Iodine intake as a risk factor for thyroid cancer: a comprehensive review of animal and human studies

Incidence of thyroid carcinomas in an extended retrospective study of 526 autopsies

Thyroid cancer accounts for 1% of all malignancies, and is becoming increasingly common worldwide. The literature reports a prevalence of ~50% of thyroid nodules detected during autopsies in subjects with unknown thyroid pathology. An extended retrospective study of 526 autopsy cases was performed to identify the prevalence of thyroid carcinoma, among various types of thyroid nodules identified incidentally. Tissue samples were taken from thyroid nodules, for investigation of the presence of thyroid carcinoma, along with their macroscopic and microscopic features by means of histopathology and immunohistochemistry (IHC) methods. Histopathological diagnosis of malignancy was found in 51 cases of analyzed thyroid samples. Systematic detailed studies demonstrated that a thyroid gland, apparently normal on macroscopic examination, may be the site of pathological manifestations, sometimes presenting carcinomatous findings. Among thyroid carcinomas, the highest frequency was that of papillary microcarcinomas, which have a long evolution, and are incidentally detected during autopsies. Papillary microcarcinoma is an extremely common incidental finding and the vast majority of these tumors pursue a benign course. Furthermore, it is therefore necessary to create national screening programs for the early detection of thyroid carcinoma.

Adiponectin and Thyroid Cancer: Insight into the Association between Adiponectin and Obesity

In recent decades, the incidence and diagnosis of thyroid cancer have risen dramatically, and thyroid cancer has now become the most common endocrine cancer in the world. The onset of thyroid cancer is insidious, and its progression is slow and difficult to detect. Therefore, early prevention and treatment have important strategic significance. Moreover, an in-depth exploration of the pathogenesis of thyroid cancer is key to early prevention and treatment. Substantial evidence supports obesity as an independent risk factor for thyroid cancer. Adipose tissue dysfunction in the obese state is accompanied by dysregulation of a variety of adipocytokines. Adiponectin (APN) is one of the most pivotal adipocytokines, and its connection with obesity and obesity-related disease has gradually become a hot topic in research. Recently, the association between APN and thyroid cancer has received increasing attention. The purpose of this review is to systematically review previous studies, give prominence to APN, focus on the relationship between APN, obesity and thyroid cancer, and uncover the underlying pathogenic mechanisms.

A Search for Causes of Rising Incidence of Differentiated Thyroid Cancer in Children and Adolescents after Chernobyl and Fukushima: Comparison of the Clinical Features and Their Relevance for Treatment and Prognosis

The incidence of differentiated thyroid cancer (DTC) is steadily increasing globally. Epidemiologists usually explain this global upsurge as the result of new diagnostic modalities, screening and overdiagnosis as well as results of lifestyle changes including obesity and comorbidity. However, there is evidence that there is a real increase of DTC incidence worldwide in all age groups. Here, we review studies on pediatric DTC after nuclear accidents in Belarus after Chernobyl and Japan after Fukushima as compared to cohorts without radiation exposure of those two countries. According to the Chernobyl data, radiation-induced DTC may be characterized by a lag time of 4–5 years until detection, a higher incidence in boys, in children of youngest age, extrathyroidal extension and distant metastases. Radiation doses to the thyroid were considerably lower by appr. two orders of magnitude in children and adolescents exposed to Fukushima as compared to Chernobyl. In DTC patients detected after Fukushima by population-based screening, most of those characteristics were not reported, which can be taken as proof against the hypothesis, that radiation is the (main) cause of those tumors. However, roughly 80% of the Fukushima cases presented with tumor stages higher than microcarcinomas pT1a and 80% with lymph node metastases pN1. Mortality rates in pediatric DTC patients are generally very low, even at higher tumor stages. However, those cases considered to be clinically relevant should be followed-up carefully after treatment because of the risk of recurrencies which is expected to be not negligible. Considering that thyroid doses from the Fukushima accident were quite small, it makes sense to assess the role of other environmental and lifestyle-related factors in thyroid carcinogenesis. Well-designed studies with assessment of radiation doses from medical procedures and exposure to confounders/modifiers from the environment as e.g., nitrate are required to quantify their combined effect on thyroid cancer risk.

Epidemiology of Thyroid Carcinomas in North Macedonia (1999-2015)

Objective:

We have set as objective to analyze epidemiological data of diagnosed thyroid carcinoma (TC) cases, incidence and prevalence rate by gender, age, histopathological type, and statistical regions in R. of N. Macedonia during the period 1999 to 2015.

Material and Methods:

Retrospective analysis of medical data collected from the 2 state thyroid departments. Inclusion criteria included newly diagnosed cases of TC in appropriate years for the period 1999 to 2015. We have evaluated: yearly incidence rate, incidence and prevalence by gender, age, the distribution in 8 statistical state regions and histopathological types and subtypes representation.

Results:

A total number of 422 TC patients were detected, average incidence rate of 1.22/10⁵, with most prevalent papillary TCs79.5%, followed by follicular 10.9%, medullar 4.1%, anaplastic 3.1%, and other rare types with 2.3%. The highest incidence rate was detected in Skopje region, while the lowest in Southeast and the Polog region. The total prevalence rate for the female gender was 32.61/10⁴ and for male 9.27/10⁴ (f/m ratio = 3.52:1), with lowest female/male difference found in the elderly > 65 years (f/m = 2.21/1).

Conclusion:

Compared with regional epidemiological data we can conclude that Republic of N. Macedonia has very low incidence and prevalence rate, while female/male ratio was similar to that described in the literature. Our low incidence and prevalence rate may be due to 2 possible reasons, 1 would be insufficient diagnosis of only small portion of the real cases in the population, or the second reason may be a real low incidence resulting of specific etiopathogenetic circumstances.

High Iodine Induces the Proliferation of Papillary and Anaplastic Thyroid Cancer Cells via AKT/Wee1/CDK1 Axis

High iodine can alter the proliferative activity of thyroid cancer cells, but the underlying mechanism has not been fully elucidated. Here, the role of high iodine in the proliferation of thyroid cancer cells was studied. In this study, we demonstrated that high iodine induced the proliferation of BCPAP and 8305C cells via accelerating cell cycle progression. The transcriptome analysis showed that there were 295 differentially expressed genes (DEGs) in BCPAP and 8305C cells induced by high iodine, among which CDK1 expression associated with the proliferation of thyroid cancer cells induced by high iodine. Moreover, the western blot analysis revealed that cells exposed to high iodine enhanced the phosphorylation activation of AKT and the expression of phospho-Wee1 (Ser642), while decreasing the expression of phospho-CDK1 (Tyr15). Importantly, the inhibition of AKT phosphorylation revered the expression of CDK1 induced by high iodine and arrested the cell cycle in the G₁ phase, decreasing the proliferation of thyroid cancer cells induced by high iodine. Taken together, these findings suggested that high iodine induced the proliferation of thyroid cancer cells through AKT-mediated Wee1/CDK1 axis, which provided new insights into the regulation of proliferation of thyroid cancer cells by iodine.

Maternal health, in-utero, and perinatal exposures and risk of thyroid cancer in offspring: a Nordic population-based nested case-control study

BACKGROUND

Thyroid cancer tends to be diagnosed at a younger age (median age 51 years) compared with most other malignancies (such as breast cancer [62 years] or lung cancer [71 years]). The incidence of thyroid cancer is higher in women than men diagnosed from early adolescence. However, few in-utero and early life risk exposures associated with increased risk of thyroid cancer have been identified.

