The value of lymph node dissection in hereditary medullary thyroid carcinoma: a retrospective, European, multicentre study

Initial surgical management of sporadic medullary thyroid cancer: Guidelines based optimal care - A systematic review

INTRODUCTION

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor from parafollicular cells that produce calcitonin (Ct). Despite several existing guidelines for the surgical management of sporadic MTC (sMTC), optimal initial surgical management of the thyroid, the central and the lateral neck remains a matter of debate.

METHODS

A systematic review in PubMed and Scopus for current guidelines addressing the surgical management of sMTC and its referenced citations was conducted as per the PRISMA guidelines.

RESULTS

Two-hundred and one articles were identified, of which 7 met the inclusion criteria. Overall, guidelines vary significantly in their recommendations for the surgical management of sMTC. Only one guideline recommended partial thyroidectomy for limited disease, but the possibility to avoid completion thyroidectomy in selected cases is acknowledged in 42% (3/7) of the remaining guidelines. The majority of guidelines (71.4%; 5/7) recommended prophylactic central neck dissection (CND) for all patients while the remaining two guidelines recommended CND based on Ct level and tumor size. The role of prophylactic lateral neck dissection based on preoperative Ct levels was recommended by 42% (3/7) of guidelines. Overall, these guidelines are based on low-quality evidence, mostly single-center retrospective series, some of which are over 20 years old.

CONCLUSION

Current surgical management guidelines of sMTC should be revised, and ought to be based on updated data challenging current recommendations, which are based on historic, low-quality evidence. Partial thyroidectomy may become a viable option for small, limited tumors. Prospective, multi-center studies may be useful to conclude whether prophylactic ND is necessary in all sMTC patients.

The revised clinical practice guidelines on the management of thyroid tumors by the Japan Associations of Endocrine Surgeons: Core questions and recommendations for treatments of thyroid cancer

The Japan Associations of Endocrine Surgeons has developed the revised version of the Clinical Practice Guidelines for Thyroid Tumors. This article describes the guidelines translated into English for the 35 clinical questions relevant to the therapeutic management of thyroid cancers. The objective of the guidelines is to improve health-related outcomes in patients with thyroid tumors by enabling users to make their practice evidence-based and by minimizing any variations in clinical practice due to gaps in evidential knowledge among physicians. The guidelines give representative flow-charts on the management of papillary, follicular, medullary, and anaplastic thyroid carcinoma, along with recommendations for clinical questions by presenting evidence on the relevant outcomes including benefits, risks, and health conditions from patients' perspective. Therapeutic actions were recommended or not recommended either strongly (◎◎◎ or XXX) based on good evidence (😊)/good expert consensus (+++), or weakly (◎, ◎◎ or X, XX) based on poor evidence (😣)/poor expert consensus (+ or ++). Only 10 of the 51 recommendations given in the guidelines were supported by good evidence, whereas 35 were supported by good expert consensus. While implementing the current guidelines would be of help to achieve the objective, we need further clinical research to make our shared decision making to be more evidence-based.

Surgery in MEN 2A Patients Older Than 5 Years with Micro-MTC

In multiple endocrine neoplasia syndrome type 2A (MEN 2A), early total thyroidectomy (TT; performed before the age of 5 years) is the best option to prevent medullary thyroid carcinoma (MTC) development, but the management of MEN 2A patients diagnosed after childhood is still under debate. Seventeen consecutive patients diagnosed with MEN 2A after the age of 5 years (mean age, 23.3 years) with a pathologic diagnosis of micro-MTC without nodal involvement were enrolled. All patients underwent TT with thymectomy and central compartment lymph node dissection. During surgery, parathyroid tissue removal occurred in 14 patients. No major postoperative complications nor persistent hypoparathyroidism was observed. After a mean follow-up of 16.6 years, no patient developed primary hyperparathyroidism or disease recurrence. Even if TT is recommended before the age of 5, when MEN 2A diagnosis is performed after this age in micro-MTC without nodal involvement, TT with thymectomy and central compartment lymphadenectomy can provide good oncologic and functional results.

Medullary thyroid carcinoma: surgical treatment advances

Since medullary thyroid cancer (MTC) was first recognized as a distinct tumor in 1959, it became clear that MTC is more difficult to cure than papillary thyroid cancer and has higher rates of recurrence and mortality. MTC represents 5-8% of thyroid cancers. It derives from parafollicular cells of the ultimobranchial body derived from the neural crest. MTC secretes calcitonin and other hormonal peptides and is considered part of the amine precursor uptake and decarboxilation system. MTC may occur either as a hereditary or nonhereditary entity. Hereditary MTC can occur either alone as the familial MTC or as the thyroid manifestation of multiple endocrine neoplasia (MEN) type 2 syndromes (MEN 2A MEN 2B). Activating point mutations of the RET proto-oncogene have demonstrated to be causative of the familial form of medullary thyroid cancer, both isolated familial MTC and associated with MEN 2A and 2B. In the last 10 years, major improvements and new technologies have been proposed and applied in thyroid surgery; among these are molecular diagnosis with genetic screening and mini-invasive video-assisted thyroidectomy. The history of thyroid surgery starts with Billroth, Kocher and Halsted, who developed the technique for thyroidectomy between 1873 and 1910. Prophylactic surgery for patients carrying a positive RET proto-oncogene has proven to be highly effective in curing those likely to experience the development of MTC. Video-assisted procedures with central compartment dissection have proved feasible for patients carrying a positive RET proto-oncogene. This paper reviews relevant medical literature published in the English language on surgery of MTC in well-controlled trials. We discuss the particular ethical and legal issues that thyroid prophylactic surgery raises. Searches were last updated in February 2007.

