MicroRNAs in thyroid cancer with focus on medullary thyroid carcinoma: potential therapeutic targets and diagnostic/prognostic markers and web based tools.

This review aimed to describe the inculpation of microRNAs (miRNAs) in thyroid cancer (TC) and its subtypes, mainly medullary thyroid carcinoma (MTC), and to outline web-based tools and databases for bioinformatics analysis of miRNAs in TC. Additionally, the capacity of miRNAs to serve as therapeutic targets and biomarkers in TC management will be discussed. This review is based on a literature search of relevant articles on the role of miRNAs in TC and its subtypes, mainly MTC. Additionally, web-based tools and databases for bioinformatics analysis of miRNAs in TC were identified and described. MiRNAs can perform as oncomiRs or antioncoges, relying on the target mRNAs they regulate. MiRNA replacement therapy using miRNA mimics or antimiRs that aim to suppress the function of certain miRNAs can be applied to correct miRNAs aberrantly expressed in diseases, particularly in cancer. MiRNAs are involved in the modulation of fundamental pathways related to cancer, resembling cell cycle checkpoints and DNA repair pathways. MiRNAs are also rather stable and can reliably be detected in different types of biological materials, rendering them favorable diagnosis and prognosis biomarkers as well. MiRNAs have emerged as promising tools for evaluating medical outcomes in TC and as possible therapeutic targets. The contribution of miRNAs in thyroid cancer, particularly MTC, is an active area of research, and the utility of web applications and databases for the biological data analysis of miRNAs in TC is becoming increasingly important.

B7-H3 and ICAM-1 are potentially therapeutic targets for thyroid carcinoma.

Although most differentiated thyroid carcinoma has a clinically favorable prognosis, some of specific types of thyroid cancer (such as anaplastic thyroid carcinoma and advanced papillary thyroid carcinoma) show fatal outcomes and require novel treatments. Immunotherapy is a promising avenue for the treatment of advanced thyroid carcinoma. B7-H3 (B7 homolog 3 protein) and ICAM-1 (intercellular adhesion molecule 1), as two important immune checkpoints (ICPs), is becoming hopeful target spots for immunotherapy. A growing amount of evidence has suggested that B7-H3 and ICAM-1 are upregulated in papillary thyroid carcinoma. However, their expression level in specific types of thyroid cancer remains largely unclear. In the present study, we explored the expression level of B7-H3 and ICAM-1 in different types of thyroid carcinoma. In the groups of the TCGA cohort, both B7-H3 and ICAM-1 mRNA were highly expressed in thyroid carcinoma. Furthermore, the patients with Stage2, 61-80y, Follicular thyroid papillary carcinoma and N0 had lower B7-H3 and ICAM-1 mRNA expression. In the groups of our cohort, PTCs and ATCs showed frequently moderate to strong expression of B7-H3 and ICAM-1 protein expression. The significant relevance of B7-H3 staining score with ICAM-1 staining score was observed in TCGA database and our cohort, which might open avenues for the combination therapy in advanced thyroid cancer.

Access to New Clinic Appointments for Patients With Cancer.

