Changing patterns of thyroid carcinoma

Association between Consumption of Iodine-Rich Foods and Thyroid Cancer Prevalence: Findings from a Large Population-Based Study

The influence of iodine-rich foods on thyroid cancer (TC) risk remains inadequately understood. Therefore, we aimed to comprehensively investigate the relationship between three iodine-rich food groups and TC prevalence using extensive data from a large Korean population. We assessed the dietary intake of 169,057 participants in the Korean Genome and Epidemiology Study (2004-2013) using a food frequency questionnaire. The top-three iodine-rich food groups (including egg, seaweed, and dairy) were selected based on Korean dietary reference intakes and categorized by weekly consumption frequency. We conducted multiple logistic regression models to examine the relationship between food consumption and TC prevalence. After adjusting for confounding factors, higher seaweed consumption (>5 times/week) was significantly associated with lower TC prevalence (odds ratio [OR], 95% confidence interval [CI] = 0.42, 0.32-0.56, p-value < 0.001). In contrast, compared with moderate dairy consumption (3-4 times/week), lower dairy product intake (<1 time/week) was associated with higher TC prevalence (OR, 95% CI = 1.32, 1.05-1.67, p-value = 0.017). Our findings suggest that sufficient seaweed consumption may offer protection against TC, and incorporating dairy products into the diet may lower TC incidence in the Korean population. The most significant limitations of our study are the absence of 24 h urine samples for iodine status assessment and the lack of clinical data on the diagnosis of thyroid cancer.

Customizing cancer treatment at the nanoscale: a focus on anaplastic thyroid cancer therapy

Anaplastic thyroid cancer (ATC) is a rare but highly aggressive kind of thyroid cancer. Various therapeutic methods have been considered for the treatment of ATC, but its prognosis remains poor. With the advent of the nanomedicine era, the use of nanotechnology has been introduced in the treatment of various cancers and has shown great potential and broad prospects in ATC treatment. The current review meticulously describes and summarizes the research progress of various nanomedicine-based therapeutic methods of ATC, including chemotherapy, differentiation therapy, radioiodine therapy, gene therapy, targeted therapy, photothermal therapy, and combination therapy. Furthermore, potential future challenges and opportunities for the currently developed nanomedicines for ATC treatment are discussed. As far as we know, there are few reviews focusing on the nanomedicine of ATC therapy, and it is believed that this review will generate widespread interest from researchers in a variety of fields to further expedite preclinical research and clinical translation of ATC nanomedicines.

Results of treatment of patients with poorly differentiated carcinoma of the thyroid gland

Introduction. Poorly differentiated carcinoma of the thyroid gland (PDTC) is characterised by aggressive, high rate of tumor growth, massive infiltration, early lymphogenous and hematogenous dissemination. Ways to improve treatment outcomes include developing individual treatment programmes. Given the unsatisfactory results of the treatment, the search for combined treatment options is well founded.

Materials and methods. An analysis was made of the treatment of PDTC in patients from May 2014 to July 2021. The study included 24 patients aged 22 to 81 years (9 (37.5 %) men and 15 (62.5 %) women). Surgical treatment was performed in 14 (58.3 %) cases. In 8 (33.3 %) cases, a course of radioiodine therapy with a total dose of 3–4 Gbq was performed in the postoperative period. Seven (29.2 %) patients underwent external beam radiation therapy. In 2 (8.3 %) cases, chemotherapy with carboplatin was performed simultaneously with external beam radiation therapy. Four (16.7 %) patients were prescribed lenvatinib. For one reason or another, 9 (37.5 %) patients did not receive treatment.

Results. For patients not treated, the overall survival rate was 5.8 ± 0.5 months, for patients treated – 9.6 ± 1.0 months (p <0.00095). According to the index Lenvatinib showed a significant increase in the general group of patients – up to 15 months.

Conclusion. Combined treatment in the form of a combination of surgical, radiation and chemotherapeutic methods at PDTC, allows to achieve much higher survival. In order to achieve longer-term stabilization, further research is needed on new ways to enhance the anti-tumor effect of modern drugs.

Circulating microRNA as potential diagnostic and prognostic biomarkers of well-differentiated thyroid cancer: A review article

Half of all people aged 50 and over develop a thyroid nodule in their lifetime, exclusion of cancer is required in each case. Nodule tissue sampling is performed by way of fine needle aspiration biopsy (FNAB), however a definite diagnosis in possible only in 30% of cases. The discovery of a diagnostic biomarker to discriminate between thyroid cancer and benign nodules would therefore greatly improve current clinical practice. Using the databases of Medline, Embase and Pubmed we identified 21 original research papers examining various microRNA as potential biomarkers. Currently, the most evidence supporting diagnostic utility exists for miRNA-222. It has been shown repeatedly to have potential in diagnosis of PTC & MTC as well as being linked with the most prognostic factors of all microRNA. To a lesser extent, evidence seems to support the diagnostic and prognostic utility of miR-146b, Let-7 family, miR-221 for PTC and miR-21 for PTC & FTC. MicroRNA appear to show promise as potential diagnostic and prognostic biomarkers, however there is still not enough data to produce a consensus. Continued research should be undertaken with streamlined protocols.

Role of Dietary and Environmental Factors on Thyroid Cancer in Romania: A Brief Review

Thyroid cancer is the most common endocrine tumor, accounting for about 1% of all human malignancies. There are environmental factors that can potentiate the onset of thyroid cancer, in particular pollutants, lifestyle or radiation exposure. Another major cause responsible for the appearance of thyroid cancer is the habitat in endemic areas where there is a deficit of iodine in the soil, drinking water and food. We operated using the PubMed database in order to find the articles of interest. After a wary review of the literature, we designated the relevant articles necessary for our study including various factors such as alimentation, effects of the Chernobyl fallout radiation and the iodine and vitamin D deficiency in Romania. The aim of this article is to make a correlation between the different environmental and dietary factors in Romania, and the increased incidence of thyroid cancer.

2021 American Thyroid Association Guidelines for Management of Patients with Anaplastic Thyroid Cancer

Background: Anaplastic thyroid cancer (ATC) is a rare but highly lethal form of thyroid cancer. Since the guidelines for the management of ATC by the American Thyroid Association were first published in 2012, significant clinical and scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, and researchers on published evidence relating to the diagnosis and management of ATC. Methods: The specific clinical questions and topics addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of the Task Force members (authors of the guideline). Relevant literature was reviewed, including serial PubMed searches supplemented with additional articles. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations. Results: The guidelines include the diagnosis, initial evaluation, establishment of treatment goals, approaches to locoregional disease (surgery, radiotherapy, targeted/systemic therapy, supportive care during active therapy), approaches to advanced/metastatic disease, palliative care options, surveillance and long-term monitoring, and ethical issues, including end of life. The guidelines include 31 recommendations and 16 good practice statements. Conclusions: We have developed evidence-based recommendations to inform clinical decision-making in the management of ATC. While all care must be individualized, such recommendations provide, in our opinion, optimal care paradigms for patients with ATC.

