Medullary thyroid carcinoma: recent advances and management update

Extent of Surgery for Medullary Thyroid Cancer and Prevalence of Occult Contralateral Foci

Importance

Standard treatment for patients with medullary thyroid cancer (MTC) consists of total thyroidectomy with central neck dissection, but the rationale for bilateral surgery in patients with unilateral disease on ultrasonography remains unclear.

Objective

To determine the presence of occult contralateral disease (lesions not seen on preoperative ultrasonography) in patients with MTC as a rationale for total thyroidectomy.

Design, Setting, and Participants

This multi-institutional, retrospective cohort study was conducted from September 1998 to April 2022 in academic medical centers and included patients with MTC who underwent thyroidectomy with preoperative imaging.

Main Outcomes and Measures

The primary end point was the prevalence of sonographically occult foci of MTC in the contralateral lobe among patients with sporadic MTC.

Results

The cohort comprised 176 patients with a median age at diagnosis of 55 years (range, 2-87 years), 69 (57.6%) of whom were female. Genetic testing was performed in 109 patients (61.9%), 48 (27.5%) of whom carried germline RET variants. Initial surgical management consisted of total thyroidectomy (161 [91.0%]), lobectomy followed by completion thyroidectomy (7 [4.0%]), and lobectomy alone (8 [4.5%]). Central and lateral neck dissections were performed as part of initial therapy for 146 patients (83.1%). In the entire cohort of 176 patients, 46 (26.0%) had contralateral foci disease and 9 (5.1%) had occult contralateral foci that were not identified on preoperative ultrasonography. Among 109 patients who underwent genetic testing, 38 (34.9%) had contralateral disease, 8 (7.3%) of whom had occult contralateral disease not seen on preoperative ultrasonography. Patients with sporadic MTC experienced a 95.7% reduction in the odds of having a focus of MTC in the contralateral lobe compared with patients with a germline RET variant (odds ratio, 0.043; 95% CI, 0.013-0.123). When adjusting for age, sex, tumor size, and lymph node involvement, the odds ratio of having contralateral MTC in patients with sporadic disease was 0.034 (95% CI, 0.007-0.116). Among patients who underwent lobectomy alone with postoperative calcitonin levels, 5 of 12 (41.7%) achieved undetectable calcitonin levels (<2.0 pg/mL; to convert to pmol/L, multiply by 0.292).

Conclusions and Relevance

The results of this cohort study suggest that a staged approach involving initial thyroid lobectomy could be considered in patients with sporadic MTC and no contralateral ultrasonography findings, with no further surgery if calcitonin levels became undetectable. Further work using prospective randomized clinical trials to evaluate lobectomy as a biochemical cure in patients presenting with unilateral disease is warranted.

Optimizing Diagnostic Accuracy of Fine Needle Aspiration Biopsy Calcitonin Measurements in Detecting Medullary Thyroid Carcinoma

Background: The optimal cutoff value of calcitonin (Ctn) levels measured using an electrochemiluminescence immunoassay (ECLIA) obtained from the washout fluid of fine needle aspiration (FNA-Ctn) for the diagnosis of medullary thyroid carcinoma (MTC) is currently not established. We evaluated the diagnostic accuracy and clinical utility of FNA-Ctn for the diagnosis and location of MTC in patients with nodular or multinodular goiters. Methods: This was a case-control study nested on a prospective multicenter cohort of patients with nodular or multinodular goiter, normal or elevated serum Ctn, and thyroidectomy indications. Ctn and FNA-Ctn were measured using ECLIA methodology before surgery. From this nested cohort, MTC cases and controls (non-medullary pathology) were identified from the final pathological analysis. Cumulative incidence sampling of controls was randomly performed at a ratio of 1:2. Sensitivity, specificity, and area under the receiver operator curve (AUROC) were calculated for patients and the total number of thyroid nodules. Results: From 1272 patients included in the prospective cohort, 50 MTC cases and 105 controls were included. In this study, 286 thyroid nodules were evaluated (63 MTC and 223 non-MTCs). The median serum Ctn value was significantly higher in cases (525 pg/mL [interquartile range (IQR), 162.5-1.200]) than in controls (1.6 pg/mL [IQR, 0.5-5.6]; p < 0.001). The median FNA-Ctn value was significantly higher in MTC nodules (3.100 pg/mL [IQR, 450-45,200]) than in non-MTC nodules (0.5 pg/mL [IQR, 0.5-0.5]; p < 0.0001). In 11 MTC patients with multinodular goiter, the FNA-Ctn value was significantly higher in non-medullary nodules located in the same lobe where an MTC nodule was diagnosed (p = 0.0002). Overall, the FNA-Ctn AUROC was 0.99 [95% confidence interval, 0.98-1.0], and a threshold of ≥220 pg/mL showed 100% sensitivity and 98% specificity for MTC diagnosis. Conclusions: The use of FNA-Ctn measured by ECLIA showed adequate diagnostic accuracy for MTC diagnosis. Moreover, it may be clinically useful for localization in multinodular goiter when lobectomy is considered. Clinical Trial Registration: Clinicaltrials.gov NCT06067594.

Different RONS Generation in MTC-SK and NSCL Cells Lead to Varying Antitumoral Effects of Alpha-Ketoglutarate + 5-HMF

BACKGROUND

Carbonylated proteins (CPs) serve as specific indicators of increased reactive oxygen and nitrogen species (RONS) production in cancer cells, attributed to the dysregulated mitochondrial energy metabolism known as the Warburg effect. The aim of this study was to investigate the potential of alpha-ketoglutarate (aKG), 5-hydroxymethylfurfural (5-HMF), and their combination as mitochondrial-targeting antioxidants in MTC-SK or NCI-H23 cancer cells.

METHODS

MTC-SK and NCI-H23 cells were cultured in the absence or presence of varying concentrations (0-500 µg/mL) of aKG, 5-HMF, and the combined aKG + 5-HMF solutions. After 0, 24, 48, and 72 h, mitochondrial activity, cancer cell membrane CP levels, cell growth, and caspase-3 activity were assessed in aliquots of MTC-SK and NCI-H23 cells.

RESULTS

The mitochondrial activity of MTC-SK cells exhibited a concentration- and time-dependent reduction upon treatment with aKG, 5-HMF, or the combined aKG + 5-HMF. The half-maximal inhibitory concentration (IC50%) for mitochondrial activity was achieved at 500 µg/mL aKG, 200 µg/mL 5-HMF, and 200 µg/mL aKG + 66.7 µg/mL 5-HMF after 72 h. In contrast, NCI-H23 cells showed a minimal reduction (10%) in mitochondrial activity even at the highest combined concentration of aKG + 5-HMF. The CP levels in MTC-SK cells were measured at 8.7 nmol/mg protein, while NCI-H23 cells exhibited CP levels of 1.4 nmol/mg protein. The combination of aKG + 5-HMF led to a decrease in CP levels specifically in MTC-SK cells. The correlation between mitochondrial activity and CP levels in the presence of different concentrations of combined aKG + 5-HMF in MTC-SK cells demonstrated a linear and concentration-dependent decline in CP levels and mitochondrial activity. Conversely, the effect was less pronounced in NCI-H23 cells. Cell growth of MTC-CK cells was reduced to 60% after 48 h and maintained at 50% after 72 h incubation when treated with 500 µg/mL aKG (IC50%). Addition of 500 µg/mL 5-HMF inhibited cell growth completely regardless of the incubation time. The IC50% for 5-HMF on MTC-CK cell growth was calculated at 375 µg/mL after 24 h incubation and 200 µg/mL 5-HMF after 72 h. MTC-SK cells treated with 500 µg/mL aKG + 167 µg/mL 5-HMF showed no cell growth. The calculated IC50% for the combined substances was 250 µg/mL aKG + 83.3 µg/mL 5-HMF (48 h incubation) and 200 µg/mL aKG + 66.7 µg/mL 5-HMF (72 h incubation). None of the tested concentrations of aKG, 5-HMF, or the combined solution had any effect on NCI-H23 cell growth at any incubation time. Caspase-3 activity increased to 21% in MTC-CK cells in the presence of 500 µg/mL aKG, while an increase to 59.6% was observed using 500 µg/mL 5-HMF. The combination of 500 µg/mL aKG + 167.7 µg/mL 5-HMF resulted in a caspase-3 activity of 55.2%. No caspase-3 activation was observed in NCI-H23 cells when treated with aKG, 5-HMF, or the combined solutions.

