Calcitonin Measurement to Detect Medullary Thyroid Carcinoma in Nodular Goiter: German Evidence-Based Consensus Recommendation

Glucagon-like Peptide-1 receptor agonists activate rodent thyroid C-cells causing calcitonin release and C-cell proliferation

Liraglutide is a glucagon-like peptide-1 (GLP-1) analog developed for type 2 diabetes. Long-term liraglutide exposure in rodents was associated with thyroid C-cell hyperplasia and tumors. Here, we report data supporting a GLP-1 receptor-mediated mechanism for these changes in rodents. The GLP-1 receptor was localized to rodent C-cells. GLP-1 receptor agonists stimulated calcitonin release, up-regulation of calcitonin gene expression, and subsequently C-cell hyperplasia in rats and, to a lesser extent, in mice. In contrast, humans and/or cynomolgus monkeys had low GLP-1 receptor expression in thyroid C-cells, and GLP-1 receptor agonists did not activate adenylate cyclase or generate calcitonin release in primates. Moreover, 20 months of liraglutide treatment (at >60 times human exposure levels) did not lead to C-cell hyperplasia in monkeys. Mean calcitonin levels in patients exposed to liraglutide for 2 yr remained at the lower end of the normal range, and there was no difference in the proportion of patients with calcitonin levels increasing above the clinically relevant cutoff level of 20 pg/ml. Our findings delineate important species-specific differences in GLP-1 receptor expression and action in the thyroid. Nevertheless, the long-term consequences of sustained GLP-1 receptor activation in the human thyroid remain unknown and merit further investigation.

Mild hypercalcitoninaemia and sporadic thyroid disease

Background

Not operating on patients with mild hypercalcitoninaemia (MHCT) and sporadic thyroid disease carries the risk of omitting curative surgery for medullary thyroid cancer, but systematic surgery would result in unnecessary treatment of benign pathology. This study reviewed the management of MCHT and non-hereditary thyroid disease in one centre.

Methods

MCHT was defined as an increase in basal and stimulated calcitonin levels not exceeding 30 and 200 pg/ml respectively. Over 15 years, 125 patients who presented with MCHT and sporadic thyroid disease were followed. Surgery was indicated only if there were local pressure symptoms or suspicious histomorphological changes in solitary nodules.

Results

Fifty-five patients underwent total thyroidectomy and 18 unilateral total lobectomy. Histological examination revealed medullary microcarcinoma in six patients (two women and four men). C-cell hyperplasia was found in 54 patients (74 per cent) and 13 (18 per cent) harboured no C-cell pathology. Calcitonin levels stabilized after lobectomy and became undetectable following thyroidectomy. They normalized during follow-up in a third of patients who did not have surgery.

Conclusion

Not all patients with MHCT and sporadic thyroid disease require surgery.

Medullary thyroid cancer: management guidelines of the American Thyroid Association

BACKGROUND

Inherited and sporadic medullary thyroid cancer (MTC) is an uncommon and challenging malignancy. The American Thyroid association (ATA) chose to create specific MTC Clinical Guidelines that would bring together and update the diverse MTC literature and combine it with evidence-based medicine and the knowledge and experience of a panel of expert clinicians.

METHODS

Relevant articles were identified using a systematic PubMed search and supplemented with additional published materials. Evidence-based recommendations were created and then categorized using criteria adapted from the United States Preventive Services Task Force, Agency for Healthcare Research and Quality.

RESULTS

Clinical topics addressed in this scholarly dialog included: initial diagnosis and therapy of preclinical disease (including RET oncogene testing and the timing of prophylactic thyroidectomy), initial diagnosis and therapy of clinically apparent disease (including preoperative testing and imaging, extent of surgery, and handling of devascularized parathyroid glands), initial evaluation and treatment of postoperative patients (including the role of completion thyroidectomy), management of persistent or recurrent MTC (including the role of tumor marker doubling times, and treatment of patients with distant metastases and hormonally active metastases), long-term follow-up and management (including the frequency of follow-up and imaging), and directions for future research.

CONCLUSIONS

One hundred twenty-two evidence-based recommendations were created to assist in the clinical care of MTC patients and to share what we believe is current, rational, and optimal medical practice.

