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

The Potential Role of Virus Infection in the Progression of Thyroid Cancer

Multiple factors have engaged in the progression of thyroid cancer (TC). Recent studies have shown that viral infection can be a critical factor in the pathogenesis of TC. Viruses, such as Epstein-Barr virus (EBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), may play an essential role in the occurrence, development, and even prognosis in TC. This review mainly explored the potential role of viral infection in the progress of TC. The possible mechanisms could be recognizing the host cell, binding to the receptors, affecting oncogenes levels, releasing viral products to shape a beneficial environment, interacting with immune cells to induce immune evasion, and altering the pituitary-thyroid axis. Thus, comprehensive knowledge may provide insights into finding molecular targets for diagnosing and treating virus-related TC.

High Incidence of Thyroid Cancer in Southern Tuscany (Grosseto Province, Italy): Potential Role of Environmental Heavy Metal Pollution

The incidence of thyroid cancer (TC) in Italy is one of the highest in Europe, and the reason for this is unclear. The intra-country heterogeneity of TC incidence suggests the possibility of an overdiagnosis phenomenon, although environmental factors cannot be excluded. The aim of our study is to evaluate the TC incidence trend in southern Tuscany, Italy, an area with particular geological characteristics, where the pollution and subsequent deterioration of various environmental matrices with potentially toxic elements (heavy metals) introduced from either geological or anthropogenic (human activities) sources are documented. The Tuscany cancer registry (ISPRO) provided us with the number of cases and EU standardized incidence rates (IR) of TC patients for all three provinces of southeast Tuscany (Siena, Grosseto, Arezzo) during the period of 2013-2016. In addition, we examined the histological records of 226 TC patients. We observed that the TC incidence rates for both sexes observed in Grosseto Province were significantly higher than those observed in the other two provinces. The increase was mostly due to the papillary (PTC) histotype (92% of cases), which presented aggressive variants in 37% of PTCs and tumor diameters more than 1 cm in 71.3% of cases. We demonstrated a high incidence of TC in Grosseto province, especially among male patients, that could be influenced by the presence of environmental heavy metal pollution.

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.

Thyroid Carcinoma: A Review for 25 Years of Environmental Risk Factors Studies

Environmental factors are established contributors to thyroid carcinomas. Due to their known ability to cause cancer, exposure to several organic and inorganic chemical toxicants and radiation from nuclear weapons, fallout, or medical radiation poses a threat to global public health. Halogenated substances like organochlorines and pesticides can interfere with thyroid function. Like phthalates and bisphenolates, polychlorinated biphenyls and their metabolites, along with polybrominated diethyl ethers, impact thyroid hormones biosynthesis, transport, binding to target organs, and impair thyroid function. A deeper understanding of environmental exposure is crucial for managing and preventing thyroid cancer. This review aims to investigate the relationship between environmental factors and the development of thyroid cancer.

Thyroid Cancer and Pesticide Use in a Central California Agricultural Area: A Case Control Study

OBJECTIVE

To examine environmental factors that influence risk of thyroid cancer.

METHODS

We performed a case-control study utilizing thyroid cancer cases from the California Cancer Registry (1999-2012) and controls sampled in a population-based manner. Study participants were included if they were diagnosed with thyroid cancer, lived in the study area at their time of diagnosis, and were ≥35 years of age. Controls were recruited from the same area and eligible to participate if they were ≥35 years of age and had been living in California for at least 5 years prior to the interview. We examined residential exposure to 29 agricultural use pesticides, known to cause DNA damage in vitro or are known endocrine disruptors. We employed a validated geographic information system-based system to generate exposure estimates for each participant.

RESULTS

Our sample included 2067 cases and 1003 controls. In single pollutant models and within a 20-year exposure period, 10 out of 29 selected pesticides were associated with thyroid cancer, including several of the most applied pesticides in the United States such as paraquat dichloride [odds ratio (OR): 1.46 (95% CI: 1.23, 1.73)], glyphosate [OR: 1.33 (95% CI: 1.12, 1.58)], and oxyfluorfen [OR: 1.21 (95% CI: 1.02, 1.43)]. Risk of thyroid cancer increased proportionately to the total number of pesticides subjects were exposed to 20 years before diagnosis or interview. In all models, paraquat dichloride was associated with thyroid cancer.

CONCLUSIONS

Our study provides first evidence in support of the hypothesis that residential pesticide exposure from agricultural applications is associated with an increased risk of thyroid cancer.