CONCLUSION

CPs may serve as potential markers for distinguishing between cancer cells regulated by RONS. The combination of aKG + 5-HMF showed induced cell death in high-RONS-generating cancer cells compared to low-RONS-generating cancer cells.

Selpercatinib Treatment of RET-Mutated Thyroid Cancers Is Associated With Gastrointestinal Adverse Effects

CONTEXT

Metastatic medullary thyroid carcinoma (MTC) and radioactive iodine-refractory differentiated thyroid carcinoma (RAI-R DTC) have poor prognosis and limited treatment options. Selpercatinib (LOXO-292), a selective kinase inhibitor targeting the RET gene, has shown a 69% to 79% objective response rate in this cohort with benefits in other tumors including lung cancer harboring the same oncogenic driver. Published reports describe only 17% of patients experiencing gastrointestinal (GI) adverse effects (AEs), which is in contrast to our local experience.

OBJECTIVE

Here we characterize the AEs and correlate them with radiological and histopathological findings.

METHODS

Sequential patients enrolled in LIBRETTO-001 at Royal North Shore Hospital, Sydney, Australia, with available imaging (n = 22) were recruited. Patients had regular visits with AEs documented and computed tomography (CT) scans every 3 months. CT at screening, at time of GI AE, and at most recent follow-up were reviewed and scored. Endoscopic examination was performed in 5 patients.

RESULTS

Of 22 patients in this cohort, the majority had somatic RET alterations (n = 18), most commonly p.Met918Thr (n = 14). Ten patients (50%) developed GI AEs. Dose reduction was required in 8 of the 10 patients, but none discontinued therapy. The majority had stable disease (n = 17). Gastric and small-bowel edema was evident in symptomatic patients after a median time of 67 weeks' treatment. Histological correlation in 5 patients revealed mucosal edema correlating with radiological evidence of congestion and edema.

CONCLUSION

GI AEs with selpercatinib may be more common than previously described. Most are self-limiting but often require dose adjustments. Histological evidence of mucosal edema observed in conjunction with the radiological findings of congestion and wall thickening suggest bowel-wall edema is a predominant mechanism of abdominal pain in these patients.

Surgical selection and prognostic analysis in patients with unilateral sporadic medullary thyroid carcinoma

PURPOSE

The extent of thyroid surgery and cervical lymph node dissection of unilateral sporadic medullary thyroid carcinoma (sMTC) is still controversial, and the aim of this study was to investigate whether hemithyroidectomy was adequate as a locally curative surgery for patients with unilateral sMTC.

METHODS

This study is a retrospective case series of patients with sMTC who underwent curative total thyroidectomy or hemithyroidectomy in our institution from January 2011 to December 2019.

RESULTS

In total, 129 patients who met the inclusion criteria were enrolled including 49 (38.0%) patients who underwent total thyroidectomy and 80 (62.0%) patients who underwent hemithyroidectomy. About 80 (62.0%) patients achieved a biochemical cure (BC), whereas there was no significant difference between two groups in biochemical cure rate (61.2% versus 62.5%, P = 0.885). A logistic regression analysis showed a strong negative correlation between the factors of preoperative calcitonin level and pTNM stage and biochemical cure. In the log-rank test, no significant difference in OS (P = 0.314) and DFS (P = 0.409) was found between the two surgical groups. Lateral cervical lymph node metastasis and pTNM stage were significant prognostic factors affecting DFS in univariate analysis; moreover, absence of biochemical cure, tumor size ≥ 4 cm and lateral cervical lymph node metastasis were independent risk factors of unilateral sMTC patients in our analysis.

CONCLUSION

For patients with unilateral sMTC, hemithyroidectomy was adequate as a locally curative surgery, because the patients underwent total thyroidectomy did not benefit more from it in the aspects of BC/OS/RFS, while the postoperative increasing incidence rate of postoperative hypocalcemia could not improve patients' quality of life.

Psychosocial Characteristics and Experiences in Patients with Multiple Endocrine Neoplasia Type 2 (MEN2) and Medullary Thyroid Carcinoma (MTC)

Multiple Endocrine Neoplasia type 2 (MEN2) is a genetic cancer syndrome for which there are limited data pertaining to the quality of life and psychosocial experiences of persons affected. Medullary thyroid carcinoma (MTC) is a rare disease of the thyroid gland often associated with MEN2. MTC often progresses slowly and may present with a myriad of physical symptoms including hair loss, sleep disturbance, fatigue, weight changes, heart palpitations, and constipation or diarrhea. Like other cancers or rare, inheritable illnesses, patients with MEN2 and MTC may be at risk for psychosocial stressors. The current, cross-sectional study administered a structured psychosocial interview and The Distress Thermometer/Problem Checklist to 63 patients with MEN2 and MTC and their caregivers. Despite reports of overall good health, 46% of adults and 44% of youth reported that pain interferes with their daily life; 53% of adults and 59% of youth reported that pain interferes with their mood. Pediatric patients frequently reported experiencing attention challenges (50%) and difficulty concentrating (65%). Parents reported that mood shifts and becoming upset easily were the most prevalent concerns for their children. The most frequent need for services included education about MTC, treatment and research participation, and the opportunity to meet others with MTC.

Preoperative serum calcitonin may improve initial surgery for medullary thyroid cancer in patients with indeterminate cytology

BACKGROUND

Medullary thyroid cancer (MTC) is rare, with poorer outcomes than differentiated thyroid cancer. We aimed to identify areas for improvement in the pre-operative evaluation of patients with possible MTC in a high-volume endocrine surgery unit in accordance with current practice guidelines. We hypothesised that the selective use of serum calcitonin (sCT) as a biomarker for possible MTC could guide the extent of initial surgical management.

METHODS

We recruited MTC patients between 2000 and 2020 from the Monash University Endocrine Surgery Unit database. Demographics, tumour characteristics, pre-operative evaluation, operative management, and outcomes were analysed.

RESULTS

Of 1454 thyroid cancer patients, 43 (3%) had MTC. Pre-operatively, 36 (84%) patients with MTC confirmed on cytology (28, 65%), elevated sCT (6, 14%) or RET mutation (2, 4%). Of these 36 patients, 31 (86%) had optimal extent of thyroidectomy and lymph node dissection (LND). Five (14%) had less than total thyroidectomy due to nerve injury. Thirty-four patients had compartmental LND. In the 12 (27%) patients with indeterminate or non-diagnostic cytology, 5 had elevated sCT and were managed as above. None of the remaining seven had LND, thus potentially suboptimal surgery.

CONCLUSION

Our findings reflect the rarity of MTC, and the challenges of pre-operative diagnosis. The addition of sCT may improve surgical planning in patients with indeterminate cytology.

Ultrasonography features of medullary thyroid cancer as predictors of its biological behavior

Background Although there are many well-known prognostic predictors of medullary thyroid carcinoma (MTC), the ultrasonography (US) findings of MTC have not been sufficiently validated in this regard. Purpose To investigate the US findings of MTC and their relationship with the biological behavior of MTC. Material and Methods The US findings and clinical and pathology records of 123 MTC nodules from 108 patients were retrospectively analyzed at two tertiary referral hospitals. MTCs were classified according to US findings, i.e. MTC with benign (B-MTC) and malignant US findings (M-MTC). We then compared the clinical and pathology findings between the two groups. Results Eighty-two M-MTCs (66.7%) and 41 B-MTCs (33.3%) were identified. M-MTCs showed a significantly higher prevalence of lateral lymph node metastases as well as extrathyroidal and extranodal extension (all P < 0.05). M-MTCs larger than 1 cm showed a significantly higher prevalence of multifocality, recurrence, extrathyroidal and extranodal extension than B-MTCs larger than 1 cm in the largest dimension (all P < 0.05). Tumors > 1 cm were more likely to be B-MTC and one-third of all MTCs had benign US features. The common findings of B-MTC included a solid, ovoid to round shape, with a smooth margin, hypoechogenicity, and without calcification. Conclusion The biological behavior of M-MTCs results in poorer outcomes than that of B-MTCs.

