study.

CONCLUSION

Although the objective response rate was low, a significant proportion of MTC patients (81%) achieved stable disease while receiving motesanib.

Potency and tolerance of calcitonin stimulation with high-dose calcium versus pentagastrin in normal adults

OBJECTIVE

The objectives of the study was to compare pentagastrin- and calcium-stimulated serum human calcitonin (hCT) levels for nonsmoking healthy adults without evidence of thyroid disorders and determine reference ranges of basal and pentagastrin- and calcium-stimulated serum hCT levels.

DESIGN

This was a healthy volunteer study including within-group and intergroup comparisons.

SETTING

The study was conducted at a tertiary referral center.

SUBJECTS

Subjects included 50 healthy, nonsmoking volunteers (25 female; aged 22-57 yr) without evidence of thyroid abnormality.

INTERVENTIONS

hCT was measured using a calcitonin two-site automated chemiluminescent immunometric assay (the most common hCT assay in clinical practice) in serum samples obtained before and 2, 5, and 15 min after iv stimulation using pentagastrin, 0.5 microg/kg body weight, or calcium gluconate, 2.5 mg/kg.

MAIN OUTCOME MEASURES

Reference ranges for basal, unstimulated, and pentagastrin- or calcium-stimulated hCT and pentagastrin and calcium tolerability in healthy adults were measured.

RESULTS

The 95th percentile basal hCT values did not differ between males and females (5.0 vs. 5.7 pg/ml). The 95th percentile maximal stimulated hCT values rose distinctly after pentagastrin (peak men, 37.8 pg/ml; women, 26.2 pg/ml) and even more so after calcium (peak men, 131.1 pg/ml, women, 90.2 pg/ml). No hCT increase was detected in four of 25 men and 12 of 25 women after pentagastrin vs. none of 24 men and two of 18 women after calcium. Calcium was associated with fewer and less intense adverse effects than was pentagastrin.

CONCLUSION

High-dose calcium is a more potent and better-tolerated hCT stimulator than is pentagastrin. The reference ranges for basal and stimulated hCT established via automated chemiluminescent assay were lower than those reported for other assays.

Medullary thyroid carcinoma and biomarkers: past, present and future

The clinical management of patients with persistent or recurrent medullary thyroid carcinoma (MTC) is still under debate, because these patients either have a long-term survival, due to an indolent course of the disease, or develop rapidly progressing disease leading to death from distant metastases. At this moment, it cannot be predicted what will happen within most individual cases. Biomarkers, indicators which can be measured objectively, can be helpful in MTC diagnosis, molecular imaging and treatment, and/or identification of MTC progression. Several MTC biomarkers are already implemented in the daily management of MTC patients. More research is being aimed at the improvement of molecular imaging techniques and the development of molecular systemic therapies. Recent discoveries, like the prognostic value of plasma calcitonin and carcino-embryonic antigen doubling-time and the presence of somatic RET mutations in MTC tissue, may be useful tools in clinical decision making in the future. In this review, we provide an overview of different MTC biomarkers and their applications in the clinical management of MTC patients.

Identification of occult metastases of medullary thyroid carcinoma by calcitonin measurement in washout fluid from fine needle aspiration of cervical lymph node

Medullary thyroid carcinoma (MTC) may occur sporadically or as a manifestation of an autosomal-dominant inherited syndrome, the multiple endocrine neoplasia type 2. DNA-based RET genotype analysis gained worldwide acceptance in the identification of asymptomatic gene carrier. MTC synthesize and secrete calcitonin, a well established tumor marker and postoperative level of serum calcitonin, indicates whether residual disease was left behind and whether reintervention is necessary. However, management is difficult when routine imaging studies for MTC are negative. This paper brings a report of an illustrative case of a patient with MTC diagnosed by molecular screening, who persisted with detectable levels of serum calcitonin after surgical procedure. After 48 months, an increase in serum calcitonin impelled us to investigate the disease focus. Cervical-US and calcitonin measurement in washout fluid from fine needle aspiration was successfully used to identify MCT metastasis in a lymph node, allowing appropriated reintervention and illustrating the potential clinical applicability of this method.

Determination of calcitonin levels in C-cell disease: clinical interest and potential pitfalls

An elevated serum calcitonin level is a highly sensitive marker for medullary thyroid carcinoma (MTC) that can be used for screening, differential diagnosis, prognostic assessment, follow-up monitoring, and assessment of treatment response. Nevertheless, additional data are required to definitively support routine measurement of calcitonin levels in the initial work-up of patients with thyroid nodules, mainly because there is no convincing evidence that such testing actually reduces MTC-related mortality. By contrast, the prognostic value of measuring calcitonin levels preoperatively, postoperatively, and during follow-up of patients with MTC is widely acknowledged. Furthermore, determination of calcitonin levels is also used to evaluate the response of MTC to novel forms of systemic treatment, such as tyrosine kinase inhibitors. In this Review, we discuss the key issues surrounding the use of this laboratory test in the clinical management of patients with MTC.

