Medullary thyroid carcinoma

Comparison of serum calcitonin and procalcitonin in detecting medullary thyroid carcinoma among patients with thyroid nodules

BACKGROUND

To prospectively evaluate the role of procalcitonin (PCT) in detecting or excluding medullary thyroid carcinoma (MTC) among patients with thyroid nodules and increased calcitonin (CT) levels.

METHODS

Fourteen of 1236 patients referred for thyroid nodules had increased serum CT >10 pg/mL. A stimulation test with pentagastrin was done and both CT and PCT were measured after stimulation. All patients underwent thyroid ultrasound, fine-needle cytology and, if indicated, surgery with histological and immunohistochemical examination of the surgical specimens.

RESULTS

After follow-up, two MTCs were found. These two patients had basal CT >100 pg/mL and detectable (>0.1 ng/mL) PCT, with 100% sensitivity. Pentagastrin stimulated CT achieved values above 100 pg/mL in two MTCs and in other two cases with no MTC outcome (50% PPV and 83% NPV). On the contrary, all patients with no MTC had both basal and stimulated undetectable PCT (100% PPV and 100% NPV).

CONCLUSIONS

The addition of basal PCT measurement in patients with thyroid nodule(s) and increased CT may significantly improve accuracy of CT measurement without needing a PG stimulation test.

Surgical management of thyroid cancer

Thyroid cancer is the most common endocrine neoplasm; however, it only accounts for less than 1% of all human malignances. Thyroid cancers are divided into well differentiated and non-well differentiated cancers, according to their histology and behavior. The surgical management options of well-differentiated thyroid cancer include total or near-total thyroidectomy, subtotal thyroidectomy and lobectomy plus isthmusectomy. The extent of surgery for thyroid cancer continues to be an area of controversy. Complications associated with thyroid surgery are directly proportional to the extent of thyroidectomy and inversely proportional to the experience of the operating surgeon. They occur less frequently with good surgical technique and better understanding of surgical anatomy, and include wound healing and infections (seroma, hematoma and wound infection), nerve injury, hypoparathyroidism, hypothyroidism, postoperative hemorrhage and respiratory obstruction.

Changes in signaling pathways induced by vandetanib in a human medullary thyroid carcinoma model, as analyzed by reverse phase protein array

BACKGROUND

Medullary thyroid carcinoma (MTC) is a rare tumor that is caused by activating mutations in the proto-oncogene RET. Vandetanib, a tyrosine-kinase inhibitor, has been recently approved to treat adult patients with metastatic MTC. The aim of this study was to investigate changes in signaling pathways induced by vandetanib treatment in preclinical MTC models, using the reverse-phase protein array method (RPPA).

METHODS

The human TT cell line was used to assess in vitro and in vivo activity of vandetanib. Protein extracts from TT cells or TT xenografted mice, treated by increasing concentrations of vandetanib for different periods of time, were probed with a set of 12 antibodies representing major signaling pathways, using RPPA. Results were validated using two distinct protein detection methods: Western immunoblotting and immunohistochemistry.

RESULTS

Vandetanib displays antiproliferative and antiangiogenic activities and inhibits RET autophosphorylation. The MAPK and AKT pathways were the two major signaling pathways inhibited by vandetanib. Interestingly, phosphorylated levels of NFκB-p65 were significantly increased by vandetanib. Comparable results were obtained in both the in vitro and in vivo approaches, as well as for the protein detection methods. However, some discrepancies were observed between RPPA and Western immunoblotting, possibly due to lack of specificity of the primary antibodies used.

CONCLUSIONS

Overall, our results confirmed the interest of RPPA for screening global changes induced in signaling pathways by kinase inhibitors. MAPK and AKT were identified as the main pathways involved in vandetanib response in MTC models. Our results also suggest alternative routes for controlling the disease, and provide a rationale for the development of therapeutic combinations based on the comprehensive identification of molecular events induced by inhibitors.

PET/CT imaging of neuroendocrine tumors with (68)Gallium-labeled somatostatin analogues: An overview and single institutional experience from India

Neuroendocrine tumors (NETs) are rare neoplasms characterized by overexpression of somatostatin receptors (SSTRs). Functional imaging plays a crucial role in management of NETs. Recently, positron emission tomography/computed tomography (PET/CT) with (68)Gallium ((68)Ga)-labeled somatostatin analogues has shown excellent results for imaging of NETs and better results than conventional SSTR scintigraphy. In this review we have discussed the utility of (68)Ga-labeled somatostatin analogue PET/CT in NETs for various established and potential indications. In addition we have also shared our own experience from a tertiary care center in India.

Metachronous appearance of second malignancies in medullary thyroid carcinoma (MTC) patients: a diagnostic challenge and brief review of the literature

Medullary thyroid carcinoma (MTC) is a rare tumour which frequently occurs in the context of the multiple endocrine neoplasia syndromes, where it coexists with other usually benign tumours. The clinical picture varies and distant metastases are frequently present at diagnosis. Calcitonin levels are elevated in the presence of metastatic disease. Two MTC cases are presented, which had elevated postoperative calcitonin levels. Imaging revealed lung lesions which were originally attributed to metastatic disease from the MTC. However, at follow-up, these cases presented unusual features. The rapid increase in the lung lesions and the development of hypercalcaemia in the first patient suggested a second unrelated tumour. Biopsy of the lung lesion was compatible with lung adenocarcinoma. In the second patient, the appearance of a liver mass, although calcitonin levels remained stable, led to biopsy of the lesion: this was negative for calcitonin and compatible with metastatic lung adenocarcinoma. These MTC cases show that further malignancies may coexist with MTC and may obscure the clinical picture and influence the therapeutic decisions, especially in the case of metastatic disease. Features such as unusual imaging characteristics and the development of hypercalcemia, never encountered in MTC outside the MEN2 syndromes, as well as 'disproportionately' low calcitonin levels, incompatible with extensive metastatic disease, were the factors that led to further work-up. Both the cases subsequently proved to carry an unsuspected second malignancy. It is crucial to discriminate the metastatic lesion attributed to MTC from another coexisting primary malignancy, because different therapeutic strategies are needed for each setting.

In vitro and in vivo activity of cabozantinib (XL184), an inhibitor of RET, MET, and VEGFR2, in a model of medullary thyroid cancer

BACKGROUND

A limited number of approved therapeutic options are available to metastatic medullary thyroid cancer (MTC) patients, and the response to conventional chemotherapy and/or radiotherapy strategies is inadequate. Sporadic and inherited mutations in the tyrosine kinase RET result in oncogenic activation that is associated with the pathogenesis of MTC. Cabozantinib is a potent inhibitor of MET, RET, and vascular endothelial factor receptor 2 (VEGFR2), as well as other tyrosine kinases that have been implicated in tumor development and progression. The object of this study was to determine the in vitro biochemical and cellular inhibitory profile of cabozantinib against RET, and in vivo antitumor efficacy using a xenograft model of MTC.

METHODS

Cabozantinib was evaluated in biochemical and cell-based assays that determined the potency of the compound against wild type and activating mutant forms of RET. Additionally, the pharmacodynamic modulation of RET and MET and in vivo antitumor activity of cabozantinib was examined in a MTC tumor model following subchronic oral administration.

