Relevance of iodine intake as a reputed predisposing factor for thyroid cancer

The Pattern of Thyroid Cancers in Nigeria: a Systematic Review and Meta-analysis

Thyroid cancer is the most common endocrine cancer. There are various histopathological types requiring different therapeutic approaches and having variable prognoses. The objective of this study was to determine the pattern of thyroid cancers in Nigeria. The systematically searched databases were African Journal Online, Google Scholar, PubMed, and SCOPUS. The pre-print databases Research Square, SciELO, and medRxiv were also systematically searched. Moreover, the available grey literature was equally searched. The quality of the selected studies was assessed using the Newcastle-Ottawa scale. The meta-analysis was done using Meta XL version 5.3. The DerSimonian Laird random effect model was used for the meta-analysis. The heterogeneity of the selected studies was determined using the I2 statistic and Cochran's Q test. Publication bias was assessed with the Luis Furuya-Kanamori (LFK) index and Doi plot. Twenty-six studies met the eligibility criteria. The total sample size was 1224. In Nigeria, thyroid cancer was most common in the 4th and 5th decades of life. It was 3.5 (95% CI 3.0-4.6, p < 0.0001) times commoner in females than males. The pooled proportions of thyroid cancers included papillary thyroid cancer, 46% (95% CI 40-53); follicular thyroid cancer, 39% (95% CI 32-45); medullary thyroid cancer, 7% (95% CI 6-9); and anaplastic thyroid cancer, 5% (95% CI 3-7). The trend showed a change from follicular cancer predominance to papillary cancer over the past two decades. Papillary thyroid cancer is the commonest type in Nigeria. Thyroid cancer is seen more in females and it occurs most commonly in middle age.

Circ_0004851 regulates the molecular mechanism of miR-296-3p/FGF11 in the influence of high iodine on PTC

The prevalence of papillary thyroid cancer (PTC) has been rising in recent years. Despite its relatively low mortality, PTC frequently metastasizes to lymph nodes and often recurs, posing significant health and economic burdens. The role of iodine in the pathogenesis and advancement of thyroid cancer remains poorly understood. Circular RNAs (circRNAs) are recognized to function as competing endogenous RNAs (ceRNAs) that modulate gene expression and play a role in various cancer stages. Consequently, this research aimed to elucidate the mechanism by which circRNA influences the impact of iodine on PTC. Our research indicates that high iodine levels can exacerbate the malignancy of PTC via the circ_0004851/miR-296-3p/FGF11 axis. These insights into iodine's biological role in PTC and the association of circRNA with the disease could pave the way for novel biomarkers and potentially effective therapeutic strategies to mitigate PTC progression.

Clinical and ultrasonography evaluation of thyroid tumor screening in symptomatic patient of Bajulmati primary care center, Banyuwangi, East Java, Indonesia

This study aims to assess the prevalence, clinical, and ultrasonography (US) in thyroid screening in healthy subjects with general symptoms of thyroid abnormality in low iodine intake in Bajulmati primary care center, East Java Indonesia. We retrospectively reviewed US thyroid examination of 74 subjects with symptoms of mass in the neck, shaky, sleep difficulties, over sweating, and chronic fatigue on September 15th, 2021. Following the WHO guidelines, subjects also underwent physical examination in which the result were classified into 3 categories, that is, no palpable nor visible goiter, palpable but no visible goiter, as well as palpable and visible goiter. We evaluate US thyroid characteristics following Korean Society of Thyroid Radiology guidelines. Image analysis was reviewed by 4 general radiologists with 2 to 13 years' experience. Categorical variables were compared using chi-squared or Fisher exact tests. Correlation between variables was measured with gamma statistics. Statistical analyses were conducted using IBM SPSS Statistics 23.0. A P-value < .05 was considered to indicate statistical significance. Of the 74 subjects, 32 (43.2%) show abnormalities. Statistical analysis showed no significant differences in the result of thyroid US in subjects with complaint fatigue (P = .464), insomnia (P = .777), over sweating (P = .158), and tremor (P = .778), but there were significant differences with the complaint of mass in the neck (P = .008). Furthermore, there was also a strong correlation between goiter palpation and US thyroid result (R = 0.773, P = .00). We conclude there were significant differences in US result of patients with and without complaint of mass in the neck. We also found a strong correlation between goiter palpation and US examination. Clinical findings, laboratory examination, cytology and molecular markers, patients' age, nodules size, and ultrasound features should be considered for the treatment planning.

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.

Differentiated thyroid carcinoma in children: A retrospective analysis of 125 pediatric cases from a single institution in India

BACKGROUND

Thyroid carcinoma (TC) is extremely rare in children. We assessed the clinicopathological features, outcomes, recurrence pattern, and associated risk factors of differentiated thyroid carcinoma (DTC).

METHODS

Children aged ≤14 years, pathologically diagnosed as DTC at a tertiary cancer institute between January 1998 and December 2015 were retrospectively analyzed. Survival outcomes were estimated using the Kaplan-Meier method.

RESULTS

During 18 years, 125 children with DTC were treated with a male:female ratio of 1:2.3. The median age was 12 years (2-14 years). Anterior neck swelling was the commonest presentation (72.8%). Histopathology revealed papillary thyroid carcinoma (PTC) in 123 children (98.4%). Extrathyroidal extension was seen in 32 children (25.6%). Sixty-eight children (54.4%) had nodal metastases and seven had distant metastasis. Relapse developed in 12 children. All were salvaged with subsequent surgery and radioiodine therapy. Eight children had persistent disease and one had a second malignant neoplasm. The median follow-up period was 9 years 1 month (1-20 years). Five-year recurrence-free survival (RFS) was 94.8% and 5-year overall survival was 100%. Larger tumors (p-value = .001), extrathyroidal extension (p-value = .001), and nodal metastasis (p-value = .022) were significant predictors for RFS in univariate analysis.

CONCLUSIONS

Pediatric DTC showed aggressive behavior characterized by a high rate of extrathyroidal extension and nodal and pulmonary metastasis. Persistent disease should be distinguished from recurrent disease as DTCs with metastatic disease remain stable for long time and usually respond well to radioiodine therapy. Our study reaffirmed favorable prognosis despite aggressive presentation and even after relapse.

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.