Tumor protein p53-induced nuclear protein (TP53INP1) expression in medullary thyroid carcinoma: a molecular guide to the optimal extent of surgery?

BACKGROUND

Medullary thyroid cancer (MTC) is characterized by early regional lymph node metastasis, the presence of which represents a critical obstacle to cure. At present no molecular markers have been successfully integrated into the clinical care of sporadic MTC. The present study was designed to evaluate TP53INP1 expression in MTC and to assess its ability to guide the surgeon to the optimal extent of surgery performed with curative intent.

METHODS

Thirty-eight patients with sporadic MTC were evaluated. TP53INP1 immunoexpression was studied on embedded paraffin material and on cytological smears.

RESULTS

TP53INP1 was expressed in normal C cells, in C-cell hyperplasia, and in 57.9% of MTC. It was possible to identify two groups of MTC according to the proportion of TP53INP1 expressing tumor cells: group 1 from 0% to <50% and group 2 from 50% to 100% of positive cells. Patients with a decreased expression of TP53INP1 (group 1) had a lower rate of nodal metastasis (18.8% versus 63.4% in group 2; P = 0.009), with only minimal lymph node involvement per N1 patient (2.7% of positive lymph nodes versus 22.9%; P < 0.001) and better outcomes (100% of biochemical cure versus 55.5%; P < 0.001). Patients with distant metastases were only observed in group 2. Cytological samples exhibit similar results to their embedded counterparts.

CONCLUSIONS

TP53INP1 immunoexpression appears to be a clinical predictor of lymph node metastasis in MTC. The evaluation of TP53INP1 expression may guide the extent of lymph node dissection in the clinically node-negative neck. These findings require prospective validation.

Expression of membrane type 1 matrix metalloproteinase in medullary thyroid carcinoma: prognostic implications

BACKGROUND

Clinical and pathologic examinations cannot always provide a prognosis for patients with medullary thyroid carcinoma. Membrane type 1 matrix metalloproteinase (MT1-MMP) can act directly on carcinogenesis and takes part in 1 of the processes of metalloproteinase 2 activation, an enzyme related to prognostic impairment of patients with such tumor.

METHODS

Thirty-five patients who were submitted to surgery were followed up for an average of 74 months. Postoperative and final medical conditions were characterized for comparison with MT1-MMP immunostainings, performed in surgical paraffin blocks. A value of p < .05 was considered statistically significant.

RESULTS

Proposed index (association of proportion and intensity of immunostaining) and proportion of immunostained cells in primary specimens were correlated with cure or persistence after initial operations (p = .0216 and p = .0098, respectively).

CONCLUSION

MT1-MMP immunostaining in primary tumor specimens is a new and complementary prognostic predictor in patients with medullary thyroid carcinomas.

Surgical approaches in thyroid cancer and lymph-node metastases

Thyroid cancer collectively encompasses a variety of tumors of disparate morphology and biology. With the exception of radio-iodine therapy for iodine-concentrating well-differentiated thyroid cancers, surgery is the foremost and generally sole effective treatment. Because the growth patterns of these tumors vary tremendously, there is a need to tailor the extent of dissection to the respective tumor entity, especially for less aggressive tumors. No international consensus exists about what precisely constitutes a 'low-risk' or 'high-risk' tumor. Established indications for less-than-total thyroidectomy include small (<or=1 cm), unifocal, and non-metastatic papillary thyroid carcinomas (PTC), and minimally invasive follicular thyroid carcinomas (FTC; invasion of the tumor capsule only). Whether occult multifocal PTC and minimally invasive FTC with histopathological evidence of vascular invasion also fall into the 'low-risk' category remains unclear. For node-positive thyroid cancers, compartment-oriented microdissection is the gold standard of care, whereas the concept of prophylactic lymph-node dissection continues to arouse controversy. Most experts agree that routine lymph-node dissection is unnecessary for low-risk well-differentiated thyroid cancer (DTC). Because occult lymph-node metastases are frequent in high-risk PTC and medullary thyroid carcinoma, compartment-oriented microdissection helps prevent reoperations for 'recurrences' arising from residual nodes, sparing patients the excess morbidity from reoperations in the neck. Because of the looming epidemic of early forms of thyroid cancer, an international consensus is needed regarding (1) the definition of low- versus high-risk tumors; (2) classification of neck nodes; and (3) lymph-node dissection terminology.