METHODS

In this population-based nested case-control study we used registry data from four Nordic countries to assess thyroid cancer risk in offspring in relation to maternal medical history, pregnancy complications, and birth characteristics. Patient with thyroid cancer (cases) were individuals born and subsequently diagnosed with first primary thyroid cancer from 1973 to 2013 in Denmark, 1987 to 2014 in Finland, 1967 to 2015 in Norway, or 1973 to 2014 in Sweden. Each case was matched with up to ten individuals without thyroid cancer (controls) based on birth year, sex, country, and county of birth. Cases and matched controls with a previous diagnosis of any cancer, other than non-melanoma skin cancer, at the time of thyroid cancer diagnosis were excluded. Cases and matched controls had to reside in the country of birth at the time of thyroid cancer diagnosis. Conditional logistic regression models were used to calculate odds ratios (ORs) with 95% CIs.

RESULTS

Of the 2437 cases, 1967 (81·4%) had papillary carcinomas, 1880 (77·1%) were women, and 1384 (56·7%) were diagnosed before age 30 years (range 0-48). Higher birth weight (OR per kg 1·14 [95% CI 1·05-1·23]) and congenital hypothyroidism (4·55 [1·58-13·08]); maternal diabetes before pregnancy (OR 1·69 [0·98-2·93]) and postpartum haemorrhage (OR 1·28 [1·06-1·55]); and (from registry data in Denmark) maternal hypothyroidism (18·12 [10·52-31·20]), hyperthyroidism (11·91 [6·77-20·94]), goiter (67·36 [39·89-113·76]), and benign thyroid neoplasms (22·50 [6·93-73·06]) were each associated with an increased risk of thyroid cancer in offspring.

INTERPRETATION

In-utero exposures, particularly those related to maternal thyroid disorders, might have a long-term influence on thyroid cancer risk in offspring.

FUNDING

Intramural Research Program of the National Cancer Institute (National Institutes of Health).

MiR-153-3p Suppresses Cell Proliferation, Invasion and Glycolysis of Thyroid Cancer Through Inhibiting E3F3 Expression

PURPOSE

The aim was to research the role of miR-153-3p and E2F3 in the development of thyroid tumors.

METHODS

A total of 91 thyroid cancer patients were involved. The role of miR-153-3p in THCA cell lines and Nthy-ori3-1 cell line was researched. qPCR was used to detect miR-153-3p and E2F3 expression. MiR-153-3p mimic, inhibitor, siE2F3 or corresponding controls were transfected in cells. CCK8 was used to verify the proliferation. Cell cycle and apoptosis was detected by flow cytometry. Transwell assay was applied for migration and invasion, and glycolysis was monitored. The binding of miR-153-3p and E2F3 was predicted by targetscan database, and verified by luciferase reporter and RNA-pull down assay. Western blot was used to detect E2F3 expression. Rescue assay was undertaken to verify the effect of siE2F3 on miR-153-3p inhibitor. Moreover, the effect of miR-153-3p mimic on tumor volume and weight was measured. IHC assay was processed to E2F3 and Ki67 expression, and TUNEL assay was used for apoptosis.

RESULTS

MiR-153-3p expressed lower in thyroid tumors and cells. The level of miR-153-3p was negatively related with TNM stage. MiR-153-3p inhibited cell proliferation, invasion migration, and induced cycle arrest and apoptosis. Moreover, it negatively regulated E2F3. siE2F3 rescued effects of miR-153-3p inhibitor in all above biological processes in thyroid cancer cells. MiR-153-3p inhibited tumor growth. Moreover, it inhibited E2F3 and Ki67 expression, and also increased apoptosis in vivo.

CONCLUSION

MiR-153-3p suppresses cell proliferation, invasion and glycolysis of thyroid cancer through inhibiting E3F3 expression, which may be a biomarker for thyroid cancer diagnose.

Geographical influences on thyroid abnormalities in adult population from iodine-replete regions: a cross-sectional study

The studies on the increasing incidence of thyroid abnormalities are scarce. The aim of this current study was to ascertain the effects of geographical region on thyroid abnormalities under the context of universal salt iodization (USI). We randomly selected 1255 participants residing in inland and 1248 in coast, with the determination of urinary iodine concentration (UIC) and functional and morphological abnormalities of thyroid gland. The median UIC was significantly higher for the inland participants (188.5 μg/L) than the coastal participants (128.5 μg/L; p < 0.001), indicating iodine sufficiency in both populations according to the recommended assessment criteria by the World Health Organization. However, the spectrum of thyroid abnormalities varied between regions, with hypothyroidism prevalent in inland and thyroid nodules in coast. The associations between region and thyroid abnormalities via binary logistic regression models showed that the coastal participants were at a higher risk of total thyroid abnormalities than those from the inland (OR 1.216, 95% CI 1.020-1.449), after the adjustment of ten confounders (demographical characteristics, smoking status, metabolism syndrome, and hyperuricemia). These results indicated that further investigations of the adverse effects of hypothyroidism and thyroid nodules on health burden is urgently needed to sustain USI program.

A review of species differences in the control of, and response to, chemical-induced thyroid hormone perturbations leading to thyroid cancer

This review summarises the current state of knowledge regarding the physiology and control of production of thyroid hormones, the effects of chemicals in perturbing their synthesis and release that result in thyroid cancer. It does not consider the potential neurodevelopmental consequences of low thyroid hormones. There are a number of known molecular initiating events (MIEs) that affect thyroid hormone synthesis in mammals and many chemicals are able to activate multiple MIEs simultaneously. AOP analysis of chemical-induced thyroid cancer in rodents has defined the key events that predispose to the development of rodent cancer and many of these will operate in humans under appropriate conditions, if they were exposed to high enough concentrations of the affecting chemicals. There are conditions however that, at the very least, would indicate significant quantitative differences in the sensitivity of humans to these effects, with rodents being considerably more sensitive to thyroid effects by virtue of differences in the biology, transport and control of thyroid hormones in these species as opposed to humans where turnover is appreciably lower and where serum transport of T4/T3 is different to that operating in rodents. There is heated debate around claimed qualitative differences between the rodent and human thyroid physiology, and significant reservations, both scientific and regulatory, still exist in terms of the potential neurodevelopmental consequences of low thyroid hormone levels at critical windows of time. In contrast, the situation for the chemical induction of thyroid cancer, through effects on thyroid hormone production and release, is less ambiguous with both theoretical, and actual data, showing clear dose-related thresholds for the key events predisposing to chemically induced thyroid cancer in rodents. In addition, qualitative differences in transport, and quantitative differences in half life, catabolism and turnover of thyroid hormones, exist that would not operate under normal situations in humans.

Changing patterns of thyroid cancer in different stages of Universal Salt Iodization in Peking Union Medical College Hospital, 1986-2018

Backgrounds

Iodine intake may be associated with increased thyroid cancer, but its effect varied from places to places. Universal salt iodization (USI) has been introduced in China from 1996 to 2012. The effects of increased iodine intake on thyroid cancer needs to be investigated in China.

Methods

From 1986 to 2018, patients who had thyroidectomies in Peking Union Medical College Hospital (PUMCH) were retrospectively studied. The detection rate, constituent ratio, mean age, sex distribution of thyroid cancer and the pattern of papillary thyroid microcarcinoma (PTMC) were compared between different historical periods.

Results

The detection rate of thyroid cancer in thyroid surgery significantly increased from 6.77% to 75.78% post-USI, with papillary thyroid cancer (PTC) being the majority, and that of follicular thyroid cancer (FTC) and medullary thyroid cancer (MTC) showed only minor changes. There was a descending trend of female/male ratio in PTC from 3.7 to 2.8, and a slight decrease of mean age observed in PTC after USI compared with during USI. The percentage of PTMC in PTC decreased from 13.99% to 8.64%, with a lower mean age after USI (44.88±10.37 vs. 46.44±10.42). Prevalence of goiter coexisting with PTMC was also lower after USI than during USI (31% vs. 41%).