Calculation and validation of a plasma calcitonin limit for early detection of medullary thyroid carcinoma in nodular thyroid disease

BACKGROUND

The early diagnosis of medullary thyroid carcinoma (MTC) is crucial for effective therapy. Elevated plasma calcitonin concentrations (pCT-Cs) are generally a specific and sensitive indicator for C-cell hyperplasia or MTC. The presence of thyroid nodules raises the possibility of MTC. Hence, in endemic goiter regions, there is a need for information regarding the pCT-C values that are indicative of C-cell hyperplasia or MTC. The aim of this study, therefore, was to determine an upper pCT-C to distinguish patients with and without MTC in a collective with nodular thyroid disease, and to give an estimation of the prevalence of MTC in an endemic goiter area.

METHODS

Basal pCT-C was measured in 21,928 patients with thyroid nodules living in central Germany, an area with endemic goiter due to previous iodine deficiency. In 218 subjects with pCT-Cs exceeding 10 ng/L, stimulated pCT-C was additionally determined, as suggested by the German consensus recommendation. A nominal normal range for basal pCT-C was calculated with data from 21,900 subjects without known MTC. The predicted upper limit was then validated using the known diagnoses of 376 patients with pCT-Cs exceeding 10 ng/L, 28 of whom presented with MTC.

RESULTS

For basal pCT-C, calculation of the three-sigma borders after logarithmic transformation revealed upper limits of the nominal normal range of 14.6 ng/L in females and 32.8 ng/L in males, respectively. However, three male patients with small MTCs had basal pCT-Cs between 15 and 33 ng/L. None of the patients with MTC had a basal pCT-C below 15 ng/L or an increase in pCT-C after pentagastrin stimulation that was less than 80 ng/L. In the basal pCT-C range between 15 and 50 ng/L (n = 192; eight with MTC), the positive predictive value for the detection of MTC was 4% in our group. Applying an upper limit for basal pCT-C of 15 ng/L in both sexes, 329 of the total of 21,928 patients exceeded this range. Among these, the final outcome is known in 231 subjects, including all 28 MTCs.

CONCLUSIONS

An upper limit of 15 ng/L instead of 10 ng/L for basal pCT-C is able to detect all MTC and reduce false-positive cases. The prevalence of MTC in nodular thyroid disease in our group was approximately 1.8 per thousand.

Hypercalcitoninemia is not pathognomonic of medullary thyroid carcinoma

Hypercalcitoninemia has frequently been reported as a marker for medullary thyroid carcinoma. Currently, calcitonin measurements are mostly useful in the evaluation of tumor size and progression, and as an index of biochemical improvement of medullary thyroid carcinomas. Although measurement of calcitonin is a highly sensitive method for the detection of medullary thyroid carcinoma, it presents a low specificity for this tumor. Several physiologic and pathologic conditions other than medullary thyroid carcinoma have been associated with increased levels of calcitonin. Several cases of thyroid nodules associated with increased values of calcitonin are not medullary thyroid carcinomas, but rather are related to other conditions, such as hypercalcemias, hypergastrinemias, neuroendocrine tumors, renal insufficiency, papillary and follicular thyroid carcinomas, and goiter. Furthermore, prolonged treatment with omeprazole (>2-4 months), beta-blockers, glucocorticoids and potential secretagogues, have been associated with hypercalcitoninemia. An association between calcitonin levels and chronic auto-immune thyroiditis remains controversial. Patients with calcitonin levels >100 pg/mL have a high risk for medullary thyroid carcinoma (approximately 90%-100%), whereas patients with values from 10 to 100 pg/mL (normal values: <8.5 pg/mL for men, <5.0 pg/mL for women; immunochemiluminometric assay) have a <25% risk for medullary thyroid carcinoma.In multiple endocrine neoplasia type 2 (MEN2), RET mutation analysis is the gold-standard for the recommendation of total preventive thyroidectomy to relatives at risk of harboring a germline RET mutation (50%). False-positive calcitonin results within MEN2 families have led to incorrect indications of preventive total thyroidectomy to RET mutation negative relatives. In this review, we focus on the differential diagnosis of hypercalcitoninemia, underlining its importance for the avoidance of misdiagnosis of medullary thyroid carcinoma and consequent incorrect recommendation for thyroid surgery.