Surgical approaches to thyroid tumors

This article includes discussions of the surgical approach to benign and malignant disease and the role of prophylactic thyroidectomy and nodal dissection for medullary thyroid cancer. The controversy regarding the extent of dissection for differentiated thyroid cancer and the role of lymph node dissection are reviewed also. A description of the authors' surgical technique for thyroidectomy is detailed. Finally, several emerging technologies are introduced.

Skip metastases in medullary thyroid carcinoma: a single-center experience

PURPOSE

Total thyroidectomy (TT) with level VI and VII central neck dissection is the initial treatment for medullary thyroid carcinoma (MTC) without identifiable neck metastasis. Level II to V lateral neck dissection is performed if neck metastasis is present or suspected. We conducted this study to identify the frequency and clinical determinants of skip neck metastasis in MTC.

METHODS

We reviewed the medical records of 32 patients who underwent TT and bilateral neck dissection for MTC. The clinical features were correlated with pN status in the central versus lateral compartments of the neck.

RESULTS

Neck lymph node metastasis (pN+) was found in 20 patients (62.5%) and skip metastases were found in 7 (35%) patients. The sensitivity of the pN status of the central compartment of the neck to predict the pN status of the lateral compartment of the neck was 53.8% and specificity was 63.2%. We found pN+ in 90% of the patients with lymph nodes >15 mm in diameter versus 50% in those with lymph nodes <15 mm in diameter.

CONCLUSIONS

There is skip metastasis in MTC. It is unsafe to use the lymph node status of the central compartment of the neck to define the pN status of the lateral neck. A lymph node greater than 15 mm in diameter is related to pN status.

NEW ERA: PROPHYLACTIC SURGERY FOR PATIENTS WITH MULTIPLE ENDOCRINE NEOPLASIA-2A

BACKGROUND

The surgical management of patients with multiple endocrine neoplasia-2A (MEN-2A) continues to evolve with specific genotype-phenotype correlations allowing for a more tailored approach. In this study, we report the surgical management of one of the largest MEN-2A families with a rearranged during transfection (RET) codon 804 mutation.

METHOD

This is a cohort study comprising all at-risk kindred within a single known MEN-2A family. Prophylactic total thyroidectomy with lymph node dissection was recommended to all mutation carriers aged 5 years and older.

RESULTS

There were a total of 48 at-risk individuals in the MEN-2A kindred, with 22 patients undergoing thyroidectomy after appropriate preoperative evaluation. A total of 9 patients had medullary thyroid cancer including 5 with a normal preoperative calcitonin level. A total of 11 patients had C-cell hyperplasia and 7 showed histological evidence of parathyroid disease. Only the index case had a phaeochromocytoma.

CONCLUSIONS

Genetic testing for germline mutations in the RET proto-oncogene has allowed precise identification of affected RET carriers and provided the opportunity for prophylactic or 'preclinical' surgery to treat and in fact to prevent medullary thyroid cancer. This concept of prophylactic surgery based on a genetic test is likely to be applied more widely as the tools of molecular biology advance.

Angiography-proven liver metastases explain low efficacy of lymph node dissections in medullary thyroid cancer patients

AIM

To report the role of liver angiography in the staging of medullary thyroid cancer (MTC) patients.

MATERIAL AND METHODS

Sixty MTC patients with persistent or recurrent hypercalcitonemia (n=49), a characteristic general symptom (diarrhea, n=4) or a normal basal calcitonin level without general symptoms (n=7) were investigated by dynamic liver CT, MRI and angiography between 06/1998 and 06/2002.

RESULTS

Dual-phase CT and MRI investigations identified hepatic metastases with relatively low frequency (8/58 on MRI, and 7/60 on CT). Angiography indicated liver involvement in 54/60 cases. The hepatic metastases were typically multiple, hypervascular, small foci (only 13 foci measured >/=10 mm). With one exception significant disease progression was not observed over 5 years of follow-up.

CONCLUSIONS

Liver angiography is a powerful tool to reveal hepatic metastases in MTC patients. Frequent, inoperable liver metastases in hypercalcitoninemic MTC patients demonstrate that secondary lymph node dissection is an inefficient technique for restoration of a normal calcitonin level.

Lymph node involvement in macroscopic medullary thyroid carcinoma

Background

Medullary thyroid carcinoma (MTC) is a rare disease, with variable tendency to lymphatic spread. The aim of this retrospective study was to identify distinctive features of large MTC with and without nodal metastases.

Methods

Between 1993 and 2003, 28 consecutive patients underwent total thyroidectomy and neck node dissection for sporadic MTC larger than 10 mm in diameter.