Incidence and Survival for Head and Neck Cancers in Estonia, 1996-2016: A Population-Based Study

Background

Changing patterns of alcohol and tobacco consumption and human papillomavirus (HPV) infection have affected the epidemiology of head and neck cancers. The aim of this study was to examine 20-year trends in the incidence and survival of head and neck cancers in Estonia by site, sex, morphology, and stage.

Methods

Data on all adult cases of invasive head and neck cancers diagnosed in Estonia in 1996–2016 were obtained from a population-based cancer registry. TNM stage was available for 2010–2016. Incidence trends were modeled with join-point regression, and five-year relative survival ratios (RSRs) were calculated.

Results

A total of 6,769 cases were included, 64% men. We observed declining incidence of lip and laryngeal cancer and substantial increases in the incidence of hypopharyngeal and oropharyngeal cancers. Over 60% of mouth and pharyngeal cancers were diagnosed at stage IV. Age-standardized 5-year RSR for mouth and pharyngeal cancer increased substantially over the study period, from 21% (95% CI 16%–25%) in 1996–2002 to 33% (29%–38%) in 2010–2016. The largest survival increases were seen for cancers of the oral cavity (reaching 44% in 2010–2016), tongue (41%), and larynx (63%), while modest changes were seen for the oropharynx (24%) and hypopharynx (17%). The latest 5-year RSR was 90% for thyroid cancers (99% for papillary carcinoma). Large female survival advantage was seen for most sites.

Conclusion

The observed trends suggest an emerging role of HPV infection in combination with traditional risk factors in the development of head and neck cancers in Estonia. Efforts targeting health behavior, HPV vaccination, and earlier diagnosis are crucial for reducing mortality from these cancers.

Is There an Ideal Diet to Protect against Iodine Deficiency?

Iodine deficiency is a global issue and affects around 2 billion people worldwide, with pregnant women as a high-risk group. Iodine-deficiency prevention began in the 20th century and started with global salt iodination programmes, which aimed to improve the iodine intake status globally. Although it resulted in the effective eradication of the endemic goitre, it seems that salt iodination did not resolve all the issues. Currently, it is recommended to limit the consumption of salt, which is the main source of iodine, as a preventive measure of non-communicable diseases, such as hypertension or cancer the prevalence of which is increasing. In spite of the fact that there are other sources of iodine, such as fish, seafood, dairy products, water, and vegetables, the high consumption of processed food with a high content of unionised salt, alternative diets or limited salt intake can still lead to iodine deficiency. Thus, iodine deficiency remains a relevant issue, with new, preventive solutions necessary. However, it appears that there is no diet which would fully cover the iodine requirements, and iodine food supplementation is still required.

Molecular Iodine Has Extrathyroidal Effects as an Antioxidant, Differentiator, and Immunomodulator

Most investigations of iodine metabolism in humans and animals have focused on its role in thyroid function. However, considerable evidence indicates that iodine could also be implicated in the physiopathology of other organs. We review the literature that shows that molecular iodine (I₂) exerts multiple and complex actions on the organs that capture it, not including its effects as part of thyroid hormones. This chemical form of iodine is internalized by a facilitated diffusion system that is evolutionary conserved, and its effects appear to be mediated by a variety of mechanisms and pathways. As an oxidized component, it directly neutralizes free radicals, induces the expression of type II antioxidant enzymes, or inactivates proinflammatory pathways. In neoplastic cells, I₂ generates iodolipids with nuclear actions that include the activation of apoptotic pathways and the inhibition of markers related to stem cell maintenance, chemoresistance, and survival. Recently, I2 has been postulated as an immune modulator that depending on the cellular context, can function as an inhibitor or activator of immune responses. We propose that the intake of molecular iodine is increased in adults to at least 1 mg/day in specific pathologies to obtain the potential extrathyroid benefits described in this review.

Dietary habits and thyroid cancer risk: A hospital-based case-control study in Sicily (South Italy)

Several studies have investigated the role of diet as a risk and/or protective factor against thyroid cancer, both considering individual foods, groups of foods and dietary patterns, but the results are not consistent. The aim of the study was to investigate the relationship between dietary habits and thyroid cancer. Cases and controls were recruited at the University Hospital "G. Rodolico" of Catania. The dietary habits were defined through the "Lifestyle Assessment Questionnaire". The frequency of consumption of each food item was reported on a 4-level scale (never, one time a week, 2-3 times a week, every day of the week). We computed the odds ratios (ORs) of thyroid cancer and the corresponding 95% confidence intervals (CIs) according to the median of control group daily intake of each food group, using multiple logistic regression models adjusted for major confounding factors. Starchy foods (OR = 1.39, 95% CI 0.83-2.32), sweets (OR = 1.39, 95% CI 0.81-2.40) and products rich in salt and fat showed a positive association with thyroid cancer risk. Conversely, an inverse association with disease risk was found for vegetables (cruciferous OR = 0.30, 95% CI 0.10-0.92, non cruciferous OR = 0.57 (0.20-1.57) milk and dairy products (OR = 0.68, 95% CI 0.40-1.13) and seafood (OR = 0.68, 95% CI 0.34-1.22). An increased risk was observed for consumption of iodized salts (OR 2.06, 95% CI 1.21-3.51), tea (OR = 1.42, 95% CI 0.84-2.41) and coca-cola (OR = 3.08, 95% CI 1.53-6.20). Finally, our results confirm the protective effect of a daily water intake of 1-2 L, but unfortunately this quantity is usually consumed by about a quarter of the sample. Dietary habits appear to modify the risk of thyroid carcinoma. A diet with a limited consumption of starchy foods, products rich in salt, fat and sugar and a higher consumption of, cruciferous/non-cruciferous vegetables, milk and dairy products and seafood could be protective towards thyroid cancer. Moreover, the water intake should be increased and the actual need to consume iodized salt should be verified for each subject/area. These results warrant further investigations and, if confirmed, they might have important public health implications for the reduction of thyroid cancer through the improvement of dietary habits.