Thyroid cancer: incidence and mortality trends in China, 2005-2015

PURPOSE

Understanding secular trends of thyroid cancer is critical to plan strategies for cancer prevention and control. Our aim was to estimate the incidence and mortality trends of thyroid cancer in China during 2005-2015.

METHODS

A retrospective cohort evaluation of thyroid cancer cases and deaths during 2005-2015 was performed using population-based data from the Chinese Cancer Registry Annual Report. The incidence and mortality rates of thyroid cancer were stratified by gender, age group (0, 1-4, 5-9, 10-14…80-84, 85-), and area (urban or rural). A Joinpoint regression model was used to examine secular trends.

RESULTS

In China, the age-standardized incidence was 3.21/10⁵ in 2005, and increased to 9.61/10⁵ in 2015. Besides, a significant increase incidence rate was observed with the average annual percent change (AAPC) of 12.4% (95% CI: 10.5%-14.4%) in the period 2005-2015. The age-standardized mortality was 0.30/10⁵ in 2005 and 0.35/10⁵ in 2015, and the AAPC was 2.9% (95% CI: 1.3%-4.5%). For both incidence and mortality, the rates of thyroid cancer were much higher in females than in males, and in urban areas rather than rural areas; however, the rates of increasing trends showed no significant differences. With respect to the highest age-specific rates, it appeared in the age group of 50-54 years old for incidence and in the age group of 80-84 years old for mortality. Notably, the rate of increasing incidence trend was lower in older age groups, especially for people aged 70-79 years old.

CONCLUSION

A rapid increase in incidence and a moderate increase in mortality of thyroid cancer were observed from 2005 to 2015 in our study. Effective measures and tailored programs should be taken to curb the growth trend and reduce the disease burden.

Urinary iodine is increased in papillary thyroid carcinoma but is not altered by regional population iodine intake status: a meta-analysis and implications

Excessive iodine intake has been associated with increased risk of thyroid cancer (TC) in many studies, but the results have not been consistent. Since it was common knowledge that urinary iodine (UI) is considered a sensitive marker of current iodine intake, we conducted a meta-analysis to clarify the association between high UI and TC. We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, and the Cochrane Collaboration. Between-group meta-analyses were performed to compare UI between TC patients and the healthy/euthyroid subjects in local residents and benign thyroid nodules (BTN) patients. Then, between-group meta-analyses to compare the incidence rate of iodine excess were also conducted. The 22 case-control studies included in the meta-analyses represented 15,476 participants. It is the first time to clarify that UI was increased in PTC patients, but was not altered by regional population iodine intake status. Compared with BTN patients, PTC patients exhibited both higher UIC and higher odds ratio of iodine excess only in adequate iodine intake status subgroup; UIC, not the odds ratio of iodine excess, was higher in patients with PTC than those with BTN in above requirements iodine intake subgroup. A novel insight is offered that high UI in PTC patients was less influenced by regional population iodine intake status. It is indicted that high iodine intake is not a risk factor for PTC and high urinary iodine is just a specific characteristic of the disease.

Sunitinib in the Treatment of Thyroid Cancer

BACKGROUND

Sunitinib (SU11248) is an oral multi-target tyrosine kinase inhibitor (TKI) with low molecular weight, that inhibits platelet-derived growth factor receptors (PDGF-Rs) and vascular endothelial growth factor receptors (VEGFRs), c-KIT, fms-related tyrosine kinase 3 (FLT3) and RET. The concurrent inhibition of these pathways reduces tumor vascularization and causes cancer cell apoptosis, inducing a tumor shrinkage. Sunitinib is approved for the treatment of imatinib-resistant gastrointestinal stromal tumor (GIST), renal carcinoma, and pancreatic neuroendocrine tumors.

METHODS

We searched the literature on PubMed library.

RESULTS

In vitro studies showed that sunitinib targeted the cytosolic MEK/ERK and SAPK/JNK pathways in the RET/PTC1 cell inhibiting cell proliferation and causing stimulation of sodium/iodide symporter (NIS) gene expression in RET/PTC1 cells. Furthermore sunitinib is active in vitro and in vivo against anaplastic thyroid cancer (ATC) cells. Most of the clinical studies report that sunitinib is effective as first- and second-line TKI therapy in patients with advanced dedifferentiated thyroid cancer (DeTC), or medullary thyroid cancer (MTC). Sunitinib 37.5 mg/day is well tolerated, and effective. The most common adverse events include: reduction in blood cell counts (in particular leukocytes), hand-foot skin reaction, diarrhea, fatigue, nausea, hypertension, and musculoskeletal pain.

CONCLUSION

Even if sunitinib is promising in the therapy of differentiated thyroid carcinoma (DTC), until now no phase III studies have been published, and additional prospective researches are necessary in order to evaluate the real efficacy of sunitinib in aggressive thyroid cancer.

Thyroid Cancer in Ecuador, a 16 years population-based analysis (2001-2016)

BACKGROUND

Thyroid cancer is the most frequent endocrine neoplasia worldwide. Information from Andean countries is scarce. In Ecuador there is no reports available of the epidemiology of this type of cancer. The aim of this study is to present the epidemiology and the burden of disease of thyroid cancer.

METHODS

This is a cross-sectional population-based analysis of thyroid cancer epidemiology in Ecuador from 2001 to 2016. The variables studied were the overall mortality rate, socio-demographics characteristics of the hospitalized patients, geographical trends and the burden of thyroid cancer in Ecuador. All the data was obtained from the official records reported by the Ministry of Public Health's and retrieved from the public databases of the Vital Statistics Deaths and Births Databases and the National Institute of Census and Statistics (INEC).

RESULTS

In Ecuador, over a period of 16 years from 2001 to 2016 a total of 23,632 hospital admissions were reported, which caused 1539 deaths due thyroid cancer. Data demonstrated an annual mean of 1477 cases, which caused 96 deaths per year in average. The annual incidence fluctuated from 3 in 2001 to 22 in 2016 per 100,000 inhabitants. Women were 5 times more likely than men to have thyroid cancer. The average length of stay for both sexes were 4 days. The mortality attributable to thyroid cancer represent less than 0.3% of all cancer deaths.

CONCLUSION

Ecuador has one of the highest rates of thyroid cancer in Latin America, ranking first among women in Latin America. Although this cancer is frequent, mortality rate is relatively low. As this is the first national report of thyroid cancer in the country, a further analysis of the pathological variants and the grading of this neoplasia is needed.