Results

All tumours were confirmed to be malignant with a locally invasive pattern of growth. Lymph node metastases were present in 16 patients (N1) and absent in 12 (N0). There were no statistically significant differences between patients with N0 and N1 tumours concerning age (mean 52·1 versus 53·4 years), male:female ratio (0·7 versus 1·0), basal preoperative calcitonin concentration (mean 3238 versus 3076 pg/ml) and tumour size (23·3 versus 23·9 mm). There were differences in the incidence of tumour invasion (P &lt; 0·001), vascular embolism (P = 0·011) and peritumoral thyroiditis (P = 0·039). Measurement of basal and stimulated calcitonin levels after surgery confirmed biochemical cure in all patients with N0 tumours and half of those with N1 disease (P = 0·006).

Conclusion

There were no preoperative factors that predicted node status for MTC larger than 1 cm in this series. Total thyroidectomy and nodal dissection remains the optimal treatment.

Advances in the management of hereditary medullary thyroid cancer

This work draws on recent advances during the era of codon-oriented prophylactic surgery for hereditary medullary thyroid cancer (MTC). Milestones included identification of RET (REarranged during Transfection) as the susceptibility gene, introduction of prophylactic surgery on evidence of a RET germline mutation, revelation of genotype-phenotype correlations within the MEN 2 spectrum and demonstration of age-related progression of MTC. Novel surgical techniques, notably systemic microdissection and compartment-oriented surgery, have greatly enhanced surgical cure. Uncovering molecular pathways from RET genotype to MEN 2 phenotype should provide treatment options for RET mutation carriers whose MTC currently is too advanced for cure.

Single Center Experience in Primary Surgery for Medullary Thyroid Carcinoma

Medullary thyroid carcinoma (MTC) is a rare disease, and most studies are either based on small numbers or multicenter studies with their inherent difficulties. Since 1995, a total of 440 patients with MTC underwent surgery in our clinic. A primary operation was performed in 188 patients (43% of 440). In 60 patients, the primary operation was performed because of a germline RET mutation ("prophylactic surgery"). Most (84%, 158/188) of the patients had pathologic calcitonin levels. Notably, MTC was found in almost 10% (3/30) of patients with normal calcitonin levels. However, all patients with lymph node metastases (LNMs) had elevated calcitonin levels. Total thyroidectomy (TTx) was performed in all patients. Lymph node dissection (LND) was performed at various extensions: one-compartment LND in 35% (66/188), three-compartment LND in 31% (58/188), and four-compartment LND in 29% (22/188). In general, lymph node dissection increased the likelihood of complications. LNM and distant metastases (DM) correlated with the extent of the primary tumor (pT category). The presence of LNM ranged from 17% (pT1 tumor) to 100% (pT4 tumor), whereas the presence of DM ranged from 0% (pT1 tumor) to 81% (pT4 tumor). Biochemical cure (normal calcitonin levels) was obtained in 72% (137/188) of patients. All 60 patients undergoing prophylactic surgery (tumor stage pT0/pT1) were biochemically cured. In contrast, only 60% (77/128) of the remaining patients were cured. The data suggest that primary surgery should be scheduled as soon as possible to treat patients at a node-negative stage. In the case of normal basal and elevated stimulated calcitonin levels, TTx and cervicocentral LND is recommended. If the basal calcitonin level is elevated, LND should include the cervicolateral compartment.

Receptor radionuclide therapy with 90Y-DOTATOC in patients with medullary thyroid carcinomas

Metastatic medullary thyroid cancer (MTC) shows a progressive course. Surgery is the only curative treatment. In advanced disease, chemo- and radiotherapy show poor results. Newly developed somatostatin analogue [DOTA0,Tyr3]octreotide (DOTATOC) labeled to 90Y is administered in patients with endocrine tumors expressing somatostatin receptors, like MTC. Preliminary studies demonstrated that 90Y-DOTATOC could be safely administered, resulting in objective responses in 27% of patients.

AIMS

To evaluate the efficacy of 90Y-DOTATOC therapy in metastatic MTC patients with positive OctreoScan, progressing after conventional treatments. Twenty-one patients were retrospectively evaluated after therapy, receiving 7.5-19.2 GBq in 2-8 cycles.

RESULTS

Two patients (10%) obtained a complete response (CR), as evaluated by CT, MRI and/or ultrasound, while a stabilization of disease (SD) was observed in 12 patients (57%); seven patients (33%) did not respond to therapy. The duration of the response ranged between 3-40 months. Using biochemical parameters (calcitonin and CEA), a complete response was observed in one patient (5%), while partial response in five patients (24%) and stabilization in three patients (14%). Twelve patients had progression (57%). Complete responses were observed in patients with lower tumor burden and calcitonin values at the time of the enrollment.

CONCLUSIONS

This retrospective analysis is consistent with the literature, regarding a low response rate in medullary thyroid cancers treated with 90Y-DOTATOC. Patients with smaller tumors and higher uptake of the radiopeptide tended to respond better. Studies with 90Y-DOTATOC administered in earlier phases of the disease will help to evaluate the ability of this treatment to enhance survival. New more specific peptides and new isotopes will also represent the key of a better treatment of MTC.