Importance: Racial and ethnic disparities have been observed in the outpatient visit rates for specialist care, including cancer care; however, little is known about patients' experience at the critical step of attempting to access new clinic appointments for cancer care. Objective: To determine simulated English-speaking, Spanish-speaking, and Mandarin-speaking patient callers' ability to access new clinic appointments for 3 cancer types (colon, lung, and thyroid cancer) that disproportionately impact Hispanic and Asian populations. Design, Setting, and Participants: This cross-sectional audit study was conducted between November 2021 and March 2023 using 479 clinic telephone numbers that were provided by the hospital general information personnel at 143 hospitals located across 12 US states. Using standardized scripts, trained research personnel assigned to the roles of English-speaking, Spanish-speaking, and Mandarin-speaking patients called the telephone number for a clinic that treats colon, lung, or thyroid cancer to inquire about a new clinic appointment. Data analysis was conducted from June to September 2023. Main Outcomes and Measures: The primary outcome was whether the simulated patient caller was able to access cancer care (binary variable, yes or no), which was defined to include being provided with a clinic appointment date or scheduling information. Multivariable logistic regression analysis was performed to determine factors independently associated with simulated patient callers being able to access cancer care. Results: Of 985 total calls (399 English calls; 302 Spanish calls; 284 Mandarin calls), simulated patient callers accessed cancer care in 409 calls (41.5%). Differences were observed based on language type, with simulated English-speaking patient callers significantly more likely to access cancer care compared with simulated Spanish-speaking and Mandarin-speaking patient callers (English, 245 calls [61.4%]; Spanish, 110 calls [36.4%]; Mandarin, 54 calls [19.0%]; P < .001). A substantial number of calls ended due to linguistic barriers (291 of 586 Spanish or Mandarin calls [49.7%]) and workflow barriers (239 of 985 calls [24.3%]). Compared with English-speaking simulated patient callers, the odds of accessing cancer care were lower for Spanish-speaking simulated patient callers (adjusted odds ratio [aOR], 0.34; 95% CI, 0.25-0.46) and Mandarin-speaking simulated patient callers (aOR, 0.13; 95% CI, 0.09-0.19). Compared with contacting clinics affiliated with teaching hospitals, callers had lower odds of accessing cancer care when contacting clinics that were affiliated with nonteaching hospitals (aOR, 0.53; 95% CI, 0.40-0.70). Conclusions and Relevance: In this cross-sectional audit study, simulated patient callers encountered substantial barriers when attempting to access clinic appointments for cancer care. These findings suggest that interventions focused on mitigating these barriers are necessary to increase access to cancer care for all patients.

Emerging therapeutic options for follicular-derived thyroid cancer in the era of immunotherapy.

Although most follicular-derived thyroid cancers are well differentiated and have an overall excellent prognosis following treatment with surgery and radioiodine, management of advanced thyroid cancers, including iodine refractory disease and poorly differentiated/undifferentiated subtypes, is more challenging. Over the past decade, better understanding of the genetic drivers and immune milieu of advanced thyroid cancers has led to significant progress in the management of these patients. Numerous targeted kinase inhibitors are now approved by the U.S Food and Drug administration (FDA) for the treatment of advanced, radioiodine refractory differentiated thyroid cancers (DTC) as well as anaplastic thyroid cancer (ATC). Immunotherapy has also been thoroughly studied and has shown promise in selected cases. In this review, we summarize the progress in the understanding of the genetic landscape and the cellular and molecular basis of radioiodine refractory-DTC and ATC, as well as discuss the current treatment options and future therapeutic avenues.

Palliative treatment of generalized metastatic follicular carcinoma of thyroid after operation: A case report and literature review.

RATIONALE: Follicular carcinoma of thyroid is a rare pathological type of thyroid carcinoma, accounting for 4.5% of the total. At present, the main treatment methods include surgery, iodine therapy, thyroid hormone inhibitors, etc. Targeted drug therapy is very important for distant metastasis and iodine-refractory differentiated thyroid cancer. PATIENT CONCERNS: This clinical case is a 51-year-old male patient with follicular carcinoma of thyroid. DIAGNOSES: After 7 years of total thyroidectomy, multiple distant metastasis occurred to bilateral lungs, bones, multiple lymph nodes, etc. INTERVENTION: After multidisciplinary consultation in the department of oncology, thoracic surgery, nuclear medicine and other departments, he received targeted drug therapy of Lenvatinib. OUTCOMES: After 3 months, his condition was partially relieved, and his quality of life was significantly improved. After 11 months of treatment, the evaluated efficacy was still in remission. LESSON: Late metastatic thyroid cancer is faced with dilemma of radioiodine refractory after traditional treatment. This will provide further evidence for therapeutic intervention in similar patients in the future.

Donafenib as neoadjuvant therapy in locally advanced thyroid cancer: protocol for the DONATHYCA phase II prospective single-arm trial in China.