Procalcitonin: a marker for the diagnosis and follow-up of patients with medullary thyroid carcinoma

CONTEXT

Calcitonin (CT) is the main medullary thyroid carcinoma (MTC) tumor marker. However, it has several limitations, including a concentration-dependent biphasic half-life, sensitivity to rapid in vitro degradation, and the presence of different isoforms/fragments. Procalcitonin (PCT), the prohormone of calcitonin, is free of these limitations but is currently used only as a sepsis marker.

OBJECTIVES

The objective of the study was to determine whether PCT is suited as a MTC tumor marker by comparing the diagnostic performance of PCT with that of CT in MTC.

DESIGN

PCT and CT were measured in a total of 835 subjects, including normal volunteers (n = 197) and patients with active-MTC (n = 91), cured-MTC (n = 42), neuroendocrine tumors (n = 225), mastocytosis (n = 48), follicular cell-derived thyroid carcinoma (cured = 120, persistent/recurrent = 55), and benign thyroid disease (n = 57).

RESULTS

PCT levels were significantly higher in the active-MTC patients (mean 126.4 ng/ml) than the cured-MTC patients (mean <0.1 ng/ml). The overall concordance between the two markers was 95.7% (kappa = 0.81). Receiver-operating characteristic curve analysis showed no significant difference in diagnostic performance between CT and PCT. PCT's diagnostic sensitivity and specificity were 91 and 96%, respectively. The corresponding values for CT were 99 and 98%. Analyte stability studies showed that CT is very unstable in vitro with a decrease of 35-50% from the original value 24 h after the blood draw, whereas PCT levels did not significantly change during this time.

CONCLUSIONS

A strong correlation was observed between PCT and CT levels in patients with MCT. Given PCT's greater analytical stability, we conclude that it represents a promising complementary MTC tumor marker.

[Hereditary thyroid cancer]

Hereditary thyroid carcinomas are present in about 5% of differentiated (DTC) and 25% of medullary thyroid carcinomas (MTC). They are part of a multiorgan tumour syndrome (e. g. FAP Gardner's syndrome with DTC and MEN 2 syndrome with MTC) or confined to the thyroid gland. Hereditary thyroid carcinomas typically show multifocal growth and occur in young patients. Due to germ cell mutations as the underlying cause of disease, partial thyroidectomies that may be justified in early sporadic carcinomas are not indicated in this type of tumours. In the case of hereditary DTC, the genetic basis of the disease has been demonstrated only in syndromatic tumour variants. In most nonsyndromatic cases, specific genetic alterations have not yet been identified. In both types of hereditary DTC, prophylactic thyroidectomy is not warranted due to the favourable prognosis of tumours that do not differ from sporadic ones. Point mutations of the RET proto-oncogene have been known for 15 years to be the genetic basis of hereditary MTC. Recently several new mutations were discovered; however, final conclusions regarding their clinical significance are not possible at present. Basically it has been shown that the clinical aggressivity of tumour development follows a genotype-phenotype correlation (risk groups 1-3). However, in mutations of all risk classes there exists a wide spectrum of different stages of hereditary C-cell disease in individual risk groups. Regarding time and extent of prophylactic thyroidectomy (without or with lymph node dissection) a combined molecular-biochemical concept including the use of pentagastrin-stimulated calcitonin values is therefore recommended.

Imaging in covert ectopic ACTH secretion: a CT pictorial review

The syndrome of ectopic adrenocorticotrophin secretion (EAS) is rare and is due to excess adrenocorticotrophin (ACTH) production from a nonpituitary tumour. These tumours can be covert, where the tumours are not readily apparent, and very small making them challenging to image. It is clinically and biochemically difficult to distinguish between covert EAS and Cushing's disease. The first-line investigation in locating the source of ACTH production is computed tomography (CT). The aim of this pictorial review is to illustrate the likely covert sites and related imaging findings. We review the CT appearances of tumours resulting in covert EAS and the associated literature. The most common tumours were bronchial carcinoid tumours, which appear as small, well-defined, round or ovoid pulmonary lesions. Rarer causes included thymic carcinoids, gastrointestinal carcinoids and pancreatic neuroendocrine tumours. Awareness of the imaging characteristics will aid identification of the source of ACTH production and allow potentially curative surgical resection.

The influence of gender, age, and RET polymorphisms on C-cell hyperplasia and medullary thyroid carcinoma

BACKGROUND

RET germline mutations predispose to the development of hereditary medullary thyroid carcinoma (hMTC). Several single nucleotide polymorphisms (SNPs) are described associated with sporadic MTC (sMTC). However, the findings regarding their influence on the clinical course and biological behavior of this disorder are discordant. To clarify the contradictory findings, we studied the association of certain SNPs considering age, gender, and histopathology in a large Austrian cohort with C-cell hyperplasia (CCH) and MTC.