FDG PET imaging in hereditary thyroid cancer

AIM

To report the role of different imaging methods in staging individuals with multiple endocrine neoplasia 2A (MEN2A) or familial medullary thyroid carcinoma (FMTC).

MATERIAL AND METHODS

Fourteen newly diagnosed gene carriers underwent cervical ultrasound scanning (US), cervical and mediastinal CT, MRI and whole-body meta-[131I]iodobenzylguanidine (MIBG) scintigraphy and [18F]fluorodeoxyglucose (FDG) PET scanning.

RESULTS

US identified seven true primary cancer. CT and MRI located only tumors > or =5 mm in diameter. MIBG scintigraphy and FDG PET could not identify MTC foci within the thyroid. Whole-body FDG PET identified two true-positive and one false-positive lymph node metastases. MIBG scintigraphy did not identify lymph node metastases. Total thyroidectomy was performed in 12 cases, and subtotal thyroidectomy in two subjects.

CONCLUSIONS

Whole-body FDG PET and cervical US help stage individuals carrying mutant genes verifying MEN2A or FMTC.

RET proto-oncogene mutations affecting codon 790/791: A mild form of multiple endocrine neoplasia type 2A syndrome?

BACKGROUND

In patients with multiple endocrine neoplasia type 2A syndrome, prophylactic thyroidectomy is generally recommended at the age of 5 to 6 years. Whether this recommendation is justified for exon 13 mutations is unknown.

METHODS

We analyzed the clinical data from 40 patients harboring RET codon 790/791 mutations (exon 13) who had been treated in 4 specialized centers.

RESULTS

Mean age was 35.2 +/- 21.6 years (range, 5.1-69.0 years). Thirteen patients were index patients (mean age, 57.7 +/- 11.3 years), 27 patients were screening patients (mean age, 24.4 +/- 16.5 years). In the index group, pT-category was: T0, n = 2; T1, n = 6; T2, n = 2; T3, n = 1; and T4, n = 2. Lymph node metastases were found in 5 patients and distant metastases in 1 patient. Postoperatively, 69% of index patients were biochemically cured. In the screening group, pT-category was: T0, n = 19; T1, n = 7; and T2, n = 1. Lymph node metastases were found in 2 patients. Postoperatively, 93% of screening patients were biochemically cured. The youngest patient with medullary thyroid carcinoma was 13.8 years, the youngest patient with lymph node metastases was 46.4 years.

CONCLUSIONS

Patients with RET codon 790/791 mutations seemed to have a less aggressive clinical course compared with patients with classic multiple endocrine neoplasia type 2A syndrome. Still, index patients had a lower biochemic cure rate in comparison with screening patients. Timely total thyroidectomy including lymph node dissection is warranted.

The role of radiotherapy in the management of elevated calcitonin after surgery for medullary thyroid cancer

Among 139 patients with medullary thyroid cancer (MTC) treated at the Royal Marsden Hospital between 1957-1998, 51 had persistently elevated calcitonin levels after initial surgery in the absence of clinically or radiologically demonstrable residual disease. Of these, 24 were treated with radiotherapy because of advanced local disease at presentation; this resulted in normalization of calcitonin in only 1 patient, although 10 remained free of clinical recurrence. Surveillance alone was used in the remaining 27 patients, of whom 8 (30%) remained free of overt disease. Local relapse rate was significantly lower after radiotherapy (29% vs. 59%) but there was no significant difference in 10-year survival between the two groups (72% vs. 60%). In view of this favorable long-term survival of patients with elevated calcitonin on observation, we cannot recommend the routine use of radiotherapy. However, it does appear to have a role in those presenting with more advanced disease to reduce the incidence of loco-regional relapse.

[Reoperation of medullary thyroid carcinoma: long-term results]

STUDY AIM

The impact of iterative surgery in medullary thyroid carcinoma is still debated. The study aim was to evaluate long-term results following reoperation for residual or recurrent medullary thyroid carcinoma.

PATIENTS AND METHOD

Among the 136 patients operated on in our centre for medullary thyroid carcinoma (MTC) between 1970 and 2000, 25 patients (10 men and 15 women) were reoperated on for locoregional residual or recurrent lesions. Their mean age was 46 years (range: 19-73 years). The MTC was sporadic in 21 patients and familial in 4: NEM 2A (n = 3), NEM 2B (n = 1). In 11 patients (44%) operated in another centre, the first procedure was a total thyroidectomy; in 2 patients (8%) a total thyroidectomy with central lymphadenectomy was performed, and in 12 patients (48%) a total thyroidectomy with central and jugulo-carotid lymphadenectomy. After the first operation, 6 patients (24%) were classified stage II, 15 (60%) stage III and 4 (16%) stage IV. Basal and post-stimulation calcitonin dosages were performed for all the patients before and after reoperation.