Contemporary Management of Anaplastic Thyroid Cancer

OPINION STATEMENT

Anaplastic thyroid cancer (ATC) is a rare but very aggressive form of undifferentiated thyroid cancer. Due to its rapid rate of progression and invasive nature, ATC poses significant risks of morbidity and mortality. The cornerstone in the management of ATC remains a prompt diagnosis of the disease and timely management of complications depending on the stage of disease. Surgery continues to offer a higher chance of a cure, although not all patients are candidates for surgical management. Patients with advanced disease may be considered for palliative surgery to reduce morbidity and complications from advanced disease. With the advent of new molecular testing and improved methods of diagnosis, novel therapeutic targets have been identified. Systemic therapy (chemotherapy and radiation therapy) as well as novel immunotherapy have shown some promise in patients with targetable genetic mutations. Patients should therefore have molecular testing of their tumor-if it is unresectable-and be tested for mutations that are targetable. Mutation-targeted therapy may be effective and may result in a significant response to allow surgical intervention for exceptional responders. Overall, patients who receive all three modalities of therapy (surgery, chemotherapy, and radiation therapy) have the highest overall survival.

Anaplastic Thyroid Cancer: Clinical Picture of the Last Two Decades at a Single Oncology Referral Centre and Novel Therapeutic Options

Anaplastic thyroid cancer (ATC) is a rare tumour but also one of the most lethal malignancies. Therapeutic modalities have usually been limited, but clinical trials with new drugs are now being implemented. The aims of this study were to analyse the clinical presentation, therapeutic modalities and independent prognostic factors for survival. We also reviewed the most recent literature on novel ATC therapies. We performed a retrospective analysis of 79 patients diagnosed between 2000 and 2018. Variables with impact on survival were identified using the Cox proportional-hazard regression model. At presentation, 6.3% had thyroid-confined disease, 30.4% evidenced extrathyroidal extension and 60.8% were already metastatic. Surgery was feasible in 41.8% and radiotherapy was applied to 35.4%, with those receiving >45 Gy having longer estimated survival (p = 0.020). Chemotherapy, either conventional or with tyrosine kinase inhibitors, was performed in 17.7% and 7.6%, respectively. Multimodality therapy with surgery, radiotherapy and chemotherapy/tyrosine kinase inhibitors (TKI) had the greatest impact on disease specific survival (DSS), providing a risk reduction of death of 96.9% (hazard ratio (HR) = 0.031, 0.005–0.210, p < 0.001). We concluded that most of these patients join reference centres at advanced stages of disease and multimodality treatment may offer the best chances for prolonging survival.

Iodine promotes thyroid cancer development via SPANXA1 through the PI3K/AKT signalling pathway

The aim of this study was to examine the impact of iodine on the development of thyroid cancer cells and to detect the underlying mechanisms. It was observed that proliferation was promoted and apoptosis was inhibited in cells treated with iodine at a specific concentration. This treatment group was then selected for further analysis, to investigate how iodine affects the development of thyroid cancer cells. It was reported that sperm protein associated with the nucleus, X-linked, family member A1 (SPANXA1) expression in iodine-treated cells was significantly upregulated. Furthermore, downregulation of SPANXA1 inhibited cell proliferation, migration and invasion, and promoted cell apoptosis. These results suggested that SPANXA1 played an important role in iodine-treated thyroid cancer cells. Novel associations between SPANXA1 and thyroid cancer were described in the current study. In addition, SPANXA1 gene silencing resulted in the downregulation of PI3K and phosphorylated (p)AKT expression in iodine-treated thyroid cancer cells, whereas iodine treatment alone resulted in upregulated PI3K and p-AKT expression. Inhibiting PI3K further suppressed cell proliferation and contributed to apoptosis, even in the presence of SPANXA1 at high levels. As a consequence, PI3K/AKT may be one of the key signalling pathways by which iodine promotes thyroid cancer development in association with SPANXA1. In addition, our results further suggested that patients with thyroid cancer may need to avoid high-iodine intake.

Clinico-Pathological Profile of Anaplastic Thyroid Carcinoma in an Endemic Goiter Area

INTRODUCTION

Anaplastic thyroid cancers (ATCs) usually present in the sixth to seventh decades of life and little is known about the disease in young patients. The aim was to analyze the clinicopathological characteristics diagnosed with ATC in an iodine-deficient area.

MATERIAL AND METHODS

The medical records of 100 patients diagnosed with ATC at a tertiary care hospital between 1991 and 2013 were reviewed.

RESULTS

The mean age of patient was 58 years. About 34 patients were ≤50 years. The common presentation was that of a rapidly growing fixed and hard mass (64%). Due to rapid expansion, 27% patients experienced severe pain. About one-third presented as sudden enlargement of pre-existing goiter over few weeks. The median duration of symptoms before diagnosis was 3 months. About 41% presented with lymph node enlargement and 31% with distant metastasis. The diagnosis was established with fine-needle aspiration or core biopsy. Histopathology was available in 32 patients and showed four major patterns: spindle cell (9), giant cell (7), epithelioid (5), squamoid (1), mixed type in 10 patients. Eight patients presenting with stridor required emergency tracheostomy for airway control. Total thyroidectomy with or without lymph node dissection was possible in 21 patients. Patients received radiotherapy with or without chemotherapy. Median overall survival was 3 months. Overall survival was significantly better in patients receiving some form of treatment.

CONCLUSION

ATC in endemic goiter areas presents at an earlier age. One-third of ATC is due to anaplastic transformation of pre-existing goiter and majority of the patients refuse treatment due to dismal outcome.

Case-Control Study of Papillary Thyroid Carcinoma on Urinary and Dietary Iodine Status in South Korea

BACKGROUND

The association between iodine levels and the risk of papillary thyroid cancer (PTC) has been suggested, but not definitively established. This study is to compare the iodine status of a group of patients with PTC (with and without BRAF ^V600E) with that of a healthy population cohort.

METHODS

A cohort of patients scheduled for thyroidectomy was enrolled, along with a community-based health-screening cohort with no known history of thyroid disease. Median urinary iodine (UI) levels, creatinine-adjusted median UI levels, and food frequency questionnaire (FFQ) scores (mean ± SD) were compared. In a subgroup analysis, these values were compared between BRAF ^V600E-positive and BRAF ^V600E-negative patients in the PTC group.

RESULTS

The PTC group consisted of 210 patients, and the control group consisted of 90 healthy individuals. Among the 191 PTC patients whose BRAF ^V600E mutational status was reported, 169 (88.5%) were revealed positive for the mutation. The median UI levels were significantly higher in the PTC group (786.0 μg/l) than the control group (112.0 μg/l; p < 0.001), as was the case with creatinine-adjusted median UI levels (884.6 μg/g creatinine versus 182.0 μg/g creatinine; p < 0.001) and FFQ scores (66.2 ± 17.5, range 13-114 versus 54.6 ± 21.5, range 16-134; p < 0.001). No significant differences were seen in the subgroup analysis between BRAF ^V600E-positive and BRAF ^V600E-negative patients.