Detection of medullary thyroid cancer: a focus on serum calcitonin levels

Medullary thyroid cancer (MTC) is a neuroendocrine tumor derived from the C cells of the thyroid. C cells are responsible for the production of calcitonin, a sensitive and specific marker for MTC. Early detection of MTC is essential; overall survival from MTC is related to patient age, stage of disease and extent of surgical resection. Elevated preoperative serum calcitonin levels have been shown to predict the likelihood of biochemical remission postoperatively. The use of routine serum calcitonin measurements as a screening measure for MTC in patients with thyroid nodules has been advocated in Europe. To date, routine calcitonin measurement has not been widely practiced in the USA; a recent cost-effectiveness analysis suggests routine serum calcitonin measurements in patients with thyroid nodules may be comparable to other widely accepted screening programs.

Calcitonin measurement in the evaluation of thyroid nodules in the United States: a cost-effectiveness and decision analysis

CONTEXT

European studies have shown that the use of routine calcitonin screening for detection of medullary thyroid cancer (MTC) in patients with thyroid nodules increases the detection of occult MTC and may improve patient outcomes. Calcitonin screening for MTC has not been recommended in recent U.S. practice guidelines.

OBJECTIVE

Our objective was to determine the cost-effectiveness (C/E) of routine calcitonin screening in adult patients with thyroid nodules in the United States.

SETTINGS/SUBJECTS

A decision model was developed for a hypothetical group of adult patients presenting for evaluation of thyroid nodules in the United States. Patients were screened using current American Thyroid Association guidelines only, or American Thyroid Association guidelines with routine serum calcitonin screening. Input data were obtained from the literature, the Surveillance Epidemiology and End Results and Healthcare Cost and Utilization Project's Nationwide Inpatient Sample databases, and the Medicare Reimbursement Schedule. Sensitivity analyses were performed for a number of input variables.

MAIN OUTCOME MEASURES

C/E, measured in dollars per life years saved (LYS), was calculated.

RESULTS

Addition of calcitonin screening to current American Thyroid Association guidelines for the evaluation of thyroid nodules would cost $11,793 per LYS ($10,941-$12,646). When extrapolated to the national level, calcitonin screening for MTC in the United States would yield an additional 113,000 life years at a cost increase of 5.3%. Calcitonin screening C/E is sensitive to patient age and gender, and to changes in disease prevalence, specificity of fine needle aspiration and calcitonin testing, calcitonin screening level, costs of testing, and length of follow-up.

CONCLUSION

Routine serum calcitonin screening in patients undergoing evaluation for thyroid nodules appears to be cost effective in the United States, with C/E comparable to the measurement of thyroid stimulating hormone, colonoscopy, and mammography screening.

Cancer médullaire de la thyroïde

Medullary thyroid carcinoma (MTC) is developed from thyroid C cells that secrete calcitonin (CT). MTC represents 5-10% of thyroid cancers with a 1-2% incidence in nodular thyroid diseases. Diagnosis is usually made by a solitary nodule often associated to nodal metastasis and confirmed by a high basal CT level which represents its biological marker. MTC may present as a sporadic form and in about 30% of case as a familial form as a part of multiple endocrine neoplasia syndrome, an hereditary dominant inherited disease related to germline mutation of the proto-oncogene RET. Both biological (CT) and genetic (RET) markers allows the optimal diagnosis and treatment of MTC; the former allows screening and early diagnosis of MTC by routinely CT measurements in nodular thyroid diseases that make the adequate and complete surgery required to be performed. The former leads to diagnose familial MTC and to identify at risk subjects in whom early or prophylactic surgery may be performed. Treatment of MTC is based on the complete surgical resection: total thyroidectomy associated to central and laterocervical nodal dissection. For locally advanced or metastatic MTC, complete cervical surgery is required and needs to be associated to other systemic treatments: as chemotherapy is not very efficient, radioimmunotherapy and RET target gene therapy (mainly tyrosine kinase inhibitors) appears as possible valuable therapeutic options for the future. Prognosis of MTC is mainly related to both the stage of the disease and the extend of the initial surgery. Ten-year survival is about 80% when the patients are not surgically cured and reaches 95% when the biological marker CT is normalized after surgery.