Multifocality in Sporadic Medullary Thyroid Carcinoma: An International Multicenter Study

BACKGROUND

Current surgical standard of care in sporadic medullary thyroid carcinoma (sMTC) consists of a minimum of total thyroidectomy with central neck dissection. Some have suggested thyroid lobectomy with isthmusectomy and central neck dissection for patients with sMTC, given their lower frequency of bilateral disease, although this topic has not been thoroughly studied. This study assessed the prevalence of multifocality in sMTC via a large international multi-institutional retrospective review to quantify this prevalence, including the impact of geography, to assess more accurately the risks associated with alternative surgical approaches.

METHODS

A retrospective chart review of sMTC patients from 11 institutions over 29 years (1983-2011) was undertaken. Data regarding focality, extent of disease, RET germline analysis plus family and clinical history for multiple endocrine neoplasia type 2 (MEN2), and demographic data were collected and analyzed.

RESULTS

Patients from four continents and seven countries were included in the sample. Data for 313 patients with documented sMTC were collected. Of these, 81.2% were confirmed with negative RET germline testing, while the remaining 18.8% demonstrated a negative family history and no manifestations of MEN2 syndromes other than MTC. Bilateral disease was identified in 17/306 (5.6%) patients, while multifocal disease was noted in 50/312 (16.0%) sMTC patients. When only accounting for germline negative patients, these rates were not significantly different (5.6% and 17%, respectively). Among them, when disease was unifocal in the ipsilateral lobe and isthmus, bilateral disease was present in 6/212 (2.8%) cases. When disease was multifocal in the ipsilateral lobe or isthmus, then bilateral disease was present in 8/37 (21.6%) cases (p < 0.001). No geographic differences in focality were identified.

CONCLUSIONS

The 5.6% prevalence of bilateral foci in sMTC suggests that total thyroidectomy should remain the standard of care for initial surgery, as less complete thyroid surgery may fail to address fully the primary site of disease. Whether ipsilateral tumor focality should be an independent factor determining the need for completion thyroidectomy when sMTC is diagnosed after hemithyroidectomy remains to be determined.

Silencing of hypoxia-inducible factor-1α promotes thyroid cancer cell apoptosis and inhibits invasion by downregulating WWP2, WWP9, VEGF and VEGFR2

Adaptation to hypoxia is an important process physiologically and pathologically. Hypoxia-inducible factor-1α (HIF-1α) participates in the cancer biology of numerous endocrine tumors, including their proliferation and differentiation. In the present study, the hypothesis that HIF-1α promotes tumorigenesis in thyroid cancer via upregulating angiogenesis-associated markers is investigated. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis were used to examine the expression of HIF-1α in thyroid cancer cell lines, and to detect the expression of WW domain containing E3 ubiquitin protein ligase (WWP)2, WWP9, vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) in MZ-CRC-1 and TT thyroid cancer cells. Cell proliferation was measured using a Cell Count Kit-8. Cell apoptosis and cell cycle was assessed by flow cytometry. Cell invasive ability was examined by Matrigel transwell analysis. RT-qPCR and western blot analyses demonstrated that the mRNA and protein expression levels of HIF-1α were significant higher in MZ-CRC-1 and TT thyroid cancer cells than in another three thyroid cancer cells (P<0.01). HIF-1α knockdown cells demonstrated inhibition of cell proliferation and invasion, arrested cell cycle at the G1 phase, and induction of cell apoptosis. The protein expression levels of WWP2, WWP9, VEGF and VEGFR2 were decreased in HIF-1α knockdown MZ-CRC-1 and TT cells. In conclusion, HIF-1α may be important in cell apoptosis and invasion of thyroid cancer cells, likely through regulating WWP2, WWP9, VEGF and VEGFR2 expression.

High Affinity Pharmacological Profiling of Dual Inhibitors Targeting RET and VEGFR2 in Inhibition of Kinase and Angiogeneis Events in Medullary Thyroid Carcinoma

Clinical evidence shows that dual inhibition of kinases as well angiogenesis provides ideal therapeutic option in the treatment of medullary thyroid carcinoma (MTC) than inhibiting either of these with the events separately. Although treatment with dual inhibitors has shown good clinical responses in patients with MTC, it has been associated with serious side effects. Some inhibitors are active agents for both angiogenesis or kinase activity. Owing to narrow therapeutic window of established inhibitors, the present study aims to identify high affinity dual inhibitors targeting RET and VEGFR2 respectively for kinase and angiogenesis activity. Established inhibitors like Vandetanib, Cabozantinib, Motesanib, PP121, RAF265 and Sunitinib served as query parent compounds for identification of structurally similar compounds by Tanimoto-based similarity searching with a threshold of 95% against the PubChem database. All the parent inhibitors and respective similar compounds were docked against RET and VEGFR2 in order to retrieve high affinity compounds with these two proteins. AGN-PC-0CUK9P PubCID: 59320403 a compound related to PPI21 showed almost equal affinity for RET and VEGFR2 and unlike other screened compounds with no apparent bias for either of the receptors. Further, AGN- PC-0CUK9P demonstrated appreciable interaction with both RET and VEGFR2 and superior kinase activity in addition to showed optimal ADMET properties and pharmacophore features. From our in silico investigation we suggest AGN-PC-0CUK9P as a superior dual inhibitor targeting RET and VEGFR2 with high efficacy which should be proposed for pharmacodynamic and pharmacokinetic studies for improved treatment of MTC.

Retrospective analysis of 140 cases of medullary thyroid carcinoma followed-up in a single institution

Familial cases of medullary thyroid carcinoma (MTC) may be diagnosed by genetic screening, while in sporadic tumors the diagnosis relies mainly on fine-needle aspiration cytology. The aim of the present study was to determine the demographic, clinical and pathological characteristics of MTC patients followed-up at the Portuguese Institute of Oncology Francisco Gentil (Lisbon, Portugal). For that purpose, a retrospective analysis of 140 MTC patients diagnosed between 1990 and 2010 was performed. The results indicated that patients with hereditary MTC (11.4%) were significantly younger than patients with sporadic MTC. Of the latter, 34.3% had no clinical suspicion of MTC prior to surgery. The sensitivity of cytology and calcitonin (CT) assay in diagnosing MTC were 51.3 and 98.7%, respectively. All familial index cases and 69.0% of sporadic cases presented with advanced stage disease at the time of diagnosis, while 73.0% of familial MTC detected by genetic/pentagastrin screening were diagnosed at the early stage of the disease. Biochemical cure (BC) was achieved in 39.7% of patients and, of these, only 6.5% relapsed. The 5 and 10-year survival rates were 79.3 and 73.6%, respectively. Age >45 years (P=0.026), advanced stage at diagnosis (P<0.001) and absence of BC (P<0.001) were predictors of a worse prognosis on univariate analysis. However, when the patients detected by genetic/pentagastrin screening were excluded from the analysis, age was no longer a prognostic factor, although disease stage remained a significant prognostic factor. On multivariate analysis, BC was the only factor with a significant impact on prognosis (P=0.031). In addition, the present study confirmed that the majority of patients were diagnosed at advanced stages, and CT determination was observed to be more sensitive than cytology to diagnose MTC. Patients at early stages were more prone to achieve BC, which was a favorable prognostic factor. To the best of our knowledge, the present study reports for the first time that age at diagnosis is not a predictor of survival for patients with MTC when cases diagnosed by genetic/pentagastrin screening (who are usually young patients at the initial stages of the disease), are excluded from the analysis.