CONCLUSIONS

Our results indicate that iodine status differs significantly between patients with PTC and healthy controls, suggesting that iodine may be involved in the occurrence of PTC, although the association between iodine levels and BRAF mutational status did not reach statistical significance.

Nutritional and Environmental Factors in Thyroid Carcinogenesis

Several epidemiological studies suggest an increased incidence of thyroid carcinoma (TC) in recent years, especially for the papillary histotype (PTC), suggesting that specific carcinogens might promote molecular abnormalities that are typical of PTC. The increased incidence is probably attributed to more intensive and sensitive diagnostic procedures, even if recent data suggest that various toxic elements could explain the phenomenon. Ionizing radiation exposure represents the most accepted risk factor for differentiated thyroid cancer that includes both the follicular and papillary histotypes. In this review, we examined the other environmental carcinogens that play a role in TC, such as eating habits, living in volcanic areas, and xenobiotic elements. Among eating habits, iodine intake represents one of the more discussed elements, because its deficiency is associated with follicular thyroid carcinomas (FTCs), while its progressive increment seems to be responsible for PTC. The gas, ash, and lava emissions of volcanoes are composed of various toxic compounds that pollute ground water, vegetables, and animals, contaminating humans via the food chain. Finally, the risk of developing PTC has also been associated with exposure of the population to xenobiotics in the environment or in the home. Their carcinogenic effects are probably caused by their accumulation, but additional studies are necessary to better understand the mechanisms of action.

Is the incidence of anaplastic thyroid cancer increasing: A population based epidemiology study

Objective

To provide an understanding of the incidence of anaplastic thyroid cancer within the United States.

Methods

Patients in the Surveillance, Epidemiology, and End Results (SEER) database were included from 1973 to 2014 based on a diagnosis of anaplastic thyroid cancer using ICD O-3 codes. Patients were categorized into cohorts based on their year of diagnosis.

Results

1527 patients were diagnosed with anaplastic thyroid cancer within the SEER 18 registries. The age-adjusted incidence rate was 0.2 per 1,000,000 people (95% CI: 0.0-0.5) in 1973 and was 1.2 per 1,000,000 people (95% CI: 0.8-1.6) in 2014 (average annual percent change: 3.0% [95% CI: 2.2%-3.7%]). Patients tended to be of older age (mean age: 70.5 [range 15.0-102.0]), of female sex (62.8%), and Caucasian (81.1%). Finally, survival over time remained the same, as median disease specific survival months was 4.00 (95% CI: 2.26-5.74) from 1995 to 1999 and 4.00 (95% CI: 3.26-4.74) from 2010 to 2014.

Conclusions

The incidence rate of anaplastic thyroid cancer has increased from 1973 to 2014. Interestingly, median survival in months did not greatly change overtime. Based on this increasing incidence, physicians must act appropriately to identify patients with anaplastic thyroid cancer as it possesses a high morbidity and mortality.

Level of evidence

4.

Thyroid cancer: trends in incidence, mortality and clinical-pathological patterns in Zhejiang Province, Southeast China

Background

Thyroid cancer is the most common malignant disease of the endocrine system. Previous studies indicate a rapid increase in the incidence of thyroid cancer in recent decades, and this increase has aroused the great public concern. The aim of this study was to analyze the trends in incidence, mortality and clinical-pathological patterns of thyroid cancer in Zhejiang province.

Methods

Population-based incidence and mortality rates of thyroid cancer were collected from eight cancer registries in Zhejiang from 2000 to 2012. The incidence and mortality rates were age-standardized to Segi’s world population. A Joinpoint model was used to examine secular trends in age-adjusted thyroid cancer rates with the Joinpoint Regression Program Version 4.0.0. Thyroid cancer patients were recruited from Zhejiang Cancer Hospital from 1972 to 2014. Patient demographics, tumor histology and tumor size were compared among the different periods of 1972–1985, 1986–1999 and 2000–2014.

Results

The age-standardized incidence rate of thyroid cancer in Zhejiang cancer registries was 2.75/10⁵ in 2000, and increased to 19.42/10⁵ in 2012. Additionally, we observed significantly increasing incidence rates with the Annual Percent Change (APC) of 22.86% (95%CI, 19.2%–26.7%). The age-standardized mortality of thyroid cancer in Zhejiang cancer registries was 0.23/10⁵ in 2000 and 0.25/10⁵ in 2012. No significant change in mortality rate was found. We observed a rapid increase in the proportions of papillary thyroid carcinoma (PTC) in 12,508 patients with thyroid carcinoma identified in the Zhejiang Cancer Hospital from 1972 to 2014 while the proportions of poorly differentiated thyroid cancer (PDTC), medullary thyroid carcinoma (MTC) and follicular thyroid carcinoma (FTC) decreased over the decades. In the PTC cases, the proportion of patients with maximum tumor diameter (MTD) < 1 cm dramatically and significantly increased from 0 in 1972–1985 to 32.1% in 2000–2014.

Conclusions

A rapid increase in incidence and a stable trend in mortality of thyroid cancer were found in the distribution of thyroid cancer. Most of the increased incidence was PTC, especially the papillary thyroid microcarcinoma (PTMC) with MTD < 1 cm. This increase in incidence might be due to increased diagnosis with advanced technology.

Anaplastic thyroid carcinoma: from clinicopathology to genetics and advanced therapies

Anaplastic thyroid carcinoma (ATC) is a rare malignancy, accounting for 1-2% of all thyroid cancers. Although rare, ATC accounts for the majority of deaths from thyroid carcinoma. ATC often originates in a pre-existing thyroid cancer lesion, as suggested by the simultaneous presence of areas of differentiated or poorly differentiated thyroid carcinoma. ATC is characterized by the accumulation of several oncogenic alterations, and studies have shown that an increased number of oncogenic alterations equates to an increased level of dedifferentiation and aggressiveness. The clinical management of ATC requires a multidisciplinary approach; according to recent American Thyroid Association guidelines, surgery, radiotherapy and/or chemotherapy should be considered. In addition to conventional therapies, novel molecular targeted therapies are the most promising emerging treatment modalities. These drugs are often multiple receptor tyrosine kinase inhibitors, several of which have been tested in clinical trials with encouraging results so far. Accordingly, clinical trials are ongoing to evaluate the safety, efficacy and effectiveness of these new agents. This Review describes the updated clinical and pathological features of ATC and provides insight into the molecular biology of this disease. The most recent literature regarding conventional, newly available and future therapies for ATC is also discussed.