Laboratory tests of thyroid function: uses and limitations

Laboratory tests are the most commonly used aids in the diagnosis and monitoring of individuals who have thyroid disease. This article briefly summarizes the common methods of laboratory testing relating to thyroid disease and discusses specific information for individual tests on methods of analysis, their limitations, and situations where caution should be used in interpreting the results of thyroid tests.

Role of CCK/gastrin receptors in gastrointestinal/metabolic diseases and results of human studies using gastrin/CCK receptor agonists/antagonists in these diseases

In this paper, the established and possible roles of CCK1 and CCK2 receptors in gastrointestinal (GI) and metabolic diseases are reviewed and available results from human agonist/antagonist studies are discussed. While there is evidence for the involvement of CCK1R in numerous diseases including pancreatic disorders, motility disorders, tumor growth, regulation of satiety and a number of CCK-deficient states, the role of CCK1R in these conditions is not clearly defined. There are encouraging data from several clinical studies of CCK1R antagonists in some of these conditions, but their role as therapeutic agents remains unclear. The role of CCK2R in physiological (atrophic gastritis, pernicious anemia) and pathological (Zollinger-Ellison syndrome) hypergastrinemic states, its effects on the gastric mucosa (ECL cell hyperplasia, carcinoids, parietal cell mass) and its role in acid-peptic disorders are clearly defined. Furthermore, recent studies point to a possible role for CCK2R in a number of GI malignancies. Current data from human studies of CCK2R antagonists are presented and their potential role in the treatment of these conditions reviewed. Furthermore, the role of CCK2 receptors as targets for medical imaging is discussed.

Calcitonin concentrations in patients with chronic kidney disease and medullary thyroid carcinoma or c-cell hyperplasia

It is currently not known which level of pentagastrin-stimulated calcitonin serum concentration indicates medullary thyroid carcinoma in patients with chronic kidney disease (CKD). We examined CKD stage 3-5 patients who had total thyroidectomy because of a pentagastrin-stimulated calcitonin concentration greater than 100 pg/ml, and tested the diagnostic performance of basal and pentagastrin-stimulated calcitonin levels for differentiating medullary thyroid carcinoma and C-cell hyperplasia in this patient population. A total of 180 CKD patients presented with an elevated calcitonin level and had a pentagastrin stimulation test. Forty patients showed a maximum pentagastrin-stimulated calcitonin concentration greater than 100 pg/ml, and 22 patients had a total thyroidectomy. Seven of these 22 patients presented with a medullary thyroid carcinoma, all other patients showed C-cell hyperplasia. Patients with medullary thyroid carcinoma showed higher unstimulated (212 pg/ml (36-577) vs 42 pg/ml (17-150); P < 0.001) and higher maximum pentagastrin-stimulated calcitonin concentrations (862 pg/ml (431-2423) vs 141 pg/ml (102-471); P < 0.001) as compared to patients with C-cell hyperplasia. The sensitivity (100%) and specificity (93%) estimates suggested that a maximum pentagastrin-stimulated calcitonin concentration greater than 400 pg/ml indicates the presence of medullary thyroid carcinoma in patients with CKD. Receiver-operating characteristic (ROC) analysis revealed an area under the ROC plot of 0.99 for maximum pentagastrin-stimulated calcitonin concentrations. A maximum pentagastrin-stimulated calcitonin concentration greater than 400 pg/ml appears to be a clinically meaningful threshold for thyroidectomy.

Digestive calcitonin-secreting tumors of the foregut: comparison with non-calcitonin-secreting tumors

OBJECTIVES

Digestive calcitonin-secreting endocrine tumors are very rare lesions of the foregut. This study was undertaken to compare the characteristics and the prognosis of these tumors and those of non-calcitonin-secreting endocrine tumors.

METHODS

All patients with a digestive endocrine tumor of the foregut followed up in Reims University Hospital and whose serum calcitonin levels were determined between 1988 and 2004 were included. Clinical and tumor characteristics of calcitonin-positive and calcitonin-negative patients were compared.