Spatial geochemical differentiation of the iodine-induced health risk and distribution of thyroid cancer among urban and rural population of the Central Russian plain affected by the Chernobyl NPP accident

The main goal was to study the spatial distribution of thyroid cancer (THYC) among the population of urban and rural settlements of four regions of Russia, which were characterized by different contents of stable iodine in soils and exposed to radioactive fallout of ¹³¹I from the Chernobyl NPP. Using GIS technologies, zoning of territories for the deficiency of ¹²⁷I and pollution with ¹³¹I was performed. The resulting risk maps were compared with the THYC distribution. The association between the spatial distribution of the total (natural and man-made) risk assessment and the incidence of THYC at the district level tended to have a higher positive correlation (r = 0.505, p < 0.001, n = 94) compared with the correlation of the latter parameter with a fallout density of ¹³¹I (r = 0.468, p < 0.001). After latent period, the incidence of THYC among residents of urban settlements of the Bryansk region was considerably higher than in rural, the difference increasing with time. The correlation between the assessed total risk and THYC distribution in risk zones was significant and higher in the rural areas than in the urban ones. A tendency for a negative significant correlation (r = - 0.55, p = 0.01) between daily iodine intake (based on the main components of the diet) and THYC cases among the rural population was found. A definite difference in the influence of geochemical environmental factors on the distribution of THYC among urban and rural populations deserves more detailed study to prevent this disease.

Prevalence of Central Compartment Lymph Node Metastases in Papillary Thyroid Micro-Carcinoma: A Retrospective Evaluation of Predictive Preoperative Features

Simple Summary

The present study focused on patients affected by stage pT1a papillary thyroid micro-carcinomas that were treated with surgery and central lymph node dissection. In this study, male sex, low age, and sub-capsular carcinoma localization resulted as independent predictive factors for central lymph node metastases.

Abstract

Papillary thyroid micro-carcinomas are considered relatively indolent carcinomas, often occult and incidental, with good prognosis and favorable outcomes. Despite these findings, central lymph node metastases are common, and are related to a poor prognosis for the patient. We performed a retrospective analysis on patients treated with surgery for stage pT1a papillary thyroid micro-carcinomas. One hundred ninety-five patients were included in the analyses. The presence of central lymph node metastases was identified and studied. A multivariate analysis employing binary logistic regression was used to calculate adjusted odds ratios with 95% confidence intervals of possible central lymph node metastases risk factors. In the performed multivariate analysis, male gender, younger age, and histopathological characteristics, such as a tumor sub-capsular localization, were significantly associated with central lymph node metastases in pT1a patients. Central compartment lymph node metastases are present in a non-negligible number of cases in patients with papillary thyroid micro-carcinoma undergoing surgical resection. Studying these factors could be an effective tool for predicting patients’ central lymph node metastases in papillary thyroid micro-carcinomas, defining a tailored surgical treatment in the future.

Alteration of Trace Elements in Multinodular Goiter, Thyroid Adenoma, and Thyroid Cancer

Modest progress has been made in understanding the role of trace elements as endocrine disruptors. The aim of this study was to examine whether there is a change in the content of trace elements in thyroid disease, as well as whether the ratio of elements could be considered a blood marker for thyroid disease. In addition, this study examined the influence of biological and clinical/pathological parameters on the elemental profile. Blood samples from patients diagnosed with multinodular goiter (MNG), thyroid adenoma (TA), and thyroid cancer (TC) were examined and compared with control samples using chemometric analysis. The concentrations of essential (Mn, Co, Cu, Zn, Se) and toxic elements (Ni, As, Cd, Pb, U) were determined by ICP-MS. This study showed for the first time that the content of Mn, Co, Ni, Cu, Zn, Se, and Pb in pathological blood samples was significantly lower compared to the control, while opposite results were obtained for As, Cd, and U. Based on the classification model, the most important trace metals for discrimination of MNG and TC from the control group (CG) were Co and Zn, while Co, Zn, and Mn influenced the distinction of CG from TA. Moreover, it was found that Cu/Zn and U/Se ratios had significantly increased values in pathological blood samples leading to the possibility of establishing new circulating screening markers. These findings can represent significant translational information since these diseases are widespread and the diagnostic procedure is still difficult in many cases.

Total thyroidectomy versus lobectomy: surgical approach to T1-T2 papillary thyroid cancer

The incidence of papillary thyroid carcinoma, which accounts for 80-90% of all thyroid cancers, has recently been increasing. The current study aimed to compare the oncological and functional outcomes of total thyroidectomy (TT) and thyroid lobectomy (TL). To this end, a retrospective single-centre cohort study involving a tertiary care institution was conducted. Data regarding demographics, clinicopathology and postoperative complications from 586 patients with papillary thyroid cancer treated in a single institution were collected. Cox proportional-hazards models were utilised to determine differences in outcomes stratified according to propensity score. Our data suggested no significant difference in the risk for locoregional recurrence or distant metastasis between TL and TT among patients with pT1-2 pN0 papillary carcinoma. TT plays an important role in improving prognosis among patients with metastatic lymph nodes in the central neck compartment (pN1a) (p = 0.001). Moreover, TT had significantly higher rates of postoperative hypocalcaemia and recurrent laryngeal nerve paralysis compared to TL (p < 0.001 and p = 0.02, respectively).