RESULTS

Thirty three reoperations were performed. In 24 cases, the recurrence was located in the laterocervical site; in 5 cases, the lymph node involvement was both central and laterocervical, in 2 cases, there was a mediastinal involvement and in 2 cases a spinal involvement. After reoperation, the calcitonin rate became normal in 4 patients (16%); in the other 21 (84%), the calcitonin rate was still high. With a mean 110 month--follow-up (range: 320-12 months), 4 patients (16%) were alive without disease, 2 (8%) died of their disease, 19 (76%) were alive with their disease, five of them with hypercalcitonemia without detectable metastasis. In addition to patients having metastasis at the time of reoperation, seven developed metastases secondarily (liver, bone, lung).

CONCLUSION

Biological cure of medullary thyroid carcinoma is rarely obtained with reoperation. Reoperations may reduce progression of the disease in selected patients. Complete removal of the lesions at the time of the first procedure must be the ideal treatment for medullary thyroid carcinoma.

Complete surgical lymph node resection does not prevent authentic recurrences of medullary thyroid carcinoma

BACKGROUND

Medullary thyroid carcinoma is a rare tumour derived from the thyroid parafollicular calcitonin-secreting cells. Calcitonin is a very specific marker of this cancer that allows preoperative diagnosis. Serum calcitonin assay is particularly useful to define the postoperative state of patients (cured, apparently cured, not cured) and, because of its great sensitivity, it has a major place in the postoperative follow-up.

OBJECTIVE

To identify, among patients thyroidectomized for medullary thyroid carcinoma (MTC), the characteristics of authentic recurrent MTC [re-elevation of stimulated serum calcitonin (CT) level measured by a sensitive immunoradiometric assay, after postoperative normalization].

PATIENTS AND METHODS

We first collected, through the national registry of the French Calcitonin Tumour Study Group (GETC), patients who had undergone a total thyroidectomy with or without lymph node surgery and who were not cured at the last follow-up visit. Among 453 such patients included in the database, 15 patients met the criteria for authentic recurrence as defined in previous studies: they had been first considered as cured during the 6 months following the initial surgical procedure (basal and pentagastrin-stimulated serum calcitonin level <or= 10 ng/l) but had a secondary rerise of their pentagastrin-stimulated calcitonin level, over 10 ng/l. Eight of them even had an undetectable (< 2 ng/l) immediate postoperative CT, confirming the initial postoperative cure. The characteristics (age, nature of disease, stage at surgery and type of node dissection) of these 15 patients were studied.

RESULTS

According to the Tumour Node Metastasis classification, nine patients were T1 and, among them, five patients had had complete lymph node surgery without any evidence of nodal metastases (N0). The recurrence was 3.2 +/- 2.2 years (range: 0.7-7.5) after the initial surgery.

CONCLUSIONS

3.3% of patients not cured at the last visit had a recurrent MTC. This recurrence occurred whatever the stage, and even if the primary surgery for MTC was a priori complete. These results emphasize the need for a regular biochemical follow-up because recurrence may appear many years after the initial surgery.

Current approaches and perspectives in the therapy of medullary thyroid carcinoma

BACKGROUND

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor derived from parafollicular cells. At present, surgery is the most important treatment for MTC.

METHODS

We describe the current approaches of MTC treatment (surgery, chemotherapy, radiation therapy, and biologic therapy).

RESULTS

MTC is currently approached surgically in the main part through total thyroidectomy and compartment-oriented microdissection of cervicomediastinal lymph nodes. Substitutive l-thyroxine administration together with close clinical monitoring and the measurement of basal and stimulated serum calcitonin are subsequently performed. Radiotherapy and chemotherapy play a marginal role in advanced MTC. Recently, it has been found that somatostatin analogs and type I interferon are able to control the neuroendocrine symptoms induced by advanced MTC and that they provide clinical benefit by improving the lifestyle of these patients.

CONCLUSION

Although these agents are poorly active in inducing a shrinkage in tumor mass, the combined use of different biologic agents and cytotoxic drugs needs to be explored in advanced MTC. However, at present, surgery is the only curative treatment for MTC.

Diagnosis and treatment of medullary thyroid cancer

Medullary carcinoma of the thyroid (MTC) is a rare tumour derived from thyroid C cells with serum calcitonin as a specific and sensitive marker. MTC is inherited in 25% of cases, with an autosomal dominant transmission, age-related penetrance and variable expressivity. MTC is an obligatory component of multiple endocrine neoplasia type 2 (MEN2), which comprises three well defined syndromes: MEN2A, which may be associated with pheochromocytoma and/or hyperparathyroidism; the much rarer MEN2B, which occurs early and is accompanied by developmental abnormalities; while in contrast, familial MTC (FMTC) is not associated with any endocrinopathy. The RET proto-oncogene is the causative gene of the MEN2 syndromes and mutations in this gene are found in >90% of inherited cases, allowing easier and more reliable family screening than pentagastrin stimulation tests. Nevertheless, the correlation between the genotype and the different clinical phenotypes is not perfect. The prognosis of MTC depends on its staging at presentation, and the early appearance of cervical lymph node metastases emphasizes the need for extensive surgery, although many patients still do not normalize calcitonin levels post-operatively, and they remain a challenge for the further management.

