Timing and criteria for prophylactic thyroidectomy in asymptomatic RET carriers - the role of Ct serum level

Medullary thyroid carcinoma in children: current state of the art and future perspectives

Medullary thyroid carcinoma (MTC) is a distinct type of malignant thyroid tumor in cell origin, biological behavior, and natural history. It accounts for 1.6% of all thyroid cancers and presents either sporadically or as a hereditary disease, the latter occurring as a part of multiple endocrine neoplasia (MEN) 2A and MEN2B syndromes or as a familial MTC disease with no other manifestations. The gene responsible for the hereditary form is the rearranged during transfection (RET) gene, a proto-oncogene located to human chromosome 10. Most pediatric MTC cases have been discovered after genetic testing investigations, leading to the concept of prophylactic surgery in presymptomatic patients. Therefore, the genetic status of the child, along with serum calcitonin levels and ultrasonographic findings, determine the appropriate age for prophylactic surgical intervention. Nevertheless, a diagnosis at an early stage of MTC warrants total thyroidectomy and central lymph node dissection with the addition of lateral/contralateral lymph node dissection depending on the tumor size, ultrasonographic evidence of neck disease, or calcitonin levels. Conversely, locally advanced/unresectable or metastatic MTC is primarily treated with multikinase inhibitors, while more specific RET inhibitors are being tested in clinical trials with promising results.

Current Advances in Thyroid Cancer Management. Are We Ready for the Epidemic Rise of Diagnoses?

A rising incidence of thyroid cancers (TCs) mainly small tumors, observed during recent years, lead to many controversies regarding treatment strategies. TCs represent a distinct molecular background and clinical outcome. Although in most cases TCs are characterized by a good prognosis, there are some aggressive forms, which do not respond to standard treatment. There are still some questions, which have to be resolved to avoid dangerous simplifications in the clinical management. In this article, we focused on the current advantages in preoperative molecular diagnostic tests and histopathological examination including noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). We discussed the controversies regarding the extent of thyroid surgery and adjuvant radioiodine therapy, as well as new treatment modalities for radioiodine-refractory differentiated thyroid cancer (RR-DTC). Considering medullary thyroid cancer (MTC), we analyzed a clinical management based on histopathology and RET (ret proto-oncogene) mutation genotype, disease follow-up with a special attention to serum calcitonin doubling time as an important prognostic marker, and targeted therapy applied in advanced MTC. In addition, we provided some data regarding anaplastic thyroid cancer (ATC), a highly lethal neoplasm, which lead to death in nearly 100% of patients due to the lack of effective treatment options.

Cabozantinib for the treatment of progressive metastatic medullary thyroid cancer

Cabozantinib (XL-184) is a potent inhibitor of MET, VEGFR 2/KDR, RET and other receptor tyrosine kinases, such as KIT, AXL and FLT3. Its efficacy against MTC has been demonstrated in a prospective, randomized, placebo-controlled study (EXAM). Cabozantinib comparing to placebo significantly prolonged progression free survival both in hereditary and sporadic MTC, 11.2 vs 4.0 months, respectively. Final analysis showed no global differences in overall survival (OS) between cabozantinib and placebo. However, in a subgroup with RET M918T mutation the difference in OS was significant: 44.3 vs 18.9 months, respectively. Among the most frequent cabozantinib-related adverse events (AEs), observed in >30% of patients were diarrhea, palmar-plantar erythrodysesthesia, decreased weight, decreased appetite, nausea, fatigue, dysgeusia, hair color changes and hypertension. Expert Commentary: Cabozantinib constitutes an effective treatment option with acceptable toxicity in MTC patients showing either germinal or sporadic tumor RET M918T mutation as the drug prolonged OS in these subjects.

Molecular diagnosis and comprehensive treatment of multiple endocrine neoplasia type 2 in Southeastern Chinese

Background

Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant inherited endocrine malignancy syndrome. Early and normative surgery is the only curative method for MEN 2-related medullary thyroid carcinoma (MTC). In patients with adrenal pheochromocytoma, cortical-sparing adrenalectomy (CSA) can be utilized to preserve adrenocortical function.

Methods

We present twenty-six of 33 MEN2 patients underwent prophylactic thyroidectomy with varying neck dissection and eight of 24 MEN2A patients with PHEO underwent adrenal-sparing surgery. Direct sequencing of entire RET exons was performed in all participants.

Results

The RET mutations (p.C634Y [n = 10], p.C634R [n = 9], p.C634F [n = 2], p.C618Y [n = 8], p.C618R [n = 3], and p.M918T [n = 1]) were confirmed in 20 symptomatic patients and identified in 13 at-risk relatives (RET carriers). Twenty-six of 33 MEN2 patients underwent thyroidectomies with neck dissections; the mean age at the time of the first thyroid surgery and the tumor diameter of the 6 RET carriers was decreased compared with 20 symptomatic patients (P < 0.001 and P = 0.007, respectively), while the disease-free survival was increased (80% vs.10%, P = 0.0001). Seven RET carriers who were declined surgery. One of 20 symptomatic patients with MTC bone metastases after surgery received vandetanib therapy for 20 months and responded well. Additionally, 8 of 24 MEN2A patients who initially had unilateral pheochromocytomas underwent CSA, 1 developed contralateral pheochromo cytomas 10 years later, then also accepted and also agreed to a CSA. None of the patients required steroid replacement therapy.