Heavy Metals in the Environment and Thyroid Cancer

In recent decades, the incidence of thyroid cancer has increased more than most other cancers, paralleling the generalized worldwide increase in metal pollution. This review provides an overview of the evidence supporting a possible causative link between the increase in heavy metals in the environment and thyroid cancer. The major novelty is that human thyroid stem/progenitor cells (thyrospheres) chronically exposed to different metals at slightly increased environmentally relevant concentrations show a biphasic increase in proliferation typical of hormesis. The molecular mechanisms include, for all metals investigated, the activation of the extracellular signal-regulated kinase (ERK1/2) pathway. A metal mixture, at the same concentration of individual metals, was more effective. Under the same conditions, mature thyrocytes were unaffected. Preliminary data with tungsten indicate that, after chronic exposure, additional abnormalities may occur and persist in thyrocytes derived from exposed thyrospheres, leading to a progeny population of transformation-prone thyroid cells. In a rat model predisposed to develop thyroid cancer, long-term exposure to low levels of metals accelerated and worsened histological signs of malignancy in the thyroid. These studies provide new insight on metal toxicity and carcinogenicity occurring in thyroid cells at a low stage of differentiation when chronically exposed to metal concentrations that are slightly increased, albeit still in the "normal" range.

Polymorphisms of IL-4 and IL-4R are associated to some demographic characteristics of differentiated thyroid cancer patients but are not determinants of risk in the Brazilian population

BACKGROUND

IL-4 is known to present abnormal expression in thyroid tumors and SNPs in the IL-4 and its receptor IL-4R genes are associated to risk and mortality of various types of cancer.

METHODS

In order to evaluate their role in differentiated thyroid cancer (DTC), we investigated genetic frequencies of two IL-4 promoter SNPs (rs2070874 C>T, rs2243250 C>T) and four non-synonymous SNPs of the IL-4R gene (rs1805010 A>G, rs1805012 C>T, rs1805013 C>T, rs1801275 A>G) in 300 DTC patients matched to 300 controls. All patients were managed according to current guidelines and followed-up for a period of 12-252 months (69.20 ± 52.70 months).

RESULTS

Although none of the six investigated SNPs showed association with risk of DTC, rs1805010 was associated with age of diagnosis and the SNPs rs1805012 and rs1801275 were associated to gender. Further, in-silico analysis showed that all these three SNPs were able to cause decreased stability of the protein. We were not able to demonstrate any other association to clinical features of aggressiveness or to patients' prognosis.

CONCLUSIONS

These findings indicate that although genetic variants in IL-4 and IL-4R do not influence the risk or outcome of DTC patients, their influence on the behavior of thyroid tumors deserves further investigation.

Trend dynamics of thyroid cancer incidence among China and the U.S. adult population from 1990 to 2017: a joinpoint and age-period-cohort analysis

BACKGROUND

Thyroid cancer (TC) is the most common malignant disease of the endocrine system. Based on the previously published reports, the incidence of TC has been increasing in the past 25 years, and the reason for the increase is not yet clear. The present study aims to reveal the long-term trends and age-period-cohort effects for the incidence of TC in China and the U.S. from 1990 to 2017.

METHODS

We examined the trends of TC incidence and the average annual percentage change (AAPC) of rate using the Joinpoint regression analysis in the two countries, for the different genders (men/women) in the Global Burden of Disease (GBD 2017). We further used an age-period-cohort model to analyze age-period-cohort effects on TC incidence.

RESULTS

The ASIR of China increased markedly with AAPC of 4.5% (95% confidence interval (CI): 4.0, 5.0%) and 1.8% (1.6, 2.0%) for men and women during 1990-2017. The ASIR of the U. S increased by 1.4% (1.0, 1.8%) and 1.3% (0.9, 1.7%) for men and women from 1990 to 2017.TC increased with the age and period. Aging was one of the most influential factors of TC in China. The age effect increased markedly in the U.S. compared with China. The period effect showed an increase in China while that tended to grow steadily during 1990-2017 in the U.S. The cohort effect peaked in 1963-1967 birth cohorts for men and women in China and declined consistently in the birth cohort in the U.S.

CONCLUSION

From 1990 to 2017, due to ionizing radiation and over-diagnosis, age-standardized TC incidence rates in both genders rose in China and the U.S. The standardized incidence rate of women is higher than that of men. It is necessary to provide women with reasonable prevention and protection measures for TC. We need to apply for health services and screening to reduce ionizing radiation.