The Role of Polybrominated Diphenyl Ethers in Thyroid Carcinogenesis: Is It a Weak Hypothesis or a Hidden Reality? From Facts to New Perspectives

In the last decades, the incidence of thyroid cancer has increased faster than that of any other malignant tumor type. The cause of thyroid cancer is likely multifactorial and a variety of both exogenous and endogenous has been identified as potential risk factors. Polybrominated diphenyl ethers (PBDEs), used since the 1970s as flame retardants, are still widespread and persistent pollutants today, although their production was definitely phased out in the western countries several years ago. Polybrominated diphenyl ethers are known endocrine disruptors, and the endocrine system is their primary target. Whereas animal studies have ascertained the ability of PBDEs to affect the normal functionality of the thyroid, evidence in humans remains inconclusive, and only a few epidemiological studies investigated the association between exposure to PBDEs and thyroid cancer. However, a number of clues suggest that a prolonged exposure to these chemicals might act a trigger of the most common malignancy of the endocrine system, whereas further studies with an advanced design are suggested.

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.

High Urinary Iodine, Thyroid Autoantibodies, and Thyroid-Stimulating Hormone for Papillary Thyroid Cancer Risk

Thyroid nodules have become a common clinical problem, and the clinical importance of thyroid nodules lies in the determination of thyroid cancer. This study aims to evaluate the risk factors for papillary thyroid cancer (PTC) with regard to urinary iodine concentration (UIC), thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TGAb) in comparison to thyroid nodular goiter (NG). Among the 2041 patients, 43.8% of which showed more than adequate (UIC 200-299 μg/L) and excessive iodine (UIC ≥ 300.0 μg/L) status. Compared with adequate iodine intake, iodine deficiency (UIC < 100 μg/L) was inversely associated with multifocality (OR 0.59, P = 0.040), while more than adequate iodine intake was independently associated with an increased risk of larger tumor size (OR 1.33, P = 0.002) in female PTC patients but not in males. No significant difference in UIC was observed between patients with PTC and NG, suggesting that high iodine intake may be related with the growth of PTC, but not with its oncogenesis. Besides, positive for TPOAb and TGAb were individually associated with papillary thyroid microcarcinoma (PTMC) risk (OR 2.05 and 1.71, respectively, both P < 0.05) in female patients with tumor foci < 1 cm but not in males. Furthermore, younger age (< 46 years), TGAb positivity and small thyroid nodules in both sexes, higher TSH, TPOAb positivity, and multifocality in females could all predict PTC risk (all P < 0.05). These results might have clinical significance for managing patients with thyroid nodules and those with thyroidectomy.

Thyroid nodules and cancer in children and adolescents affected by Hashimoto's thyroiditis

OBJECTIVE

To investigate the rates of thyroid nodules and cancer in pediatric cases of Hashimoto's thyroiditis (HT) in Korea.

METHODS

We retrospectively reviewed 89 pediatric and adolescent patients (age, 3-18.0 years) with HT who underwent thyroid ultrasonography (US) at our institution from February 2006 to July 2016. The diagnosis of HT was based on the presence of thyroid autoantibodies. The presence of any thyroid nodules with US and cytopathologic features was analyzed. The malignancy rate was also determined.

RESULTS

Thyroid nodules were in 20 of the 89 patients (22.4%). Eight of these 20 patients (40%) had colloid cysts, two (10%) had nodular hyperplasia, one (5%) had follicular adenoma, and two (10%) had lymphocytic thyroiditis. Seven of the 89 patients (7.9%) were confirmed to have a malignancy, all of which were papillary thyroid carcinoma (PTC); of those, five patients had diffuse sclerosing variant PTC, and two had conventional PTC on pathology.

CONCLUSION

The prevalence of thyroid nodules in children and adolescents with HT was 22.4%. The malignancy rate of children with HT was 7.9%. The malignancy rate among thyroid nodules was 35%, which is higher than the 26% rate generally reported for children with nodules. Therefore, using thyroid US to survey known or suspected thyroid nodules might be helpful in children and adolescents with HT and may provide further useful diagnostic information. Advances in knowledge: Thyroid US could help to assess HT patients who have known or suspected thyroid nodules.

Thyroid Cancer and Iodine Deficiency Status: A 10-Year Review at a Single Cancer Center in Tanzania

Objective

To highlight the magnitude and distribution of thyroid cancer at the largest cancer center in Tanzania and to correlate patient region of residence with regions of dietary iodine adequacy and deficiency in the country.

Study Design

A retrospective cross-sectional chart review to characterize patients with thyroid cancer and regions of residence.

Setting

Ocean Road Cancer Institute (ORCI), the largest cancer center in Tanzania.

Subjects and Methods

Subjects had histologically confirmed thyroid cancer and no history of cancer treatment. Between January 2006 and April 2016, the cases of 139 consecutive patients with thyroid cancer at ORCI were retrospectively reviewed. Patients were grouped into those from iodine-adequate and iodine-deficient regions, based on the Tanzania demographic and health survey.

Results

Patients' median age was 47 years (range, 17-73 years), and the male:female ratio was 1:5. The number of people with thyroid cancer seen at ORCI increased steadily during the study period, with no significant difference between papillary (46%) and follicular (45%) diagnoses. Nonpapillary cancers occurred more frequently among males and patients ≥45 years of age, but these did not reach statistical significance. Seventy-five percent of all thyroid cancers were from areas of iodine deficiency, and this was similar in papillary and follicular cancer subtypes.

Conclusion

The incidence of differentiated thyroid cancer is increasing at the largest cancer center in Tanzania, whereby papillary and follicular subtypes were significantly higher in regions with long-standing dietary iodine deficiency.

A PRISMA-compliant systematic review and meta-analysis of the relationship between thyroid disease and different levels of iodine intake in mainland China

BACKGROUND

Low-iodine intake has historically been an issue in China, causing widespread iodine deficiency diseases (IDD). China started to introduce universal salt iodization in 1995, but reports of increased thyroid disease are a concern and appropriate levels of iodine intake must be considered.

OBJECTIVE

To assess the prevalence of thyroid disease with different urinary iodine concentrations (UICs) in the general population of those residing in mainland China. Furthermore, we aimed to analyze the relationship between thyroid disease and UIC, to provide guidance in establishing effective health policies regarding iodine intake.