RESULTS

In biochemical assays, cabozantinib inhibited multiple forms of oncogenic RET kinase activity, including M918T and Y791F mutants. Additionally, it inhibited proliferation of TT tumor cells that harbor a C634W activating mutation of RET that is most often associated with MEN2A and familial MTC. In these same cells grown as xenograft tumors in nude mice, oral administration of cabozantinib resulted in dose-dependent tumor growth inhibition that correlated with a reduction in circulating plasma calcitonin levels. Moreover, immunohistochemical analyses of tumors revealed that cabozantinib reduced levels of phosphorylated MET and RET, and decreased tumor cellularity, proliferation, and vascularization.

CONCLUSIONS

Cabozantinib is a potent inhibitor of RET and prevalent mutationally activated forms of RET known to be associated with MTC, and effectively inhibits the growth of a MTC tumor cell model in vitro and in vivo.

Vandetanib: opening a new treatment practice in advanced medullary thyroid carcinoma

Medullary thyroid cancer (MTC) is frequently diagnosed in a locally advanced or metastatic stage, and 10-year survival rates in these cases are below 20 %. Cytotoxic chemotherapy has no significant impact on overall or progression-free survival. Vandetanib (Caprelsa(®), AstraZeneca) is a once-daily oral tyrosine kinase inhibitor that selectively inhibits signalling mediated by growth-factor receptor tyrosine kinase RET (constitutively activated in roughly 60 % of all MTCs), vascular endothelial growth-factor receptors 2 and 3, and epidermal growth-factor receptors. It is the first systemic drug with demonstrated anti-tumor benefits in advanced MTC, and it has recently been approved for locally advanced or metastatic MTC by the United States Food and Drug Administration (April 2011) and the European Medicines Agency (February 2012). This review, starting from the phases II and III efficacy and safety data that led to these approvals, explores important issues related to dosing, patient selection, and strategies for managing the substantial risk of toxicity associated with the drug (including life-threatening cardiac events that are the subject of a black-box warning in the United States). All these issues still remain to be defined. Vandetanib is becoming a standard of care for symptomatic, progressive, metastatic MTCs, to be used selectively in those patients who are likely to benefit from it.

Depicting medullary thyroid cancer recurrence: the past and the future of nuclear medicine imaging

CONTEXT

Inherited and sporadic medullary thyroid cancer (MTC) is an uncommon and medically challenging malignancy. Even if the extent of initial surgery is deemed adequate, the recurrence rate remains high, up to 50% in most series. Measurement of serum calcitonin is important in the follow-up of patients with MTC, and reliably reflects the existence of the disease.

EVIDENCE ACQUISITION

There is no single sensitive diagnostic imaging method to reveal all MTC recurrences or metastases. Conventional morphologic imaging methods (U/S, CT, and MRI) and several methods of nuclear medicine have been used for this purpose with variable accuracy.

RESULTS

The main role of nuclear medicine imaging is the detection of residual or recurrent tumor in the postoperative follow-up. In this review we present the radiopharmaceuticals used in the diagnosis of MTC recurrence, and comparison among them.

CONCLUSIONS

The most used radiopharmaceuticals labelled with γ emitters are: Metaiodobenzylguanidine (MIBG), labelled with (131)I or (123)I, (111)In-pentetreotide (Octreoscan), 99mTc-pentavalent dimercaptosuccinic acid ((99m)Tc(V)-DMSA), and (99m)Tc-EDDA/HYNIC-Tyr3-Octreotide ( Tektrotyd). The radiopharmaceuticals labelled with a positron-emitting radionuclide (β+), suitable for positron emission tomography (PET) imaging are: (18)F-fluorodeoxyglucose ((18)F-FDG), (18)F-fluorodihydroxyphenylalanine (18F-DOPA), and 68Ga-labelled somatostatin analogues (68Ga-DOTATATE or DOTATOC).

Changes in signaling pathways induced by vandetanib in a human medullary thyroid carcinoma model, as analyzed by reverse phase protein array

BACKGROUND

Medullary thyroid carcinoma (MTC) is a rare tumor that is due to activating mutations in the proto-oncogene RET. Vandetanib, a tyrosine-kinase inhibitor, has been recently approved to treat adult patients with metastatic MTC. The aim of this study was to investigate changes in signaling pathways induced by vandetanib treatment in preclinical MTC models, using the reverse-phase protein array method (RPPA).

METHODS

The human TT cell line was used to assess in vitro and in vivo activity of vandetanib. Protein extracts from TT cells or TT xenografted mice, treated by increasing concentrations of vandetanib for different periods of time, were probed with a set of 12 antibodies representing major signaling pathways, using RPPA. Results were validated using two distinct protein detection methods, western-immunoblotting and immunohistochemistry.

RESULTS

Vandetanib displays antiproliferative and antiangiogenic activities and inhibits RET auto-phosphorylation. MAPK and AKT pathways were the two major signaling pathways inhibited by vandetanib. Interestingly, phosphorylated levels of NFκB-p65 were significantly increased by vandetanib. Comparable results were obtained in both the in vitro and in vivo approaches as well as for the protein detection methods, although some discrepancies were observed between RPPA and western-immunoblotting.

CONCLUSIONS

Results confirmed the reliability and the utility of RPPA for screening global changes induced in signaling pathways by kinase inhibitors. MAPK and AKT were identified as the main pathways involved in vandetanib response in MTC models. Our results also suggest alternative routes for controlling the disease and provide a rationale for the development of therapeutic combinations based on the comprehensive identification of molecular events induced by inhibitors.

Divergent role of (68)Ga-labeled somatostatin analogs in the workup of patients with NETs: AIIMS experience

Neuroendocrine tumors (NETs) encompass a wide range of rare and heterogeneous neoplasms arising from the neural crest. Diagnosis of NETs is conventionally done by a combination of common clinical symptoms and biochemical evidence of hormonal excess, which these tumors are known to secrete. After a diagnosis of NET is established, a search for its localization is carried out using common morphologic imaging methods such as ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). The main problem with structural imaging is, however, its inability to distinguish between endocrine and exocrine lesions. Functional imaging of NETs started with use of iodine-131-meta-iodobenzylguanidine ((131)I-MIBG) and has come a long way since. From accurate demonstration of functioning tumors to detection of small and occult lesions, functional imaging has penetrated almost every aspect of NET management. Procedures such as (131/123)I-MIBG, (111)In-Octreoscan and others are rapidly giving way to use of PET/CT based on the superior resolution of the system and the availability of target-specific positron-emitting radiotracers. The availability of (68)Ga from generator-based radionuclide systems, namely (68)Ge/(68)Ga generators, opened up a new era of molecular imaging for NETs. A multitude of somatostatin analogs can be easily radioliganded with (68)Ga using heterocyclic macromolecular bifunctional chelating systems for targeted diagnosis of somatostatin receptor-expressing tumors, used most effectively to date for detection of NETs. This chapter focuses on our experience at the All India Institute of Medical Sciences, New Delhi regarding the divergent roles of (68)Ga-labeled somatostatin analogs in the workup of patients with NETs.