METHODS

Genotyping of SNPs located in RET codons 691, 769, 836, and 904 from 199 patients with MTC and CCH (basal calcitonin > 10 pg/mL, pentagastrin stimulated > 100 pg/mL) was performed, and the results were analyzed considering gender, age at diagnosis, and histopathology.

RESULTS

No significant difference of SNP frequencies was found in the study patients versus normal controls. In sMTC and sporadic CCH (sCCH) no significant association of SNP frequency with the age at diagnosis was found. In patients with sporadic C-cell disease (sCCH and sMTC), 3.7 times more males than females suffered synchronously from papillary or follicular thyroid cancer (20/97 [20.6%] males; 3/54 [5.6%] females; p = 0.02). sCCH was revealed more frequently in males (89/97, 91.7%) than in females (27/54, 50%; p = 10(-8)). In contrast to males, the ratio of CCH to total C-cell disease was significantly higher in females with hereditary (26/32, 81%) compared to those with sporadic disease (27/54, 50%; p = 0.006).

CONCLUSIONS

In this study RET SNPs had no clinical impact on the development of sporadic C-cell disease when the age of diagnosis or gender is considered. C-cell disease seems to predispose males to the development of papillary and follicular thyroid cancer. In addition, at least in females with CCH RET germline mutation, screening is recommended even if the family history is negative for MTC.

Long-term prognosis of medullary thyroid carcinoma

OBJECTIVE

The clinical course of patients with medullary thyroid carcinoma (MTC) is variable, even in the subgroup of patients after surgery with curative intent and postoperatively persistent elevated calcitonin levels. This study aimed to evaluate the long-term prognosis of survival in patients with MTC.

PATIENTS

Long-term survival was analysed in 32 patients with MTC being treated in an endocrine centre over a 40-year period. Patients were classified as having sporadic MTC, familial MTC (FMTC), multiple endocrine neoplasia (MEN) IIA or MEN IIB.

RESULTS

Seventeen patients had sporadic MTC (53.1%), eight had MEN IIA (25%) and three had MEN IIB (9.4%); the remaining four patients (12.5%) had not undergone genetic analysis until now. The overall average age at diagnosis was 42.0 years, and the median follow-up time was 9.5 years (range 0.5-39 years). Mortality due to progressive MTC was 15.6%. The 5-year survival rate was 96% (95% CI 89-100), the 10-year survival rate 91% (95% CI 79-100), and the 15-year survival rate 85% (95% CI 78-100). The estimated mean survival time after initial diagnosis was 31 years (95% CI 26.7-37.0). There is a significant difference in survival time between patients achieving complete remission compared with patients with biochemical persistent disease (P = 0.038) or metastasis (P = 0.0003). In five patients, advanced imaging with positron emission tomography/computed tomography (PET/CT) identified additional sites of tumour load. Eight more lymph node metastases were found in four patients and one local tumour recurrence in one patient by PET/CT.

CONCLUSION

The overall prognosis of MTC is favourable, even if the rate of biochemical cure is lower in MTC than in differentiated types of thyroid cancer. This is also true for patients with biochemically persistent disease. Whether the identification of further tumour sites by advanced imaging procedures such as PET/CT translates into a better prognosis in patients with persistently elevated calcitonin levels remains to be investigated.

Type 2 iodothyronine deiodinase is highly expressed in medullary thyroid carcinoma

Type II deiodinase (D2) plays a critical role in controlling intracellular T3 concentration and early studies indicated a follicular but not a parafollicular C-cell origin of D2 activity in the thyroid gland. Here, we show that D2 is highly expressed in human medullary thyroid carcinoma (MTC), a tumor that arises from the C-cells. D2 transcripts were detected in all MTC samples obtained from 12 unselected MTC patients and the levels of D2 activity were comparable to those found in surrounding normal follicular tissue (0.41+/-0.10 fmol min mg protein vs. 0.43+/-0.41 fmol min mg protein, P=0.91). Additional analysis in the TT cells, a human MTC cell line, demonstrated that the D2 expression is downregulated by thyroid hormones and enhanced by cAMP analogs and dexamethasone. The thyroid hormone receptor alpha1 and beta isoforms were also detected in all MTC samples and in TT cells, thus suggesting a potential role of T3 locally produced by D2 in this neoplastic tissue.

Response to [90Yttrium-DOTA]-TOC treatment is associated with long-term survival benefit in metastasized medullary thyroid cancer: a phase II clinical trial

PURPOSE

We aimed to explore the efficacy of (90)Yttrium-1,4,7,10-tetra-azacyclododecane N,N',N'',N-'''-tetraacetic acid ((90)Y-DOTA)-Tyr(3)-octreotide (TOC) therapy in advanced medullary thyroid cancer.

EXPERIMENTAL DESIGN

In a phase II trial, we investigated the response, survival, and long-term safety profile of systemic [(90)Y-DOTA]-TOC treatment in metastasized medullary thyroid cancer. Adverse events were assessed according to the criteria of the National Cancer Institute. Survival analyses were done using multiple regression models.