Conclusions

With the popularization of iodized salt, PTC has become the major type in surgery for thyroid cancer, and trends in other histological subtypes remained mostly stable over the periods. The increase in PTC cannot be attributed to the increase of PTMC which is smaller than 1 cm, indicating that contributing factors other than diagnostic activities, may play a role in the increase of PTC.

Clinical Utility of BRAF, NRAS, and TERT Promoter Mutation in Preoperative Thyroid Fine-Needle Aspiration Biopsy: A Diagnostic Study From Dharmais Cancer Hospital

Objective:

Molecular testing of thyroid nodules becomes important for improving the accuracy of fine-needle aspiration biopsy (FNAB). This study aimed to investigate the diagnostic utility of BRAF, NRAS, and TERT promoter mutation in thyroid nodules at Dharmais Cancer Hospital.

Methods:

We performed a prospective diagnostic study involving 50 patients with thyroid nodules who needed surgery between September 2013 and August 2014. Mutational hotspots in BRAF exon 15, NRAS exon 3, and TERT promoter region were analyzed by Sanger sequencing from FNAB specimens. Cytology and molecular data were compared to histopathology results.

Results:

Of the 50 cases included in the analysis, 39 cases (78%) were thyroid malignancies. Mutations of BRAF, NRAS, and TERT promoter were detected in 31% (12/39), 18% (7/39), and 13% (5/39) cases, respectively. BRAF and NRAS mutations were found mutually exclusive, while all of TERT promoter mutation was found coexistent either with BRAF (40%) or NRAS (60%). The combination of FNAB cytology and molecular testing resulted in 69% sensitivity, 100% specificity, 100% positive predictive value, 48% negative predictive value, and 76% accuracy.

Conclusion:

Molecular testing of BRAF, NRAS, and TERT mutations improve the sensitivity of thyroid FNAB and is beneficial for more definitive treatment in selective cases. However, the NPV is relatively low to avoid the need for diagnostic surgery. Therefore, further studies to identify more sensitive methods and more comprehensive molecular markers in the diagnosis of thyroid nodules are needed.

Thyroid Cancer Incidence in Bulgaria before and after the Introduction of Universal Salt Iodization: An Analysis of the National Cancer Registry Data

Background:

Thyroid cancer is the most common malignancy of the endocrine system and it has become the fastest growing cancer among women. The suspected risk factors include increased exposure to ionizing radiation during childhood, environmental pollutants, possible iodine deficiency, and excessive iodine exposure.

Aims:

To analyze the thyroid cancer incidence between 1980 and 2013 in Bulgaria and to determine the incidence rate before and after the introduction of universal salt iodization in 1994 in regions with different iodine deficiency levels.

Study Design:

Retrospective cohort.

Methods:

The study was a retrospective analysis of the total number of thyroid cancer cases with all histological types in Bulgaria (thyroid cancer, ICD10 code C73), diagnosed between 01/01/1980 and 31/12/2013, and retrieved from the anonymous cancer registry database of the Bulgarian National Cancer Registry. Age-standardized rates of thyroid cancer per 100,000 persons were calculated for each year of the periods mentioned below by sex and age, utilizing the WHO world reference populations with a special statistical module of the Bulgarian National Cancer Registry’s software CancerRegBG, 2011. Incidence rates were reported by age, sex, and period of diagnosis (1980-86, 1987-93, 1994-99, 2000-2006, 2007-2013). Trends among males and females were analyzed separately, as well as by age category: 0-19, 20-44, 45-64, and 65+. Annual percentage changes of age-standardized incidence rates were analyzed by Joinpoint regression to determine trends using the Joinpoint statistical software SEER* Stat Software, Version 4.1.1, 2014.

Results:

The age-standardized rates of thyroid cancer in Bulgaria has been increasing since 1990, being higher among women compared to men (4.68 vs 2.81). The highest age-standardized rates of thyroid cancer was observed in women in the 2007-2013 period. The only significant joinpoint was recorded in 1990 for females and in 1991 for males. The highest incidence rates was in the Smolyan district, a region with historically existing iodine deficiency and relatively high post-Chernobyl radiation exposure.

Conclusion:

Our results showed that, in different regions, the age-standardized thyroid cancer rates between endemic and non-endemic differ greatly depending on the radiation dose from the Chernobyl accident. The role of iodine intake in thyroid cancer remains uncertain, but iodine deficiency could be a contributing factor to the increased risk of thyroid cancer.

Thyroid Cancer Incidence in Bulgaria before and after the Introduction of Universal Salt Iodization: An Analysis of the National Cancer Registry Data

Background

Thyroid cancer is the most common malignancy of the endocrine system and it has become the fastest growing cancer among women. The suspected risk factors include increased exposure to ionizing radiation during childhood, environmental pollutants, possible iodine deficiency, and excessive iodine exposure.

Aims

To analyze the thyroid cancer incidence between 1980 and 2013 in Bulgaria and to determine the incidence rate before and after the introduction of universal salt iodization in 1994 in regions with different iodine deficiency levels.

Study Design

Retrospective cohort.

Methods

The study was a retrospective analysis of the total number of thyroid cancer cases with all histological types in Bulgaria (thyroid cancer, ICD10 code C73), diagnosed between 01/01/1980 and 31/12/2013, and retrieved from the anonymous cancer registry database of the Bulgarian National Cancer Registry. Age-standardized rates of thyroid cancer per 100,000 persons were calculated for each year of the periods mentioned below by sex and age, utilizing the WHO world reference populations with a special statistical module of the Bulgarian National Cancer Registry’s software CancerRegBG, 2011. Incidence rates were reported by age, sex, and period of diagnosis (1980-86, 1987-93, 1994-99, 2000-2006, 2007-2013). Trends among males and females were analyzed separately, as well as by age category: 0-19, 20-44, 45-64, and 65+. Annual percentage changes of age-standardized incidence rates were analyzed by Joinpoint regression to determine trends using the Joinpoint statistical software SEER* Stat Software, Version 4.1.1, 2014.

Results

The age-standardized rates of thyroid cancer in Bulgaria has been increasing since 1990, being higher among women compared to men (4.68 vs 2.81). The highest age-standardized rates of thyroid cancer was observed in women in the 2007-2013 period. The only significant joinpoint was recorded in 1990 for females and in 1991 for males. The highest incidence rates was in the Smolyan district, a region with historically existing iodine deficiency and relatively high post-Chernobyl radiation exposure.

Conclusion

Our results showed that, in different regions, the age-standardized thyroid cancer rates between endemic and non-endemic differ greatly depending on the radiation dose from the Chernobyl accident. The role of iodine intake in thyroid cancer remains uncertain, but iodine deficiency could be a contributing factor to the increased risk of thyroid cancer.

Mendelian randomization supports a causative effect of TSH on thyroid carcinoma

Evidence from observational studies suggest a positive association between serum thyroid-stimulating hormone (TSH) levels and differentiated thyroid carcinoma. However, the cause-effect relationship is poorly understood and these studies are susceptible to bias and confounding. This study aimed to investigate the causal role of TSH in both benign thyroid nodules and thyroid cancer in up to 451,025 UK Biobank participants, using a genetic technique, known as Mendelian randomization (MR). Hospital Episode Statistics and Cancer Registry databases were used to identify 462 patients with differentiated thyroid carcinoma and 2031 patients with benign nodular thyroid disease. MR methods using genetic variants associated with serum TSH were used to test causal relationships between TSH and the two disease outcomes. Mendelian randomization provided evidence of a causal link between TSH and both thyroid cancer and benign nodular thyroid disease. Two-sample MR suggested that a 1 s.d. higher genetically instrumented TSH (approximately 0.8 mIU/L) resulted in 4.96-fold higher odds of benign nodular disease (95% CI 2.46-9.99) and 2.00-fold higher odds of thyroid cancer (95% CI 1.09-3.70). Our results thus support a causal role for TSH in both benign nodular thyroid disease and thyroid cancer.

