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The three deiodinase selenoenzymes are key regulators of intracellular thyroid hormone (TH) levels. The two TH-activating deiodinases (D1 and D2) are normally expressed in follicular thyroid cells and contribute to the overall TH production. During thyroid tumorigenesis, the deiodinase expression profile changes to customize intracellular TH levels to different requirements of cancer cells. Differentiated thyroid cancers overexpress the TH-inactivating D3, likely to reduce the TH signaling within the tumor. Strikingly, recent evidences suggest that during the late-stage of thyroid tumorigenesis D2 expression raises and this, together with a reduction in D3 expression levels, increases TH intracellular signaling in dedifferentiated thyroid cancers. These findings call into question the different function of TH on the various stages of thyroid cancers.

Low-risk papillary cancers, which represent the vast majority of thyroid cancers diagnosed today, do not require aggressive treatment or follow-up. Initial treatment consists of a total thyroidectomy without prophylactic lymph node dissection. A hemithyroidectomy is an alternative in some patients with an intrathyroidal tumor and with a normal contralateral lobe at pre-operative neck ultrasonography. The use of post-operative radioiodine should be restricted to selected patients. Follow-up at 6–18 months is based on serum thyroglobulin (Tg), Tg-antibody determination and neck ultrasonography. In the absence of any abnormality (excellent response to treatment), the risk of recurrence is extremely low and follow-up may consist of serum TSH monitoring that is maintained in the normal range, and a Tg and Tg-antibody titer determination every year. There is no need for referral to a specialized center. In patients with detectable serum Tg or detectable Tg antibodies, the trend over time of these markers on levothyroxine treatment will dictate subsequent follow-up: a decreasing trend is reassuring, but an increasing trend should lead to imaging, starting with neck ultrasonography.

Based on experimental data, the inhibition of the MAPkinase pathway in patients with radioiodine-refractory thyroid cancer was capable of inducing a redifferentiation. Preliminary data obtained in a small series of patients were encouraging and this strategy might become an alternative treatment in those patients with a druggable mutation that induces a stimulation of the MAP kinase pathway. This is an active field of research to answer many still unresolved questions.

Distant metastases from thyroid cancer of follicular origin are uncommon. Treatment includes levothyroxine administration, focal treatment modalities with surgery, external radiation therapy and thermal ablation, and radioiodine in patients with uptake of ¹³¹I in their metastases. Two-thirds of distant metastases become refractory to radioiodine at some point, and when there is a significant tumor burden and documented progression on imaging, a treatment with a kinase inhibitor may provide benefits.

Anaplastic thyroid cancer (ATC) is a rare thyroid tumor that frequently originates from the dedifferentiation of a well-differentiated papillary or follicular thyroid cancer. Type 2 deiodinase (D2), responsible for the activation of the thyroid hormone T4 into T3, is expressed in normal thyroid cells and its expression is strongly downregulated in papillary thyroid cancer. In skin cancer, D2 has been associated with cancer progression, dedifferentiation and epithelial-mesenchymal transition. Here, we show that D2 is highly expressed in anaplastic compared to papillary thyroid cancer cell lines and that D2-derived T3 is required for ATC cell proliferation. D2 inhibition is associated with G1 growth arrest and induction of cell senescence, together with reduced cell migration and invasive potential. Finally, we found that mutated p5372R(R248W), frequently found in ATC, is able to induce D2 expression in transfected papillary thyroid cancer cells. Our results show that the action of D2 is crucial for ATC proliferation and invasiveness, providing a potential new therapeutic target for the treatment of ATC.

There are limited treatment options for patients with radioactive iodine refractory, progressive differentiated thyroid cancer. Although there is consensus that multikinase inhibitor therapy should be considered in patients with progressive disease with considerable tumor load or symptomatic disease, uncertainty exists on the optimal timing to treat with a multikinase inhibitor, especially for asymptomatic patients. RIFTOS MKI is an international, prospective, open-label, multicenter, noninterventional study with the primary objective to compare the time to symptomatic progression from study entry in asymptomatic patients with radioactive iodine refractory, progressive differentiated thyroid cancer for whom there is a decision to initiate multikinase inhibitors at study entry (cohort 1) with those for whom there is a decision to not initiate multikinase inhibitors at study entry (cohort 2). Secondary endpoints are overall survival and progression-free survival, which will be compared between cohorts 1 and 2. Additional secondary endpoints are postprogression survival from time of symptomatic progression, duration of and response to each systemic treatment regimen and dosing of sorafenib throughout the treatment period. Asymptomatic, multikinase inhibitor-naive patients aged ≥18 years with histologically/cytologically documented differentiated thyroid cancer that is radioactive iodine refractory are eligible. Patients may receive any therapy for differentiated thyroid cancer, including sorafenib or other multikinase inhibitors if indicated and decided on by the treating physician. In total, 700 patients are estimated to be enrolled from >20 countries. Final analysis will be performed once the last enrolled patient has been followed up with for 24 months (ClinicalTrials.gov identifier: Nbib2303444).