RESULTS

Thirty-two patients were included. Among the five (15.6%) with high calcitonin levels (median: 340 pg/ml, range: 42-7460 pg/ml), only one tumor was functioning (diarrhea). Significant differences between patients with positive and negative calcitonin levels were, respectively: liver metastases [5 (100%) versus 11 (40.7%); P=0.04], type according to the World Health Organization 2000 histological classification [notably 4 (80%) versus 3 (12.5%) poorly differentiated endocrine carcinomas; P=0.02] and Ki67 proliferation index [median: 25% (range: 20-30%) versus 7% (0-80%); P=0.03]. The only calcitonin-positive well-differentiated endocrine carcinoma had a high proliferation index (30%). Survival also differed significantly (P=0.001), as all calcitonin-positive patients died, with a median survival of 22.6 months (range: 1.2-27.2 months), versus five (18.5%) calcitonin-negative patients. Median follow-up period for the latter was 42.3 months (range: 3.4-208 months).

CONCLUSIONS

The secretion of calcitonin appears predictive of a poor prognosis. Digestive endocrine calcitonin-secreting tumors correspond histopathologically to poorly differentiated or well-differentiated carcinomas with high proliferation indexes.

Isthmus-Preserving Total Bilobectomy: An Adequate Operation for C-Cell Hyperplasia

BACKGROUND

Autopsy studies show that C cells deriving from the ultimobranchial body and migrating into the thyroid do not reach the isthmus region and are distributed along the vertical axes of thyroid lobes. This was confirmed in a surgical series of 58 patients (34 with preoperatively normal and 24 with elevated serum calcitonin) where no calcitonin-positive cells were demonstrable immunohistochemically within separately investigated isthmi. Consequently, isthmus-preserving total bilateral lobectomy (IPTB) may be regarded as an adequate surgical procedure for C-cell hyperplasia (CCH).

PATIENTS AND METHODS

IPTB was performed from October 2001 to December 2004 in 64 patients, 59 patients with nodular goiter and slightly to moderately elevated serum calcitonin (stimulated under 500 pg/ml) (group A, apparently sporadic cases) and in 5 patients undergoing prophylactic surgery for hereditary medullary thyroid carcinoma (MTC) with intermediate- or low-risk RET mutations (non-634) (group B). The surgical procedure focused on meticulous total extracapsular resection of both thyroid lobes, preservation of an isthmus remnant of about 3 ml (smaller in children), and histologic workup of the border zones of resection in addition to that of the completely removed lobes. When malignancy could be proven intraoperatively (7 patients) or when the isthmus turned out to contain nodular lesions (4 patients), completion total thyroidectomy (plus lymphadenectomy) was performed as a one-stage procedure. Second-stage total thyroidectomy was performed in 3 cases. Thus, IPTB was the definitive surgical procedure in 50 patients (45 of group A and all 5 of group B).

RESULTS

In all of the 50 definite IPTB cases, postoperative serum calcitonin was below the measurable limit (2 pg/ml); stimulated calcitonin was below the measurable limit in 47 (including all of group B) and was measurable in 3 sporadic cases in a lower-normal range between 2.4 and 3.5 pg/ml. Genetic screening of the apparently sporadic cases with CCH was positive in one (codon 791). The risk of recurrent laryngeal nerve paralysis seems not to be elevated (0% permanent); permanent hypocalcemia occurred in 1 patient (2%). Follow-up data of 37 patients, median 18 (6-36) months, showed continuously nonmeasurable serum calcitonin with one exception, where it was in the normal range after 18 months. All IPTB patients are still under substitution therapy with L-thyroxine (median 125 mug/day) with decreasing tendency in all 3 children after prophylactic operation, the latter also showing an increasing volume of well-vascularized isthmi (from 1.5 to 2.5 ml).

CONCLUSION

IPTB reliably removes all C cells. There may not be need for total thyroidectomy (TTx) in cases with CCH. When necessary, completion TTx can be performed easily without additional risk. IPTB leaves a functionally relevant remnant, corresponding to that of a subtotal resection. This might be of importance especially for prophylactic surgery in children where the isthmus can compensate for the loss of thyroid function with time.