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.

Changes in the Demographic and Clinicopathological Characteristics of Thyroid Cancer: A Population-Based Investigation in Algeria, 1993-2013

Over the last three decades, the incidence of thyroid cancer has increased worldwide. The reasons for this increase remain controversial. In Algeria, however, to date, information on thyroid cancer has been limited to a hospital-based case series. We analyzed data from a population-based cohort study in Oran District, Algeria, to describe demographic and clinicopathological characteristics of patients diagnosed with thyroid cancer between 1993 and 2013. Medical records and pathology reports of thyroid cancer patients who had surgery were reviewed. Changes in demographic and clinicopathological features over the 21-year period are described. During the study period, thyroid cancer was diagnosed in 1248 women (86.5%, mean age 43.7 ± 15.2 years) and 195 men (23.4%, mean age 48.1 ± 15.9 years). Most cases (83.1% for women and 69.8% for men) sought a diagnosis following a self-neck check. The most common histologic types were papillary (58.3%), follicular (29.7%), anaplastic (4.1%), and medullary (0.8%) carcinomas. The incidence of papillary carcinomas significantly increased (p < 0.001) while the incidence of other histologic types significantly decreased over time. Tumor size overall significantly decreased (p < 0.001) while the frequency of small (≤20 mm) and larger (>20 mm) carcinomas significantly increased (p < 0.05). The frequency of thyroid cancers with capsular effractions and angioinvasions also decreased over time. Thyroid cancer incidence in Algeria has increased substantially in line with international trends with changes in clinical practice being a possible contributing factor. However, the increasing papillary-to-follicular cancer ratio may be due to changes in iodine nutrition status in Algeria. Further research, including exploration of biological and molecular features of thyroid cancer, will enable a better understanding of risk factors and etiopathogenetic mechanisms.

Diagnosis and Management of Hypothyroidism in Gulf Cooperation Council (GCC) Countries

Hypothyroidism is one of the most common chronic endocrine conditions. However, as symptoms of hypothyroidism are non-specific, up to 60% of those with thyroid dysfunction are unaware of their condition. Left untreated, hypothyroidism may contribute to other chronic health conditions. In the Arabian Gulf States, hypothyroidism is thought to be common, but is underdiagnosed, and management approaches vary. An advisory board of leading Saudi endocrinologists and policy advisers was convened to discuss and formulate recommendations for the diagnosis and management of hypothyroidism in Saudi Arabia based on their clinical expertise. The final document was shared with leading endocrinologists from the other Gulf  Cooperation Council (GCC) and aconsensus report was generated and summerized in this article. While there is no consensus regarding population screening of hypothyroidism, current recommendations suggest screening patients with risk factors, including those with a history of head or neck irradiation, a family history of thyroid disease or pharmacological treatment that may affect thyroid function. Evidence from a cross-sectional study in Saudi Arabia suggests screening the elderly (> 60 years), at least in the primary care setting. In Saudi Arabia, the incidence of congenital hypothyroidism is approximately 1 in every 3450 newborns. Saudi nationwide population prevalence data are lacking, but a single-centre study estimated that the prevalence of subclinical hypothyroidism in the primary care setting was 10%. Prevalence rates were higher in other cross-sectional studies exclusively in women (13-35%). The recommendations included in this  article aim to streamline the diagnosis and clinical management of hypothyroidism in the GCC, especially in the primary care setting, with the intention of improving treatment outcomes. Further study on the incidence, prevalence and risk factors for, and clinical features of, hypothyroidism in the GCC countries is required.

Thyroid-Gut-Axis: How Does the Microbiota Influence Thyroid Function?

A healthy gut microbiota not only has beneficial effects on the activity of the immune system, but also on thyroid function. Thyroid and intestinal diseases prevalently coexist-Hashimoto's thyroiditis (HT) and Graves' disease (GD) are the most common autoimmune thyroid diseases (AITD) and often co-occur with Celiac Disease (CD) and Non-celiac wheat sensitivity (NCWS). This can be explained by the damaged intestinal barrier and the following increase of intestinal permeability, allowing antigens to pass more easily and activate the immune system or cross-react with extraintestinal tissues, respectively. Dysbiosis has not only been found in AITDs, but has also been reported in thyroid carcinoma, in which an increased number of carcinogenic and inflammatory bacterial strains were observed. Additionally, the composition of the gut microbiota has an influence on the availability of essential micronutrients for the thyroid gland. Iodine, iron, and copper are crucial for thyroid hormone synthesis, selenium and zinc are needed for converting T4 to T3, and vitamin D assists in regulating the immune response. Those micronutrients are often found to be deficient in AITDs, resulting in malfunctioning of the thyroid. Bariatric surgery can lead to an inadequate absorption of these nutrients and further implicates changes in thyroid stimulating hormone (TSH) and T3 levels. Supplementation of probiotics showed beneficial effects on thyroid hormones and thyroid function in general. A literature research was performed to examine the interplay between gut microbiota and thyroid disorders that should be considered when treating patients suffering from thyroid diseases. Multifactorial therapeutic and preventive management strategies could be established and more specifically adjusted to patients, depending on their gut bacteria composition. Future well-powered human studies are warranted to evaluate the impact of alterations in gut microbiota on thyroid function and diseases.

Long-Term Declines of Thyroid Cancer Mortality: An International Age-Period-Cohort Analysis

Background: Thyroid cancer (TC) incidence rates have been increasing in many countries, predominantly due to overdiagnosis. It is, however, not yet clear whether a true increase in exposure to risk factors might have also contributed to the TC epidemic. We assessed the TC mortality trends, which should not be affected by overdiagnosis, to disentangle the specific contribution of period and cohort effects. Methods: We analyzed long-term mortality data in 24 countries from 5 continents using age-period-cohort (APC) models. Nonidentifiability of the APC models was circumvented by integrating evidence of a consistent relationship between age and TC mortality, allowing to estimate period and cohort linear effects. Results: Substantial heterogeneity existed in the historical TC mortality rates across countries, but long-term rates declined over time in most of the countries, converging around a value of 0.5/100,000. The shape of the age-specific curves was consistently similar across countries and periods, resembling straight lines on the log-log scale, with the slopes ranging between 4.0 and 6.0. Both period and cohort effects showed long-term declines in most countries for both genders. In some countries, such as the United States, Canada, and Australia, substantial long-term declines by period were visible until the 1980s and 1990s, but then stabilized or increased slightly. Declining cohort effects were also seen in almost all countries, and were particularly pronounced in women from Switzerland, whereas stable cohort effects were recorded in South Africa. Although there were some indications of possible increasing risks of deaths among the youngest generations in some countries for both men and women, changes are too recent to be treated as unequivocal and estimates suffered from large statistical variability due to small numbers of deaths. Conclusions: Global long-term declines in TC mortality have been accompanied by downward trends in both period and cohort effects. Our results suggest lack of evidence of a possible major contribution of "real" risk factors in TC mortality, and indirectly confirm the main role of overdiagnosis in the epidemic of TC incidence.

Thyroid cancer risk factors and Pakistani University students' awareness towards its preventive practice

OBJECTIVES

Thyroid Cancer is one of the rarest cancers but its prevalence has been increasing worldwide for the last couple of decades.

METHODS

The data collection tool was designed to assess knowledge, awareness, perception, and attitude towards preventive practices of thyroid cancer in Pakistani university students. The data were collected over a duration of six months and a total number of 3722 students participated.