METHODS

PubMed, Cochrane, Embase, CNKI, Wan fang, and CQVIP databases were searched for random community-based relevant studies with UIC published before January 2016 in mainland China. Two independent reviewers extracted data from eligible citations, and obtained prevalence of thyroid disease for different UICs, as well as the intergroup interaction P values.

RESULTS

Forty-three articles were included. The prevalence of thyroid nodules was 22.3% (95% confidence interval [CI]: 20.6%-24.1%) for the low-iodine group, 25.4% (95% CI: 20.8%-28.8%) for the medium-iodine group, and 6.8% (95% CI: 2.8%-11.5%) for the high-iodine group. In the high-iodine group, the prevalence of thyroid nodules was lower than the other groups. The prevalence of 8.3% (95% CI: 3.8%-17.3%) for subclinical hypothyroidism in the high-iodine group was significantly higher than the low- and medium-iodine groups (P < .01). The prevalence of hypothyroidism in the medium-iodine group was 0.2% (95% CI: 0.1%-0.4%), and was lower than the prevalence of the other 2 groups (P < .01). There was no difference in prevalence of hyperthyroidism in each group.

CONCLUSIONS

Thyroid nodules are the most easily detectable thyroid disease. These have a lower prevalence in the high-iodine group. The prevalence of most thyroid diseases is lowest for a UIC ranging from 100 to 299 μg/L. This serves as a reference for health policy-making with respect to iodine levels. Further studies on this topic should be carried out according to sufficient thyroid cancer data.

Oncogenesis of Thyroid Cancer

Thyroid neoplasms encompass a variety of lesions that range from benign adenomas to malignancies. These latter can be well-differentiated, poorly differentiated or undifferentiated (anaplastic) carcinomas. More than 95% of thyroid cancers are derived from thyroid follicular cells, while 2-3% (medullary thyroid cancers, MTC) originate from calcitonin producing C-cells. Over the last decade, investigators have developed a clearer understanding of genetic alterations underlying thyroid carcinogenesis. A number of point mutations and translocations are involved, not only in its tumorigenesis, but also as have potential use as diagnostic and prognostic indicators and therapeutic targets. Many occur in genes for several important signaling pathways, in particular the mitogen-activated protein kinase (MAPK) pathway. Sporadic (isolated) lesions account for 75% of MTC cases, while inherited MTC, often in association with multiple endocrine neoplasia (MEN) type 2A and 2B syndromes, constitute the remainder. However, non-MEN familial MTC may also occur. Advances in genetic testing have revolutionized the management of MTC, with prospects of genetic screening, testing and early prophylactic thyroidectomy. Ethical concerns of these advances are addressed.

Review of Factors Related to the Thyroid Cancer Epidemic

Thyroid cancer is the most common endocrine cancer, of which the incidence has dramatically increased worldwide in the past few decades. The reasons for the observed rapid increase still are not fully understood, but evidence suggests that overdiagnosis, with the advancement in detection methods and screening policies, is not the sole driver of the substantial increase of the incidence. However, the effect of environmental/lifestyle factors remains speculative other than that of radiation exposure at a young age. This review tries to give a balanced view of debated factors leading to the thyroid cancer epidemic, to offer some alternatives in understanding the controversies, and to suggest potential directions in the search of modifiable risk factors to help reduce thyroid cancer.

Etiopathogenesis of Differentiated Thyroid Carcinomas

INTRODUCTION

Thyroid malignomas are a heterogeneous group of neoplasm consisting of most frequent differentiated encountered carcinomas, papillary and follicular thyroid carcinoma, then medullary thyroid carcinoma originating from neuroendocrine calcitonin-producing C-cells and rare forms of thyroid lymphomas arising from intrathyroidal lymphatic tissue, thyroid sarcomas and poorly differentiated anaplastic thyroid carcinoma. There are increasing numbers of epidemiological studies and publications that have suggested increased incidence rate of thyroid carcinomas. We have read, analysed and compare available reviews and original articles investigating different etiological factors in the development of thyroid carcinomas through Google Scholar and PubMed Database.

DISCUSSION

Aetiology involved in the development of thyroid carcinomas is multifactorial and includes external influences, as well as constitutional predispositions and genetic etiological factors. The actual effect of environmental and constitutional factors is on promoting genetic and epigenetic alterations which result in cell proliferation and oncogenesis. Until now are identified numerous genetic alterations, assumed to have an important role in oncogenesis, with MAPK and PI3K-AKT as crucial signalling networks regulating growth, proliferation, differentiation and cell survival/apoptosis.

CONCLUSION

This new molecular insight could have a crucial impact on diagnosis and also on improving and selecting an appropriate treatment to the patients with thyroid malignancies.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY DISEASE STATE CLINICAL REVIEW: THE INCREASING INCIDENCE OF THYROID CANCER

OBJECTIVE

(1) Describe current epidemiology of thyroid cancer in the United States; (2) evaluate hypothesized causes of the increased incidence of thyroid cancer; and (3) suggest next steps in research and clinical action.

METHODS

Analysis of data from Surveillance, Epidemiology and End Results System and the National Center for Vital Statistics. Literature review of published English-language articles through December 31, 2013.

RESULTS

The incidence of thyroid cancer has tripled over the past 30 years, whereas mortality is stable. The increase is mainly comprised of smaller tumors. These facts together suggest the major reason for the increased incidence is detection of subclinical, nonlethal disease. This has likely occurred through: health care system access, incidental detection on imaging, more frequent biopsy, greater volumes of and extent of surgery, and changes in pathology practices. Because larger-size tumors have increased in incidence also, it is possible that there is a concomitant true rise in thyroid cancer incidence. The only clearly identifiable contributor is radiation exposure, which has likely resulted in a few additional cases annually. The contribution of the following causes to the increasing incidence is unclear: iodine excess or insufficiency, diabetes and obesity, and molecular disruptions. The following mechanisms do not currently have strong evidence to support a link with the development of thyroid cancer: estrogen, dietary nitrate, and autoimmune thyroid disease.

CONCLUSION

Research should focus on illuminating which thyroid cancers need treatment. Patients should be advised of the benefits as well as harms that can occur with treatment of incidentally identified, small, asymptomatic thyroid cancers.