RESULTS

Thirty-one patients were enrolled. A median cumulative activity of 12.6 GBq (range, 1.7-29.6 GBq) of [(90)Y-DOTA]-TOC was administered. Response was found in nine patients (29.0%). Four patients (12.9%) developed hematologic toxicities and seven patients (22.6%) developed renal toxicities. Response to treatment was associated with longer survival from time of diagnosis (hazard ratio, 0.20; 95% confidence interval, 0.05-0.81; P = 0.02) and from time of first [(90)Y-DOTA]-TOC therapy (hazard ratio, 0.16; 95% confidence interval, 0.04-0.63; P = 0.009). The visual grade of scintigraphic tumor uptake was not associated with treatment response or survival.

CONCLUSIONS

Response to [(90)Y-DOTA]-TOC therapy in metastasized medullary thyroid cancer is associated with a long-term survival benefit. Treatment should be considered independently from the result of the pretherapeutic scintigraphy.

Growth inhibition of medullary thyroid carcinoma cells by pyrazolo-pyrimidine derivates

There is no effective treatment for recurrent or metastatic medullary thyroid carcinoma (MTC), a tumor arising from thyroid C-cells commonly presenting an inherited or acquired RET mutation. In this study we examined the sensitivity of two human MTC cell lines to novel pyrazolopyrimidine derivates, able to inhibit src-family tyrosine kinase activity. In TT cells [carrying the multiple endocrine neoplasia (MEN)2A Ret mutation Cys 634Trp] and MZ-CRC-1 cells (carrying the MEN2B RET mutation Met891Thr), one of these compounds, namely Si 34, determined a significant growth inhibitory effect (approximately 90% vs control for TT, 80% vs control for MZ-CRC-1) mainly due to enhanced cell mortality after a 6-day incubation. At concentrations that increased cell mortality, neither biochemical or morphological characteristics of apoptosis were detected in TT and MZCRC- 1 cells treated with Si 34. These results, when confirmed in other in vivo preclinical models, suggest that this novel tyrosine kinase inhibitor may be useful for the treatment of MTC.

Imaging medullary thyroid carcinoma with persistent elevated calcitonin levels

PURPOSE

Because calcitonin level remains elevated after initial treatment in many medullary thyroid carcinoma (MTC) patients without evidence of disease in the usual imaging work-up, there is a need to define optimal imaging procedures.

PATIENTS AND METHODS

Fifty-five consecutive elevated calcitonin level MTC patients were enrolled to undergo neck and abdomen ultrasonography (US); neck, chest, and abdomen spiral computed tomography (CT); liver and whole-body magnetic resonance imaging (MRI); bone scintigraphy; and 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)/CT scan (PET).

RESULTS

Fifty patients underwent neck US, CT, and PET, and neck recurrence was demonstrated in 56, 42, and 32%, respectively. Lung and mediastinum lymph node metastases in the 55 patients were demonstrated in 35 and 31% by CT and in 15 and 20% by PET. Liver imaging with MRI, CT, US, and PET in 41 patients showed liver in 49, 44, 41, and 27% patients, respectively. Bone metastases in 55 patients were demonstrated in 35% by PET, 40% by bone scintigraphy, and 40% by MRI; bone scintigraphy was complementary with MRI for axial lesions but superior for the detection of peripheral lesions. Ten patients had no imaged tumor site despite elevated calcitonin level (median 196 pg/ml; range 39-816). FDG uptake in neoplastic foci was higher in progressive patients but with a considerable overlap with stable ones.

CONCLUSION

The most efficient imaging work-up for depicting MTC tumor sites would consist of a neck US, chest CT, liver MRI, bone scintigraphy, and axial skeleton MRI. FDG PET scan appeared to be less sensitive and of low prognostic value.

Hypereosinophilia as the presentation of metastatic medullary thyroid carcinoma: a remarkable event

Hypereosinophilic syndrome is a rare disorder characterized by persistent eosinophilia combined with organ system dysfunction. This report is of a 37-year-old man who had eosinophilia, periodic fever, weight loss, and generalized bone pain. A small nodule in left lobe of thyroid was detected in his physical examination. The patient underwent surgery and histopathological study, which confirmed that the patient had medullary carcinoma of thyroid. The patient died 6 months after the surgery. Eosinophilia is more commonly seen with benign conditions. However, less frequent but malignant etiologies always should be contemplated.

Palliation of advanced thyroid malignancies

While most thyroid cancers are slow-growing and have an excellent prognosis after appropriate treatment, a subset of thyroid cancers behave aggressively, and approximately 1500 individuals in the US will die of the disease in the year 2007. Advanced thyroid malignancies can cause distressing and life-threatening symptoms by local invasion in the neck, growth of distant metastases in the lung, bone, and other organs, and tumor production of bioactive substances in the case of medullary thyroid cancer. This article will review palliative modalities, including surgery, radioactive iodine, external beam radiation, and chemotherapy, as well as novel targeted therapies, for the treatment of patients with advanced thyroid malignancies.