Incidence of thyroid cancer in the Kingdom of Saudi Arabia, 2000-2010

BACKGROUND

Thyroid cancer is the second most common malignancy among females at King Faisal Specialist Hospital and Research Centre (KFSH&RC) and in Saudi Arabia, accounting for about 11% of all newly diagnosed female cancers in the country in 2008. Over the past several decades, an increasing incidence of thyroid cancer has been reported in the Kingdom of Saudi Arabia. There are no comprehensive clinical epidemiological data for the trends of thyroid cancer incidence compared to the global incidence. This report reviews the thyroid cancer incidence in KFSH&RC and compares that with Saudi Arabia, the Gulf region, North America and globally from 2000 to 2010.

METHODS

Retrospective review of patients with thyroid cancer was carried out from 2000 to 2010, using the hospital Tumor Registry program as per the American College of Surgeons standards. Trends and patterns of all well-known prognostic factors were sub-stratified by age, stage and grade.

RESULTS

A total of 2292 patients with thyroid cancer were treated at KFSH&RC, Riyadh, Saudi Arabia, from 2000 to 2010. Thyroid cancer constitutes about 9% of all malignancies and 12% of all female malignancies at KFSH&RC, which are significantly higher compared to the USA, where thyroid cancer represents only 2.9% of all malignancies and 4.6% of all female malignancies. Papillary adenocarcinoma was the most common histological subtype followed by papillary carcinoma, follicular variant. Median age at diagnosis was 40 for females and 44years for males. Overall Age-Standardized Incidence Rate (ASR) was 4.4/100,000 (6.8 for female and 2/100,000 for males) in the Kingdom in 2008. Median age at diagnosis was 38years and the highest incidence was in the 30-39year age group in KFSH&RC. About 48% of patients presented in the localized stage and 60% underwent combined modality treatment consisting of surgery, radiation and hormonal therapy. There was significantly increased incidence among females as compared to males. The age-adjusted thyroid cancer incidence rates from 2000 to 2010 varied three-fold more for females than for males. Considerable geographical variations were present in thyroid cancer incidence in Saudi Arabia.

CONCLUSION

Thyroid cancer incidence rates have increased exponentially between 2000 and 2010 and there is significant geographical variation in the incidence of thyroid cancer throughout the Kingdom. Thyroid cancer has become the second most common cancer among young Saudi women with a male to female ratio at 0.3:1. Rising incidence of thyroid cancer in Saudi Arabia may be due to the increased detection and diagnosis of the thyroid cancers and not only an increase in the true occurrence of thyroid cancer. More studies are required to determine this significant difference at the molecular level.

Standardized Ultrasound Report for Thyroid Nodules: The Endocrinologist's Viewpoint

BACKGROUND

Ultrasonography (US) plays a crucial role in the diagnostic management of thyroid nodules, but its widespread use in clinical practice might generate heterogeneity in ultrasound reports.

OBJECTIVES

The aims of the study were to propose (a) a standardized lexicon for description of thyroid nodules in order to reduce US reports of interobserver variability and (b) a US classification system of suspicion for thyroid nodules in order to promote a uniform management of thyroid nodules.

METHODS

RELEVANT PUBLISHED ARTICLES WERE IDENTIFIED BY SEARCHING MEDLINE AT PUBMED COMBINING THE FOLLOWING SEARCH TERMS: ultrasonography, thyroid, nodule, malignancy, carcinoma, and classification system. Results were supplemented with our data and experience.

RESULTS

A STANDARDIZED US REPORT SHOULD ALWAYS DOCUMENT POSITION, EXTRACAPSULAR RELATIONSHIPS, NUMBER, AND THE FOLLOWING CHARACTERISTICS OF EACH THYROID LESION: shape, internal content, echogenicity, echotexture, presence of calcifications, margins, vascularity, and size. Combining the previous US features, each thyroid nodule can be tentatively classified as: malignant, suspicious for malignancy, borderline, probably benign, and benign.

CONCLUSIONS

We propose a standardized US report and a tentative US classification system that may become helpful for endocrinologists dealing with thyroid nodules in their clinical practice. The proposed classification does not allow to bypass the required cytological confirmation, but may become useful in identifying the lesions with a lower risk of neoplasm.

Local bystander effect induces dormancy in human medullary thyroid carcinoma model in vivo

The extent of local bystander effect induced by fusion yeast cytosine deaminase::uracil phosphoribosyltransferase (yCD) in combination with 5-fluorocytosine (5FC) was evaluated in xenogeneic model of human medullary thyroid carcinoma (MTC). This approach to gene-directed enzyme/prodrug therapy (GDEPT) induces strong bystander cytotoxicity. Effector yCD-TT mixed with target EGFP-TT cells in a ratio 2:9 could achieve significant tumor regression and 14-fold decrease in serum marker calcitonin upon 5FC administration. Histopathological analysis unraveled that antitumor effect resulted in tumor dormancy and proliferation arrest of remaining tumor cell clusters in vivo. yCD/5FC combination represents another GDEPT approach to achieve tumor growth control in MTC.

Medullary thyroid carcinoma: the influence of policy changing in clinical characteristics and disease progression

OBJECTIVE

Medullary thyroid carcinoma (MTC) has varying clinical course. We assessed trends in MTC presentation during the last 34 years.

DESIGN

Retrospective study.

METHODS

One hundred and fifty one patients (44.4% males) were followed for 0.934 years. Patients were classified according to year of diagnosis: group 1, 1977-2000 (n=53) and group 2, 2001-2011 (n=98). Extent of disease at diagnosis, during follow-up, number of surgeries, and pre- and postoperative calcitonin levels were recorded.

RESULTS

In total, 48.34% reported family history of MTC. Group 1 had larger tumors (median 1.70 (intraquartile range (IQR) 1.7) vs 1.1 (1.2) cm, P=0.045, Mann-Whitney), they presented less frequently micro-MTCs (27.8 vs 46.1%, P=0.045), and underwent more multiple surgeries (63.3 vs 20.0%, P<0.001). Group 1 had more frequently progressive disease (35.8 vs 12.2%, P=0.003) and distant metastasis at follow-up (39.7 vs 17.4%, P=0.017). Chronological group (HR 0.15, 95% CI 0.03-0.68, P=0.015) and distant metastases at follow-up (HR 0.07, 95% CI 0.015-0.30, P=0.001) were independently associated with 10-year disease progression (P<0.001). In sporadic cases, cervical lymph node invasion and distant metastases at diagnosis were more frequent in group 1 (72.7 vs 45.5%, P=0.032 and 27.3 vs 5%, P=0.019 respectively); disease stage at diagnosis was more advanced (P=0.004). They underwent more multiple surgeries (P<0.001), presented more frequently distant metastasis at follow-up (67.7 vs 20.0%, P=0.002), had less frequently remission, and more frequently progressive disease (21.4 vs 58.0% and 64.3 vs 14.0% respectively, P<0.001). Postoperative calcitonin levels were higher (P=0.024).

CONCLUSIONS

Recently, an increase in micro-MTCs is observed, while indices of invasiveness and persistence of disease are better. Increased awareness in familial cases, routine calcitonin measurements, and improved surgical procedures could be responsible.