Follicular cell-derived thyroid cancer

Follicular cell-derived thyroid cancers are derived from the follicular cells in the thyroid gland, which secrete the iodine-containing thyroid hormones. Follicular cell-derived thyroid cancers can be classified into papillary thyroid cancer (80-85%), follicular thyroid cancer (10-15%), poorly differentiated thyroid cancer (<2%) and undifferentiated (anaplastic) thyroid cancer (<2%), and these have an excellent prognosis with the exception of undifferentiated thyroid cancer. The advent and expansion of advanced diagnostic techniques has driven and continues to drive the epidemic of occult papillary thyroid cancer, owing to overdiagnosis of clinically irrelevant nodules. This transformation of the thyroid cancer landscape at molecular and clinical levels calls for the modification of management strategies towards personalized medicine based on individual risk assessment to deliver the most effective but least aggressive treatment. In thyroid cancer surgery, for instance, injuries to structures outside the thyroid gland, such as the recurrent laryngeal nerve in 2-5% of surgeries or the parathyroid glands in 5-10% of surgeries, negatively affect quality of life more than loss of the expendable thyroid gland. Furthermore, the risks associated with radioiodine ablation may outweigh the risks of persistent or recurrent disease and disease-specific mortality. Improvement in the health-related quality of life of survivors of follicular cell-derived thyroid cancer, which is decreased despite the generally favourable outcome, hinges on early tumour detection and minimization of treatment-related sequelae. Future opportunities include more widespread adoption of molecular and clinical risk stratification and identification of actionable targets for individualized therapies.

Association of radiation dose with prevalence of thyroid nodules among atomic bomb survivors exposed in childhood (2007-2011)

IMPORTANCE

Few studies have evaluated the association of radiation dose with thyroid nodules among adults exposed to radiation in childhood.

OBJECTIVE

To evaluate radiation dose responses on the prevalence of thyroid nodules in atomic bomb survivors exposed in childhood.

DESIGN, SETTING, AND PARTICIPANTS

This survey study investigated 3087 Hiroshima and Nagasaki atomic bomb survivors who were younger than 10 years at exposure and participated in the thyroid study of the Adult Health Study at the Radiation Effects Research Foundation. Thyroid examinations including thyroid ultrasonography were conducted between October 2007 and October 2011, and solid nodules underwent fine-needle aspiration biopsy. Data from 2668 participants (86.4% of the total participants; mean age, 68.2 years; 1213 men; and 1455 women) with known atomic bomb thyroid radiation doses (mean dose, 0.182 Gy; median dose, 0.018 Gy; dose range, 0-4.040 Gy) were analyzed.

MAIN OUTCOMES AND MEASURES

The prevalence of all thyroid nodules having a diameter of 10 mm or more (consisting of solid nodules [malignant and benign] and cysts), prevalence of small thyroid nodules that were less than 10 mm in diameter detected by ultrasonography, and atomic bomb radiation dose-responses.

RESULTS

Thyroid nodules with a diameter of 10 mm or more were identified in 470 participants (17.6%): solid nodules (427 cases [16.0%]), malignant tumors (47 cases [1.8%]), benign nodules (186 cases [7.0%]), and cysts (49 cases [1.8%]), and all were significantly associated with thyroid radiation dose. Excess odds ratios per gray unit were 1.65 (95% CI, 0.89-2.64) for all nodules, 1.72 (95% CI, 0.93-2.75) for solid nodules, 4.40 (95% CI, 1.75-9.97) for malignant tumors, 2.07 (95% CI, 1.16-3.39) for benign nodules, and 1.11 (95% CI, 0.15-3.12) for cysts. The interaction between age at exposure and the dose was significant for the prevalence of all nodules (P = .003) and solid nodules (P < .001), indicating that dose effects were significantly higher with earlier childhood exposure. No interactions were seen for sex, family history of thyroid disease, antithyroid antibodies, or seaweed intake. No dose-response relationships were observed for small (<10-mm diameter) thyroid nodules.

CONCLUSIONS AND RELEVANCE

Radiation effects on thyroid nodules exist in atomic bomb survivors 62 to 66 years after their exposure in childhood. However, radiation exposure is not associated with small thyroid nodules.

Correlation between iodine intake and thyroid disorders: a cross-sectional study from the South of China

Great changes have taken place in the incidence of thyroid diseases since the implementation of universal salt iodization (USI). However, the high incidence of thyroid diseases caused by the high iodine intake has been contentious. The aim of this study was to investigate the relationship between iodine intake and thyroid diseases through the comparison of urine iodine concentration (UIC) between patients with thyroid diseases and healthy volunteers and to assess the status of iodine intake among the residents. From November 2013 to May 2014, 905 patients who underwent thyroid surgeries and 272 subjects of healthy controls were enrolled and were divided into two groups: the case group and the control group, respectively. Levels of thyroid hormones and thyroid autoantibodies in serum from blood were analyzed among all the patients. UIC and thyroid B ultrasounds were performed on each participant. The median urinary iodine (MUI) concentration was 184.5 and 169.6 μg/L for case group and control group, respectively (P = 0.003). Significant differences of the MUI were found between healthy controls and patients with Hashimoto's thyroiditis (MUI = 221.3 μg/L), nodular goiter (MUI = 193.5 μg/L), multiple nodules (MUI = 185.9 μg/L), nodule diameter ≥1 cm (MUI = 194.4 μg/L), hyperthyroidism (MUI = 258.7 μg/L), thyroid peroxidase antibody (TPOAb) (+), and thyroglobulin antibody (TGAb) (+) (MUI = 196.4 μg/L), and P values were 0.003, 0.000, 0.002, 0.000, 0.000, and 0.001, respectively. The susceptibility of the thyroid diseases among normal people was significantly associated with female sex (odds ratio (OR) = 3.3), older age (OR = 2.1), and high iodine intake (OR = 1.3). In conclusion, high iodine intake was likely to lead to the occurrence of thyroid diseases, such as Hashimoto thyroiditis, nodular goiter, and hyperthyroidism, through a long-term mechanism. USI should continue to be carried out and individual UIC detection was recommended for the disequilibrium of the iodine nutritional status among normal people.

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.