Clinical challenges with calcitonin-negative medullary thyroid carcinoma

PURPOSE

Medullary thyroid carcinoma (MTC) is a relatively uncommon malignant tumor of the parafollicular C cells of the thyroid, which distinguishing feature is the production of calcitonin (CT). CT is a well-recognized tool in the diagnosis and the postsurgical follow-up of patients with MTC with a high sensitivity and specificity, and represents a powerful prognostic indicator. Usually, there is a direct correlation between tumor size and basal CT levels. However, few cases of CT-negative MTCs have been reported in literature and criteria for diagnosis and follow-up are still controversial.

METHODS

We performed a brief review on CT-negative MTC and reported our experience on this rare condition, focusing on the clinical characteristics at presentation, the histological and immunostaining features, and the management.

RESULTS

Fifteen cases of large, palpable, CT-negative MTCs have been reported in the literature so far; moreover, we reported four cases followed at our center.

CONCLUSIONS

Although CT-negative MTC is rare, normal/low serum levels of CT and CEA cannot completely exclude the possibility of the diagnosis, when suspected. It is well accepted that early diagnosis is crucial, but there is still no consensus on the optimal postoperative surveillance strategy. The ultrasound evaluation of the cervical region, together with abdominal computerized tomography scan, chest X-ray, and fluorine18-fluorodeoxyglucose ((18)F-FDG) PET/computed tomography (FDG-PET/CT), would be recommended in the follow-up of such cases.

Distribution of RET Mutations and Evaluation of Treatment Approaches in Hereditary Medullary Thyroid Carcinoma in Turkey

OBJECTIVE

This retrospective multicenter study, centrally conducted and supported by the Society of Endocrinology and Metabolism of Turkey, aimed to evaluate the impact of free RET proto-oncogene testing in medullary thyroid carcinoma (MTC) patients. Surgical timing, adequacy of the treatment, and frequency of prophylactic thyroidectomy (PTx) in mutation carriers were also assessed.

METHODS

Genetic testing for MTC and pheochromocytoma was conducted between July 2008 and January 2012 in 512 patients. Application forms and RET mutation analyses of these patients whose blood samples were sent from various centers around Turkey were assessed retrospectively. An evaluation form was sent to the physicians of the eligible 319 patients who had confirmed sporadic MTC, familial MTC (FMTC), multiple endocrine neoplasia type 2 (MEN2), or who were mutation carriers. Physicians were asked to give information about the surgical history, latest calcitonin levels, morbidity, mortality, genetic screening, and PTx among family members. Twenty-five centers responded by filling in the forms of 192 patients.

RESULTS

Among the 319 patients, RET mutation was detected in 71 (22.3%). Cys634Arg mutation was the most prevalent mutation (43.7%), followed by Val804Met in 18 patients (25.4%), and Cys634Tyr in 6 patients (8.5%). Among 192 MTC patients, the diagnosis was sporadic MTC in 146 (76.4%), FMTC in 14 (7.3%), MEN2A in 15 patients (7.9%), and MEN2B in one patient. The number of mutation carriers among 154 apparently sporadic MTC patients was 8 (5.2%). Ten patients were submitted to PTx out of twenty-four mutation carriers at a mean age of 35±19 years.

CONCLUSION

Turkish people have a similar RET proto-oncogene mutation distribution when compared to other Mediterranean countries. Despite free RET gene testing, the number of the PTx in Turkey is limited and relatively late in the life span of the carriers. This is mainly due to patient and family incompliance and incomplete family counselling.

Elevated level of serum carbohydrate antigen 19.9 as predictor of mortality in patients with advanced medullary thyroid cancer

BACKGROUND

Medullary thyroid cancer (MTC) is capable of secreting several proteins, such as calcitonin (Ct), carcinoembryonic antigen (CEA), chromogranin and others. Recently, we observed an aggressive MTC with high levels of serum carbohydrate antigen 19.9 (Ca 19.9) and a rapid evolution to death.

OBJECTIVE

The aim of this study was to evaluate whether high levels of serum Ca 19.9 could be a prognostic factor of death in patients with advanced MTC.

PATIENTS AND METHODS

We measured Ca 19.9, CEA and Ct in 100 advanced structural recurrent/persistent MTC patients and in 100 cured or biochemically affected MTC patients. Clinical and pathological data were also collected.

RESULTS

Sixteen percent of the patients with advanced MTC had high levels of Ca 19.9. The group with abnormal Ca 19.9 levels had significantly higher levels of CEA and Ct compared with the group with normal values of Ca 19.9 (P<0.0001 for both Ct and CEA). At variance, all 100 patients in the MTC control group showed normal levels of Ca 19.9. Moreover, among the advanced cases, the Ca 19.9-positive group showed a higher mortality rate than the group with normal levels. A logistic regression analysis demonstrated that an elevated level of Ca 19.9 is a predictor of mortality (OR=3.78, P=0.04), independent from Ct doubling time.

CONCLUSIONS

These results demonstrated that an elevated value of serum Ca 19.9 appears to be a predictive factor of poor prognosis in advanced MTC patients and identifies those cases with a higher risk of mortality in the short term.

A Calcitonin-Negative Neuroendocrine Tumor Derived from Follicular Lesions of the Thyroid

Neuroendocrine lesions of the thyroid are rare. The most common types are medullary thyroid carcinomas (MTCs) and C-cell hyperplasia. MTCs originate from thyroid parafollicular cells that secrete calcitonin which serves as a serum marker of MTCs. Here, the rare case of a calcitonin-negative neuroendocrine tumor (NET) derived from follicular lesions of the thyroid is described. A 34-year-old man presented at our hospital for the surgical management of an incidental thyroid nodule that was observed on an ultrasound sonography (USG) of the neck. Initially, USG-guided aspiration cytology was performed, and a MTC was suspected. The expressions of thyroglobulin and thyroid transcription factor-1, which are thyroid follicular cell markers, and synaptophysin and chromogranin A, which are neuroendocrine markers, was confirmed following surgical pathology. However, the staining of calcitonin, a marker of MTCs, was not observed. A nonmedullary NET of the thyroid is uncommon, and the distinction between calcitonin-negative NETs and MTCs of the thyroid may be important due to differences in their clinical courses and management.

Characterization of V804M-mutated RET proto-oncogene associated with familial medullary thyroid cancer, report of the largest Turkish family

PURPOSE

Analysis of the RET proto-oncogen is very important for diagnosis and prognosis of medullary thyroid cancer (MTC). Genotype-phenotype correlation is also well known. Here we report features of the largest known family in Turkey with the V804M-mutated RET proto-oncogene.

METHODS

Thirty members from three generations were evaluated. A RET proto-oncogen mutation, calcitonin (Ct) measurement and thyroid ultrasound were performed on all individuals. Seventeen members had V804M mutation. Fourteen of these patients underwent total thyroidectomy and additional central lymph node dissection for five subjects.

RESULTS

The mean age of patients with MTC was 46.5 (30-61) years. The mean calcitonin level of RET positive members was 13.27 pg/mL (1-49.8 pg/mL). Three had a basal Ct level above normal limits. Seven of the 14 patients were diagnosed with MTC, and two were diagnosed with papillary thyroid cancer without MTC. One patient had central neck metastasis. Hyperparathyroidism or pheochromocytoma was not detected in any case. Patients who were RET negative, had normal Ct levels and no suspected nodule on ultrasound examination.

CONCLUSIONS

Our study revealed a relatively good prognosis in patients with V804M mutation. Despite the surgery was performed in older age no advance disease was observed.