Nuclear medicine procedures in the diagnosis and therapy of medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor originating in the parafollicular cells (C cells) of the thyroid and secretes both calcitonin and carcino-embryonic antigen (CEA). Genetic and biochemical testing allow early pre-clinical identification of familial forms. Sporadic MTC usually presents as a solitary thyroid nodule; the diagnosis can be made preoperatively by fine-needle aspiration or by calcitonin assay, though it is usually established at the time of surgery. In the diagnostic assessment of MTC, nuclear medicine imaging provides its contribution mainly in the post-operative work-up to detect residual/recurrent tumor. For such purpose a number of radiopharmaceuticals, which take advantage of the specific expression of receptors (the somatostatin analogue (111)In-octreotide), hormone transporters (radiolabelled MIBG) or molecular targets (radiolabelled anti-CEA monoclonal antibodies) by MTC lesions are available; these tracers may be used also for the palliative treatment of advanced MTC. Interesting perspectives for MTC imaging are offered by PET radiopharmaceuticals.

Medullary thyroid cancer treated by capecitabine

Medullary thyroid carcinoma with distant metastases is generally incurable, with 20% overall survival at 10 years. The treatment goal is palliative. Chemotherapy has a limited role, with low response rates and high toxicities with the different regimens. Here, we report the case of 64-year-old man with metastatic medullary thyroid carcinoma in progression after primary treatment with cisplatin-doxorubicin. The patient received capecitabine 2000 mg/m total per day x 14 days followed by 1-week rest. He received 41 cycles, and presented prolonged and objective tumor response (30 months), without any toxicity.

New drugs in thyroid cancer

This review is focused on "new drugs" that might be developed for thyroid cancer treatment. Thyroid cancer is frequently associated to the activation of specific protein (RET, BRAF) and lipid [PI(3)K] kinases. There is good evidence that these genetic lesions are causative events in thyroid cancer initiation or progression. Therefore, novel compounds able to target these kinases might be useful for thyroid cancer treatment. The power of this approach is witnessed by the examples of BCR-ABL, c-KIT and EGFR inhibitors in the treatment of chronic myelogenous leukemia (CML), gastro-intestinal stromal tumors (GIST) and non-small cell lung carcinoma (NSCLC).

Medullary thyroid cancer: a retrospective analysis of a cohort treated at a single tertiary care center between 1970 and 2005

OBJECTIVE

To identify prognostic factors of clinical outcome and long-term survival in medullary thyroid cancer (MTC).

DESIGN

Retrospective case series of 51 consecutive patients (mean age 46.9 years, 57% female) treated at a single tertiary university medical center from 1970 to 2005. Medical records were reviewed for demographic data, laboratory and clinical course, treatment, and long-term outcome.

MAIN OUTCOME

At presentation, 25 patients (49%) had local disease and 26 (51%) had metastatic disease (three with distant metastases). RET mutations were identified in nine of 23 patients tested. The patients with hereditary disease were younger than the patients with sporadic disease (p < 0.001) and had lower calcitonin levels at diagnosis (p = 0.004) and more multicentric tumors (p = 0.02). Initial surgery consisted of total thyroidectomy in 47 patients, with neck dissection in 26; 22 patients achieved long-term remission. The 5-, 10- and 15-year survival rates were 88%, 85%, and 77%, respectively. On univariate analysis, distant metastases during the course of the disease and elevated calcitonin levels postoperatively were significant prognostic factors of reduced survival (p = 0.001 and 0.016, respectively). Lymph node involvement at initial surgery was associated with a lower remission rate (p = 0.016) but had no impact on long-term survival (p = 0.269).

CONCLUSION

Patients with MTC have a generally favorable outcome, perhaps owing to recent advances in diagnosis and treatment. Although postoperative serum calcitonin level and distant metastases are the only determinants of long-term survival, the presence of cervical metastases is predictive of a higher risk of recurrent or persistent disease.

MEDULLARY THYROID CARCINOMA: A 20-YEAR EXPERIENCE FROM A CENTRE IN SOUTH INDIA

BACKGROUND

Management of medullary thyroid carcinoma (MTC) remains controversial despite many advances over the past five decades. We attempt to review the presentation, management and prognosis of MTC at our institution over the last two decades.

METHODS

We conducted a retrospective review of the records of 40 patients with MTC over a period of 20 years.

RESULTS

Ten patients had hereditary MTC and 30 had sporadic MTC. The mean age of presentation was 41 years. Sixty-five per cent of the patients had a definite thyroid swelling and 43% had lymphadenopathy at the time of presentation. Total thyroidectomy with a central neck dissection was carried out in 82.5% of patients. Adjuvant therapy was given in 75% of patients because of extensive/residual disease. Postoperative hypercalcitoninaemia was seen 73% of patients. (131)I metaiodobenzylguanidine scanning was carried out in 16 patients with persistent hypercalcitoninaemia; the uptake was positive in 10 and negative in 6, indicating a positivity of 62%.