INTRODUCTION: The invasion of important structures in locally advanced thyroid cancer (LATC) hinders radical resection, increases the risk of recurrence and even prevents surgery. Creating the opportunity for radical operation in patients with LATC is critical for improving their prognosis. Multitarget tyrosine kinase inhibitors were used as neoadjuvant therapy in several studies. Donafenib produced survival benefits over placebo in Chinese patients with radioiodine-refractory differentiated thyroid cancer in a recent study, but its efficacy in the neoadjuvant setting remains unknown. This study thus aims to assess the efficacy and safety of donafenib as neoadjuvant therapy in LATC. METHODS AND ANALYSIS: DONATHYCA is a prospective, exploratory, single-arm phase II study evaluating the efficacy and safety of donafenib as neoadjuvant therapy in patients with LATC. 13 patients will be enrolled. The primary endpoint is the objective response rate as per Response Evaluation Criteria in Solid Tumours V.1.1. The secondary objectives include progression-free survival, the duration of response, the disease control rate, the R0/R1 resection rate, quality of life and toxicity during treatment according to Common Terminology Criteria for Adverse Events V.4.0. Patients will receive donafenib 300 mg two times a day continuously in a 21-day treatment cycle for six cycles. ETHICS AND DISSEMINATION: This study was approved by the Ethics Committee of Fujian Cancer Hospital (K2023-144-02) on 27 July 2023 and registered in the China Clinical Trial Registry on 20 September 2023. The results of the study will be presented at academic conferences and published in scientific publications. TRIAL REGISTRATION NUMBER: ChiCTR2300075973.

Risk of second primary thyroid cancer in cancer survivors.

A risk factor for thyroid cancer (TC) may be a history of former cancer and cancer therapy. The precise risk of a second primary thyroid carcinoma has not yet been revealed. In this study, we evaluated standardized incidence ratios (SIRs) of second primary thyroid cancer (SPTC) with consideration of different conditions and further analyzed the clinicopathological characteristics and survival of these patients. The cohort was selected from the US Surveillance, Epidemiology, and End Results (SEER) Program between 1975 and 2019. The standardized incidence ratios, morbidity risk, clinicopathological features, and survival of second primary thyroid carcinoma were analyzed. Propensity score matching (PSM) was used to balance covariates. Kaplan-Meier method was performed to assess the survival outcomes. Overall, 7066 patients with SPTC and 83,113 patients with primary TC were identified. The SIR of TC in tumor patients was 1.51/10,000, statistically higher than the natural population (0.94/10,000, P < 0.05). The most significant tumors contributing to the increased SIRs of SPTC were acute lymphocytic leukemia (3.49/10,000), Hodgkin's lymphoma-nodal (3.29/10,000), salivary gland cancer (3.23/10,000), and kidney and renal pelvis cancer (3.05/10,000). The incidence of TC increased significantly in tumor patients who received radiotherapy/chemotherapy before age 35. The age at diagnosis of the SPTC was much older than the primary TC (64.01 vs. 49.55 years, p < 0.001). The SPTC had a higher percentage of histological grades 3/4 (23.14% vs. 15.19%, p < 0.001). Survival analyses demonstrated a worse prognosis for the SPTC group compared to the primary TC group. But after PSM, the survival outcomes of the two groups tended to be equivalent (P = 0.584). The SIRs of TC are higher in tumor patients. The most significant factors contributing to the increased risk of SPTC were some specific former tumors and acceptance of radiotherapy/ chemotherapy before age 35. There was no significant difference in survival between SPTC and primary TC.

Geographic disparities in thyroid cancer staging at presentation: Insights from an Australian context.

BACKGROUND: Thyroid cancer diagnoses have increased over recent decades at a rate much higher than that of any other cancer in Australia. Rural patients are known to have reduced access to healthcare and may have different thyroid cancer presentation rates. This study examined the relationship between thyroid cancer diagnosis and patient rurality. METHODS: Data from the Australia and New Zealand Thyroid Cancer Registry from 2017 to 2022 were analyzed, stratifying patient postcodes into rurality groups using the Australian Statistical Geography Standard. The American Thyroid Association (ATA) guidelines were used to stratify risk categories and management to compare treatment adequacy between the groups. Statistical analysis assessed demographic, clinical, and management differences. RESULTS: Among 1766 patients, 70.6% were metropolitan (metro) and 29.4% were non-metropolitan (non-metro). Non-metro patients were older at diagnosis (median 56 vs. 50 years, p < 0.001), presented more frequently with T stage greater than 1 (stage 2-4, 41.9% vs. 34.8%, and p = 0.005), AJCC stage greater than 1 (stage 2-4, 18.5% vs. 14.6%, and p = 0.019), and cancers larger than 4 cm (14.3% vs. 9.9%, p = 0.005). No significant differences in treatment adequacy were observed between the groups for ATA low-risk cancers. CONCLUSIONS: Non-metropolitan patients in the registry present with more advanced thyroid cancer, possibly due to differences in healthcare access. Further research should assess long-term survival outcomes and influencing factors. Understanding the impact on patient outcomes and addressing healthcare access barriers can optimize thyroid cancer care across geographic regions in Australia.