Everolimus is an active agent in medullary thyroid cancer: a clinical and in vitro study

Everolimus, an mTOR inhibitor, which has been demonstrated to induce anti-tumour effects in different types of neuroendocrine tumours, has never been evaluated in patients with medullary thyroid cancer (MTC). The aim of this study was to evaluate the in vitro and in vivo effects of everolimus in combination with octreotide in MTC. Two patients with progressive metastatic MTC and high calcitonin levels were treated with everolimus 5–10 mg/day. Both patients were under treatment with octreotide LAR at the study entry. An in vitro study was also performed to assess everolimus effects on MTC cell lines (TT and MZ-CRC-1 cells). A tumour response was observed in both patients. Serum calcitonin decreased by 86% in patient 1 and by 42% in patient 2. In TT and MZ-CRC-1 cells, everolimus induced a significant dose-dependent inhibition in cell proliferation. This effect seems to be related to a cell cycle arrest in G₀/G₁ phase in both cell lines and to the induction of cellular senescence in TT cells. Everolimus in combination with octreotide may be active as anti-tumour therapy in patients with progressive metastatic MTC, suggesting to further evaluate this agent in MTC patients in a large prospective study.

MicroRNA expression signatures in solid malignancies

An ongoing challenge in cancer research is represented by the identification of new specific clinical molecular markers and pharmacological targets. During the last 10 years, microRNAs (miRNAs) have become one of the hottest subjects in the area of cancer genomics. MicroRNAs are single-stranded RNAs of 19 to 24 nucleotides in length generated through a complex maturation process. Recent studies have demonstrated that microRNAs can have an oncogene or tumor suppressor role by regulating the expression of target genes. Therefore, microRNAs are highly related to cancer processes, including initiation, growth, apoptosis, invasion, and metastasis. In this panorama, several high-through put technologies studies have revealed miRNA roles in classifying tumors and predicting patient outcome with high accuracy. We provide a review highlighting recent progress on the understanding of the cellular function of human microRNAs and their expression in solid tumors.

Somatic RAS mutations occur in a large proportion of sporadic RET-negative medullary thyroid carcinomas and extend to a previously unidentified exon

CONTEXT

Medullary thyroid carcinoma (MTC) is characterized by proto-oncogene RET mutations in almost all hereditary cases as well as in more than 40% of sporadic cases. Recently, a high prevalence of RAS mutations was reported in sporadic MTC, suggesting an alternative genetic event in sporadic MTC tumorigenesis.

OBJECTIVE

This study aimed to extend this observation by screening somatic mutational status of RET, BRAF, and the three RAS proto-oncogenes in a large series of patients with MTC.

MATERIALS AND METHODS

Direct sequencing of RET (exons 8, 10, 11, 13, 14, 15, 16), BRAF (exons 11 and 15), and KRAS, HRAS, and NRAS genes (exons 2, 3, and 4) was performed on DNA prepared from 50 MTC samples, including 30 sporadic cases.

RESULTS

Activating RET mutations were detected in the 20 hereditary cases (germline mutations) and in 14 sporadic cases (somatic mutations). Among the 16 sporadic MTC without any RET mutation, eight H-RAS mutations and five K-RAS mutations were found. Interestingly, nine RAS mutations correspond to mutation hot spots in exons 2 and 3, but the other four mutations were detected in exon 4. The RET and RAS mutations were mutually exclusive. No RAS gene mutation was found in hereditary MTC, and no BRAF or NRAS mutation was observed in any of the 50 samples.

CONCLUSIONS

Our study confirms that RAS mutations are frequent events in sporadic MTC. Moreover, we showed that RAS mutation analysis should not be limited to the classical mutational hot spots of RAS genes and should include analysis of exon 4.

MicroRNA profiles in familial and sporadic medullary thyroid carcinoma: preliminary relationships with RET status and outcome

BACKGROUND

MicroRNAs (miRNAs) are involved in the pathogenesis of human cancers, including medullary thyroid carcinoma (MTC). The aim of this study was to test the hypothesis that different miRNA profiles are related to RET status and prognosis in patients with hereditary MTC (hMTC) and sporadic MTC (sMTC).

METHODS

We analyzed the expression of nine miRNAs (miR-21, miR-127, miR-154, miR-224, miR-323, miR-370, miR-9*, miR-183, and miR-375) by quantitative real-time-polymerase chain reaction in 34 cases of sMTC, 6 cases of hMTC, and 2 cases of C-cell hyperplasia (CCH). We also analyzed the immunohistochemical expression of PDCD4, an miR-21 gene target. sMTC (n=34) was genotyped for somatic RET and RAS mutations. Disease status was defined on the basis of the concentration of serum calcitonin at the latest follow-up and other parameters as indicated in the results.

RESULTS

MTC and CCH were both characterized by a significant overexpression of the whole set of miRNAs (the increase being 4.2-fold for miR-21, 6.7-fold for miR-127, 8.8-fold for miR-154, 6.6-fold for miR-224, 5.8-fold for miR-323, 6.1-fold for miR-370, 13-fold for miR-9*, 6.7-fold for miR-183, and 10.1 for miR-375, p<0.0001). PDCD4 expression was significantly downregulated in MTC samples, consistent with miR-21 upregulation. Significantly lower miR-127 levels were observed in sMTC carrying somatic RET mutations in comparison to sMTC carrying a wild-type RET. In sMTC and familial MTC, the miR-224 upregulation correlated with the absence of node metastases, lower stages at diagnosis, and with biochemical cure during follow-up.

CONCLUSIONS

miRNAs are significantly dysregulated in MTC, and this dysregulation is probably an early event in C-cell carcinogenesis. miR-224 upregulation could represent a prognostic biomarker associated with a better outcome in MTC patients.

A Case of F-18 FDG PET-CT Detection of Sporadic Medullary Thyroid Carcinoma and Cervical Lymph Node Metastasis of Ovarican Cancer

Medullary thyroid carcinoma (MTC) is derived from the parafollicular or C-cells. As surgical resection is the only curative therapy for MTC, the early diagnosis is important for the patient's survival. F18-Fluorodeoxyglucose positron emission tomography-computed tomography (F-18 FDG PET CT) is a noninvasive imaging method which can be used to diagnose malignant thyroid tumors including recurrent or residual MTC. However, due to the limitations of this technique, it is difficult to differentiate benign from malignant thyroid tumors. We herein present a 47-year-old woman with ovarian cancer history who was found to have thyroid incidentaloma with metastatic cervical lymph node through F-18 FDG PET CT. Thyroid incidentaloma of the patient was examined by fine needle aspiration and the result of this diagnostic procedure showed suspicious MTC. The patient was subsequently diagnosed as having sporadic medullary thyroid carcinoma and metastatic cervical lymph node due to ovarian cancer.

Vandetanib for the treatment of metastatic medullary thyroid cancer

Medullary thyroid cancer (MTC) represents an aggressive form of thyroid malignancy. Some may occur spontaneously or can be associated with Multiple Endocrine Neoplasia syndromes, or Familial Medullary Thyroid Cancer syndrome. In these patients, the protooncogene RET (rearranged during transfection) is mutated. In patients who have unresectable or metastatic disease, the long term prognosis is poor. New treatments for this disease have focused on the use of targeted agents that inhibit the receptor tyrosine kinase of RET. One of these treatments, Vandetanib (Caprelsa, Astra Zeneca), recently has received approval from the Food and Drug Administration for the treatment of patients with progressive locally advanced and/or metastatic disease. This review highlights the studies that led to the drug's approval, and discusses on the potential financial costs of treatment and side effects of this therapy. The main clinical studies evaluating Vandetanib for the treatment of other solid tumors will also be reviewed.