CONCLUSION

Medullary thyroid carcinoma accounts for 2.5% of thyroid carcinomas. There is a small male preponderance. In our series (131)I metaiodobenzylguanidine scan had a better positivity than what has been reported in the published work. Persistent postoperative hypercalcitoninaemia was associated with a poorer prognosis that did not reach statistical significant.

Codon Y791F Mutations in a Large Kindred: Is Prophylactic Thyroidectomy Always Indicated?

BACKGROUND

RET proto-oncogene mutations are associated with medullary thyroid carcinomas usually requiring preventive thyroidectomy in gene carriers. We present a large kindred with the Y791F mutation in the RET proto-oncogene that did not have medullary thyroid carcinomas.

PATIENTS AND METHODS

Eight members of a Danish family with the Y791F mutation participated. All gene carriers underwent pentagastrin testing, and measurements of serum calcitonin. In the index person, exons 10, 11, and 13-16 of the RET proto-oncogene were screened. In the rest of the individuals only exon 13 was analysed. Mutation analysis was done by direct bidirectional sequencing of PCR products on an ABI 3100 Genetic Analyzer (Applied Biosystems, Foster City, CA, USA).

RESULTS

The index person was screened genetically due to goitre at a young age. A total of 27 members of the family underwent genetic testing. Twelve (44.4%, 95% CI: 25.5%-64.7%) had the mutation (age range 13-84 years). None of these had abnormal pentagastrin tests (0%, 95% CI: 0%-26.5%). We found no significant differences in basal serum calcitonin concentrations between gene carriers (mean +/- SD: 0.16 +/- 0.54 pmol/l, n = 11) and non-gene carriers (0.55 +/- 0.86 pmol/l, n = 6, 2 P = 0.29). None showed signs of primary hyperparathyroidism or phaeochromocytoma.

CONCLUSIONS

The Y791F RET proto-oncogene mutation may have a low penetrance. In selected cases, prophylactic thyroidectomy may be replaced by watchful waiting with repeated pentagastrin testing, provided careful evaluation of risks and benefits is performed.

Cdk5 regulates STAT3 activation and cell proliferation in medullary thyroid carcinoma cells

The biological behaviors of thyroid cancer are varied, and the pathological mechanisms remain unclear. Some reports indicated an apparent aggregation of amyloid accompanying medullary thyroid carcinoma (MTC). Amyloid aggregation in neurodegeneration leads to hyperactivation of Cdk5 and subsequent neuronal death. Based on the connection with amyloid, the role of Cdk5 in MTC is worthy of investigation. Initially, the expression of Cdk5 and its activator, p35, in MTC cell lines was identified. Cdk5 inhibition by specific inhibitors or short interfering RNA decreased the proliferation of MTC cell lines, which reveals the importance of Cdk5 in MTC cell growth. Although p35 cleavage has been considered as an important element in neurodegeneration, it seems that p35 cleavage was not a major cause in Cdk5 activity-dependent MTC cell proliferation because neither Cdk5 activity nor cell growth was affected by the inhibition of p35 cleavage. Clearance of amyloid by antibody neutralization indicated that MTC cell proliferation was supported by calcitonin-derived extracellular amyloid and subsequent Her2 and Cdk5 activation. Significantly, the STAT3 pathway was involved in Cdk5-dependent proliferation of MTC cells through Ser-727 phosphorylation. In addition, Cdk5 inhibition reduced nuclear distributions of both the Cdk5-p35 complex and phospho-STAT3 in MTC cells. Finally, Cdk5 inhibition retarded tumor formation in vivo accompanying the reduction of phospho-STAT3. Our findings suggest the first demonstration of a novel and specific role for Cdk5 kinase in supporting the proliferation of the medullary thyroid carcinoma cells and could shed light on a new field for diagnosis and therapy of thyroid cancer.

Biochemical markers in the follow-up of medullary thyroid cancer

Medullary thyroid cancer (MTC) shares biochemical features with other neuroendocrine tumors but the particular characteristics are largely unexplored. We investigated the biochemical neuroendocrine profile of MTC and whether specific markers could be useful in follow-up. In addition to the standard tumor marker calcitonin, plasma carcino-embryonic antigen (CEA), plasma catecholamines, (platelet) serotonin, chromogranin A, tryptase, and urinary markers of catecholamine, histamine, and serotonin metabolism were prospectively determined in 46 patients with histologically proven MTC. Patients were divided according to the stage of disease: group 1, no evidence; group 2, stable disease (SD); and group 3, progressive disease (PD). Plasma dopamine was increased in the majority of the patients with SD and PD; however it did not correlate with extent of disease. Elevated plasma platelet levels of serotonin were only present in patients with multiple endocrine neoplasia 2 with SD or PD but did not differ between those groups. Histamine metabolites were elevated in 20% of patients with SD and PD. In addition to plasma calcitonin, only CEA and chromogranin A could differentiate between stable and progressive MTC. MTCs are capable of synthesizing catecholamines, serotonin, and histamine metabolites underscoring that MTCs have metabolic characteristics in common with other neuroendocrine tumors. Thus far, clinical usefulness and relevance seems limited. The most useful markers in the follow-up of MTC are plasma calcitonin and CEA.