Conclusions

Based on our results, integrated RET screening and the pre-operative calcitonin level is an excellent strategy to ensure earlier diagnosis and standard thyroidectomy. CSA can be utilized to preserve adrenocortical function in patients with pheochromocytomas.

Electronic supplementary material

The online version of this article (doi:10.1186/s13053-015-0026-1) contains supplementary material, which is available to authorized users.

The rare intracellular RET mutation p.S891A in a Chinese Han family with familial medullary thyroid carcinoma

We report intracellular RET mutation in a Han Chinese pedigree with familial medullary thyroid carcinoma (FMTC). Direct sequencing of RET proto-oncogene identified a missense c.2671T greater than G (p.S891A) mutation in 6 of 14 family members. The single nucleotide polymorphisms c. 135A greater than G (p.A45A), IVS4 + 48A greater than G, c. 1296A greater than G (p.A432A), c. 2071G greater than A (p.G691S), c. 2307T greater than G (p.L769L) and a variant c. 833C greater than A (p.T278N) were also found in 6 carriers. Among 5 of the 6 carriers presented medullary thyroid carcinoma (MTC) as an isolated clinical phenotype, with elevated basal serum calcitonin (Ct). Two underwent non-normative thyroidectomy either two or four times without physician awareness or diagnosis of this disease at initial treatment, but with elevated Ct. One with elevated pre-Ct accepted total thyroidectomy (TT) with modified bilateral neck dissection (MBiND), and whose seventh posterior rib MTC metastases was confirmed 5 months after surgery. Moreover, results of two affected individuals with elevated Ct were reduced to normal after TT with MBiND or prophylactic VI compartmental dissection. However, only another carrier with the variant p.T278N had slightly elevated Ct rejected surgery and was strictly monitored. Given these case results, we suggest that screening of RET and pre-surgical Ct levels in the management of MTC patients is essential for earlier diagnosis and more normative initial treatment, that FMTC patients with cervical lymph nodes metastases may be cured by TT with MBiND, and that prophylactic VI compartmental dissection should be avoided when Ct levels are low.

The value of genetic screening in medullary thyroid cancer

Medullary thyroid cancer (MTC) accounts for ~10% of thyroid carcinomas and occurs in sporadic and hereditary forms. Early diagnosis significantly impacts the clinical course, management and outcome of the disease. The identification of germline-activating mutations of the rearranged during transfection oncogene in patients with hereditary MTC led to significant progress in the diagnostic and therapeutic approach, thus improving the quality of care provided, and consequently, disease prognosis. In the present review, various aspects of genetic screening (GS) in MTC will be covered, which elucidate the value of GS in guiding clinical decision making, therapy selection and appropriate genetic counseling of the affected families. GS should be offered to every MTC patient, based on the personal and family medical history, to allow optimal clinical management and follow-up.

Presentation of points of general discussion and voting among the speakers of the European Thyroid Association-Cancer Research Network (ETA-CRN) meeting in Lisbon, 2009, entitled "European comments to ATA medullary thyroid cancer guidelines"

The main subjects of discussion, held online within the ETA-CRN board invited 16 expert-panelists are shown. The ad hoc emerged ETA-CRN panel of experts (EPE) first congratulated Professor Kloos and the ATA Taskforce for the extensive work on medullary thyroid cancer, and appreciated discussing the ATA guidelines during the ETA-CRN meeting. As it was not possible for all experts to visit the meeting, they enclosed their comments in the online ETA forum. The overall intention was to evaluate certain discrepancies between the ATA guidelines and were biased European clinical practice.

All discussants were aware that the ATA guidelines had followed evidence based medicine rules; however, it was intended to reach an European consensus in this matter. The results of online voting among the EPE are shown.

We received answers from nine experts. The particular ATA guidelines devoted to the management of MTC ranged in agreement in 0/9 to 4/9. This did not reflect the general, good assessment of the guidelines, as of votes a set of questions.

The strongest discrepancies were found in assessment of the usefulness of pentagastrin (Peptavlon®) stimulated calcitonin secretion. The majority of the EPE (5/9) chose an option: “the increase of the basal Ct >100 ng/L means the substantial risk of MTC. However, there should also have been a recommendation for the grey zone 10-100 ng/L, where stimulation with pentagastrin is useful. The cut-off to perform stimulation test at ≤ 15-20 ng/L and values >100 ng/L means a significant suspicion of MTC”.

Similarly, attention from the EPE was raised towards the surgical procedures in MTC, particularly the extent and indications for lymph node surgical intervention. Four questions were related to the indications to lymphadenectomy and extent of surgery. The equal number (4/8) of EPE agreed with the ATA R61 and half of the ETA-CRN panel of experts disagreed because the indications to lymphadenectomy (Lx) depended in their opinion on the tumors detected by the Ct screening, in which prophylactic Lx might not be necessary.

“Notwithstanding the evidence based guidelines, their final acceptation requires unrestricted discussion and consideration of differences in clinical practice and experience between countries”.