RESULTS

The knowledge of risk factors of thyroid cancer was an important parameter of this study. The students who knew all the early signs of thyroid cancer were 28.7%. In this study, the independent variables such as age, gender, demographic location, and financial status were found to be highly significant with knowledge, attitude towards warning signs of cancer, and the perception of students about developing thyroid cancer.

CONCLUSIONS

The participants were found to have poor knowledge about early signs of thyroid cancer. The study participants perception, behavior, and attitude towards preventive practices of thyroid cancer were found inadequate and appropriate measures on a National level should be taken to enhance the knowledge about preventive practices of thyroid cancer. Increasing knowledge and awareness shall help decrease the overall morbidity and mortality linked with thyroid carcinomas and thyroid diseases.

Dietary iodine intake, therapy with radioiodine, and anaplastic thyroid carcinoma

Background Anaplastic thyroid cancer (ATC) is one of the most aggressive tumors. The aim of the study was to determine the correlation between a higher dietary intake of iodine, frequency of ATC and the characteristics of ATC, and to find out how often patients with ATC had a history of radioiodine (RAI) therapy. Patients and methods This retrospective study included 220 patients (152 females, 68 males; mean age 68 years) with ATC who were treated in our country from 1972 to 2017. The salt was iodinated with 10 mg of potassium iodide/ kg before 1999, and with 25 mg of potassium iodide/kg thereafter. The patients were assorted into 15-year periods: 1972-1986, 1987-2001, and 2002-2017. Results The incidence of ATC decreased after a higher iodination of salt (p = 0.04). Patients are nowadays older (p = 0.013) and have less frequent lymph node metastases (p = 0.012). The frequency of distant metastases did not change over time. The median survival of patients in the first, second, and third periods was 3, 4, and 3 months, respectively (p < 0.05). The history of RAI therapy was present in 7.7% of patients. Conclusions The number of patients with a history of RAI therapy did not change statistically over time. The incidence of ATC in Slovenia decreased probably because of higher salt iodination.

Imaging and Imaging-Based Management of Pediatric Thyroid Nodules

Thyroid nodules are less frequent in children than adults. Childhood thyroid nodules carry specific features, including a higher risk of malignancy than nodules in adults, rendering them unique in terms of management. Subsequently, they should be considered a distinct clinical entity with specific imaging recommendations. Initial evaluation requires a thorough workup, including clinical examination, and a detailed personal and familial history to determine the presence of possible risk factors. Laboratory and radiologic evaluation play an integral part in the diagnostic algorithm, with ultrasonography (US) being the first diagnostic test in all patients. US elastography has been recently introduced as an incremental method, reducing the subjectivity of the clinical diagnosis of nodule firmness associated with increased malignancy risk. However, fine-needle aspiration biopsy (FNAB) remains the mainstay in the diagnostic work-up of thyroid nodules and is documented to be best method for differentiating benign from malignant thyroid nodules. In addition, thyroid scintigraphy provides functional imaging information, which has a role both in the diagnostic management of thyroid nodules and during follow up in malignancies. Finally, despite providing additional information in certain clinical scenarios, ¹⁸F-fludeoxyglucose Positron Emission Tomography (¹⁸F-FDG-PET), computed tomography (CT), and magnetic resonance imaging (MRI) imaging are not routinely recommended for the evaluation of patients with newly detected thyroid nodules or in all cases of thyroid cancer. The objective of this review is to summarize the concepts in imaging and imaging-based management of nodular thyroid disease in the pediatric population, acknowledging the unique features that this patient group carries and the specific approach it requires.

Nutritional status and follicular-derived thyroid cancer: An update

The incidence of differentiated thyroid cancer has been increasing in the last decades all over the world. Such a steady growth cannot be entirely attributable to more intensive thyroid nodule screening and more sensitive diagnostic procedures. Several environmental factors have changed with sufficient rapidity in the same time frame and may represent credible candidates for this increase. They include modified iodine intake, lifestyle-associated risk factors, exposure to various toxic compounds, pollutants and xenobiotics, nutritional deficiencies, eating habits and comorbidities. Foremost, nutritional patterns have gained high interest as possible promoters and modifiable risk factors for thyroid cancer in recent years. The aim of this narrative review is to focus on the relationship between thyroid cancer and nutritional factors, dietary habits and obesity. Low iodine intake has been associated to increased risk of thyroid cancer, favoring the development of more aggressive histotypes. Moreover, correction of iodine deficiency can shift thyroid cancer subtypes toward less aggressive forms, without affecting the overall risk for cancer. Actually, evidence regarding the association between selenium and vitamin D deficiency and thyroid cancer is very limited, despite their well-known anti-cancer potentials, and the clinical usefulness of their supplementation is still uncertain in this setting. Albeit the relationship between single foods and thyroid cancer is difficult to examine, fish and iodine-rich foods, vegetables, and fruits might exert protective effects on thyroid cancer risk. Conversely, no clear association has been found for other foods to date. Lastly, a clear association between obesity and the risk of thyroid cancer, with more aggressive behavior, seems to emerge from most studies, likely involving variations in thyroid function and chronic inflammation mediated by cytokines, insulin, leptin and adiponectins. Although no definite association between dietary factors and thyroid cancer has been firmly established so far, some nutritional patterns, together with excessive weight, seem to play a relevant role in thyroid cancer carcinogenesis as well as in its severity and aggressiveness. These effects may play an additive role to the well-established one exerted by environmental carcinogens, such as pollutants and radiation exposure.

Early Diagnosis of Low-Risk Papillary Thyroid Cancer Results Rather in Overtreatment Than a Better Survival

We are witnessing a rapid worldwide increase in the incidence of papillary thyroid carcinoma (PTC) in the last thirty years. Extensive implementation of cancer screening and wide availability of neck ultrasound or other imaging studies is the main reason responsible for this phenomenon. It resulted in a detection of a growing number of clinically asymptomatic PTCs, mainly low-risk tumors, without any beneficial impact on survival. An indolent nature of low-risk PTC, particularly papillary thyroid microcarcinoma (PTMC), and the excellent outcomes raise an ongoing discussion regarding the adequacy of treatment applied. The question of whether PTMC is overtreated or not is currently completed by another, whether PTMC requires any treatment. Current ATA guidelines propose less extensive preoperative diagnostics and, if differentiated thyroid cancer is diagnosed, less aggressive surgical approach and limit indications for postoperative radioiodine therapy. However, in intrathyroidal PTMCs in the absence of lymph node or distant metastases, active surveillance may constitute alternative management with a low progression rate of 1%-5% and without any increase in the risk of poorer outcomes related to delayed surgery in patients, in whom it was necessary. This review summarizes the current knowledge and future perspectives of active surveillance in low-risk PTC.

Review of Factors Contributing to Nodular Goiter and Thyroid Carcinoma

There is an increased incidence of thyroid nodules and cancer. In this article, the reasons for this increase are evaluated and discussed. The factors causing increases in the incidence of nodules are the same as those causing increases in thyroid cancer. There are publications from all over the world regarding the rising incidence of thyroid cancer; it is especially associated with papillary cancer. The literature was reviewed and evaluated with regard to this significant phenomenon. Thyroid-stimulating hormone (TSH) is the main mitotic factor. Any agent that elevates TSH will stimulate nodule formation. Therefore, the incidence of thyroid nodules is high in endemic goiter regions due to iodine deficiency. This paper has described many of the factors causing this higher incidence. Of note, metabolic syndrome and insulin resistance are important factors associated with the increased incidence of nodular goiter and papillary thyroid cancer today. However, these data must be confirmed by other studies in the future.