Correlation between Calcitonin Levels and [(18)F]FDG-PET/CT in the Detection of Recurrence in Patients with Sporadic and Hereditary Medullary Thyroid Cancer

Purpose. Measurement of serum calcitonin is important in the followup of patients with medullary thyroid carcinoma (MTC) and reliably reflects the presence of the disease. This is the largest study so far in bibliography investigating the diagnostic accuracy of combined [(18)F]FDG-PET/CT in patients with MTC and elevated calcitonin levels. Methods. Between February 2007 and February 2011, 59 [(18)F]FDG-PET/CT were performed on 51 patients with MTC and elevated calcitonin levels for localization of recurrent disease. Conventional morphologic imaging methods were negative or showed equivocal findings. Results. Among the 59 [(18)F]FDG-PET/CT, 29 were positive (26 had true-positive and 3 false-positive findings) and 30 negative. The overall per-patient sensitivity of [(18)F]FDG-PET/CT was 44.1%. Using as cut-off point the calcitonin value of 1000 pg/ml, in patients with calcitonin exceeding this value, sensitivity raised to 86.7%. The overall sensitivity of [(18)F]FDG-PET/CT was lower (23%) in patients with MEN IIA syndrome. Conclusion. The findings of this paper show that [(18)F]FDG-PET/CT is valuable for the detection of recurrence in patients with highly elevated calcitonin levels, >1000 pg/mL, but in patients with lower calcitonin levels, its contribution is questionable. Also, there is evidence that the sensitivity of [(18)F]FDG-PET/CT is lower in patients with MTC as part of MEN IIA syndrome.

Anti-tumor activity of motesanib in a medullary thyroid cancer model

BACKGROUND

Medullary thyroid cancer (MTC) is frequently associated with mutations in the tyrosine kinase Ret and with increased expression of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2). Motesanib is an investigational, orally administered small molecule antagonist of VEGFR1, 2, and 3; platelet-derived growth factor receptor (PDGFR); Kit; and possibly Ret.

AIM

The aim of this study was to investigate the effects of motesanib on wildtype and mutant Ret activity in vitro and on tumor xenograft growth in a mouse model of MTC.

METHODS/RESULTS

In cellular phosphorylation assays, motesanib inhibited the activity of wild-type Ret (IC(50)=66 nM), while it had limited activity against mutant Ret C634W (IC(50)=1100 nM) or Ret M918T (IC(50)>2500 nM). In vivo, motesanib significantly inhibited the growth of TT tumor cell xenografts (expressing Ret C634W) and significantly reduced tumor blood vessel area and tumor cell proliferation, compared with control. Treatment with motesanib resulted in substantial inhibition of Ret tyrosine phosphorylation in TT xenografts and, at comparable doses, in equivalent inhibition of VEGFR2 phosphorylation in both TT xenografts and in mouse lung tissue.

CONCLUSIONS

The results of this study demonstrate that motesanib inhibited thyroid tumor xenograft growth predominantly through inhibition of angiogenesis and possibly via a direct inhibition of VEGFR2 and Ret expressed on tumor cells. These data suggest that targeting angiogenesis pathways and specifically the VEGF pathway may represent a novel therapeutic approach in the treatment of MTC.

[Calcitonin: indications and interpretation]

Calcitonin is the sensitive and specific marker of the medullary thyroid cancers. It is a diagnostic, pronostic and follow-up marker. Medullary thyroid cancer is a rare disease representing 4% of the thyroid cancers and occurring in 0.4% of nodular thyroid pathology. The use of sex specific adults normal ranges allows a better interpretation of the moderately elevated calcitonin levels. Hypercalcitoninaemia non due to medullary thyroid cancer are attributed mainly to male sex, tobacco use, overweight, renal failure and other endocrine tumors. CT is associated to carcinoembryonic antigen and possible procalcitonin assays. Calcitonin can be assayed in the wash-out fluid of the fine needle aspiration too. Stimulation tests give poor additional diagnostic information and are about to be abandoned.

XL184 (cabozantinib) for medullary thyroid carcinoma

INTRODUCTION

Intrathyroidal medullary thyroid carcinoma (MTC) can generally be cured by surgery, but distant metastases are often already present at diagnosis.Currently, there is no effective treatment for metastatic MTC. In these cases, consensus treatment guidelines explicitly recommend new experimental drugs. Several kinase inhibitors are now being tested for treatment of MTC in clinical trials and XL184, an oral, small-molecule multi-kinase inhibitor, seems to be one of the most promising of these compounds.

AREAS COVERED

We review preliminary data on the safety and efficacy of XL184 in metastatic MTC based on an extensive search of the literature, which included published articles, abstracts and website information. In particular,the review focuses on the rationale for using XL184 in advanced MTC. The compound has been specifically designed to target multiple signaling pathways,and this is expected to produce synergistic antitumor effects superior to those achieved by single-kinase inhibition. Preliminary results from the Phase I study of XL184 seem to support this hypothesis.

EXPERT OPINION

Multiple receptor tyrosine kinases (RTKs) are concomitantly activated in the same tumor. The blockade of a single RTK may engage compensatory signaling that maintains cell growth. Targeting multiple kinases might overcome both intrinsic and acquired resistance to antitumoral drugs.

MicroRNA profiling of sporadic and hereditary medullary thyroid cancer identifies predictors of nodal metastasis, prognosis, and potential therapeutic targets

PURPOSE

While the molecular basis of hereditary medullary thyroid cancer (HMTC) has been well defined, little is known about the molecular pathogenesis of sporadic medullary thyroid cancer (SMTC). In addition, microRNAs (miRNAs) have been shown to be important diagnostic and prognostic markers in cancer but have not been defined in MTC. Our aim was to study the miRNA profile of MTC to identify prognostic biomarkers and potential therapeutic targets.

EXPERIMENTAL DESIGN

MiRNA microarray profiling was carried out in fresh frozen tissues from patients with SMTC (n = 12) and HMTC (n = 7). Differential expression of three miRNAs was confirmed in a validation cohort of SMTC and HMTC samples (n = 45) using quantitative reverse transcriptase-PCR and correlated with clinical outcomes. The functional role of a selected miRNA was investigated in vitro in the human medullary thyroid carcinoma cell line (TT cells) using cell proliferation assays and Western blotting analysis.

RESULTS

MiRs-183 and 375 were overexpressed (P = 0.001; 0.031) and miR-9* was under-expressed (P = 0.011) in SMTC versus HMTC. Overexpression of miRs-183 and 375 in MTC predicted lateral lymph node metastases (P < 0.001; P = 0.001) and was associated with residual disease (P = 0.001; 0.003), distant metastases (P = 0.003; 0.001), and mortality (P = 0.01; 0.011). Knock down of miR-183 expression in the TT cell line induced a significant decrease in the viable cell count and upregulation of the protein LC3B, which is associated with autophagy.

CONCLUSIONS

Our data indicate that miRNAs play a pivotal role in the biology of MTC and represent an important class of prognostic biomarkers and therapeutic targets warranting further investigation.