Strong association of high urinary iodine with thyroid nodule and papillary thyroid cancer

This study demonstrates a strong association of high urinary iodine with thyroid nodules and papillary thyroid cancer as well as aggressive cancer features, suggesting that high urinary iodine is a risk factor for thyroid cancer. The risk of high iodine intake for thyroid cancer has been suggested but not established. The objective of the study was to evaluate the relationship between urine iodine levels and thyroid nodule and thyroid cancer. We preoperatively tested fasting urine iodine in 154 thyroid nodule patients and correlated the results with pathological diagnoses and compared with 306 subjects as normal control. The median urine iodine (MUI) was 331.33 μg/L in patients with benign thyroid nodules versus 466.23 μg/L in patients with papillary thyroid cancer (PTC) (P=0.003), both of which were in the excessive iodine state and higher than the MUI of 174.30 μg/L in the control group (P < 0.001), which was in the sufficient iodine state. Excessive iodine state (MUI>300 μg/L) was seen in 62.75% of patients with benign thyroid nodules and 66.99% of patients with PTC, both of which were significantly higher than the iodine excessive rate of 19.93% in the control group (P<0.001). Moreover, MUI in patients with PTC with lymph node metastasis was significantly higher than that of PTC patients without lymph node metastasis (P<0.001). Urine iodine of thyroid cancer patients with stage III and IV disease was significantly higher than that of patients with stage I and II diseases (P<0.001). Multivariable analyses showed that, like sand calcification of thyroid nodule and TSH, urine iodine was an independent risk factor for PTC. These data demonstrate a significant association between high urinary iodine and benign and malignant thyroid nodules and PTC aggressiveness, supporting high urinary iodine as a risk factor for thyroid malignancy. Further studies are warranted to confirm these findings.

Dietary factors and the risk of thyroid cancer: a review

In the past few decades, the incidence of thyroid cancer has rapidly increased worldwide. Thyroid cancer incidence is relatively high in regions where the population's daily iodine intake is insufficient. While low dietary iodine has been considered as a risk factor for thyroid cancer development, previous studies found controversial results across different food types. Among different ethnic groups, dietary factors are influenced by various dietary patterns, eating habits, life-styles, nutrition, and other environmental factors. This review reports the association between dietary factors and thyroid cancer risk among ethnic groups living in different geologic regions. Iodine-rich food such as fish and shellfish may provide a protective role in populations with insufficient daily iodine intake. The consumption of goitrogenic food, such as cruciferous vegetables, showed a positive association with risk. While considered to be a risk factor for other cancers, alcohol intake showed a protective role against thyroid cancer. High consumption of meat such as chicken, pork, and poultry showed a positive association with the risk, but dairy products showed no significant association. Regular use of multivitamins and dietary nitrate and nitrite also showed a positive association with thyroid cancer risk. However, the study results are inconsistent and investigations into the mechanism for how dietary factors change thyroid hormone levels and influence thyroid function are required.

TERT promoter mutations and their association with BRAF V600E mutation and aggressive clinicopathological characteristics of thyroid cancer

CONTEXT

Promoter mutations chr5:1,295,228C>T and chr5:1,295,250C>T (termed C228T and C250T, respectively) in the gene for telomerase reverse transcriptase (TERT) have been reported in various cancers and need to be further investigated in thyroid cancer.

OBJECTIVE

The aim of the study was to explore TERT promoter mutations in various thyroid tumors and examine their relationship with BRAF V600E mutation, iodine intake, and clinicopathological behaviors of thyroid cancer.

DESIGN

TERT promoter and BRAF mutations were identified by sequencing genomic DNA of primary thyroid tumors from normal- and high-iodine regions in China, and clinicopathological correlation was analyzed.

RESULTS

The C228T mutation was found in 9.6% (39 of 408) of papillary thyroid cancer (PTC), C250T was found in 1.7% (7 of 408) of PTC, and they were collectively found in 11.3% (46 of 408) of PTC. C228T was found in 31.8% (7 of 22) and C250T in 4.6% (1 of 22) of follicular thyroid cancer (FTC), and they were collectively found in 36.4% (8 of 22) of FTC. No TERT mutation was found in 44 benign thyroid tumors. The two mutations occurred in 3.8% (6 of 158) of BRAF mutation-negative PTC vs 16.0% (40 of 250) of BRAF mutation-positive PTC (P = 5.87 × 10(-4)), demonstrating their association. Unlike BRAF mutation, TERT promoter mutations were not associated with high iodine intake, but they were associated with older patient age, larger tumor size, extrathyroidal invasion, and advanced stages III/IV of PTC. Coexisting TERT and BRAF mutations were even more commonly and more significantly associated with clinicopathological aggressiveness.

CONCLUSIONS

In this large cohort, we found TERT promoter mutations to be common, particularly in FTC and BRAF mutation-positive PTC, and associated with aggressive clinicopathological characteristics.

The geographical pattern of thyroid cancer mortality between 1980 and 2009 in Italy

BACKGROUND

Mortality for thyroid cancer (TC) is low and has been decreasing worldwide; yet few population studies based on mortality have been conducted. Several nonradiation risk factors have been associated with TC, including residence in goiter-endemic areas (as an indicator of iodine deficiency). We used mortality data to perform a spatial-temporal analysis regarding TC in Italy and investigated the association between mortality and socioeconomic status and geographical features (residing in a mountainous area is a proxy for iodine deficiency).

METHODS

We analyzed data from Italy's National Mortality Database (1980-2009). To evaluate temporal trends in mortality the age-standardized death rate (ASR) was used; to identify geographic areas with excess deaths due to TC standardized mortality rates (SMR) were calculated. We also calculated the rate ratios (RR) of the ASR and the 95% CI by sex. We performed a cluster analysis to identify municipalities with major departures from expected mortality, both in the entire study period and in two separate periods to evaluate the spatial-temporal variability. Finally, we evaluated the association between mortality and index of deprivation and altitude.

RESULTS

There were 16,473 deaths due to TC (10,690 females, 5783 males). The mean ASR was unsurprisingly low (0.58/100.000). There was a trend of decrease in mortality throughout Italy (-42% for 2007-2009 vs. 1980-1984), more pronounced among women. The decrease was greater in the north. Four geographic clusters were identified when considering the entire study period, two in the north and two in the south; however, the clusters in northern Italy refer to the earlier period (1980-1994) and those in southern Italy to the later period (1995-2009). Mortality was associated with residing in a mountainous area. A slight association with high socioeconomic status was found.