Effect of Iodine treatments on Ocimum basilicum L.: Biofortification, phenolics production and essential oil composition

Iodine biofortification has been gaining interest in recent years as a sustainable and innovative approach to eradicate iodine deficiency disorders. Studying the impact of iodine biofortification on plant phenotype, biochemical and physiological parameters is crucial to leverage the expertise and best practices for the agro-food industry and human health. The aim of this study was to evaluate iodine biofortification on the main quantitative and qualitative traits of basil (Ocimum basilicum L.) plants cultivated both in open field and in growth chamber. The impact of KI and KIO3 treatments was evaluated on biomass production, as well as on the synthesis of phenolic compounds, especially rosmarinic acid and other caffeic acid derivatives, and on the essential oil (EO) composition. These compounds are typically accumulated in basil leaves and strongly contribute to the plant nutraceutical value and aroma. In open field, the use of increasing concentrations of both iodine salts gradually enhanced iodine accumulation in leaves, also determining an increase of the antioxidant power, total phenolics, rosmarinic acid and cinnamic acid accumulation. The composition of EO was only slightly affected by the treatments, as all the samples were characterized by a linalool chemotype and a minor alteration in their relative content was observed. A growth chamber experiment was performed to test EO variation in controlled conditions, broadening the range of iodine concentrations. In this case, plant chemotype was significantly affected by the treatments and large EO variability was observed, suggesting that iodine form and concentration can potentially influence the EO composition but that in open field this effect is overcome by environmental factors.

Phytoestrogens and Thyroid Cancer Risk: A Population-Based Case-Control Study in Connecticut

BACKGROUND

Very few previous studies have examined the relationship between thyroid cancer risk and intake of phytoestrogens (PE); furthermore, these studies have reached inconsistent results.

METHODS

We analyzed data from a population-based case-control study in Connecticut from 2010 to 2011, including 387 histologically confirmed thyroid cancer cases and 433 population-based controls, with compound data available concerning specific PEs. Multivariate unconditional logistic regression models were used to estimate the associations between specific PEs and the risk of thyroid cancer, adjusting for potential confounders.

RESULTS

An elevated risk of thyroid cancer was associated with moderate to high levels of coumestrol intake [OR = 2.48, 95% confidence interval (CI), 1.39-4.43 for 40-80 μg/day; OR = 2.41, 95% CI, 1.32-4.40 for 80-130 μg/day; and OR = 2.38, 95% CI, 1.26-4.50 for >200 μg/day compared with <40 μg/day], and the main elevation in risk appeared among microcarcinomas (≤1 cm). A decreased risk of papillary macrocarcinomas (>1 cm; OR = 0.26, 95% CI, 0.08-0.85 for 1,860-3,110 μg/day compared with <760 μg/day) was associated with moderate genistein intake among women.

CONCLUSIONS

Our study suggests that high coumestrol intake increases the risk of thyroid cancer, especially microcarcinomas, whereas moderate amounts of genistein intake appear to be protective for females with thyroid macrocarcinomas.

IMPACT

The study highlights the importance of distinguishing between microcarcinomas and macrocarcinomas in future research on the etiology of thyroid cancer.

Attributable risk fraction of four lifestyle risk factors of thyroid cancer: a meta-analysis

Background

Lifestyle risk factors such as obesity, overweight, smoking and radiation exposure related to thyroid cancer. This study estimated the amount of excess risk that attributed to risk factors.

Methods

Major electronic databases were searched until February 2016. Epidemiological studies addressing the association between lifestyle risk factors and thyroid cancer were enrolled. The results were expressed as ARF with 95% confidence intervals (CIs) using a random-effects-model.

Results

We identified a total of 13 321 references and included 17 studies. The excess risk of thyroid cancer attributable to radiation exposure was 14% (95% CI: 5%, 23%; eight studies, I2 = 88.7%), to obesity was 13% (95% CI: 5%, 21%; four studies, I2 = 68.7%), to overweight was 10% (95% CI: 2%, 17%; four studies, I2 = 4.1%) and to smoking was -13% (95% CI: -33%, 6%; five studies, I2 = 30.6%). So obesity, overweight and radiation exposure are significantly associated with increased thyroid cancer risk and smoking has a protective effect on thyroid cancer but not significant.

Conclusion

A significant amount of the incidence of thyroid cancer is attributable to lifestyle risk factors. Since these factors are entirely preventable, so it is necessary to reduce factors that are associated with increased thyroid cancer risk and proper education to the community. Thus weight loss and protection against radiation can effectively reduce the incidence rate of thyroid cancer but smoking can have a protective effect.

Does relatively low iodine intake contribute to thyroid cancer? An ecological comparison of epidemiology

Research on the relationship between iodine intake and thyroid cancer (TC) risk is limited, and the findings are inconclusive. The objective of this study was to provide emerging evidence for the association between iodine intake and TC risk in a Chinese population.An ecological study of epidemiology is used to compare the iodine intake among populations with different TC incidence in Zhoushan, China. Incidence rates of TC were investigated and compared among four counties of the Zhoushan Islands from 2014 to 2018. Iodized salt consumption rate and the level of urinary iodine concentration (UIC) were analyzed for pupils and pregnant women from four counties.During 2014 to 2018, a total of 2495 new cases of TC were diagnosed in Zhoushan Islands. The mean crude incidence rate of TC was 51.29 per 100,000 inhabitants, and the standardized (world population) incidence rate (SIR) was 31.34 per 100,000 population. Incidence rates (SIR and crude incidence rates) were significantly higher in women than in men (χ test, P < .05). Both male and female, the incidence of TC in Daishan County is higher than the other three counties of Zhoushan. Iodized salt consumption rate and median UIC in pupils and pregnant women in Daishan County was significantly lower than the other three counties (χ test and Kruskal-Wallis test, all P < .05). The population with high TC incidence has a lower iodized salt consumption and a lower level of UIC compare with the relative low TC incidence populations.The low consumption of iodized salt with mild iodine deficiency may contribute to explain the exceptionally high incidence of TC in Daishan County. Further subtle designed studies are needed to provide additional insights into the epidemiology and etiology of TC and help identify the safe limit of iodine intake for prevention.

Thyroid Cancer in the Pediatric Population

Thyroid cancer is rare in the pediatric population, but thyroid carcinomas occurring in children carry a unique set of clinical, pathologic, and molecular characteristics. In comparison to adults, children more often present with aggressive, advanced stage disease. This is at least in part due to the underlying biologic and molecular differences between pediatric and adult thyroid cancer. Specifically, papillary thyroid carcinoma (which accounts for approximately 90% of pediatric thyroid cancer) has a high rate of gene fusions which influence the histologic subtypes encountered in pediatric thyroid tumors, are associated with more extensive extrathyroidal disease, and offer unique options for targeted medical therapies. Differences are also seen in pediatric follicular thyroid cancer, although there are few studies of non-papillary pediatric thyroid tumors published in the literature due to their rarity, and in medullary carcinoma, which is most frequently diagnosed in the pediatric population in the setting of prophylactic thyroidectomies for known multiple endocrine neoplasia syndromes. The overall shift in the spectrum of histotypes and underlying molecular alterations common in pediatric thyroid cancer is important to recognize as it may directly influence diagnostic test selection and therapeutic recommendations.

Exposure to Polybrominated Diphenyl Ethers and a Polybrominated Biphenyl and Risk of Thyroid Cancer in Women: Single and Multi-Pollutant Approaches

BACKGROUND

Thyroid cancer incidence is the most rapidly increasing malignancy; rates are three times higher in women than men. Thyroid hormone-disrupting flame-retardant chemicals, including polybrominated diphenyl ethers (PBDE) and polybrominated biphenyls (PBB), may contribute to this trend.