Ultrasonographic findings of medullary thyroid cancer: differences according to tumor size and correlation with fine needle aspiration results

BACKGROUND

Complete initial tumor resection is a key prognostic factor in patients with medullary thyroid carcinomas (MTCs), hence precise preoperative diagnosis is very important. Thyroid ultrasonography (US) is a first-line modality and can lead to the appropriate next diagnostic procedure.

PURPOSE

To evaluate the US characteristics of MTCs, to evaluate whether or not there is a difference in US findings according to tumor size, and to correlate the US findings with fine needle aspiration (FNA) results.

MATERIAL AND METHODS

Thirty patients with 36 MTCs who had a preoperative US and a MTC diagnosis based on surgery were included. The US findings of each nodule were retrospectively analyzed in terms of size, internal content, shape, margin, echogenicity of solid portions, the presence of calcifications, the type of calcifications, and the presence of a halo by two radiologists. Each lesion was classified as suspiciously malignant, indeterminate, or probably benign according to known US criteria. The FNA results for the 28 MTCs were reviewed from the cytology reports.

RESULTS

The lesion size varied from 5.7-90.0 mm (mean 22.4 ± 14.4 mm). The predominate US findings included solid internal content (91.7%), round-to-oval shape (63.9%), smooth margins (52.8%), hypoechogenicity (72.2%), and micro- or macro-calcifications (61.1%). Twenty-six nodules (72.2%) were classified as suspiciously malignant, and 10 nodules (27.8%) were classified as indeterminate. Of the 27 MTCs classified as suspiciously malignant, 21 MTCs (77.8%) had micro- or macro-calcifications, which was the most common malignant feature. MicroMTCs (≤1 cm) had spiculated margins more frequently than macroMTCs (66.7% vs. 13.3%; P = 0.014) and macroMTCs (>1 cm) had smooth margins more frequently than microMTCs (63.4% vs. 0%; P = 0.006). Twenty-one MTCs with positive FNA results showed smooth margins and a larger size more frequently than seven MTCs with negative FNA results (66.7% vs. 14.3%; P = 0.029; mean diameter, 24.28 ± 13.45 mm vs. 11.74 ± 4.73 mm, P = 0.004, respectively).

CONCLUSION

Based on US, the majority of MTCs can be classified as suspiciously malignant due to the presence of micro- or macro-calcifications. Small MTC size (≤ 10 mm) and a smooth margin may be factors predicting false-negative FNA results.

Molecular analysis of the RET proto-oncogene key exons in patients with medullary thyroid carcinoma: a comprehensive study of the Iranian population

BACKGROUND

Germ-line mutations of RET proto-oncogene are the known cause of hereditary medullary thyroid carcinoma (MTC), which account for approximately 25% of all MTC cases and occur as multiple endocrine neoplasia type 2 syndromes. Here, we present the first comprehensive genetic screening and analysis of MTC among Iranian families.

METHODS

A total of 55 patients with MTC (male to female ratio=1:1.6; average age of disease onset = 33 ± 13 years) from 53 independent families participated in this study. All of the patients had undergone total thyroidectomy between 1999 and 2006, and 51 of them were clinically characterized as apparently sporadic cases. Genomic DNA samples were obtained and following highly-specific polymerase chain reaction amplification of the 6 RET key exons (10, 11, 13, 14, 15, and 16) were subjected to direct DNA sequencing without a requirement for a purification step.

RESULTS

Sequence analysis revealed that 9 (17.6%) of the apparently sporadic cases (from 8 kindreds) carried an RET germ-line mutation. Of the seven different mutations identified among all of the families studied, five were in the cysteine codons, with Cys634Arg having the highest prevalence (45.5%) among the afflicted families. Mutation carriers have an earlier age of onset (21 ± 6) versus the sporadic cases (37 ± 12).

CONCLUSIONS

This is the first comprehensive genetic screening and analysis of MTC among Iranian families. The results further confirm the need and advantages of DNA sequencing for identification of hereditary MTC cases. There does not seem to be a meaningful correlation between single nucleotide polymorphism patterns and the average age of disease onset. Geographical distribution of the sporadic cases, however, shows a significant concentration toward the Northern regions of the country, noticeably the provinces situated directly to the south of the Caspian Sea.

Liraglutide - overview of the preclinical and clinical data and its role in the treatment of type 2 diabetes

Type 2 diabetes is characterized by a progressive decline in glycaemic control. Many standard diabetes treatments, however, fail to achieve or maintain glycaemic control, and are often associated with an increased risk of hypoglycaemia and weight gain. Recently developed incretin-based therapies are a promising addition to the current armamentarium of diabetes treatments. Two types of incretin-based therapies are currently available: glucagon-like peptide (GLP)-1 receptor agonists (liraglutide and exenatide) and dipeptidyl peptidase-4 inhibitors (sitaglipin, vildagliptin and saxagliptin). This review aims to summarize the key efficacy and safety data of liraglutide, a once-daily human GLP-1 analogue. Extensive phase III clinical trials have shown liraglutide to improve glycaemic control with additional benefits on body weight, blood pressure and β-cell function. Liraglutide is also generally well tolerated with a low risk of hypoglycaemia. Liraglutide has recently been approved for marketing in Europe, Japan and the USA.

Prognostic factors of disease-free survival after thyroidectomy in 170 young patients with a RET germline mutation: a multicenter study of the Groupe Francais d'Etude des Tumeurs Endocrines

BACKGROUND

In hereditary medullary thyroid carcinoma (HMTC), prophylactic surgery is the only curative option, which should be properly defined both in time and extent.

OBJECTIVES

To identify and characterize prognostic factors associated with disease-free survival (DFS) in children from HMTC families.

DESIGN

We conducted a retrospective analysis of a multi-center cohort of 170 patients below age 21 at surgery. Demographic, clinical, genetic, biological data [basal and pentagastrine-stimulated calcitonin (CT and CT/Pg, respectively)], and tumor node metastasis (TNM) status were collected. DFS was assessed based on basal CT levels. Kaplan-Meier curves, Cox regression, and logistic regression models were used to determine factors associated with DFS and TNM staging.

RESULTS

No patients with a preoperative basal CT <31 ng/ml had persistent or recurrent disease. Medullary thyroid carcinoma defined by a diameter ≥10 mm [hazard ratio (HR): 6.0; 95% confidence interval (95% CI): 1.8-19.8] and N1 status (HR: 20.8; 95% CI: 3.9-109.8) were independently associated with DFS. Class D genotype [odds ratio (OR): 48.5, 95% CI: 10.6-225.1], preoperative basal CT >30 ng/liter (OR: 43.4, 95% CI: 5.2-359.8), and age >10 (OR: 5.5, 95% CI: 1.4-21.8) were associated with medullary thyroid carcinoma ≥10 mm. No patient with a preoperative basal CT <31 ng/ml had a N1 status. Class D genotype (OR: 48.6, 95% CI: 8.6-274.1), and age >10 (OR: 4.6, 95% CI: 1.1-19.0) were associated with N1 status.

CONCLUSION

In HMTC patients, DFS is best predicted by TNM staging and preoperative basal CT level below 30 pg/ml. Basal CT, class D genotype, and age constitute key determinants to decide preoperatively timely surgery.