Medullary carcinoma of the thyroid

Medullary thyroid cancer (MTC) is a distinct C-cell tumor of the thyroid. We review the oncogenesis and management of both sporadic tumors and those tumors arising as part of specific inherited syndromes. The RET proto-oncogene plays a role in the development of inherited forms of MTC and has become important in the clinical management of patients and their families. The recognition of the high rate of regional nodal involvement has led to lymphadenectomy being strongly considered for patients undergoing thyroidectomy for MTC.

[Medullary cancer of the thyroid]

INTRODUCTION

Medullary thyroid carcinoma is a rare disease which originates from the secretion of calcitonin by thyroid parafollicular cells. Sporadic (75%) and inherited (25%) forms of the disease are encountered. Familial forms (termed multiple endocrine neoplasia type IIa, IIb, or familial medullary thyroid carcinoma) may or may not be associated with other endocrinopathies such as pheochromocytoma and/or hyperparathyroidism.

CURRENT KNOWLEDGE AND KEY POINTS

Circulating forms of calcitonin, a marker of the disease, are heterogeneous in blood, thus explaining why assays lead to different results according to the method used.

FUTURE PROSPECT AND PROJECTS

Family screening is much easier, as germ line mutations of the proto-oncogene RET have recently been identified in inherited forms of the disease. Treatment includes extensive surgery. This, and prophylactic thyroidectomy in gene carriers, is discussed. Prognosis is much better nowadays, but precise follow-up has to be instituted.

Predictive DNA testing for multiple endocrine neoplasia 2: a therapeutic challenge of prophylactic thyroidectomy in very young children

BACKGROUND

Patients with multiple endocrine neoplasia (MEN) type 2 are at risk for early medullary thyroid carcinoma (MTC). Recently, the cloning of the ret oncogene has made it possible to identify patients at risk for MEN 2 syndrome with a high degree of reliability before presenting any symptoms.

METHODS

Children of families with MEN 2 were screened genetically if one of the parents was a known gene carrier of the RET proto-oncogene. If they were carriers, thyroidectomy was performed.

RESULTS

The authors report five children with MEN 2 who underwent prophylactic thyroidectomy irrespective of the results of calcitonin screening tests after genetic screening had shown that they were carrier of the RET proto-oncogene. Apart from a temporary hypocalcemia in one, the operations were uneventful. Pathology results showed MTC in three children of one family with MEN 2A at age 2, 3, and 6 years. In two families with MEN 2B the thyroidectomy specimen showed bilateral MTC in a 1-year-old and a 3-year-old child.

CONCLUSIONS

These findings show that MTC occurs at very young age in children with MEN 2. The authors advocate performing prophylactic thyroidectomy in the first year of life in children with MEN 2B and at age 2 years in children with MEN 2A to obtain an optimal cure rate.

Current perspectives in the surgery of multiple endocrine neoplasias

Multiple endocrine neoplasia is an uncommon but fascinating condition. In this review we examine the multifaceted presentations, the diagnostic challenges and different management strategies for various syndromes. This is an attempt to share our knowledge and experience towards achieving better outcomes in the management of the diseases.

Sporadic medullary microcarcinoma of the thyroid: a retrospective analysis of eighty cases

Clinical characteristics and prognosis of 80 patients (53 women and 27 men) with sporadic medullary thyroid carcinomas (MTC), less than 1 cm in size (micro-MTC), operated on between 1971 and 1996 are reported (73 total and 7 partial thyroidectomies). These patients, obtained from a national database of 899 patients with MTC, were compared with 357 cases of sporadic MTC greater than 1 cm and 149 subjects with familial MTC less than 1 cm (familial micro-MTC). Median age at surgery was 52.5 years, a distribution similar to larger sporadic MTC. Micro-MTC was identified due to elevated calcitonin (47.5%), clinically identified lymph node (10.0%), distant metastases (6.3%) or pathologic finding at surgery (36.2%). Diarrhea and/or flushing were observed in 6 patients including 4 with clinically identified lymph node. Among patients who had lymph node dissection at surgery (68.8%), lymph node involvement with tumor was observed in 30.9%, and was significantly more frequent in multifocal (7/11) than in unifocal micro-MTC (p < 0.03). All sporadic micro-MTC were unilateral. Survival rate was 93.9% +/- 4.4% (SE) at 10 years, greater than that observed in sporadic macro-MTC (p = 0.04). Normal postoperative basal calcitonin (CT) was obtained in 71.1% of micro-MTC patients versus 33.6% in sporadic macro-MTC (p < 0.01). Sporadic micro-MTC is much more frequent than expected, 15% of MTC in our series. Although specific survival rate and percentage of biological cure in micro-MTC are significantly better than for larger tumors, the frequency of lymph node involvement, however, justifies an aggressive surgical approach including total thyroidectomy and bilateral central lymph node dissection.