RET oncogene mutations are found in familial medullary thyroid carcinomas (MTC) and in one-third of sporadic cases. Oncogenic mechanisms involved in non-RET mutated sporadic MTC remain unclear. To study alterations associated with the development of both inherited and sporadic MTC, pangenomic DNA microarrays were used to analyze the transcriptome of 13 MTCs (four familial and nine sporadic). By using an ANOVA test, a list of 173 gene sequences with at least a twofold change expression was obtained. A subset of differentially expressed genes was controlled by real-time quantitative PCR and immunohistochemistry on a larger collection of MTCs. The expression pattern of those genes allowed us to distinguish two groups of sporadic tumors. The first group displays an expression profile similar to that expressed by inherited RET634 tumors. The second presents an expression profile close to that displayed by inherited RET918 tumors and includes tumors from patients with distant metastases. It is characterized by the overexpression of genes involved in proliferation and invasion (PTN, ESM1, and CEACAM6) or matrix remodeling (COL1A1, COL1A2, and FAP). Interestingly, RET918 tumors showed overexpression of the PTN gene, encoding pleiotrophin, a protein associated with metastasis. Using a MTC cell line, silencing of RET induced the inhibition of PTN gene expression. Overall, our results suggest that familial MTC and sporadic MTC could activate similar oncogenic pathways.

Survival of metastatic gastroenteropancreatic well-differentiated endocrine carcinoma (GEP WDEC) is not well characterized. We evaluated the long-term outcome and prognostic factors for survival in 118 patients with distant metastases from GEP WDEC. Inclusion criteria were 1) pathological review by a single pathologist according to the present WHO criteria, 2) absence of previous therapy apart from surgery, 3) complete morphological evaluation within 3 months including somatostatin receptor scintigraphy, and 4) follow-up at Gustave-Roussy Institute until death or study's end. Clinical, biological marker, and pathological parameters were analyzed in univariate and multivariate statistical models. Survival after the first complete imaging work-up of the metastatic disease was determined using Kaplan–Meier method. Overall, survival for 5 years after the diagnosis of metastatic disease was 54%. In multivariate analysis, age (hazard ratio (HR): 1.05, 95% confidence interval (CI): 1.01–1.08, P=0.01), the number of liver metastases (HR: 3.4, 95% CI: 1.4–8.3, P=0.01), tumor slope (HR: 1.1, 95% CI: 1.0–1.1, P=0.001), and initial surgery (HR: 0.3, 95% CI: 0.1–0.8, P=0.01) were predictive of survival. Five-year survival was 100%, 91% (95% CI, 51–98%), 62% (95% CI, 37–83%), and 9% (95% CI, 6–32%) when patients had 0, 1, 2, 3 or more poor prognostic features respectively. This study enables the stratification of metastatic GEP WDEC patients into distinct risk groups. These risk categories can be used to tailor therapeutic approaches and also to design and interpret clinical trials.

Both external and internal exposure to ionizing radiation are strong risk factors for the development of thyroid tumors. Until now, the diagnosis of radiation-induced thyroid tumors has been deduced from a network of arguments taken together with the individual history of radiation exposure. Neither the histological features nor the genetic alterations observed in these tumors have been shown to be specific fingerprints of an exposure to radiation. The aim of our work is to define ionizing radiation-related molecular specificities in a series of secondary thyroid tumors developed in the radiation field of patients treated by radiotherapy. To identify molecular markers that could represent a radiation-induction signature, we compared 25K microarray transcriptome profiles of a learning set of 28 thyroid tumors, which comprised 14 follicular thyroid adenomas (FTA) and 14 papillary thyroid carcinomas (PTC), either sporadic or consecutive to external radiotherapy in childhood. We identified a signature composed of 322 genes which discriminates radiation-induced tumors (FTA and PTC) from their sporadic counterparts. The robustness of this signature was further confirmed by blind case-by-case classification of an independent set of 29 tumors (16 FTA and 13 PTC). After the histology code break by the clinicians, 26/29 tumors were well classified regarding tumor etiology, 1 was undetermined, and 2 were misclassified. Our results help shed light on radiation-induced thyroid carcinogenesis, since specific molecular pathways are deregulated in radiation-induced tumors.

Effective adverse event (AE) management is critical to maintaining patients on anticancer therapies. The DECISION trial was a multicenter, randomized, double-blind, placebo-controlled, Phase 3 trial which investigated sorafenib for treatment of progressive, advanced, or metastatic radioactive iodine-refractory, differentiated thyroid carcinoma. Four hundred and seventeen adult patients were randomized (1:1) to receive oral sorafenib (400 mg, twice daily) or placebo, until progression, unacceptable toxicity, noncompliance, or withdrawal. Progression-free survival, the primary endpoint of DECISION, was reported previously. To elucidate the patterns and management of AEs in sorafenib-treated patients in the DECISION trial, this report describes detailed, by-treatment-cycle analyses of the incidence, prevalence, and severity of hand–foot skin reaction (HFSR), rash/desquamation, hypertension, diarrhea, fatigue, weight loss, increased serum thyroid stimulating hormone, and hypocalcemia, as well as the interventions used to manage these AEs. By-cycle incidence of the above-selected AEs with sorafenib was generally highest in cycle 1 or 2 then decreased. AE prevalence generally increased over cycles 2–6 then stabilized or declined. Among these AEs, only weight loss tended to increase in severity (from grade 1 to 2) over time; severity of HFSR and rash/desquamation declined over time. AEs were mostly grade 1 or 2, and were generally managed with dose interruptions/reductions, and concomitant medications (e.g. antidiarrheals, antihypertensives, dermatologic preparations). Most dose interruptions/reductions occurred in early cycles. In conclusion, AEs with sorafenib in DECISION were typically grade 1 or 2, occurred early during the treatment course, and were manageable over time.