METHODS

We investigated the relationship between PBDE/PBB exposure and papillary thyroid cancer (PTC) in 250 incident female papillary thyroid cancer cases and 250 female controls frequency-matched on age. Interviews and postdiagnostic serum samples were collected from 2010 to 2013. Serum samples were analyzed for 11 congeners. We calculated ORs and 95% confidence intervals (95% CI) using single-pollutant logistic regression models for continuous and categorical lipid-adjusted serum concentrations of PBDE/PBB, adjusted for age, alcohol consumption, and education. We applied three multi-pollutant approaches [standard multipollutant regression models, hierarchical Bayesian logistic regression modeling (HBLR), principal components analysis (PCA)] to investigate associations with PBDE/PBB mixtures.

RESULTS

In single-pollutant models, a decreased risk was observed at the highest (>90th percentile) versus lowest (<median) category of BDE-209 concentrations (OR, 0.47; 95% CI, 0.23-0.98); an elevated PTC risk was observed at the highest versus lowest category of BB-153 concentrations (OR, 1.81; 95% CI, 0.96-3.39). In standard multi-pollutant models, an interquartile range increase in BDE-100 concentrations was associated with increased PTC risk (OR, 1.18; 95% CI, 1.01-1.38). HBLR and PCA yielded no statistically significant results.

CONCLUSIONS

Our results using single- and multi-pollutant modeling do not generally support a positive association with PBDE/PBB and PTC risk.

IMPACT

Prospective studies with more advanced statistical approaches to analyze mixtures and populations with higher exposures could reveal new insights.

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.

High iodine intake and central lymph node metastasis risk of papillary thyroid cancer

The relationship between iodine intake and clinicopathologic characteristics of papillary thyroid cancer (PTC) is unclear. We aim to investigate the relationship between iodine intake and central lymph node metastasis (CLNM) of PTC. A total of 4040 consecutive patients with PTC receiving thyroidectomy and central lymph node dissection were enrolled from 2013 to 2018. Pathological features of tumors and urinary iodine concentration (UIC) were recorded. Multivariate analysis was performed to investigate the association between iodine intake and CLNM of PTC. More than adequate (UIC: 200.0-299.9 μg/L) and excessive iodine intake (UIC ≥ 300.0 μg/L) were present in 1741 cases (43.09%). Iodine deficiency (UIC ≤ 99.9 μg/L) was inversely associated with female PTC risk only with OR (95% CI): 0.48 (0.29-0.80) relative to adequate iodine intake (UIC: 100.0-199.9 μg/L). However, more than adequate and excessive iodine intake was not associated with PTC risk among the general population and patients with thyroid nodules. In addition, high iodine intake was not associated CLNM risk of PTC. After defining CLNM as metastatic lymph nodes ≥ 2, excessive iodine intake was marginally associated with CLNM among female PTC patients with OR (95% CI): 1.25 (0.99-1.57) by multivariate analysis. Additionally, excessive iodine intake was marginally associated with larger tumor size and capsular invasion. Furthermore, we found that female PTC patients were more closely linked with iodine intake than male ones. In conclusion, high iodine intake appears not to be an initiator, but may be a weak promoter for female PTC progression, which needs further validation.

Increased Incidence of Thyroid Cancer among World Trade Center First Responders: A Descriptive Epidemiological Assessment

An increased incidence of thyroid cancer among 9/11 rescue workers has been reported, the etiology of which remains unclear but which may, at least partly, be the result of the increased medical surveillance this group undergoes. This study aimed to investigate thyroid cancer in World Trade Center (WTC) responders by looking at the demographic data and questionnaire responses of thyroid cancer cases from the Mount Sinai WTC Health Program (WTCHP). WTCHP thyroid cancer tumors were of a similar size (p = 0.4), and were diagnosed at a similar age (p = 0.2) compared to a subset of thyroid cancer cases treated at Mount Sinai without WTC exposure. These results do not support the surveillance bias hypothesis, under which smaller tumors are expected to be diagnosed at earlier ages. WTCHP thyroid cancer cases also reported a past history of radiation exposure and a family history of thyroid conditions at lower rates than expected, with higher than expected rates of previous cancer diagnoses, family histories of other cancers, and high Body Mass Indexes (BMIs). Further research is needed to better understand the underlying risk factors that may play a role in the development of thyroid cancer in this group.

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.

Fluoride Exposure Induces Inhibition of Sodium/Iodide Symporter (NIS) Contributing to Impaired Iodine Absorption and Iodine Deficiency: Molecular Mechanisms of Inhibition and Implications for Public Health

The sodium iodide symporter (NIS) is the plasma membrane glycoprotein that mediates active iodide transport in the thyroid and other tissues, such as the salivary, gastric mucosa, rectal mucosa, bronchial mucosa, placenta and mammary glands. In the thyroid, NIS mediates the uptake and accumulation of iodine and its activity is crucial for the development of the central nervous system and disease prevention. Since the discovery of NIS in 1996, research has further shown that NIS functionality and iodine transport is dependent on the activity of the sodium potassium activated adenosine 5'-triphosphatase pump (Na+, K+-ATPase). In this article, I review the molecular mechanisms by which F inhibits NIS expression and functionality which in turn contributes to impaired iodide absorption, diminished iodide-concentrating ability and iodine deficiency disorders. I discuss how NIS expression and activity is inhibited by thyroglobulin (Tg), tumour necrosis factor alpha (TNF-α), transforming growth factor beta 1 (TGF-β1), interleukin 6 (IL-6) and Interleukin 1 beta (IL-1β), interferon-γ (IFN-γ), insulin like growth factor 1 (IGF-1) and phosphoinositide 3-kinase (PI3K) and how fluoride upregulates expression and activity of these biomarkers. I further describe the crucial role of prolactin and megalin in regulation of NIS expression and iodine homeostasis and the effect of fluoride in down regulating prolactin and megalin expression. Among many other issues, I discuss the potential conflict between public health policies such as water fluoridation and its contribution to iodine deficiency, neurodevelopmental and pathological disorders. Further studies are warranted to examine these associations.

Excess iodine intake: sources, assessment, and effects on thyroid function

Iodine is essential for thyroid hormone synthesis. High iodine intakes are well tolerated by most healthy individuals, but in some people, excess iodine intakes may precipitate hyperthyroidism, hypothyroidism, goiter, and/or thyroid autoimmunity. Individuals with preexisting thyroid disease or those previously exposed to iodine deficiency may be more susceptible to thyroid disorders due to an increase in iodine intake, in some cases at intakes only slightly above physiological needs. Thyroid dysfunction due to excess iodine intake is usually mild and transient, but iodine-induced hyperthyroidism can be life-threatening in some individuals. At the population level, excess iodine intakes may arise from consumption of overiodized salt, drinking water, animal milk rich in iodine, certain seaweeds, iodine-containing dietary supplements, and from a combination of these sources. The median urinary iodine concentration (UIC) of a population reflects the total iodine intake from all sources and can accurately identify populations with excessive iodine intakes. Our review describes the association between excess iodine intake and thyroid function. We outline potential sources of excess iodine intake and the physiological responses and consequences of excess iodine intakes. We provide guidance on choice of biomarkers to assess iodine intake, with an emphasis on the UIC and thyroglobulin.