Clinical and Paraclinical Considerations Regarding ki67's Role in the Management of Differentiated Thyroid Carcinoma-A Literature Review.

Background and Objectives: The ki67 nuclear protein is a tool for diagnosis and prognosis in oncology that is used to evaluate cell proliferation. Differentiated thyroid carcinoma is usually a slow-growing neoplasm, the most common type being the papillary form. Some clinical and pathological aspects may predict aggressive behaviour. There are reported cases of recurrence without clinico-pathological findings of aggressiveness. To obtain better predictions of the disease outcome in thyroid carcinoma, many immunohistochemical markers have been studied. The aim of this narrative literature review is to identify the benefits that ki67 may add to the management of patients with differentiated thyroid carcinoma, according to the latest evidence. Materials and Methods: We performed a search on the PubMed and Google Scholar databases using controlled vocabulary and keywords to find the most suitable published articles. A total number of sixty-eight items were identified, and five other articles were selected from other sources. After refining the selection, the inclusion criteria and exclusion criteria were applied, and a total number of twenty-nine articles were included in this literature review. Results and Discussion: The studies consist of retrospective studies (89.66%), case reports (6.9%) and literature reviews (3.45%), evaluating the role, implications and other parameters of ki67 as a diagnostic and/or prognostic tool. The statistical correlations between ki67 and other features were systematized as qualitative results of this review in order to improve the treatment strategies presented in the included articles. Conclusions: The included studies present converging data regarding most of the aspects concerning ki67. The ki67 proliferation index is a diagnostic/prognostic tool of interest in differentiated thyroid carcinoma and a good predictor of disease-free survival, disease recurrence and metastatic development. Prospective studies on large cohorts may add value for ki67 as a specific tool in the management strategy of differentiated thyroid carcinoma.

Identification and Economic Evaluation of Differentiated Thyroid Cancer Care Consumption Patterns Using Sequence Analysis.

Objectives: This study aims to assess the impact of care consumption patterns and individual characteristics on the cost of treating differentiated thyroid carcinoma (DTC), in France, with a specific emphasis on socioeconomic position. Methods: The methodology involved a net cost approach utilising cases from the EVATHYR cohort and controls from the French National Health Insurance database. Care consumption patterns were created using Optimal Matching and clustering techniques. The individual characteristics influence on patterns was assessed using multinomial logistic regression. The individual characteristics and patterns influence on care costs was assessed using generalised estimating equations. Results: The findings revealed an average cost of €13,753 per patient during the initial 3 years. Regression models suggested the main predictors of high DTC specific care consumption tended to include having a high risk of cancer recurrence (OR = 4.97), being a woman (OR = 2.00), and experiencing socio-economic deprivation (OR = 1.26), though not reaching statistical significance. Finally, high DTC-specific care consumers also incurred higher general care costs (RR = 1.35). Conclusion: The study underscores the increased costs of managing DTC, shaped by consumption habits and socioeconomic position, emphasising the need for more nuanced DTC management strategies.

[Controversy and boundary in the diagnose and treatment of thyroid cancer].

In recent years, the incidence of thyroid cancer has rapidly increased, whereas the mortality rate has not risen correspondingly. Therefore, scholars at home and abroad have proposed the view of overdiagnosis in thyroid cancer, sparking intense debates about the phenomenon of overdiagnosis and overtreatment. A historical review and discussion of the primary reasons for the increase in thyroid cancer incidence and the improvement in treatment outcomes are beneficial. It helps clarify that the real increase in thyroid cancer is primarily due to the higher incidence rate, rather than overdiagnosis. Additionally, it allows us to reevaluate which factors guarantee favorable efficacy in thyroid cancer.

Molecular Imaging and Therapy of Differentiated Thyroid Carcinoma in Adults.

ABSTRACT: Differentiated thyroid carcinoma (DTC) has been increasing in incidence in the United States over the last several decades, although mortality rates have remained low. Radioactive iodine therapy (RAI-T) has been a mainstay of treatment for DTC since the 1940s. Imaging of DTC before and after RAI-T primarily focuses on molecular imaging of the sodium iodide symporter. The expanding understanding of the molecular profile of DTC has increased available treatment options. Incorporation of risk stratification to treatment approaches has led to deintensification of both surgical and nonsurgical treatments, leading to decreased morbidity without compromising disease control.