GLP-1 and calcitonin concentration in humans: lack of evidence of calcitonin release from sequential screening in over 5000 subjects with type 2 diabetes or nondiabetic obese subjects treated with the human GLP-1 analog, liraglutide

BACKGROUND

Serum calcitonin (CT) is a well-accepted marker of C-cell proliferation, particularly in medullary thyroid carcinoma. Chronic glucagon-like peptide-1 (GLP-1) receptor agonist administration in rodents has been associated with increased serum CT levels and C-cell tumor formation. There are no longitudinal studies measuring CT in humans without medullary thyroid carcinoma or a family history of medullary thyroid carcinoma and no published studies on the effect of GLP-1 receptor agonists on human serum CT concentrations.

AIM

The aim of the study was to determine serum CT response over time to the GLP-1 receptor agonist liraglutide in subjects with type 2 diabetes mellitus or nondiabetic obese subjects.

METHODS

Unstimulated serum CT concentrations were measured at 3-month intervals for no more than 2 yr in a series of trials in over 5000 subjects receiving liraglutide or control therapy.

RESULTS

Basal mean CT concentrations were at the low end of normal range in all treatment groups and remained low throughout the trials. At 2 yr, estimated geometric mean values were no greater than 1.0 ng/liter, well below upper normal ranges for males and females. Proportions of subjects whose CT levels increased above a clinically relevant cutoff of 20 ng/liter were very low in all groups. There was no consistent dose or time-dependent relationship and no consistent difference between treatment groups.

CONCLUSIONS

These data do not support an effect of GLP-1 receptor activation on serum CT levels in humans and suggest that findings previously reported in rodents may not apply to humans. However, the long-term consequences of GLP-1 receptor agonist treatment are a subject of further studies.

Identification of soluble candidate biomarkers of therapeutic response to sunitinib in medullary thyroid carcinoma in preclinical models

PURPOSE

Medullary thyroid carcinoma (MTC), an aggressive rare tumor due to activating mutations in the proto-oncogene RET, requires new therapeutic strategies. Sunitinib, a potent inhibitor of RET, VEGF receptor (VEGFR)-1, VEGFR-2, VEGFR-3, and platelet-derived growth factor receptor (PDGFR)α/β, has been reported as clinically effective in some patients with advanced MTC. In this study, we examine molecular mechanisms of action of sunitinib and identify candidate soluble biomarkers of response.

EXPERIMENTAL DESIGN

Both in vitro and in vivo assays, using the human TT RET(C634W) MTC cell line, were done to assess the activity of sunitinib. Kinetic microarray studies were used to analyze molecular pathways modified by sunitinib and to identify candidate biomarkers that were subsequently investigated in the serum of patients.

RESULTS

Sunitinib displayed antiproliferative and antiangiogenic activities and inhibited RET autophosphorylation and activation of downstream signaling pathways. We showed that sunitinib treatment induced major changes in the expression of genes involved in tissue invasion and metastasis including vimentin (VIM), urokinase plasminogen (PLAU), tenascin-C (TN-C), SPARC, and CD44. Analyzing downregulated genes, we identified those encoding secreted proteins and, among them, interleukin (IL)-8 was found to be modulated in the serum of xenografted mice under sunitinib treatment. Furthermore, we demonstrated that metastatic MTC patients presented increased serum levels of IL-8 and TGF-β2.

CONCLUSIONS

Experimental models confirm the clinical efficacy of sunitinib observed in a few studies. Molecular pathways revealed by genomic signatures underline the impact of sunitinib on tissue invasion. Selected soluble candidate biomarkers could be of value for monitoring sunitinib response in metastatic MTC patients.

Early diagnosis of medullary thyroid carcinoma: is systematic calcitonin screening appropriate in patients with nodular thyroid disease?

Because of its poor prognosis and high mortality rate, early diagnosis of medullary thyroid carcinoma (MTC) is a challenge. For almost two decades, routine serum calcitonin (CT) measurement has been used as a tool for early MTC diagnosis, with conflicting results. In 2006, the European Thyroid Association (ETA) recommended serum CT measurement in the initial workup of thyroid nodules, whereas the American Thyroid Association (ATA) declined to recommend for or against this approach. In late 2009, the revised ATA guidelines were published, and in June 2010 the ETA released new guidelines for the diagnosis and management of thyroid nodules that had been drafted in collaboration with the American Association of Clinical Endocrinologists and with the Associazione Medici Endocrinologi, and the picture became even more complex. The ATA still takes no stand for or against screening but acknowledges that, if testing is done, a CT value >100 pg/ml should be considered suspicious and an indication for treatment. As for the ETA, it seems to have taken a step back from its 2006 position, and it now advocates CT screening only in the presence of clinical risk factors. These new positions are more cautious and less straightforward because prospective, randomized, large-scale, long-term trial data are lacking. Are such studies feasible? Can they solve the CT dilemma? In the absence of adequate evidence, selective aggressive case finding should be pursued to improve MTC prognosis.

Medullary thyroid carcinoma: long-term outcomes of surgical treatment

BACKGROUND

Medullary thyroid carcinoma (MTC) accounts for 5 to 10% of all thyroid cancers but is responsible for a disproportionate number of deaths.

METHODS

We performed a retrospective review to describe clinical outcomes in patients with medullary thyroid carcinoma, screening a subset of patients for somatic mutations in the RET and p18 genes and performing genotype-phenotype correlation in a tertiary-care referral hospital from 1967 to 2009.

RESULTS

We studied a total of 94 patients identified from a prospectively maintained thyroid cancer database. Data gathered included patient demographics, serum calcitonin, clinical outcomes, histopathology, genetic analysis, and status at final follow-up. A subset cohort (n = 50) was screened for somatic mutations in the RET gene and the three exons of the p18 gene. The subset cohort was composed of hereditary medullary thyroid carcinoma (HMTC) (n = 19, index patients = 10, screen detected = 9) and sporadic medullary thyroid carcinoma (SMTC) (n = 31). There were no mutations in the p18 gene in the subset cohort.

CONCLUSIONS

A total of 67 SMTC and 27 (28.7%) HMTC cases identified. SMTC were older at initial presentation (52 vs. 34, P = 0.003), had higher preoperative serum calcitonin levels (7968 vs. 1346 ng/L, P = 0.008), and had lymph node recurrence (P = 0.001) compared to HMTC. The tumors were smaller in HMTC (P = 0.038). Overall 10-year survival in SMTC versus HMTC was 69 versus 93% (P = 0.12). On multivariate analysis, vascular invasion (hazard ratio 6.4, P = 0.019) was an adverse predictor for disease-free survival. HMTC in the era of RET analysis presents with a smaller primary tumor, lower preoperative serum calcitonin levels, and lower rates of lymph node metastasis. Mutations in the p18 gene were not a major factor in medullary thyroid carcinoma tumorigenesis.

A decrease of calcitonin serum concentrations less than 50 percent 30 minutes after thyroid surgery suggests incomplete C-cell tumor tissue removal

CONTEXT AND OBJECTIVES

The prognosis of medullary thyroid carcinoma (MTC) depends on the completeness of the first surgical treatment. To date, it is not possible to predict whether the tumor has been completely removed after surgery. The aim of this study was to evaluate the reliability of an intraoperative calcitonin monitoring as a predictor of the final outcome after surgery in patients with MTC.