CONCLUSIONS

This study reveals space-time differences in TC mortality in Italy. It shows an association between mortality and residing in mountainous areas, which is a proxy of iodine deficiency. The observed temporal north-south shift cannot be explained by socioeconomic differences, whereas the efficient prophylaxis program implemented in the 1980s in some areas of northern Italy can help to explain the disappearance of the clusters in those areas in the period 1995-2009.

New developments in the diagnosis and treatment of thyroid cancer

Thyroid cancer exists in several forms. Differentiated thyroid cancers include those with papillary and follicular histologies. These tumors exist along a spectrum of differentiation, and their incidence continues to climb. A number of advances in the diagnosis and treatment of differentiated thyroid cancers now exist. These include molecular diagnostics and more advanced strategies for risk stratification. Medullary cancer arises from the parafollicular cells and not the follicular cells. Therefore, diagnosis and treatment differs from those of differentiated thyroid tumors. Genetic testing and newer adjuvant therapies have changed the diagnosis and treatment of medullary thyroid cancer. This review will focus on the epidemiology, diagnosis, workup, and treatment of both differentiated and medullary thyroid cancers, focusing specifically on newer developments in the field.

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.

Are risk factors common to thyroid cancer and nodule? A forty years observational time-trend study

A progressive increase in the incidence of thyroid cancer (TC) has been reported over the last few decades. This either reflects the increased number of newly discovered and accurately selected thyroid nodules with more sensitive technologies and a relative more potent carcinogenic effect of pathogenetic factors in malignant, but not benign nodules. This observational time-trend study addresses this issue by analysing the proportion of TC within 8411 consecutive thyroid nodule (TN) patients evaluated in Pisa by the same pathology Department and individual clinician over a four-decade period. From 1972 to 1979 surgery was used to detect TC among the TN patients: 1140 TN patients were operated on and 35 cancers were detected (3.1% of all the TN patients). Subsequently, needle aspiration techniques were used to select TN for surgery. From 1980 to 1992, 5403 TN patients were examined, 483 were selected for surgery, and 150 cancers were found (2.8% of all the TN patients). From 1993 to 2010, 1568 TN patients were examined, 143 were selected for surgery, and 46 cancers were found (2.9% of all the TN patients). Therefore, in the University Hospital of Pisa, and independent of preoperative TN selection protocols, these proportions of TN eventually found to harbor TC remained statistically unchanged over 40 years (p = 0.810). This finding suggests that pathogenic risk factors and more sensitive diagnostic technologies did not differentially affect the incidence of TN and TC.

Effect of iodine-enriched yeast supplementation of diet on performance of laying hens, egg traits, and egg iodine content

The aim of the study was to evaluate the effect of iodine yeast (I-yeast) supplementation on the performance, egg traits, and iodine content of eggs of laying hens. The experiment was conducted as a completely randomized design. A total of 60 laying hens (Hy-Line Brown), 25 wk of age, was divided into 3 groups (4 replicates), and a feeding experiment was conducted for 12 wk. The concentrations and forms of iodine added to the basal diet were as follows: control group, 1 mg of iodine/kg of feed, Ca(IO(3))(2)•H(2)O; experimental groups E1 and E2, 1 and 2 mg of iodine per kilogram of feed, I-yeast, respectively. The iodine yeast did not significantly affect BW gain. Lower level of hen day egg production for groups E1 and E2 was not confirmed statistically; however, it was probably the consequence of low replication. Feed intake was the lowest in the E1 group and feed conversion rate was the highest in the E2 group. Furthermore, the egg and albumen weight was the highest in the group supplemented with 2 mg/kg of iodine from I-yeast (P < 0.05). The concentration of iodine in the egg yolk from groups E1 and E2 was respectively about 80 and 90% higher, compared with the control group. Eggshells from the group fed with 2 mg/kg of I-yeast contained almost 3 times more iodine than eggshells from the control group. The results suggest that iodine yeast supplementation in the diet of laying hens is an effective method for increasing iodine concentration in eggs and thus could contribute to elimination of iodine deficiency disorders in humans consuming iodine-enriched eggs.

Iodine-deficiency-induced long lasting angiogenic reaction in thyroid cancers occurs via a vascular endothelial growth factor-hypoxia inducible factor-1-dependent, but not a reactive oxygen species-dependent, pathway

BACKGROUND

In the thyroid, iodine deficiency (ID) induces angiogenesis via a tightly controlled reactive oxygen species (ROS)-hypoxia inducible factor-1 (HIF-1)-vascular endothelial growth factor (VEGF) dependent pathway (ROS-HIF-VEGF). Deficient iodine intake may be associated with increased thyroid cancer incidence. The hypothesis of this work is to test whether ID affects the angiogenic processes in thyroid malignant cells by altering the ROS-HIF-VEGF pathway.

METHODS

Goiters were obtained in RET/PTC3 transgenic and wild-type (wt) mice and ID was induced in three thyroid carcinoma cell lines (TPC-1, 8305c, and R082-w1). Thyroid blood flow, VEGF mRNA and protein, and HIF-1α protein expression were measured. The role of HIF-1 and of ROS was assessed using echinomycin and N-acetylcysteine (NAC), respectively.

RESULTS

The goitrogen treatment increased the thyroid blood flow in wt and RET/PTC3 mice. Compared with wt mice, basal VEGF expression was higher in RET/PTC3 mice and increased with goitrogen treatment. In the three cell lines, ID induced marked increases in VEGF mRNA, and moderate increases in HIF-1α protein expression that were not transient as in normal cells. ID-induced VEGF mRNA expression was fully (8305c), partially (TPC-1), or not (R082-w1) blocked by echinomycin. NAC had no effect on ID-induced VEGF mRNA and HIF-1α protein expression in the three cell lines.

CONCLUSIONS

ID induces a long lasting angiogenic phenotype in thyroid cancer cells that occurs through VEGF induction via a pathway partially mediated by HIF-1, but not by ROS. These results suggest that, in contrast with normal cells, ID-induced angiogenesis in cancer cells occurs via alternative and likely less controlled routes, thereby leading to uncontrolled growth.