Ghrelin in human medullary thyroid carcinomas

OBJECTIVE

Ghrelin is a novel gastrointestinal hormone involved in several metabolic functions. It has been identified previously in several normal and tumoral neuroendocrine tissues, including human medullary thyroid carcinomas (MTCs). The aim of the study was to evaluate ghrelin levels in patients with MTC and nontoxic goitre (NTG) with elevated calcitonin (CT) levels, as an additional marker of the disease.

PATIENTS AND DESIGN

The study included 22 patients with MTC (four before and 18 after thyroidectomy), 12 patients with NTG with basal CT levels exceeding 10 ng/l and 15 healthy subjects matched for age, sex and body mass index (BMI). After thyroidectomy, MTC patients were considered cured when basal and pentagastrin-stimulated CT levels were < 0.2 and < 10 ng/l, respectively. A pentagastrin-induced CT peak over 50 ng/l was considered as an abnormal response while 100 ng/l was the cut-off accepted for the diagnosis of C-cell hyperplasia or tumour. Circulating ghrelin and CT levels were evaluated at baseline in patients and controls and at -10, 0, 1, 2, 5 and 15 min after pentagastrin injection (0.5 microg/kg body weight) in 12 patients with MTC and nine with NTG. Four surgically removed MTCs were tested for ghrelin expression.

MEASUREMENTS

Total plasma ghrelin and CT levels were measured with a commercially available radioimmunoassay (RIA) and two-site chemiluminescence immunometric assays, respectively. In paraffin-embedded MTC samples ghrelin immunostaining was performed with a polyclonal antibody (1:1000) and the reaction visualized by an indirect immunoperoxidase system.

RESULTS

Plasma ghrelin levels found in cured or not cured MTC and in NTG patients were similar to those of BMI-matched healthy controls. No correlation between ghrelin and CT levels, thyroid disease or previous thyroidectomy was observed. The administration of pentagastrin caused a 17% increase in ghrelin levels (basal ghrelin vs. peak: 162 +/- 62 pmol/l vs. 189 +/- 58 pmol/l, P < 0.05) that was particularly evident (33% increase) in patients with an abnormal CT response to the test (CT > 50 ng/l). Immunohistochemistry showed positivity for ghrelin in a small proportion of CT positive cells from the four MTCs removed.

CONCLUSIONS

Patients with MTC, NTG and controls showed similar ghrelin levels, ruling out this parameter as a marker of MTC. The increase in ghrelin levels in patients with a positive CT response to pentagastrin, together with the immunopositivity for ghrelin in some MTC cells, suggests C cells as minor source of ghrelin production.

Reversibility of 'secondary hypercalcitoninemia' after kidney transplantation

Whether the increase of calcitonin (CT) concentration in patients with chronic kidney disease (CKD) is reversible or not after kidney transplantation is not known. We examined the effect of kidney transplantation on basal and pentagastrin-stimulated CT in CKD patients with elevated screening CT levels. Before transplantation, the median basal CT concentration of 17 patients was 31 pg/mL (13-76), and decreased to 8 pg/mL (4-28) at 23 months (2-34) after kidney transplantation (p < 0.00005). The maximum concentration of pentagastrin-stimulated CT was 63 pg/mL (25-110) before transplantation and decreased to 20 pg/mL (8-91) (p < 0.00005) thereafter. There was a linear association between CT and calcium as well as between phosphorus and parathyroid hormone at the time of screening. After transplantation, CT correlated with serum creatinine. Therefore, the increase of CT concentration in patients with impaired kidney function presumably reflects 'secondary hypercalcitoninemia' due to C-cell hyperactivity.

[Diagnosis and therapy of thyroid nodules]

Thyroid nodules and goitre can be diagnosed in up to 50% in populations living in iodine deficiency areas. Because of the necessity to exclude malignancy they therefore represent a significant diagnostic and economic problem. Sonography as well as TSH determination are the basic constituents of any thyroid diagnostic work up. Thyroid scintigraphy should be performed with any solitary thyroid nodule >10 mm if the scintigraphic result (together with the sonographic result) is likely to influence the treatment. Except of hot nodules any thyroid nodule should be evaluated by fine needle aspiration biopsy. Because of the lack of controlled studies including sufficient numbers of patients, there is a lack of evidence for some aspects of our everyday clinical practice. The aim of this article is therefore to summarize latest results on pathogenesis, diagnostic tools and recommendations concerning therapy and follow up.