Poorly differentiated thyroid carcinoma: molecular, clinico-pathological hallmarks and therapeutic perspectives.

Poorly differentiated thyroid carcinoma (PDTC) is a rare and extremely aggressive tumor, accounting for about 2-15% of all thyroid cancer. PDTC has a distinct biological behavior compared to well-differentiated and anaplastic thyroid carcinoma and, in last years, it has been classified as a separate entity from both anatomopathological and clinical points of view. Nevertheless, there is still a lack of consensus among clinicians regarding inclusion criteria and definition of PDTC that affects its diagnosis and clinical management. Due to its rarity and difficulty in classification compared to other tumors, very few studies are available to date and series often include different histotypes in addition to PDTC. This review focuses on main studies concerning PDTC summarizing the evolution in the definition of its diagnosis criteria, clinicopathological features, management, and outcome. The data available confirm that the pathological evaluation and classification of PDTC are crucial and should therefore be standardized. Since the clinical presentation and prognosis of PDTC may vary widely depending on the different stage of the disease at diagnosis, the patient's management may differ in treatment and should be tailored to each patient. Finally, this review discusses advances in molecular insights of PDTC that, together with the implementation of both in vitro and in vivo models, will provide valuable insights into biological mechanisms of progression, metastasis, and invasion of this aggressive thyroid carcinoma. Further studies on larger, carefully selected series are needed to better assess the peculiar features of PDTC and to better define its management by focusing on the best diagnostic and therapeutic approaches.

Management of Advanced Medullary Thyroid Carcinoma: Current Systemic Therapy Options.

The current rapid development of more selective and effective drugs for the treatment of thyroid cancer has open a new era in the treatment of patients with this condition, in the past limited to the possibility of only radioactive iodine for well differentiated tumor and surgery for medullary thyroid carcinoma (MTC). The treatment of advanced medullary thyroid carcinoma has evolved in the last few years and options for patients with advanced disease are now available. Multikinase inhibitors (MKIs) with nonselective RET inhibition like Vandetanib and Cabozantinib were approved for the treatment of MTC, although the efficacy is limited due to the lack of specificity resulting in a higher rate of drug-related adverse events, leading to subsequent dose reductions, or discontinuation, and the development of a resistance mechanism like seen on the RET Val804 gatekeeper mutations. MTC is associated with mutations in the RET protooncogene, and new highly selective RET inhibitors have been developed including Selpercatinib and Pralsetinib, drugs that have demonstrate excellent results in clinical trials, and efficacy even in the presence of gatekeeper mutations. However, despite their efficacy and great tolerability, mechanisms of resistance have been described, such as the RET solvent front mutations. Due to this, the need of constant evolution and drug research is necessary to overcome the emergence of resistance mechanisms.

Identification of 10 differentially expressed and cuproptosis-related genes in immune infiltration and prognosis of thyroid carcinoma.

The association between the cuproptosis-related genes and the immune infiltration and their prognostic value in thyroid carcinoma is still unexplored. Bioinformatics analyses were performed with data obtained from the TCGA dataset. The aberrantly expressed genes were selected. KEGG and GO analyses were conducted to explore the enriched pathways of the up-regulated or down-regulated genes in thyroid carcinoma. Totally 1495 genes were differentially expressed (691 up-regulated, 804 down-regulated) in thyroid carcinoma (p<0.05). The 10 cuproptosis-related RNAs (DLD, LIAS, LIPT1, FDX1, DLAT, MTF1, PDHA1, CDKN2A, GLS and PDHB) were also demonstrated to be aberrantly expressed in thyroid carcinoma patients tissues. FDX1 expression was correlated with the overall survival in thyroid carcinoma patients (HR=0.4995, 95% CI: 0.2688-0.9285, p=0.0282). Further multivariate cox regression analysis revealed that DLD (HR=24.8869, 95% CI: 4.48772-138.01181, p=0.00024), and LIAS (HR=7.74092, 95% CI: 1.12194-53.40898, p=0.03783) were associated with the survival of thyroid carcinoma patients. The immune infiltration analysis demonstrated that significant correlation between the 10 cuproptosis-related genes and immune infiltration in thyroid carcinoma (p<0.01). We presented the expression profiles of dysregulated genes in thyroid carcinoma. The findings of our study highlighted the potential of cuproptosis-related genes as prognostic biomarkers for thyroid carcinoma.