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.

Molecular advances in medullary thyroid cancer diagnostics

Germline activating mutations in the RET proto-oncogene cause inherited medullary thyroid cancer (MTC) and the multiple endocrine neoplasia type 2 (MEN2) syndrome. Identification of a RET mutation in an individual with MEN2 allows pre-symptomatic genetic testing of other at-risk family members, and guides early intervention to prevent death and serious morbidity from MTC. Developments in the understanding of downstream RET receptor signalling pathways and how activating mutations disturb receptor function has led to insights into the possible molecular mechanisms underlying the different MEN2 phenotypes. Mutation analysis of RET in individuals with MEN2 has identified a number of different mutations, and correlation with cancer biology and clinical outcome has led to tailoring of management according to the mutation detected.

An introduction to managing medullary thyroid cancer

MTC is a rare neuroendocrine thyroid tumour accounting for 3% to 10% of all thyroid malignancies. It can occur in a sporadic and a hereditary clinical setting. Hereditary MTC may either occur alone (familial MTC, FMTC) or as part of multiple endocrine neoplasia (MEN) type 2A, or MEN 2B. These disorders are due to germline mutations in the RET (REarranged during Transfection) gene. In carriers of MEN 2B-associated RET mutations, prophylactic thyroidectomy is indicated before the first year of life. In the case of MEN 2A-associated germline RET mutations with a high-risk profile, total thyroidectomy is warranted before the age of 2 years and certainly before the age of 4 years. At that age the risk of invasive MTC and metastases is acceptably low. Depending on the type of RET mutation, thyroidectomy can take place at an older age in patients with a lower risk profile. In case of elevated basal or stimulated serum calcitonin, preventive surgery including total thyroidectomy and central compartment dissection should be performed regardless of age. When MTC presents as a palpable tumour, total thyroidectomy should be combined with extensive lymph node dissection of levels II-V on both sides and level VI to prevent locoregional recurrences.

Are possible risk factors for differentiated thyroid cancer of prognostic importance?

OBJECTIVE

The only established risk factor for differentiated thyroid cancer (DTC) is ionizing radiation. How ionizing radiation and other possible risk factors for DTC influence the prognosis has not extensively been investigated. We studied if factors such as smoking, number of children, previous thyroid disorders, previous radiotherapy toward the neck, family history of thyroid diseases, and malignancies influenced survival for patients with DTC.

DESIGN

A nested case-control study was conducted within the cohort of all patients diagnosed with DTC in Sweden between 1958-1987. Cases consisted of patients who died from DTC. One control, matched by age at diagnosis, gender, and calendar period was randomly selected from the risk set for each case. Information of risk factors was collected from the medical records. Associations between these factors and prognosis were assessed using conditional logistic regression.

MAIN OUTCOME

Smokers had a borderline significant increased risk of dying from DTC. Previous radiotherapy towards the neck region had no prognostic implication. A family history of DTC influenced prognosis although not significant due to few cases. The remaining risk factors studied did not influence survival.

CONCLUSIONS

In conclusion, smokers seemed to have a worsened prognosis compared to nonsmokers and a family history of thyroid cancer had a nonsignificant negative effect on survival.

A rare RET gene exon 8 mutation is found in two Greek kindreds with familial medullary thyroid carcinoma: implications for screening

OBJECTIVE

Familial medullary thyroid carcinoma (FMTC) is caused by germ-line mutations in the RET proto-oncogene. These mutations concern mainly cysteine residues in exons 10 and 11, whereas noncysteine mutations in exons 13-16 are rare. Mutations in other exons have been reported only in isolated families. In this study we have analysed the RET gene in two FMTC families negative for mutations in the above exons.

DESIGN

We have analysed exons 7-19 and 21 in one index patient from each family using DNA sequencing.

PATIENTS

Twenty-eight subjects from both families were clinically assessed and subsequently molecularly analysed for the presence of RET gene mutations.

RESULTS

We have found the mutation c.1597G-->T (Gly533Cys) in two Greek families with FMTC. The mutation was detected in all seven MTC patients of both families as well as in 13 asymptomatic relatives in the heterozygote state, although one of the patients was also a homozygote due to consanguinity. The mutation shows a wide clinical heterogeneity, as there are carrier patients with age of diagnosis ranging from 23 to 88 years.