PATIENTS AND METHODS

Twenty patients underwent total thyroidectomy and central lymph node dissection on the basis of a positive pentagastrin test. In six cases a preoperative diagnosis of MTC was achieved at the cytological examination. During the surgical intervention, calcitonin was measured at the time of anesthesia, at the time of manipulation, and 10 and 30 min after surgical excision. At the histological examination, 10 patients had MTC and 10 had C cell hyperplasia.

RESULTS

As compared with calcitonin levels before thyroidectomy, a decrease of calcitonin greater than 50% 30 min after surgery was able to significantly distinguish patients who were cured from those who experienced persistence of disease. It was not possible to find a similar result when the decrease of calcitonin 10 min after surgery was considered.

CONCLUSIONS

A rate of calcitonin decrease less than 50% 30 min after thyroidectomy plus central neck lymph node dissection suggests the persistence of tumor tissue in patients operated for MTC. These results indicate that intraoperative calcitonin monitoring may be a useful tool to predict the completeness of surgery in patients with MTC.

Targeted molecular therapies in thyroid carcinoma

Thyroid cancer incidence has significantly increased in the last three decades and many patients seek medical attention for its treatment every year. Among follicular cell-derived tumors, the majority are differentiated thyroid carcinomas (DTC), whose prognosis is very good with only 15% of the cases presenting disease persistence or recurrence after initial treatment. Medullary thyroid carcinoma has a worse prognosis, especially in patients with diffused cancers at the time of initial surgery. Traditional treatment options for persistent or recurrent disease include additional surgery, radioiodine treatment and TSH-suppression in DTC patients; external beam radiotherapy, and cytotoxic chemotherapy, often have low efficacy and many patients with advanced disease ultimately die. In the last two decades many of the molecular events involved in cancer formation have been uncovered. This knowledge has prompted the development of novel therapeutic strategies mainly based on the inhibition of key molecular mediators of the tumorigenic process. In particular the class of small-molecule tyrosine kinase inhibitors was enriched by many compounds that have reached clinical trials and in some cases have had approval for clinical use in specific cancers. Many of these compounds entered clinical trials also for locally advanced or metastatic thyroid carcinomas showing very promising results.

Increased expression of vascular endothelial growth factor and its receptors, VEGFR-1 and VEGFR-2, in medullary thyroid carcinoma

BACKGROUND

Vascular endothelial growth factor (VEGF-A) expression is upregulated in the majority of human tumors, where it stimulates proliferation, migration, and survival of endothelial cells. Studies have suggested that VEGF inhibitors can be used as an alternative therapy in medullary thyroid carcinoma (MTC), but data about expression of VEGF-A and its receptor in this tumor are scarce. The aims of this study were to evaluate VEGF-A, VEGF receptor (VEGFR)-1, VEGFR-2, and microvessel density (MVD) expression in MTC samples and correlate it with clinical parameters.

METHODS

Paraffin-embedded samples from 38 MTC patients were evaluated for VEGF-A, VEGFR-1, VEGFR-2, and MVD expression by immunohistochemistry. Clinical data were retrospectively reviewed in medical records.

RESULTS

Thirty-eight patients aged 31.8 +/- 17.1 years were enrolled. Twenty-seven patients had hereditary disease (71.1%). Twenty-five of them were found to have multiple endocrine neoplasia (MEN) 2A and two were found to have MEN 2B. VEGF-A immunohistochemical staining was detected in 95% (36/38), VEGFR-1 in 96% (36/37), and VEGFR-2 in 91% (31/34) of MTC samples. Age at surgery was positively correlated with VEGFR-2 (p = 0.003). There was no correlation between VEGF-A, VEGFR-2, and tumor stage (tumor node metastasis). Nevertheless, VEGFR-1 was found to be inversely correlated with tumor node metastasis (p = 0.034). We also observed a trend toward an association between VEGFR-1 signal intensity and cure of disease, although this did not reach statistical significance (p = 0.054). Neither VEGF-A nor VEGFR-2 was associated with disease outcome after a median follow-up period of 5 years (p = 0.882 and p = 0.236, respectively). As expected, MVD was correlated with age at surgery (p = 0.005) and tumor size (p = 0.03). Patients with the hereditary form of the disease had a stronger intensity for VEGFR-1 (p = 0.039), whereas patients with sporadic disease displayed higher MVD counts (44 [27-63] vs. 21 [9-49], p = 0.018).

CONCLUSION

The VEGF-A, VEGFR-1, and VEGFR-2 immunoreactive proteins are overexpressed in MTC lesions and might be implicated in tumor progression. It is not clear, however, if expression of these molecules provides prognostic information regarding the spread or outcome of MTC.

Combined treatment and survival of medullary thyroid carcinoma patients

The aim of this study is to analyze the impact of combined treatment (thyroidectomy and radiotherapy and radioactive iodine treatment) on patients’ long-term survival with medullary thyroid carcinoma. This is a retrospective study of 59 patients treated from 1977 to 2006 for medullary carcinoma at the Institute of Oncology in Vilnius, Lithuania. Survival was estimated by the Kaplan-Meier method. Univariate and multivariate Cox proportional hazard models were used to explore the association of prognostic factors with long-term survival. The survival of MTC patients was 88.0% (95% CI 68.0–88.9), 67.9% (95% CI 52.3–79.4) and 60.5% (95% CI 43.2–74.0), respectively, 5, 10 and 15 years after diagnosis. In survival analysis, only the type of surgery and lymph node involvement were found to be significant prognostic factors. The results of this study suggest that treatment with radioiodine and external beam radiotherapy do not improve significantly the long-term survival of surgically treated MTC patients.

Drosophila as a novel therapeutic discovery tool for thyroid cancer

BACKGROUND

Multiple endocrine neoplasia type II (MEN2) is a rare but aggressive cancer for which no effective treatment currently exists. A Drosophila model was developed to identify novel genetic modifier loci of oncogenic RET, as well as to provide a whole animal system to rapidly identify compounds that suppressed RET-dependent MEN2. ZD6474 (Vandetanib), currently in phase III trials, suppressed tumorigenesis in MEN2 model flies, demonstrating for the first time the effectiveness of a Drosophila-based whole animal model for identifying therapeutically useful compounds.

SUMMARY

Clinical data suggest that drug mono-therapy for MEN2 and other cancers typically yield only moderate benefits as patients develop drug resistance and suffer from drug-induced pathway feedback. Combinations of drugs that target different nodes of the oncogenic pathway are an effective way to prevent resistance as well as feedback. Identifying the optimal drug-dose combinations for therapy poses a significant challenge in existing mouse models. Fly models offer a means to quickly and effectively identify drug combinations that are well tolerated and potently suppress the MEN2 phenotype. This approach may also identify differences in therapeutic responses between the two subtypes of MEN2--MEN2A and MEN2B--providing additional therapeutic insights.

CONCLUSIONS

Fly models have proven useful for identifying known drugs as well as novel compounds that, as single agents or in combinations, effectively suppress the MEN2 syndrome. These findings validate the use of fly models for both drug discovery as well as identification of useful drug combinations. In the future, rapid pairing of new genomic information with increasingly complex fly models will aid us in efforts to further tailor drug treatments toward personalized medicine.