Iodine Deficiency, Still a Global Problem?

Iodine Deficiency Disorders are a major public health problem worldwide affecting all groups of people of which children and lactating women are the most vulnerable categories. At a global scale, aproximately 2 billion people suffer of iodine deficiency (ID) of which aproximately 50 million present with clinical manifestations. Assesing iodine levels through different methods has proven to have a key role when discussing treatment options. Screening programs, and early ID diagnostic is important for pregnant women’s follow-up, especially in known countries with iodine dificiency. Universal salt iodization programs have been proposed over the world, but unfortunately have covered about 71% of the world’s population. The aim of this article is to adress the current standings of iodine status and influence on general population with a general focus on newborns and pregnant women and to review the worldwide perspective on available prevention methods.

More surprises in the global greenhouse: Human health impacts from recent toxic marine aerosol formations, due to centennial alterations of world-wide coastal food webs

Reductions of zooplankton biomasses and grazing pressures were observed during overfishing-induced trophic cascades and concurrent oil spills at global scales. Recent phytoplankton increments followed, once Fe-, P-, and N-nutrient limitations of commensal diazotrophs and dinoflagellates were also eliminated by respective human desertification, deforestation, and eutrophication during climate changes. Si-limitation of diatoms instead ensued during these last anthropogenic perturbations of agricultural effluents and sewage loadings. Consequently, ~15% of total world-wide annual asthma trigger responses, i.e. amounting to ~45 million adjacent humans during 2004, resulted from brevetoxin and palytoxin poisons in aerosol forms of western boundary current origins. They were denoted by greater global harmful algal bloom [HAB] abundances and breathing attacks among sea-side children during prior decadal surveys of asthma prevalence, compiled here in ten paired shelf ecosystems of western and eutrophied boundary currents. Since 1965, such inferred onshore fluxes of aerosolized DOC poisons of HABs may have served as additional wind-borne organic carriers of toxic marine MeHg, phthalate, and DDT/DDE vectors, traced by radio-iodine isotopes to potentially elicit carcinomas. During these exchanges, as much as 40% of mercury poisonings may instead have been effected by inhalation of collateral HAB-carried marine neurotoxic aerosols of MeHg, not just from eating marine fish. Health impacts in some areas were additional asthma and pneumonia episodes, as well as endocrine disruptions among the same adjacent humans, with known large local rates of thyroid cancers, physician-diagnosed pulmonary problems, and ubiquitous high indices of mercury in hair, pesticides in breast milk, and phthalates in urine.

Anaplastic Thyroid Cancer in Sicily: The Role of Environmental Characteristics

BACKGROUND

Anaplastic thyroid cancer (ATC) is a rare but extremely aggressive cancer of the thyroid, contributing up to 30-40% of thyroid cancer-specific mortality. We analyzed ATC characteristics and survival rates in Sicily to evaluate the possible influence of environmental factors. With this aim, data regarding ATC incidences in urban/rural and industrial, iodine-deficient, and volcanic vs control areas were compared in Sicily as well as ATC data from Sicily and USA.

METHODS

Using the Sicilian Register of Thyroid Cancer (SRTC) database incidence, age, gender, tumor size and histotype, extrathyroidal extension, stage, and coexistence with pre-existing differentiated thyroid cancer (DTC) were evaluated in different areas of Sicily and also compared with Surveillance Epidemiology and End Results data in USA.

RESULTS

Forty-three ATCs were identified in Sicily in the period 2002-2009. In our series only age <70 years at diagnosis (p = 0.01), coexistence with DTC (p = 0.027) and tumor size ≤6 cm (p = 0.012) were significant factors for increased survival at univariate analysis (only age at multivariate analysis). No difference in ATC incidence was found in urban vs rural areas and in iodine-deficient and industrial vs control areas. By contrast, in the volcanic area of Sicily, where DTC incidence is doubled relative to the rest of the island, also ATC incidence was increased. ATC data in Sicily were similar to those reported in the same period in the USA where overall survival rate at 6 and 12 months, however, was smaller.

CONCLUSION

The similar ATC data observed in Sicily and USA (having different genetic background and lifestyle) and the increased ATC incidence in the volcanic area of Sicily paralleling the increased incidence of papillary thyroid cancer are compatible with the possibility that casual additional mutations, more frequent in a background of increased cell replication like DCT, are the major causes of ATC rather than genetic background and/or direct environmental influences.

Description and Comparison of the Sonographic Characteristics of Poorly Differentiated Thyroid Carcinoma and Anaplastic Thyroid Carcinoma

OBJECTIVES

Although poorly differentiated thyroid carcinoma and anaplastic thyroid carcinoma account for a substantial portion of the morbidity and mortality associated with thyroid cancer, a chance of a cure exists with aggressive treatment, especially in patients with poorly differentiated thyroid carcinoma. The goal of this study was to evaluate the sonographic characteristics of poorly differentiated thyroid carcinoma and to compare the sonographic findings of poorly differentiated and anaplastic thyroid carcinomas.

METHODS

The study included 29 patients with 30 poorly differentiated thyroid carcinomas and 26 patients with 26 anaplastic thyroid carcinomas. Two radiologists retrospectively reviewed sonographic findings. Clinical and sonographic findings were compared between poorly differentiated and anaplastic thyroid carcinomas by univariate and multivariate analyses.

RESULTS

In the group of patients with poorly differentiated thyroid carcinoma, the mean age was 53.7 years (range, 14-73 years), and the mean tumor size was 3.6 cm (range, 0.6-10.0 cm). The common sonographic findings of poorly differentiated thyroid carcinoma were heterogeneous echogenicity (93.3%), solitary nodules (80.0%), a circumscribed margin (63.3%), an oval-to-round shape (63.3%), and hypoechogenicity (60.0%). A circumscribed margin (P = .003) and an oval-to-round shape (P = .015) were significantly more frequent in poorly differentiated thyroid carcinoma than in anaplastic thyroid carcinoma. In the multivariate analysis, only the circumscribed margin on sonography was an independent predicting factor for poorly differentiated thyroid carcinoma (odds ratio, 4.642).

CONCLUSIONS

Both poorly differentiated thyroid carcinoma and anaplastic thyroid carcinoma commonly present as a relatively large malignant mass on sonography; however, poorly differentiated thyroid carcinoma showed a significantly higher incidence of a circumscribed margin and an oval-to-round shape than anaplastic thyroid carcinoma. Knowledge of sonographic characteristics will be useful for differentiation of poorly differentiated and anaplastic thyroid carcinomas.