CONCLUSIONS

It is likely that this mutation causes FMTC, as no other mutation was found in the RET gene, the mutation co-segregates with FMTC, and family members without the mutation are clinically unaffected. As the same point mutation was previously found in a large Brazilian family, it may be present in other populations as well. Therefore, exon 8 of RET should be screened in FMTC families with no identified common RET mutations.

Gene therapy for thyroid cancer

Although most thyroid cancers may be cured by surgery and ¹³¹I therapy, approximately 10-20% of patients die from advanced differentiated and anaplastic tumors that are unresponsive to conventional treatments. Thus, alternative approaches such as gene therapy are of interest, especially using targeted therapeutic gene delivery. Several strategies have been designed specifically for thyroid cancer and some have proven to be feasible in preclinical studies. In particular, it is suggested that combined gene therapy approaches, as well as multimodality therapeutic regimens, including gene therapy and conventional treatments, should be pursued to achieve clinically significant results. The recent discovery of new markers of thyroid cancer should improve the efficacy of gene therapy.

Treatment of neuroendocrine tumors with somatostatin analogs

Neuroendocrine tumors constitute a group of hormone producing tumors originating from neuroendocrine cells in different organs. Most tumors have a low proliferation index measured by Ki67 and the progression of the tumor is slow. However, many patients suffer from endocrine symptoms induced by the hormones produced and released by the tumor cells. For some patients these symptoms can be life- threatening as in midgut carcinoid patients suffering from carcinoid crises with extensive flushes and hypotension or in patients with severe diarrhea induced by tumors producing vasointestinal polypeptide. In many other patients the hormone-induced symptoms interfere with the ability to carry out ordinary daily activities. The introduction of somatostatin analogs in the treatment of these hormone related symptoms has made it possible to control most of them and has added significantly to the quality of life for this group of patients. Unfortunately, the clinical inhibitory effect on tumor growth has not been very good with only 5-10% of the patients showing an objective response. However, stabilization of tumor growth may be achieved in a significant number of patients. In the future, the hope is that development of new somatostatin analogs with broader receptor-binding profiles will give us new analogs which are more efficient with regard to their antiproliferative effect. This possibility will be studied in future trials.

Medullary thyroid carcinoma arises in the absence of prolactin signaling

Prolactin, a pituitary hormone, exerts pleiotropic effects in various cells. These effects are mediated by a membrane receptor highly expressed in many tissues. To analyze prolactin effects on the thyroid gland, we first identified prolactin receptor (PRLR) mRNAs by in situ hybridization. To further evaluate the physiologic relevance of PRLR actions in the thyroid in vivo, we used PRLR knockout mice. Whereas the histologic structure of thyroid of PRLR-null mice was not disturbed, we show that T4 levels are lower in null animals (13.63 +/- 2.98 versus 10.78 +/- 2.25 pmol/L in null mice), confirming that prolactin participates in the control of thyroid metabolism. To further investigate thyroid effects in mice, we measured body temperature and thyroid-stimulating hormone in young and adult male and/or female PRLR-null mice and their normal siblings. Surprisingly, in null animals, we saw medullary thyroid carcinoma (MTC) arising from parafollicular C cells producing calcitonin. The incidence of these carcinomas attained 41% in PRLR-null mice, whereas this malignant tumor occurs sporadically or as a component of the familial cancer syndrome in humans. This finding suggests that PRLR-null mice could represent a valuable animal model for MTC, which could be compared with existing MTC models. These observations suggest a possible link between the appearance of this carcinoma and the absence of prolactin signaling.

Ret proto-oncogene mutations in apparently sporadic Turkish medullary thyroid carcinoma patients: Turkmen study

OBJECTIVE

Medullary thyroid carcinoma (MTC) frequently occurs in a sporadic form, but a substantial number of cases are hereditary and appear as part of the multiple endocrine neoplasia type 2 (MEN2) syndromes. Germline mutations in ret proto-oncogene have been shown to be the underlying cause of MEN2 syndromes.

DESIGN

We carried out a multi-center study that aimed to perform mutational analysis of so called sporadic MTC patients.

METHODS

Fifty-six MTC patients verified by histopathologic examination were subjected to genetic analysis. Exon 10, 11, 13, 14, 15 and 16 of the ret gene were analyzed by DNA sequencing and restriction enzyme digestion method.

RESULTS

Among 56 apparently sporadic MTC patients, we identified 6 (10.7%) ret germline mutation carriers. Three individuals carried mutations at codon 634 in exon 11, one at codon 618 in exon 10, and two at codon 804 in exon 14. Identification of the predisposition gene mutation has allowed DNA-based strategy for direct mutation detection in patients with apparently sporadic MTCs. A substantial number of patients with apparently sporadic MTC carried germline mutations and 50% of their first degree relatives are expected to have or to develop MTC and/or other endocrine tumors.

CONCLUSIONS

These results indicate the importance of careful genetic surveillance of any patient with apparently sporadic MTCs.