Quantitative assessment of the association between L769L and S836S polymorphisms at RET gene and medullary thyroid carcinoma risk

RET single nucleotide polymorphisms (SNPs) have been implicated in the pathogenesis and progression of medullary thyroid carcinoma (MTC). Epidemiologic studies have evaluated the association between RET L769L and S836S polymorphisms and predisposition to MTC. However, the results were inconclusive. A literature search was performed using the PubMed database for relevant studies published through October 31, 2013. A total of 13 eligible studies were selected for this meta-analysis, including 1,117 cases and 1,916 controls for L769L and 1,230 cases and 2,246 controls for S836S. The carrier frequency of the variant alleles was 26.3 % in patients with MTC and 24.6 % in controls for L769L polymorphism, and 6.6 % in patients with MTC and 5.0 % in controls for S836S polymorphism. In our pooled analysis of all these studies, the results of our meta-analysis suggested that the RET L769L variant was not significantly associated with an elevated MTC risk (odds ratio (OR) 1.06, 95 % confidence interval (CI) 0.94-1.19). And there was no evidence for the association between the S836S variant and MTC risk (OR 1.20, 95 % CI 0.97-1.49). Moreover, no significant differences were found when considering patients or controls heterozygous or homozygous for RET L769L and S836S polymorphisms. In conclusion, this meta-analysis suggests that RET L769L and S836S polymorphisms may not be associated with MTC development.

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.

A Case of medullary thyroid carcinoma with de novo V804M RET germline mutation

Many cases of RET proto-oncogene mutations of hereditary medullary thyroid carcinoma (MTC) have been reported in Korea. However, MTC with V804M RET proto-oncogene germline mutations have not been reported in Korea. A 33-yr-old man was diagnosed with a 0.7-cm sized thyroid nodule. Laboratory testing revealed serum calcitonin was elevated. The patient underwent total thyroidectomy with central compartment neck dissection for the thyroid tumor. RET gene analysis was performed in both the index patient and his family. There were no V804M RET mutation and abnormal laboratory findings within his family except the index patient. Therefore, this patient was a de novo V804M RET germline mutation.

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.

Additive effect of RET polymorphisms on sporadic medullary thyroid carcinoma susceptibility and tumor aggressiveness

OBJECTIVE

RET single nucleotide polymorphisms (SNPs) have been implicated in the pathogenesis and progression of medullary thyroid carcinoma (MTC). Here, we investigated the influence of multiple RET variants (G691S, L769L, S836S, and S904S) on the risk of MTC and tumor behavior.

DESIGN AND METHODS

One hundred and seven MTC patients and 308 cancer-unaffected control individuals were included. SNPs were analyzed using Custom TaqMan Genotyping Assays. Haplotypes based on the combination of allelic variants were inferred using a Bayesian statistical method.

RESULTS

The minor allele frequencies in MTC patients were as follows: L769L: 28.0%, S836S: 8.9%, and G691S/S904S: 22.2%. The RET L769L and S836S SNPs were associated with increased risk of MTC (odds ratio (OR)=1.95, 95% CI: 1.2-3.1, P=0.005 and OR=2.29, 95% CI: 1.2-4.5, P=0.017 respectively). The adjusted OR for individuals harboring haplotypes with three or more polymorphic alleles was 3.79 (95% CI: 1.5-9.5; P=0.004), indicating an additive effect of these variants on the risk for MTC. Among MTC patients, no significant associations were observed between RET variants and age of diagnosis or tumor size but serum calcitonin levels increased according to the number of risk alleles (P=0.003). Remarkably, patients carrying haplotypes with three or four risk alleles had increased risk for lymph node and distant metastases at diagnosis (OR=5.84, 95% CI: 1.1-31.2, P=0.039). Further analysis using Kaplan-Meier model demonstrated that metastatic disease occurred earlier in individuals harboring multiple risk alleles.

CONCLUSION

Our results demonstrated an additive effect of RET polymorphic alleles on the estimated risk of developing aggressive MTC.

Alternative surgical strategies in patients with sporadic medullary thyroid carcinoma: Long-term follow-up

The extent of surgical resection in patients with sporadic medullary thyroid carcinoma (SMTC) remains controversial. The aim of the present study was to discuss the prognosis of sporadic medullary thyroid carcinoma with different surgical treatments. Of 73 patients with SMTC (mean age of 43.78 years at diagnosis), 70 patients were followed up for 12.0-169.0 months (median 90.0). Having given their informed consent, 12 patients underwent total thyroidectomy with bilateral central neck dissection (group A), 40 underwent subtotal thyroidectomy preserving contralateral thyroid tissue on the entrance point of the recurrent laryngeal nerve into the larynx with ipsilateral modified radical neck dissection (group B), and 18 patients underwent subtotal thyroidectomy preserving contralateral thyroid tissue on the entrance point of the recurrent laryngeal nerve into the larynx with bilateral modified radical neck dissection (group C). The diagnosis was confirmed by a pathology examination. The incidences of hypoparathyroidism and recurrent laryngeal nerve injury, the cancer recurrence rates and survival time were investigated post-operatively. Significant differences were found between groups A, B and C in the incidence of hypoparathyroidism (χ(2)=40.9, P<0.01), as well as that of recurrent laryngeal nerve injury (χ(2)=32.9, P<0.01). The cancer recurrence rates in groups A, B and C were 75.0% (9/12), 2.5% (1/40) and 44.4% (8/18) respectively, (χ(2)=31.1, P<0.01) and the cure rates were 25, 97.5 and 55.6% respectively (χ(2)=31.1, P<0.01). The mean survival times in groups A, B and C were 77.8, 106.1 and 111.0 months respectively, but significant difference was noted (χ(2)=3.2, P>0.05). In conclusion, compared to total thyroidectomy with bilateral central neck dissection, subtotal thyroidectomy with ipsilateral/bilateral modified radical neck dissection showed a lower incidence of hypoparathyroidism, recurrent laryngeal nerve injury and lower rates of recurrence, along with a similar cumulative survival.

Predominant RET Germline Mutations in Exons 10, 11, and 16 in Iranian Patients with Hereditary Medullary Thyroid Carcinoma

Medullary thyroid carcinoma occurs in both sporadic (75%) and hereditary (25%) forms. The missense mutations of RET proto-oncogene in MTC development have been well demonstrated. To investigate the spectrum of predominant RET germline mutations in exons 10, 11, and 16 in hereditary MTC in Iranian population, 217 participants were included. Genomic DNAs were extracted from the leukocytes using the standard Salting Out/Proteinase K method. Mutation detection was performed through PCR-RFLP and DNA sequencing. In 217 participants, 43 missense mutations were identified in exons 10 (6%), 11 (13%), and 16 (0.9%). Moreover, a novel germline mutation was detected in exon 11 (S686N). Also four different polymorphisms were found in intron 16 in eight patients. The obtained data showed the frequency profile of RET mutations in Iranian individuals with MTC (19.8%). The most frequent mutation in our population was C634G whereas in most population it was C634R. Altogether, these results underline the importance of the genetic background of family members of any patient with MTC.

Peripheral glutamate signaling in head and neck areas

The major excitatory neurotransmitter glutamate is also found in the periphery in an increasing number of nonexcitable cells. In line with this it became apparent that glutamate can regulate a broad array of peripheral biological responses, as well. Of particular interest is the discovery that glutamate receptor reactive reagents can influence tumor biology. However, the knowledge of glutamate signaling in peripheral tissues is still incomplete and, in the case of head and neck areas, is almost lacking. The roles of glutamate signaling pathways in these regions are manifold and include orofacial pain, periodontal bone production, skin and airway inflammation, as well as salivation. Furthermore, the interrelations between glutamate and cancers in the oral cavity, thyroid gland, and other regions are discussed. In summary, this review shall strengthen the view that glutamate receptor reagents may also be promising targets for novel therapeutic concepts suitable for a number of diseases in peripheral tissues. The contents of this review cover the following sections: Introduction; The "Glutamate System"; The Taste of Glutamate; Glutamate Signaling in Dental Regions; Glutamate Signaling in Head and Neck Areas; Glutamate Signaling in Head and Neck Cancer; A Brief Overview of Glutamate Signaling in Other Cancers; and Conclusion.