Effect of different iodine concentrations on well-differentiated thyroid cancer cell behavior and its inner mechanism

High iodine intake might be an important factor in the promotion of thyroid cancer and the incidence of thyroid carcinoma has increased obviously these years especially in area of high iodine intake, though the mechanism of which remains unknown. The aim of present study was to gain more insight into the influence of different iodine concentrations on cell behavior, such as proliferation and migration, and to further investigate its molecular mechanism using two well-differentiated thyroid cancer cell lines. Our study evaluated the effect of different iodine concentrations on cell behavior and investigated relevant molecules involved. The results indicated that iodine in vitro could promote the growth of thyroid cancer cells with the increase of iodine concentration in a specific range. Such effect may be related to signaling pathways as Akt and Erk and cytokine VEGF-A.

Anaplastic thyroid cancer

PURPOSE OF REVIEW

Anaplastic thyroid cancer (ATC) is a rare malignancy of the thyroid with a high mortality rate. Conventional therapy has not been effective. Several biological agents are being investigated. The purpose of the review is to highlight the current standards for treatment and review new targets for treating ATC.

RECENT FINDINGS

Retrospective studies have led to formulation of guidelines for management, including those by the American Thyroid Association. An expansion in the understanding of the genetic mutations has led to several newer biological agents being tested to treat ATC. Aurora kinase inhibitors, PPAR γ agonists, and vascular targeting agents are some of the latest therapeutic agents that have shown promise and could become standard of therapy with further supporting research.

SUMMARY

Further well coordinated preclinical and clinical research is needed to support the emerging treatments for ATC.

Increasing incidence of thyroid cancer in the Commonwealth of Pennsylvania

IMPORTANCE

The incidence of thyroid cancer in the United States has increased rapidly and Pennsylvania is the state with the highest rate of thyroid cancer in the country, although the factors driving this increase are unknown. Moreover, it remains unclear whether the increase in thyroid cancer represents a true increase in disease or is the result of overdiagnosis.

OBJECTIVE

To compare the increase in thyroid cancer incidence and tumor characteristics in Pennsylvania with the rest of the United States and gain insight into the factors influencing the increased incidence of thyroid cancer.

DESIGN, SETTING, AND PARTICIPANTS

In a population-based study, data on thyroid cancer from the Surveillance Epidemiology and End Results 9 (SEER-9) registry and the Pennsylvania Cancer Registry (PCR) from 1985 through 2009 were collected and reviewed for information regarding sex, race, histologic type of thyroid cancer, staging, and tumor size at diagnosis. International Classification of Diseases for Oncology, Third Edition code C739 (thyroid carcinoma) was used to identify 110,615 records in the SEER-9 registry and 29,030 records in the PCR.

MAIN OUTCOMES AND MEASURES

Average annual percent change (AAPC) in thyroid cancer incidence across various demographic groups in Pennsylvania.

RESULTS

The AAPC for thyroid cancer in Pennsylvania was 7.1% per year (95% CI, 6.3%-7.9%) vs 4.2% (95% CI, 3.7%-4.7%) per year in the remainder of the United States, and trends in incidence were significantly different (P < .001). Females experienced a higher AAPC (7.6% per year; 95% CI, 6.9%-8.3%) compared with males (6.1% per year; 95% CI, 4.9%-7.2%) (P < .01), and trend analysis revealed that thyroid cancer may be increasing more rapidly among black females (8.6% per year; 95% CI, 5.4%-11.9%) than among white females (7.6% per year; 95% CI, 6.8%-8.4) (P = .60; but despite the similarity in AAPC between the 2 groups, the joinpoint models fit to the data were not parallel [P < .005]). The rate of tumors with regional (7.0% per year; 95% CI, 5.8%-8.1%) or distant (1.1% per year; 95% CI, 0.3%-1.8%) spread (P < .05) and tumors that were 2 to 4 cm (7.1% per year; 95% CI, 5.2%-9.0%) (P < .05) or larger than 4 cm (6.4% per year; 95% CI, 4.5%-8.2%) (P < .05) at diagnosis also increased.

CONCLUSIONS AND RELEVANCE

The incidence of thyroid cancer is rising at a faster rate in Pennsylvania than in the rest of the nation, as is the rate of tumors that are larger and higher stage at diagnosis. These findings suggest that rising disease burden has contributed to the increased incidence of thyroid cancer. Etiologic factors promoting the rise in thyroid cancer in Pennsylvania must be investigated and may provide insight into the drivers of the national increase in thyroid cancer.

Iodine Supplementation: Usage "with a Grain of Salt"

Iodine supplementation through salt iodization is a worldwide, effective strategy for preventing iodine deficiency-related problems. Its safety and efficacy profile has been extensively investigated, and benefits far outweigh the potential iodine-induced risks. Moreover, iodine supplementation during pregnancy in order to avoid brain damage in the newborn is considered a mainstay of preventive medicine. Exposure to high amounts of iodine is actually well tolerated in most cases and can be unrecognized. Nevertheless, at-risk individuals may develop thyroid dysfunction even when they are exposed to increases in iodine intake universally considered as safe. Iodine-induced thyroid disorders include thyroid autoimmunity, thyrotoxicosis, iodine-induced goiter, and hypothyroidism. Moreover, a relationship between iodine intake and histotype distribution of differentiated thyroid cancer has been observed, with a progressive shift from follicular to papillary thyroid cancer. To date, evaluating iodine status in a clinical setting has limitations, and assessing the actual risk for each individual can be challenging, since it is influenced by personal history, genetics, and environmental factors. In conclusion, iodine supplementation programs need to be continued and strengthened, but iodine should be used "with a grain of salt," because a growing number of susceptible individuals will be exposed to the risk of developing iodine-induced thyroid disorders.

The influence of the environment on the development of thyroid tumors: a new appraisal

Most epidemiological studies concerning differentiated thyroid cancers (DTC) indicate an increasing incidence over the last two decades. This increase might be partially explained by the better access to health services worldwide, but clinicopathological analyses do not fully support this hypothesis, indicating that there are carcinogenetic factors behind this noticeable increasing incidence. Although we have undoubtedly understood the biology and molecular pathways underlying thyroid carcinogenesis in a better way, we have made very little progresses in identifying a risk profile for DTC, and our knowledge of risk factors is very similar to what we knew 30-40 years ago. In addition to ionizing radiation exposure, the most documented and established risk factor for DTC, we also investigated the role of other factors, including eating habits, tobacco smoking, living in a volcanic area, xenobiotics, and viruses, which could be involved in thyroid carcinogenesis, thus, contributing to the increase in DTC incidence rates observed.