High iodine content in local animal milk and risk of exceeding EFSA upper intake level for iodine among Saharawi women

Excessive iodine intake is a major public health problem in the Saharawi refugee camps in Algeria, where animal milk is an important source of iodine. The purpose of this study was to assess the association between iodine concentrations in locally produced animal milk and in animal drinking water and further to assess the risk of exceeding European Food Safety Authority (EFSA) tolerable upper intake level for iodine (600 μg/d) among Saharawi women. In 2009 and 2010, 202 milk samples from goats and sheep and 52 milk samples from camel were collected. Iodine in milk was determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). In addition, iodine in 56 water samples from the general water system and 54 water samples from wells, was determined by modified Sandell-Kolthoff reaction. Animal milk is generally consumed mixed with water. The median (min, max) iodine intake from goat/sheep milk mixed with water in camps with high iodine content in human drinking water was 284 (57, 2889) μg/d and 19% of participants exceeded EFSA upper intake level for iodine. The median (min, max) iodine intake from camel milk mixed with water in all camps was 2100 (210, 11100) and 47% of participants exceeded the EFSA upper intake level. The median (min, max) iodine content in goat/sheep milk from camps with moderate and high iodine content in water was 507 (101, 4791) μg/L and 1612 (487, 9323) μg/L, respectively (p < 0.001). The iodine content in goat/sheep milk was positively associated with iodine content in animal drinking water (regression coefficient, B 5.71, 95% CI 4.03, 7.39). In conclusion, consumption of camel milk and living in camps with high water iodine content increased the risk of exceeding the EFSA upper intake level for iodine. We suggest that purified water for both human and animal consumption should be provided.

A Linkage Between Thyroid and Breast Cancer: A Common Etiology?

Breast and thyroid cancers are two malignancies with highest incidence in women. These cancers often occur metachronously. Women with thyroid cancer are at increased risk for subsequent breast cancer; women with breast cancer have an increased incidence of later development of thyroid cancer, suggesting a common etiology. This bidirectional relationship is reported worldwide; however, the underlying reasons for this co-occurrence are unknown. In this review, we summarize the current epidemiologic evidence and putative mechanisms of these metachronous or synchronous cancers. Key potential causative factors are chemotherapy and radiotherapy of the primary tumor, genetic variants linking the two diseases, hormonal signaling both from the thyroid gland and from estrogens, and lifestyle and environmental factors. There is a critical need for additional epidemiologic studies focused on gender and regional incidence together with molecular investigations on common tumorigenic pathways in these endocrine cancers. Understanding the putative mechanisms will aid in the diagnosis and clinical management of both diseases.

Prevalence of papillary thyroid cancer in subacute thyroiditis patients may be higher than it is presumed: retrospective analysis of 137 patients

Background The association of subacute thyroiditis (SAT) and papillary thyroid carcinoma is a rare finding. In this study, we aimed to investigate the prevalence of differentiated thyroid cancer in a cohort of patients followed with the diagnosis of SAT. Patients and methods We retrospectively screened medical records of Endocrinology and Metabolism outpatient clinic in the past 20 years for patients with SAT. Patients with nodules and suspicious ultrasonography findings who underwent fine needle aspiration biopsy (FNAB) and operated due to malignancy risk were identified. Results We identified 137 (100 females, 37 males) patients with reliable records to confirm the diagnosis of SAT. The mean age of female patients was 41.1 ± 9.1 (range, 20-64) and of male patients was 43.0 ± 9.3 (range, 20-65). One or more FNAB was performed in 23 of the patients (16.8%) at the beginning and/or during the follow-up period when needed. Seven patients with suspicious FNAB findings were operated, and histopathological examination of the nodules confirmed the diagnosis of papillary thyroid carcinoma in 6 patients (4.4%). Conclusions Our observations suggesting a relatively higher prevalence of thyroid cancer in a small series of SAT patients warrant further studies to identify the real frequency of differentiated thyroid cancer and its association with inflammatory pathogenesis of SAT. This finding is compatible with the trend of increased thyroid cancer incidence all over the world. A repeat ultrasonography after resolution of clinical and inflammatory findings, and FNAB should be recommended to all patients with suspicious nodules.

Assessment of thyroid cancer risk in more than 334,000 patients with inflammatory bowel disease: a case-control study and a meta-analysis

BACKGROUND

Potential risk of thyroid cancer in patients with inflammatory bowel disease has not been well investigated. The aim of the study was to reveal the relationship between history of inflammatory bowel disease and risk of thyroid cancer.

METHODS

First, 1392 patients with inflammatory bowel disease and 1392 controls were included in a case-control study. All patients did not receive immunosuppressive therapy. A multivariate logistic regression analysis was adopted to determine the relationship between history of inflammatory bowel disease and risk of thyroid cancer. Second, a literature search was performed and eight articles were collected. Pooled odds ratios with 95% confidence intervals were reported for relevant risk estimates in fixed or random effect model.

RESULTS

In the case-control study, thyroid cancer was more common in patients with inflammatory bowel disease than in controls (P = 0.032). After Bonferroni correction, association of thyroid cancer risk with history of total inflammatory bowel disease or its two subtypes was not found. In the meta-analysis, patients with total inflammatory bowel disease or ulcerative colitis showed an increased risk of thyroid cancer, but patients with Crohn's disease did not. Furthermore, inflammatory bowel disease patients with immunosuppressive therapy showed an increased risk of the cancer, but patients without immunosuppressive therapy did not have this finding.

CONCLUSIONS

Risk of thyroid cancer probably elevates in patients with inflammatory bowel disease. Inflammatory bowel disease (particularly ulcerative colitis) itself and use of immunosuppressant might contribute to the development of the cancer.

Reversibility of Proliferative Thyroid Lesions Induced by Iodine Deficiency in a Laboratory Zebrafish Colony

A laboratory zebrafish colony developed red masses, predominantly under the jaw, in a significant portion of the population. The masses were diagnosed histopathologically as thyroid follicular hyperplasia, adenoma, or carcinoma in accordance with published morphologic criteria. After switching to a higher iodine brand of salt used to maintain a low level of salinity within the water system and a small diet change, the thyroid lesions regressed dramatically. Within 5 months the masses were no longer grossly visible. At the population level, external evaluations and histopathological assessments of whole-body sections document a regression in the prevalence of thyroid neoplasia and hyperplasia to normal thyroid conformation by 11 months after salt change. These findings suggest that a wide range of proliferative thyroid lesions, including neoplasms, in zebrafish may be hormone-dependent, even following lesion development. In addition, these results suggest that zebrafish have an adaptive ability to absorb iodine from water and food, which should be considered in discussions to standardize diets and when describing environmental parameters in publications.

Young age is associated with increased rates of residual and recurrent paediatric differentiated thyroid carcinoma

OBJECTIVE

Differentiated thyroid carcinoma is rare in young children. There are conflicting data as to whether disease in this age group differs from that in adolescents and specifically, if it is more aggressive. Current practice guidelines do not differentiate treatment between these groups, but speculate that differences may exist. We sought to compare clinical features, treatment and outcomes between children (<12 years) and adolescents (12-18 years) with thyroid nodules and thyroid malignancy over a 20-year period.

DESIGN

Retrospective case series at a single tertiary care hospital.

PATIENTS

A total of 177 children 0-18 years of age at the time of diagnosis of a thyroid nodule and/or malignancy between 1992 and 2012.

RESULTS

There was a significantly higher female-to-male ratio in patients 12-18 years with benign and malignant nodules compared to those under 12. There was no difference across age groups with respect to cytology or histology, size, surgical approach or nodal status. Younger patients had a higher lymph node ratio. Younger patients received a higher cumulative dose of radioactive iodine (97.6 mCi/m² ) vs older patients (75.9 mCi/m² ) and had higher rates of pulmonary metastatic disease, although the differences did not achieve significance. Finally, children were less likely than adolescents to achieve a state of undetectable disease and fewer of the younger children remained disease-free.

CONCLUSIONS

Despite comparable apparent initial disease burden and treatment, younger children have poorer outcomes when compared to adolescents, even in the absence of nodal metastases and thus may warrant intensification of primary therapy and/or tumour surveillance.