Molecular imaging of neuroendocrine tumors

Neuroendocrine tumors (NET) are a heterogeneous group of tumors that arise from neuroendocrine cells. These tumors may arise from various organs, including lung, thymus, thyroid, stomach, duodenum, small bowel, large bowel, appendix, pancreas, adrenal, and skin. Most are well differentiated and have the ability to produce biogenic amines and various hormones. NET usually occur sporadically but they also be associated with various familial syndromes. For the vast majority of NET, surgical resection is the treatment of choice whenever feasible. Localization of NET prior to surgery and for staging and follow-up relies on both anatomic and functional imaging modalities. In fact, the unique secretory characteristics of these tumors lend themselves to imaging by molecular imaging modalities, which can target specific metabolic pathways or receptors. Neuroendocrine cells have a variety of such target receptors and pathways for which radiopharmaceuticals have been developed, including [(123)I/(131)I]-metaiodobenzylguanidine (MIBG), [(111)In]pentetreotide, [(68)Ga] somatostatin analogs, [(18)F] fluorodeoxyglucose (FDG), [(11)C/(18)F] dihydroxyphenylalanine (DOPA), [(11)C] 5-hydroxytryptophan (5-HTP) (99m)Tc pentavalent dimercaptosuccinic acid ([(99m)Tc] (V) DMSA, and [(18)F] fluorodopamine (FDA). Here, we review the molecular imaging approaches for NET using various radiopharmaceuticals.

Ectopic production of parathyroid hormone in a patient with sporadic medullary thyroid cancer

Elevation of serum parathyroid hormone (PTH) in patients with medullary thyroid cancer (MTC) is usually found in multiple endocrine neoplasia type 2A (MEN2A). However, ectopic production of PTH is rare and its molecular etiology remains largely uninvestigated. We report a case of ectopic production of PTH by a sporadic MTC. The etiology of ectopic PTH gene expression was examined, focusing on GCM2 which has a crucial role in developing parathyroid glands. We observed ectopic expression of the PTH and GCM2 genes in tissues from the tumor and metastatic lymph nodes. However, GCM2 gene expression was also detected in adjacent thyroid tissue and lymphoblasts, in which PTH gene expression was absent. Hypomethylation of the PTH promoter, which is reportedly associated with ectopic production of PTH, was not seen in either the tumor tissue or metastatic lymph nodes. Meanwhile, DNA hypomethylation was seen in a CpG island identified in the GCM2 promoter region, regardless of whether or not the GCM2 gene was expressed. We showed that transcriptional activity of the CpG island sequences cloned into a reporter plasmid was dependent upon DNA methylation. Finally, we present the first report of a PTH-producing MTC. There was no apparent association between ectopic PTH and GCM2 gene expression, despite co-expression of the two genes. Neither genomic rearrangement nor DNA hypomethylation in the PTH gene appeared responsible for ectopic production of PTH. Although DNA hypomethylation may be necessary for the GCM2 gene expression, ectopic expression of GCM2 won't be possible by DNA hypomethylation alone.

Sporadic medullary thyroid carcinoma: clinical data from a university hospital

INTRODUCTION

Medullary thyroid carcinoma may occur in a sporadic (s-medullary thyroid carcinoma, 75%) or in a multiple endocrine neoplasia type 2 form (MEN2, 25%). These clinical forms differ in many ways, as s-medullary thyroid carcinoma cases are RET-negative in the germline and are typically diagnosed later than medullary thyroid carcinoma in MEN2 patients. In this study, a set of cases with s-medullary thyroid carcinoma are documented and explored.

PURPOSE

To document the phenotypes observed in s-medullary thyroid carcinoma cases from a university group and to attempt to improve earlier diagnosis of s-medullary thyroid carcinoma. Some procedures for diagnostics are also recommended.

METHOD

Patients (n=26) with apparent s-medullary thyroid carcinoma were studied. Their clinical data were reviewed and peripheral blood was collected and screened for RET germline mutations.

RESULTS

The average age at diagnosis was 43.9 years (+/- 10.82 SD) and did not differ between males and females. Calcitonin levels were increased in all cases. Three patients presented values that were 100-fold greater than the normal upper limit. Most (61.54%) had values that were 20-fold below this limit. Carcinoembryonic antigen levels were high in 70.6% of cases. There was no significant association between age at diagnosis, basal calcitonin levels or time of disease onset with thyroid tumor size (0.6-15 cm). Routine thyroid cytology yielded disappointing diagnostic accuracy (46.7%) in this set of cases. After total thyroidectomy associated with extensive cervical lymph node resection, calcitonin values remained lower than 5 pg/mL for at least 12 months in eight of the cases (30.8%). Immunocyto- and histochemistry for calcitonin were positive in all analyzed cases. None of the 26 cases presented germline mutations in the classical hotspots of the RET proto-oncogene.

CONCLUSION

Our cases were identified late. The basal calcitonin measurements and immunostaining for calcitonin were highly useful for diagnosing s-medullary thyroid carcinoma. The rate of complete patient recovery was low, and none of the parameters analyzed were useful predictors of the thyroid tumor size. Our findings support previous recommendations for routine serum calcitonin evaluation and immunostaining analysis involving single thyroid nodules.

The role of somatostatin analogues in the treatment of neuroendocrine tumours

Neuroendocrine tumours belong to a heterogeneous family of neoplasms, originating in endocrine glands (such as the pituitary, parathyroid or the neuroendocrine adrenal glands), in endocrine islets (within the thyroid or pancreas) as well as in endocrine cells dispersed between exocrine cells throughout the digestive or respiratory tracts. The clinical behaviour of neuroendocrine tumours is variable; they may be functioning or not functioning, ranging from well-differentiated slow growing neuroendocrine tumours to poorly differentiated neuroendocrine tumours, which are highly aggressive malignant tumours. The development of somatostatin analogues as important diagnostic and treatment tools have revolutionised the clinical management of patients with neuroendocrine tumours. However, although symptomatic relief and stabilisation of tumour growth for various periods of time are observed in many patients treated with somatostatin analogues, tumour regression is rare. Development of new somatostatin analogues and new drug combination therapies should further improve the clinical management of these patients.

Locoregional control in patients with palpable medullary thyroid cancer: results of standardized compartment-oriented surgery

BACKGROUND

Extent of neck dissection is controversial in patients with palpable medullary thyroid cancer (MTC).

METHODS

We evaluated 64 MTC patients (19 hereditary, 45 sporadic) with palpable thyroid nodules (group 1, n = 35) or palpable lymph node metastases (group 2, n = 29). Standard surgery included total thyroidectomy, central compartment dissection, and additional neck dissection on indication.

RESULTS

In group 1, 40% of the patients were cured. Thirty-one percent of all patients had central, 23% ipsilateral, 14% contralateral, and 14% mediastinal, metastases. Fifty-one percent developed locoregional recurrence. Locoregional recurrence (p = .043) and reoperations (p = .020) were noted more often after a less than standard initial procedure. In group 2, no patients were cured. All had central, 93% ipsilateral, 45% contralateral, and 52% mediastinal metastases. Thirty-eight percent developed locoregional recurrence.

CONCLUSIONS

Locoregional recurrence frequently occurs in palpable MTC, and tumor control may be improved by standard central, bilateral, and upper mediastinal neck dissection.

Sensitivity and prognostic value of positron emission tomography with F-18-fluorodeoxyglucose and sensitivity of immunoscintigraphy in patients with medullary thyroid carcinoma treated with anticarcinoembryonic antigen-targeted radioimmunotherapy

CONTEXT

Patients with progressive medullary thyroid carcinoma (MTC) undergo multiple imaging procedures for diagnosis of relapse and staging.

OBJECTIVE

Our objective was to assess the sensitivity and prognostic value of 18F-2-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)/computed tomography (CT), and the imaging sensitivity of pretargeted iodine-131-radioimmunotherapy (RIT) in patients with progressive MTC.