Immune response in thyroid cancer: widening the boundaries

The association between thyroid cancer and thyroid inflammation has been repeatedly reported and highly debated in the literature. In fact, both molecular and epidemiological data suggest that these diseases are closely related and this association reinforces that the immune system is important for thyroid cancer progression. Innate immunity is the first line of defensive response. Unlike innate immune responses, adaptive responses are highly specific to the particular antigen that induced them. Both branches of the immune system may interact in antitumor immune response. Major effector cells of the immune system that directly target thyroid cancer cells include dendritic cells, macrophages, polymorphonuclear leukocytes, mast cells, and lymphocytes. A mixture of immune cells may infiltrate thyroid cancer microenvironment and the balance of protumor and antitumor activity of these cells may be associated with prognosis. Herein, we describe some evidences that immune response may be important for thyroid cancer progression and may help us identify more aggressive tumors, sparing the vast majority of patients from costly unnecessary invasive procedures. The future trend in thyroid cancer is an individualized therapy.

The extrathyronine actions of iodine as antioxidant, apoptotic, and differentiation factor in various tissues

BACKGROUND

Seaweed is an important dietary component and a rich source of iodine in several chemical forms in Asian communities. Their high consumption of this element (25 times higher than in Western countries) has been associated with the low incidence of benign and cancerous breast and prostate disease in Japanese people.

SUMMARY

We review evidence showing that, in addition to being a component of the thyroid hormone, iodine can be an antioxidant as well as an antiproliferative and differentiation agent that helps to maintain the integrity of several organs with the ability to take up iodine. In animal and human studies, molecular iodine (I2) supplementation exerts a suppressive effect on the development and size of both benign and cancerous neoplasias. Investigations by several groups have demonstrated that these effects can be mediated by a variety of mechanisms and pathways, including direct actions, in which the oxidized iodine dissipates the mitochondrial membrane potential, thereby triggering mitochondrion-mediated apoptosis, and indirect effects through iodolipid formation and the activation of peroxisome proliferator-activated receptors type gamma, which, in turn, trigger apoptotic or differentiation pathways.

CONCLUSIONS

We propose that the International Council for the Control of Iodine Deficient Disorders recommend that iodine intake be increased to at least 3 mg/day of I2 in specific pathologies to obtain the potential extrathyroidal benefits described in the present review.

Worldwide increasing incidence of thyroid cancer: update on epidemiology and risk factors

Background. In the last decades, thyroid cancer incidence has continuously and sharply increased all over the world. This review analyzes the possible reasons of this increase. Summary. Many experts believe that the increased incidence of thyroid cancer is apparent, because of the increased detection of small cancers in the preclinical stage. However, a true increase is also possible, as suggested by the observation that large tumors have also increased and gender differences and birth cohort effects are present. Moreover, thyroid cancer mortality, in spite of earlier diagnosis and better treatment, has not decreased but is rather increasing. Therefore, some environmental carcinogens in the industrialized lifestyle may have specifically affected the thyroid. Among potential carcinogens, the increased exposure to medical radiations is the most likely risk factor. Other factors specific for the thyroid like increased iodine intake and increased prevalence of chronic autoimmune thyroiditis cannot be excluded, while other factors like the increasing prevalence of obesity are not specific for the thyroid. Conclusions. The increased incidence of thyroid cancer is most likely due to a combination of an apparent increase due to more sensitive diagnostic procedures and of a true increase, a possible consequence of increased population exposure to radiation and to other still unrecognized carcinogens.

Anaplastic thyroid cancer

PURPOSE

Anaplastic thyroid cancer (ATC) is a lethal disease causing a global disproportionate number of thyroid cancer-related deaths. The American Thyroid Association (ATA) has recently produced clear and comprehensive guidelines to assist physicians treating ATC.

METHODS

The recent ATA guideline publication was reviewed. A systematic review of studies indexed in Medline and Pubmed was also undertaken using search terms relevant to ATC.

RESULTS

Patients with ATC have a median survival of 5 months and less than 20% survive 1 year. Early tumor dissemination results in 20-50% percent of patients having distant metastases and 90% having adjacent tissue invasion on presentation. This highlights the necessity for effective combined therapy. Stage IVA/ IVB, resectable disease may benefit from a multimodal (surgery, IMRT for loco regional control, and systemic therapy) approach. However, a majority of patients present with unresectable locoregional disease. Early palliative care involvement is inclusive of life-prolonging therapies. ATC management demands rapid, complex and integrated multidisciplinary decision making.

CONCLUSION

In this article we discuss the multidisciplinary strategies that exist to optimize the management of these patients in accordance with the recent guidelines from The American Thyroid Association.

Uptake and antitumoral effects of iodine and 6-iodolactone in differentiated and undifferentiated human prostate cancer cell lines

BACKGROUND

Evidence indicates that iodine per se could be implicated in the physiology of several organs that can internalize it. In thyroid and breast cancer, iodine treatments inhibit cell proliferation and induce apoptosis through a direct (mitochondria) and/or indirect effect (iodolipid generation). Here, we determined the uptake of iodide (I(-) ) and iodine (I(2) ), as well as the antiproliferative and apoptotic effects of 6-iodolactone (6-IL) and both forms of iodine in human prostate cells lines.

METHODS

Non-cancerous (RWPE-1) and cancerous (LNCaP, DU-145) cells, as well as nude mice xenotransplanted with DU-145 cells were used as cancer models. Iodine uptake was analyzed with radioactive tracers, transporter expression by qRT-PCR, cell proliferation by blue trypan, apoptosis by enzyme immunoassay or fluorescence, BAX and BCL-2 by western-blot, and caspsase 3 by enzymatic assay.

RESULTS

All three cell lines take up both forms of iodine. In RWPE-1 cells, I(-) uptake depends on the Na(+) /I(-) symporter (NIS), whereas it was independent of NIS in LNCaP and DU-145 cells. Antiproliferative effects of iodine and 6-IL were dose and time dependent; RWPE-1 was most sensitive to I(-) and 6-IL, whereas LNCaP was more sensitive to I(2) . In the three cell lines both forms of iodine activated the intrinsic apoptotic pathway (increasing the BAX/BCL-2 index and caspases). Iodine supplementation impaired growth of the DU-145 tumor in nude mice.

CONCLUSION

Normal and cancerous prostate cells can take up iodine, and depending on the chemical form, it exerts antiproliferative and apoptotic effects both in vitro and in vivo.