Current diagnosis and management of medullary thyroid carcinoma

BACKGROUND

Medullary thyroid carcinoma (MTC) originates in the thyroid C cells, accounting for 5% to 10% of all thyroid malignancies. Approximately 75% of cases are sporadic. Significant advances have been made in the molecular biology of MTC, but some aspects of diagnosis and management still remain controversial.

DESIGN

We reviewed relevant articles published in major English-language medical journals. We used the MEDLINE database, selected bibliographies, and articles available in our personal files.

RESULTS

Mutations of the RET proto-oncogene have been identified in the germline DNA of patients with familial MTC syndromes. Genetic testing can identify patients affected by multiple endocrine neoplasia types IIA and IIB and familial MTC, allowing early diagnosis and possible cure. Surgical treatment is total thyroidectomy. Plasma calcitonin measurements are excellent markers for postoperative follow-up. Adjunctive therapy includes radiotherapy and chemotherapy. The overall prognosis is worse than papillary thyroid carcinoma.

CONCLUSIONS

Recent advances in genetic testing allow early diagnosis and treatment of familial MTC syndromes. Despite some advances in treatment, optimal management remains controversial.

Prognostic factors for survival and for biochemical cure in medullary thyroid carcinoma: results in 899 patients. The GETC Study Group. Groupe d'étude des tumeurs à calcitonine

BACKGROUND

Prognostic factors of sporadic or inherited medullary thyroid carcinoma (MTC) are still controversial and have been assessed in old and small series. A better knowledge of these factors would improve patient management.

OBJECTIVE

To evaluate factors involved in the prognosis of MTC in a large series of cases, using uni- and multivariate analysis.

DESIGN AND PATIENTS

Clinical, biological, surgical and epidemiological data on 899 MTC patients, diagnosed between 1952 and 1996, were collected by the French Calcitonin Tumors Study Group (GETC) with a standardized questionnaire, and processed in a national database.

MEASUREMENTS

Survival and biochemical cure (i.e. normal basal post-operative serum calcitonin levels) were analysed with Kaplan and Meier and log-rank test statistical procedures. Data are presented as adjusted rather than observed survival, to consider only patients who died of MTC. Cox's forward-stepping proportional hazard model was used to analyse factors with a significant influence on survival by univariate analysis.

RESULTS

Apart from the large proportion of familial forms (43%), the general characteristics of our population were similar to those in other studies: mean age at surgery = 43.4 years; sex ratio = 1 male/1.35 female; stage I = 20.8%; stage II = 21.2%; stage III = 46.5% and stage IV = 11.5%. 863 (96%) patients underwent surgery; 43% of operated patients were biochemically cured. Adjusted survival was 85.7 +/- 1.5% at 5 years and 78.4 +/- 2.1% at 10 years. Multivariate analysis showed that age and stage were independent predictive factors of survival. Gender, type of surgery, type of familial form were predictive only in univariate analysis. Biochemical cure predicts a survival rate of 97.7% at 10 years. Authentic recurrence, that is subsequent elevation of calcitonin (CT) after post-operative normalization, was found in 4.9%. In non-cured patients (57%), survival was still good: 80.2% (+/- 2.2%) and 70.3% (+/- 2.9%) at 5 and 10 years, respectively. Similarly, prediction of biochemical cure was solely dependent on stage.

CONCLUSION

Survival of these medullary thyroid carcinoma patients appears better than expected even in non-cured patients. Considering the strong impact of stage, the necessity for pre-operative diagnosis of MTC is obvious.

Advances and controversies in the diagnosis and management of medullary thyroid carcinoma

Recent advances in the diagnosis and treatment of medullary thyroid carcinoma (MTC) have been significant, but some issues remain controversial. MTC may occur either as a hereditary or a nonhereditary entity. Hereditary MTC can occur either alone--familial MTC (FMTC)--or as the thyroid manifestation of multiple endocrine neoplasia type 2 (MEN 2) syndromes (MEN 2A and MEN 2B). These hereditary disorders are due to germline mutations in the RET proto-oncogene. Early diagnosis and treatment considerably improve the prognosis in patients with MTC. Genetic testing can identify almost all affected individuals with hereditary disease and permits early thyroidectomy in gene carriers. Plasma CT is an excellent marker for postoperative follow-up. Imaging studies help delineate recurrent or metastatic lesions. Treatment of recurrent or metastatic disease is primarily surgical, including either palliative or microdissective surgery. Radiation therapy is reserved for skeletal metastasis or nonresectable metastatic MTC. Efficacy of current chemotherapy programs is not well established. Overall, the 10-year survival rates are approximately 65%.