DESIGN/SETTING/PATIENTS

We performed a prospective multicenter study in high-risk patients with rapidly progressing MTC enrolled in a phase-II pretargeted RIT study, as documented by short serum calcitonin (Ct) or carcinoembryonic antigen (CEA) doubling time (DT). INTERVENTIONS/MAIN OUTCOME MEASURES: Patients underwent neck-thoracic-abdominal CT, spine and pelvic magnetic resonance imaging, whole-body post-RIT immunoscintigraphy (IS) with iodine-131, and whole-body 18F-FDG-PET/CT imaging. Imaging sensitivity and the correlation between FDG uptake and biomarkers DT were evaluated.

RESULTS

A total of 33 patients with mean CEA and Ct DTs of 1.90 yr (range 0.21-8.50) and 1.52 yr (range 0.09-6.01), respectively, were evaluated. Sensitivity of FDG-PET/CT was 83% for neck, 85% for mediastinal, 75% for lung, 60% for liver, and 67% for bone metastases; overall sensitivity was 76%. Median standardized uptake value (SUVmax) was 5.23 (2.06-13.90). SUVmax correlated significantly with Ct DT (P = 0.011) and minimal DT (minimal value between CEA DT and Ct DT) (P = 0.027). Overall sensitivity of post-RIT IS, CT, and bone magnetic resonance imaging were 94, 74, and 85%, respectively.

CONCLUSIONS

These results demonstrate the value of FDG-PET/CT for staging of patients with progressive MTC, especially in the neck and mediastinum, with possible prognostication by SUV quantification. Post-RIT IS was the most sensitive of the imaging modalities studied prospectively.

Neuroblastoma and other neuroendocrine tumors

Neuroblastoma is the most common extracranial solid tumor of childhood. It commonly presents in children younger than 2 years of age, with 90% being younger than 5 years of age. There is marked variability in clinical behavior ranging from spontaneous regression or differentiation into benign tumors to rapid and progressive fatal disease. Approximately 50% of patients will have metastases at presentation. The management is dependent on age, stage of disease, and biological and biochemical markers. Nuclear medicine plays an important role in the initial staging, as a prognostic indicator, for assessment of response to treatment, and also in therapy. The most common nuclear medicine diagnostic studies are (99m)Tc-disphosphonate bone scintigraphy and (123)I-MIBG (metaiodobenzylguanidine) scintigraphy. Bone scintigraphy has been the main investigational modality to diagnose skeletal metastases. Whole body imaging with (123)I-MIBG has become the preferred diagnostic test because this agent accumulates in neuroblastoma in 90% to 95% of cases and will accumulate in the primary tumor and metastases particularly in bone, bone marrow, lymph nodes, and soft tissues. MIBG can be used to assess therapy response and is a significant prognostic indicator. Other diagnostic techniques include positron emission tomography (PET)/computed tomography, mainly using (18)F-fluorodeoxyglucose. Other more experimental PET agents, as well as radiolabeled antibodies and octreotide, also are being investigated. Therapy has mainly focused on palliation and has been used alone or in combination with chemotherapy in high-risk refractory or relapsed patients. Major attention is being placed on stratification of patients to try and reduce the side effects associated with intensive megatherapy in the low to intermediate risk patients. Neuroendocrine tumors (NETs) are rare in childhood, but nuclear medicine techniques, mainly using MIBG and somatostatin receptor agents, have a role in diagnosis, staging, and a limited role in therapy. Newer radiopharmaceuticals, including PET agents, are being evaluated for the assessment of NET. Nuclear medicine techniques play a major role in the management of neuroblastoma and NET.

Fine Needle Aspiration Cytology Stained with Riu's Method in Quicker Diagnosis of Medullary Thyroid Carcinoma

BACKGROUND/PURPOSE

The cytologic features of medullary thyroid carcinoma (MTC) have been described and documented in the literature. Most of the studies were related to the Papanicolaou stain or the May-Grnwald-Giemsa stain. The aim of the present study was to analyze detailed cytologic characteristics of MTC diagnosed by fine-needle aspiration cytology (FNAC) stained with a quick method, Rius stain.

METHODS

We collected the FNAC slides of 38 cases with MTC that were proven by surgical pathology. The cytologic findings were reviewed under a light microscope. The median age at diagnosis was 46.5 years, ranging from 13 to 83 years; 20 were women and 18 were men. Among them, seven cases were familial forms and the others were sporadic.

RESULTS

The majority of these cases showed moderate to abundant cellularity. Small round cells, spindle-shaped cells and large oval to polygonal cells formed the usual components. Twenty-seven cases were categorized as pleomorphic cell type and 11 cases as monomorphic type. Except in one case, cohesive and clustered small round cells predominated in all cases, alone or coupled with cohesive spindle cells and/or scattered large oval to polygonal cells. The diagnosis of mixed medullary-follicular thyroid carcinoma was made in the case composed solely of grouped polygonal cells. Cytoplasmic granularities were noted in 14 cases and vacuolations were seen in eight. Binucleated and multinucleated cells were not uncommon, while intranuclear cytoplasmic inclusions were less frequent. The diagnostic sensitivity for MTC by FNAC was 89%.

CONCLUSION

The distinctive cytopathologic characteristics of MTC by Rius stain allowed us to make the diagnosis in aspiration biopsies accurately and quickly.

Heat shock treatment of tumor lysate-pulsed dendritic cells enhances their capacity to elicit antitumor T cell responses against medullary thyroid carcinoma

BACKGROUND

In vitro and in vivo studies have shown that dendritic cells (DCs) can stimulate antitumor T cell responses against medullary thyroid carcinoma (MTC). However, despite promising results in selected cases, the clinical efficacy of DC immunotherapy in patients with MTC has been limited. Recently, it has been demonstrated in mice that heat shock enhances the capacity of bone-marrow-derived DCs to stimulate antigen-specific T cells. The aim of our investigations was to evaluate whether heat shock also increases the capacity of human monocyte-derived DCs to stimulate antitumor T cell responses against MTC tumor cells.

METHODS

DCs from six patients with metastatic MTC were pulsed with tumor lysate derived from allogeneic MTC tumor cells and were heat shocked for 12 h at 40 C or kept at 37 C. Thereafter, the DCs were matured and cocultured with T cells. Finally, the cytotoxic activity of T cells against MTC tumor cells was measured in vitro.

RESULTS

In all patient samples, cytotoxic T cell responses against MTC tumor cells could be induced. Notably, heat-shocked DCs were more potent stimulators of cytotoxic T cell responses than control DCs, with T cells stimulated with heat-shocked DCs displaying a significantly increased cytotoxic activity against MTC tumor cells as compared with T cells stimulated with control DCs. In none of the experiments was a cytotoxic T cell response against unrelated pancreatic tumor cells (PANC-1) observed, using both control and heat-shocked DCs.

CONCLUSIONS

Our study shows that heat-shocking DCs may be a valuable strategy to increase the immunostimulatory capacity of DCs used for immunotherapy of MTC.

Role of 18F-FDG-PET and PET/CT imaging in thyroid cancer

In patients affected by differentiated thyroid cancer (DTC), the lacking of 131Iodine trapping by metastatic tissue does not allow 131Iodine whole body scintigraphy to visualize matastatic spread as well as the use of 131Iodine therapy to cure such metastatic spread. Prognosis of 131Iodine-negative DTC metastasis, so-called non-functioning metastasis, is significantly worst. In these patients an early diagnosis of non-functioning metastasis and their surgical extirpation remains the optimal therapeutic approach. In this view, a high sensitive localizing imaging different form 131Iodine whole body scintigraphy is required. Ultrasonography is characterized by a relatively high sensitivity in these patients but it is highly operator-dependent and, moreover, it can be used to explore neck alone. Computed tomography (CT) scan and magnetic resonance (MR) imaging are characterized by a relatively low sensitivity even if they are useful to provide the surgeon with anatomical information of the operating basin. Various tumor-seeking radiotracers have been proposed, mainly using SPECT as 201Thallium, 99mTc-Sestamibi and 99mTc-Tetrofosmin with good results. Even more favorable results have been reported with some positron radiotracers, mainly the 18F-FDG with PET and more recently with PET/CT tomographs. The typical indication to performing with examination is the DTC patient previously treated by total thyroidectomy and 131Iodine ablative therapy, with increased serum thyroglobulin (Tg) or anti-thyroglobulin (TgAb) antibodies during follow-up but with negative 131Iodine whole body scintigraphy even obtained after high, therapeutic 131Iodine doses. Several studies in literature have reported high sensitivity (up to 85%) and specificity (up to 95%) of FDG-PET in metastatic DTC patients. The integrated PET/CT fusion imaging systems, seem able to provide some additional advantages over PET alone, mainly related to a better anatomical localization of the hypermetabolic metastatic lesions. A change in the management of DTC patients affected by non-functioning metastatic spread not visualized by other imaging techniques has been reported in 30% of patients. Lastly, the role of PET and PET/CT fusion imaging systems seem to be promising also in patients affected by medullary thyroid carcinoma (MTC), especially for the detection of neck and mediastinal lesions, with a sensitivity superior to the other currently available imaging methods, however the data reported on medullary cancer are little and further studies are needed to elucidate the preliminary promising results.