American Thyroid Association guidelines for management of patients with anaplastic thyroid cancer

BACKGROUND

Anaplastic thyroid cancer (ATC) is a rare but highly lethal form of thyroid cancer. Rapid evaluation and establishment of treatment goals are imperative for optimum patient management and require a multidisciplinary team approach. Here we present guidelines for the management of ATC. The development of these guidelines was supported by the American Thyroid Association (ATA), which requested the authors, members the ATA Taskforce for ATC, to independently develop guidelines for ATC.

METHODS

Relevant literature was reviewed, including serial PubMed searches supplemented with additional articles. The quality and strength of recommendations were adapted from the Clinical Guidelines Committee of the American College of Physicians, which in turn was developed by the Grading of Recommendations Assessment, Development and Evaluation workshop.

RESULTS

The guidelines include the diagnosis, initial evaluation, establishment of treatment goals, approaches to locoregional disease (surgery, radiotherapy, systemic therapy, supportive care during active therapy), approaches to advanced/metastatic disease, palliative care options, surveillance and long-term monitoring, and ethical issues including end of life. The guidelines include 65 recommendations.

CONCLUSIONS

These are the first comprehensive guidelines for ATC and provide recommendations for management of this extremely aggressive malignancy. Patients with stage IVA/IVB resectable disease have the best prognosis, particularly if a multimodal approach (surgery, radiation, systemic therapy) is used, and some stage IVB unresectable patients may respond to aggressive therapy. Patients with stage IVC disease should be considered for a clinical trial or hospice/palliative care, depending upon their preference.

Managing anaplastic thyroid carcinoma

Anaplastic thyroid cancer is one of the most lethal malignancies, with dismal prognosis, resistance to multimodal treatments and a median survival of only 5-6 months. Advances in the discovery of genetic pathway aberrations involved in this aggressive disease have been made, and multiple novel therapies targeting these pathways are undergoing clinical trials. So far, there is no single effective treatment for this disease; however, multimodal therapies with a combination of surgery, radiation and chemotherapy hold some promise. We conducted a PubMed search using the words thyroid neoplasm, anaplastic thyroid carcinoma, anaplastic thyroid cancer and anaplastic thyroid neoplasm, revealing 1673 publications. We review the pathophysiology, current treatments and advances made in identifying the alterations in genetic pathways, as well as novel therapies targeting these pathways.

Anaplastic thyroid carcinoma: pathogenesis and emerging therapies

Anaplastic thyroid carcinoma ranges from 1.3 to 9.8% of all thyroid cancers globally. Mutations, amplifications, activation of oncogenes and silencing of tumour suppressor genes contribute to its aggressive behaviour, and recent studies (e.g. microarrays, microRNAs) have provided further insights into its complex molecular dysregulation. Preclinical studies have identified numerous proteins over- or underexpressed that affect critical cellular processes, including transcription, signalling, mitosis, proliferation, cell cycle, apoptosis and adhesion, and a variety of agents that effectively inhibit these processes and tumour growth. In clinical studies of 1771 patients, 64% were women, the median survival was 5 months, and 1-year survival was 20%. The variables associated with survival in some series included age, tumour size, extent of surgery, higher dose radiotherapy, absence of distant metastases at presentation, co-existence of differentiated thyroid cancer and multimodality therapy. However, considerable bias exists in these non-randomised studies. Although more aggressive radiotherapy has reduced locoregional recurrences, the median overall survival has not improved in over 50 years. Newer systemic therapies are being tried, and more effective combinations are needed to improve patient outcomes.

Iodine induces apoptosis via regulating MAPKs-related p53, p21, and Bcl-xL in thyroid cancer cells

Thyroid cancer is the most common endocrine malignancy and exhibits the full range of malignant behaviors from the relatively indolent occult differentiated thyroid cancer to uniformly aggressive and lethal anaplastic thyroid cancer. Iodine is a well known key element in thyroid normal function maintenance and thyroid cancer development. However, the effects induced by iodine and the molecular mechanisms involved remain poorly understood in thyroid cancer. We investigated the apoptotic effect of iodine on three different subtypes of thyroid cancer cells. We observed that apoptosis induced by iodine was mitochondrial-mediated. Iodine treatment decreased the level of mutant p53 including the R273H mutant that possesses anti-apoptotic features, but increased the p21 level. Surprisingly, high doses of iodine promoted instead of suppressed the expression of anti-apoptotic protein Bcl-xL expression. Moreover, iodine transiently activated the subfamily members of mitogen activated protein kinases (MAPKs) (ERK1/2, p38 and JNK1/2) which contribute to modulate p53, p21 and Bcl-xL expression. The further results showed the three subfamily members of MAPKs all worked as anti-apoptotic factors. Collectively, iodine-induced apoptotic pathway is involved in the activation of MAPKs-related p21, Bcl-xL and mutant p53 regulation. The findings provide solid molecular evidence to explain the potential pathway for iodine to influence thyroid cancer development. It may also reveal some novel molecular targets for the treatment of thyroid cancer.

Increasing incidence of differentiated thyroid cancer in the United States, 1988-2005

BACKGROUND

Studies have reported an increasing incidence of thyroid cancer since 1980. One possible explanation for this trend is increased detection through more widespread and aggressive use of ultrasound and image-guided biopsy. Increases resulting from increased detection are most likely to involve small primary tumors rather than larger tumors, which often present as palpable thyroid masses. The objective of the current study was to investigate the trends in increasing incidence of differentiated (papillary and follicular) thyroid cancer by size, age, race, and sex.

METHODS

Cases of differentiated thyroid cancer (1988-2005) were analyzed using the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) dataset. Trends in incidence rates of papillary and follicular cancer, race, age, sex, primary tumor size (<1.0 cm, 1.0-2.9 cm, 3.0-3.9 cm, and >4 cm), and SEER stage (localized, regional, distant) were analyzed using joinpoint regression and reported as the annual percentage change (APC).

RESULTS

Incidence rates increased for all sizes of tumors. Among men and women of all ages, the highest rate of increase was for primary tumors <1.0 cm among men (1997-2005: APC, 9.9) and women (1988-2005: APC, 8.6). Trends were similar between whites and blacks. Significant increases also were observed for tumors > or =4 cm among men (1988-2005: APC, 3.7) and women (1988-2005: APC, 5.70) and for distant SEER stage disease among men (APC, 3.7) and women (APC, 2.3).

CONCLUSIONS

The incidence rates of differentiated thyroid cancers of all sizes increased between 1988 and 2005 in both men and women. The increased incidence across all tumor sizes suggested that increased diagnostic scrutiny is not the sole explanation. Other explanations, including environmental influences and molecular pathways, should be investigated.