Excess iodine and high-fat diet combination modulates lipid profile, thyroid hormone, and hepatic LDLr expression values in mice

The aim of this study was to illustrate the combined effect of excess iodine and high-fat diet on lipid metabolism and its potential molecular mechanism. Sixty Balb/c mice were randomly allocated to three control groups or three excess iodine groups and fed with a high-fat diet in the absence or presence of 1,200 μg/L iodine for 1, 3, or 6 months, respectively. Serum lipid parameters and serum thyroid hormones were measured. Expressions of scavenger receptor class B type-I (SR-BI) and low density lipoproteins receptor (LDLr) mRNA and protein in liver were detected. Thyroid histology and liver type 1 iodothyronine deiodinase activity were analyzed. At the end of 3 and 6 months, compared with control, serum TC, TG, and LDL-C in excess iodine group were significantly lower (p < 0.05). LDLr expression in liver was increased significantly (p < 0.05) and parallel to the change of serum TC and TG. TT3 and TT4 levels in serum were elevated and TSH decreased significantly (p < 0.05). Liver type I iodothyronine deiodinase activity was significantly higher (p < 0.05) than control at the end of 6 months. Moreover, a time course damage effect of excess iodine combined with high-fat diet on thyroid glands was observed. The present findings demonstrated that excess iodine combined with high-fat diet could cause damage to thyroid glands and lead to thyroid hormone disorder. Those in turn caused the upregulation of hepatic LDLr gene, which resulted in the disorder in serum lipids.

BMI, diet and female reproductive factors as risks for thyroid cancer: a systematic review

Background

Thyroid cancer incidence rates have been increasing worldwide but the reason behind this is unclear. Both the increasing use of diagnostic technologies allowing the detection of thyroid cancer and a true increase in thyroid cancer incidence have been proposed. This review assesses the role of body mass index (BMI), diet, and reproductive factors on the thyroid cancer trend.

Methods

Epidemiologic studies of the selected risk factors up to June 2010 were reviewed and critically assessed.

Results

Among the thirty-seven studies reviewed and despite variation in the risk estimates, most papers supported a small but positive association for BMI (risk estimate range: 1.1–2.3 in males and 1.0–7.4 in females.). Among specific dietary components, there was no consistent association of thyroid cancer risk with iodine intake through fortification (risk estimate range: 0.49–1.6) or fish consumption (risk estimate range 0.6–2.2), nor with diets high in cruciferous vegetables (risk estimate range 0.6–1.9). A small number of studies showed a consistent protective effect of diets high in non-cruciferous vegetable (risk estimate range: 0.71–0.92). Among reproductive factors (pregnancy, parity, number of live births, use of prescription hormones, menstrual cycle regularity, and menopausal status), none were consistently associated with higher thyroid cancer risk.

Conclusions

BMI had the strongest link to thyroid cancer risk among those examined. Detailed examinations of population-level risk factors can help identify and support prevention efforts to reduce the burden of thyroid cancer.

Thyroid cancer: is ethnicity relevant?

Objective:

This study aimed to determine the age at which various ethnic groups present with thyroid cancer.

Method:

Retrospective, observational study based at three district general hospitals in the West Midlands, serving a widely diverse ethnic population. We assessed all patients undergoing an operative or core biopsy procedure for a thyroid nodule from 1 January 1998 to 31 December 2009. Only patients diagnosed with thyroid cancer were included. Variables examined included the patient's ethnic origin, sex and age at presentation.

Result:

We identified 263 patients diagnosed with thyroid cancer. Papillary carcinoma predominated. Ethnicity was categorised as Caucasian, Asian, black or other. Thyroid cancer was predominantly seen in women, in all ethnic groups. The mean age of thyroid cancer presentation was 50 years in Asians and 56 years in Caucasians, for both sexes combined. The mean presentation age of Asian women was significantly younger (46 years) than that of Caucasian women (56 years) (p = 0.01).

Conclusion:

In this population, Asian women presented with thyroid cancer at a significantly younger mean age than Caucasian women.

Dose and time-dependent hypercholesterolemic effects of iodine excess via TRbeta1-mediated down regulation of hepatic LDLr gene expression

BACKGROUND

With the global improvement of iodine nutrition, iodine excess is emerging as a new concern.

AIM OF STUDY

The aim of this study is to illustrate the physiological effects and potential molecular mechanisms of excessive iodine intake on lipid metabolism.

METHODS

Balb/c mice were given drinking water containing different levels of iodine for 1 month and treated with 1.2 microg/mL iodine for different periods of time, respectively. Plasma lipid parameters and serum thyroid hormones were measured. Expressions of hepatic genes were detected by real-time polymerase chain reactions and Western blot.

RESULTS

Dose-dependent hypercholesterolemic effects were detected in mice (TC, r = 0.615; p < 0.01). Drinking 1.2 microg/mL iodine water for 1 month had no significant effect on serum lipid metabolism, while prolonged exposure induced an increase of serum cholesterol. Serum thyroid hormones were not affected by iodine throughout the study. At the molecular level, we detected a dose-dependent attenuation of hepatic low density lipoprotein receptor (LDLr) and thyroid hormone receptor beta1 (TRbeta1) expression in parallel to the change of serum cholesterol. Treatment with 1.2 microg/mL iodine water for 1 month did not affect LDLr and TRbeta1 expression, while 3 or 6 months exposure resulted in a decrease of their expression.

CONCLUSION

Present findings demonstrated dose- and time-dependent hypercholesterolemic effects of iodine excess. Furthermore, our data suggests that TRbeta1-mediated down regulation of hepatic LDLr gene may play a critical role in iodine excess-induced hypercholesterolemic effects.

Absence of Peritumoral Fibrosis or Inflammatory Infiltrate May Be Related to Clinical Progression of Papillary Thyroid Microcarcinoma

Rio Grande do Norte (RN) shows the highest relative incidence of papillary carcinomas in Brazil. To analyze histological features that might be associated with this incidence, the authors compared thyroid glands from 463 autopsies performed in RN with 427 surgical and autopsy glands previously studied in Sao Paulo (SP). The authors found 41 papillary thyroid microcarcinomas (PTMs) in 35 glands (8.1%), an incidence similar to the one reported in SP (7.8%). However, PTMs were predominantly nonencapsulated nonsclerosing at microscopy (44.0%), in contrast with SP where these types of lesion represented only 4 out of 32 PTMs (12.5%; P = .0046). The authors suggest that these nonencapsulated lesions with no sign of inflammation may represent an early stage that may evolve to clinical cancers, contributing to the high incidence of clinically differentiated thyroid carcinomas observed in RN.