Human Medullary Thyroid Carcinoma: A Source and Potential Target for Relaxin-Like Hormones

We investigated the expression of H1, H2 relaxin and INSL-3, mRNA and protein, and LGR7 and LGR8 transcripts in human C-cell hyperplasia, primary medullary thyroid carcinoma (MTC) tissues, MTC metastases, and the human MTC-TT and mouse MTC-M cell lines. Relaxin-like peptide hormones were detected in C-cell hyperplasia and in MTC tissues, but were absent in human normal parafollicular C-cells of benign goiter tissues. In contrast to calcitonin, mRNA, and immunoreactive protein, no differences in the expression of relaxin and INSL3 were observed in MTC tissues of different pTNM classification or between primary and metastatic MTC tissues studied. All MTC tissues constitutively expressed LGR7 and LGR8 transcripts. Thus, relaxin-like hormones appear to be present early during C-cell hyperplasia and potentially functional relaxin/INSL3 ligand-receptor systems are present in human MTC tissues and in MTC cell lines.

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.

Familial medullary thyroid cancer: clinical aspects and prognosis

OBJECTIVE

To assess clinical features and long-term results of treatment of familial medullary thyroid carcinoma (FMTC).

DESIGN

Retrospective analysis of all patients with familial forms of MTC diagnosed between 1949-2000 and treated in our unit.

RESULTS

Fifty five patients (25 males, 30 females) were identified with at least two first-degree relatives affected by medullary thyroid cancer; 26 were classified as MEN 2A, 1 as MEN 2B and 28 as FMTC. Median age at diagnosis was 35 years (MEN 2A), 25 (MEN 2B) and 47.5 (FMTC). Median follow-up was 9 years (range: 4-24). Total or near-total thyroidectomy was performed in all patients and 11 received adjuvant external beam radiotherapy. Cause specific survival was 89% at 10 years and 77% at 20 years for MEN patients, 51% and 32% for those with sporadic MTC, and 46% and 26% for those with FMTC. In multivariate analysis, factors predicting survival were presence of metastases, nodal status and age at diagnosis.

CONCLUSIONS

Improved survival rates associated with familial types of MTC can be accounted for by the earlier stage at which disease is detected and the younger age at presentation. These observations emphasize the need for early detection in those at risk.

Dendritic cell vaccination in medullary thyroid carcinoma

PURPOSE

Prognosis and treatment effectiveness for medullary thyroid carcinoma (MTC) are strictly related to tumor stage. Palliative treatment options show no significant benefit. A promising treatment approach for human cancer is based on the vaccination of autologous dendritic cells (DCs).

EXPERIMENTAL DESIGN

The objective of this study was to evaluate the effectiveness of DC vaccines in MTC patients. Therefore, we generated autologous tumor lysate-pulsed DCs from 10 patients suffering from advanced MTC for repeated vaccination. Mature DCs were derived from peripheral blood monocytes by using CD14 magnetic bead selection and subsequent culture in the presence of granulocyte macrophage colony-stimulating factor, interleukin 4, and tumor necrosis factor alpha with or without addition of IFN-gamma. DCs were loaded with tumor lysate and further injected into a groin lymph node. Toxicity, tumor marker profile, immune response, and clinical response were determined.

RESULTS

Vaccination was well tolerated and induced a positive immunological response in all of the tested patients as evaluated by in vivo delayed-type hypersensitivity reactivity or in vitro intracytoplasmic IFN-gamma detection assay. Three patients had a partial response, 1 patient presented a minor response, and 2 patients showed stable disease. The remaining 4 patients had progressive disease.

CONCLUSIONS

These data provide strong evidence that vaccination with tumor-lysate pulsed DCs results in the induction of a specific immune response in patients suffering from MTC. Objective clinical responses could be observed even for far-advanced disease. Therefore, we suggest that MTC is particularly suited for DC-based immunotherapy.

RET proto-oncogene mutations are restricted to codon 634 and 618 in Korean families with multiple endocrine neoplasia 2A

Identification of the germline mutation in the RET proto-oncogene is important for the diagnosis of hereditary medullary thyroid carcinoma (MTC). Hereditary forms account for approximately 25%-30% of all cases of MTC. The objective of this study was to evaluate the prevalence of the RET mutation and the genotype-phenotype relation in Korean patients with MTC. Genomic DNAs were obtained from 33 patients with MTC (M:F = 10:23, 39.8 +/- 12.0 years) who underwent total thyroidectomy between 1997 and 2003 at the Samsung Medical Center. Exons 10, 11, 13, 14, 15 and 16 of the RET proto-oncogene were amplified with specific primers using polymerase chain reaction (PCR). Sequence analysis was performed on the polymerase chain reaction (PCR) product using an automatic sequence analyzer. Nine of the 33 patients (M:F = 3:6, 33.3 +/- 10.0 years) were identified as having RET mutations. Six patients had multiple endocrine neoplasia (MEN) 2A and one had familial medullary thyroid carcinoma (FMTC). The remaining two patients were thought to have sporadic MTC. Five of the patients with MEN 2A had RET mutations in codon 634 of exon 11 (3 patients, C634Y; 2 patients, C634R) and the other patient with MEN 2A had a RET mutation in codon 618 of exon 10 (C618R). The patient with FMTC had a mutation in codon 634 (C634W). The two patients with sporadic MTC had RET mutations in codon 634 (1 patient, C634Y; 1 patient, C634S). We were not able to identify any genotype-phenotype relations because of the limited number of patients. Twenty-seven percent (9/33) of the patients with MTC in this study had RET mutations. Taking other studies into account, 77% (10/13) of Korean families with MEN 2A, including 7 other families in three reports from Korea, had RET mutations in codon 634 (5 families, C634Y; 4 families, C634R; 1 family, C634W), and 23% (3/13) had RET mutations in codon 618 (2 families, C618R; 1 family, C618S). RET proto-oncogene mutations were restricted to codon 634 and 618 in Korean families with MEN 2A.

Medullary thyroid carcinoma: nationwide Japanese survey of 634 cases in 1996 and 271 cases in 2002

Medullary thyroid carcinoma (MTC) occurs sporadically or as an inherited disease, with the latter occurring in the form of multiple endocrine neoplasia (MEN) type 2A, MEN type 2B, or familial non-MEN medullary carcinoma (FMTC). MTC is inherited as an autosomal dominant trait and is associated with germline mutations of the RET proto-oncogene. Genetic testing identifies carriers of the mutant gene and enables preventive thyroidectomy. A nationwide questionnaire-based survey was conducted in 1996 and again in 2002, and we report here the results of the two surveys that characterize the clinical course of the inherited form of MTC. The data show a higher rate of inherited MTC than previously described, although MEN2A was found to be the most common inherited form of MTC, the same as in earlier studies. The most important finding was the difference in method of detection of MTC between the two surveys. Since the discovery of the genetic association with the disease, genetic testing has become the diagnostic method of choice, replacing indicators such as neck mass and elevated non-stimulated serum calcitonin level. Genetic testing enables early detection of the disease, which provides patients with the possibility of better outcome.