Development and validation of a nomogram to predict overall survival in patients with redefined anaplastic thyroid carcinoma based on the SEER database.

BACKGROUND: According to the latest classification of thyroid tumors released by the WHO in 2022, primary squamous cell carcinoma of the thyroid (PSCCTh) is classified as anaplastic thyroid carcinoma (ATC). The objective of this study was to determine the differences in characteristics between ATC and PSCCTh and develop a nomogram to predict overall survival patients with the redefined anaplastic thyroid carcinoma (rATC). METHODS: Patients diagnosed with ATC and PSCCTh between 2000 and 2018 from the Surveillance, Epidemiology, and End Results (SEER) database were enrolled and randomly divided into a training cohort and a validation cohort with a ratio of 7:3. Overall survival (OS) and cancer-specific survival (CSS) was estimated using the Kaplan-Meier method and compared using log-rank tests. The univariate and multivariate Cox proportional hazards regression analyses were used to determine independent prognostic factors of rATC patients. We then developed and validated nomograms to predict the 3-, 6- and 12-month OS of rATC and the results were evaluated by C-index and calibration curves. RESULTS: After application of the inclusion and exclusion criteria, a total of 1338 ATC and 127 PSCCTh patients were included in the study. Further, OS and CSS of patients with PSCCTh were better than that of patients with ATC. Prognostic factors were not identical for the two cancers. Multivariate Cox model analysis indicated that age, tumor size, metastasis, surgery, radiotherapy, chemotherapy are independent prognostic factors for CSS in patients with ATC; while for patients with PSCCTh, the corresponding factors are age, and surgery. We selected six survival predictors (age, tumor size, metastasis, surgery, radiation, and, chemotherapy) for nomogram construction. The C-indexes in the training and validation cohort were 0.740 and 0.778, respectively, reflecting the good discrimination ability of the model. The calibration curves also showed good consistency in the probability of 3-, 6-, and 12-month OS between the actual observation and the nomogram prediction. CONCLUSION: We constructed a nomogram to provide a convenient and reliable tool for predicting OS in rATC patients. Prognostic factors influencing CSS were not identical in patients with ATC and PSCCTh. These findings indicate that different clinical treatment and management plans are required for patients with these two types of thyroid cancer.

Development of TSHR-CAR NK-92 cells for Differentiated Thyroid Cancer.

Differentiated thyroid cancer (DTC) is the predominant type of thyroid cancer, with some patients experiencing relapse, distant metastases, or refractoriness, revealing limited treatment options. Chimeric antigen receptor (CAR)-modified Natural Killer (NK) cells are revolutionary therapeutic agents effective against various resistant cancers. Thyroid-stimulating hormone receptor (TSHR) expression in DTC provides a unique tumor-specific target for CAR therapy. Here, we developed an innovative strategy for treating DTC using modified NK-92 cells armed with a TSHR-targeted CAR. The modified cells showed enhanced cytotoxicity against TSHR-positive DTC cell lines and exhibited elevated degranulation and cytokine release. After undergoing irradiation, the cells effectively halted their proliferative capacity while maintaining potent targeted killing ability. Transfer of these irradiation-treated cells into NSG mice with DTC tumors resulted in profound tumor suppression. NK-92 cells modified with TSHR-CAR offer a promising, off-the-shelf option for advancing DTC immunotherapy.

Metastatic merkel cell carcinoma to the thyroid gland: Case report and review of the literature.

BACKGROUND: Merkel cell carcinoma (MCC) is an aggressive and rare neuroendocrine tumor, accounting for less than 1% of skin cancers. Metastasis primarily manifests in the cervical lymph nodes but rarely affect the thyroid. METHODS: We report a case of primary head and neck cutaneous MCC with metastasis to the thyroid gland. A review of the literature of MCC with thyroid metastasis was conducted. RESULTS: We identified five cases of MCC with thyroid metastasis. Primary sites included the distal upper and lower extremities, axilla, buttock, and groin. Treatment courses varied including thyroidectomy, immunotherapy, and expectant palliative measures. Time from initial diagnosis to thyroid metastasis ranged from four months to four years. Tissue diagnosis was achieved in 5 of 6 cases. CONCLUSIONS: MCC with thyroid metastasis is rare and likely represents aggressive disease. Despite advances in treatment and surveillance, outcomes for MCC remain poor. Ongoing research may establish predictors for treatment response.