Appraisal of Metal Imbalances in the Blood of Thyroid Cancer Patients in Comparison with Healthy Subjects

Cancer incidence and mortality rates have been increasing rapidly worldwide. A growing body of evidence revealed that exposure to trace metals is the most important aetiology for development of the cancer. Therefore, present study was intended to evaluate the imbalances in the concentrations of selected metals (Na, K, Ca, Mg, Sr, Li, Fe, Zn, Cu, Co, Mn, Ag, Cd, Cr, Ni and Pb) in the blood of newly diagnosed thyroid cancer patients in comparison with counterpart healthy subjects/controls. Concentrations of the metals were quantified by flame atomic absorption spectrometry by employing nitric acid/perchloric acid-based wet digestion method. Average concentrations of Pb (774.6 μg/dL), Cr (757.9 μg/dL), Cd (472.5 μg/dL) and Ni (360.5 μg/dL) were found to be significantly higher in the blood of cancer patients than controls. Correlation study and multivariate analysis showed strong mutual relationships among Fe-Cd-Ca-Mg-Pb, Co-Sr-Zn, Li-Ag-Na-K and Cu-Ni in the blood of thyroid cancer patients while Na-K-Fe-Co-Pb, Zn-Sr-Cr, Ca-Mg and Li-Ag-Cu-Ni exhibited strong mutual associations in the blood of healthy donors. Significant variations in the trace metal levels were observed with the age, gender, habitat, food habits and smoking habits of both donor groups. Metal levels also exhibited considerable disparities with the stages and types of thyroid cancer. Multivariate analysis of the metal data revealed significantly divergent apportionment of the metals in the blood of cancer patients compared with the healthy group.

Epstein-Barr virus induces morphological and molecular changes in thyroid neoplastic cells

Although the evolution of differentiated thyroid cancer (DTC) is usually indolent, some tumors grow fast, metastasize, and may be fatal. Viruses have been associated with many human tumors, especially the Epstein-Barr virus (EBV), which shows a high viral load in DTC. In order to evaluate the ability of the virus to cause morphological and molecular changes in neoplastic thyroid cell lines TPC-1, BCPAP, and 8505C, a viral adaptation was performed for the analysis of EBV cytopathic effect (CPE), viral kinetics and gene expression analysis of oncogenes KRAS, NRAS, HRAS, and TP53. Comparison of inoculated cells with non-inoculated control cells showed that all tumor cell lines were permissive to the virus. The virus caused CPE in the TPC-1 and 8505C, but not in BCPAP cells. Viral kinetic was similar in both BCPAP and 8505C with a point of eclipse at 24 h post infection. TPC-1 cell line displayed a decreasing growth curve, with highest viral load right after inoculation, which decreased over time. There was hyperexpression of TP53 and NRAS in BCPAP cell (p = 0.012 and p = 0.0344, respectively). The 8505C cell line presented NRAS hyperexpression (p = 0.0255), but lower TP53 expression (p = 0.0274). We concluded that neoplastic thyroid cell lines are permissive to EBV that the virus presents different viral kinetic patterns in different cell lines and produces a CPE on both well-differentiated and undifferentiated thyroid cell lines. We also demonstrated that EBV interferes in oncogene expression in thyroid neoplastic cell lines, suggesting that these effects could be related to different tumor progression patterns.

Immunomodulatory Effects of Vitamin D in Thyroid Diseases

Vitamin D is a secosteroid with a pleiotropic role in multiple physiological processes. Besides the well-known activity on bone homeostasis, recent studies suggested a peculiar role of vitamin D in different non-skeletal pathways, including a key role in the modulation of immune responses. Recent evidences demonstrated that vitamin D acts on innate and adaptative immunity and seems to exert an immunomodulating action on autoimmune diseases and cancers. Several studies demonstrated a relationship between vitamin D deficiency, autoimmune thyroid disorders, and thyroid cancer. This review aims to summarize the evidences on the immunomodulatory effect of vitamin D on thyroid diseases.

Increased Thyroid Cancer Incidence in Volcanic Areas: A Role of Increased Heavy Metals in the Environment?

Thyroid cancer incidence is significantly increased in volcanic areas, where relevant non-anthropogenic pollution with heavy metals is present in the environment. This review will discuss whether chronic lifelong exposure to slightly increased levels of metals can contribute to the increase in thyroid cancer in the residents of a volcanic area. The influence of metals on living cells depends on the physicochemical properties of the metals and their interaction with the target cell metallostasis network, which includes transporters, intracellular binding proteins, and metal-responsive elements. Very little is known about the carcinogenic potential of slightly increased metal levels on the thyroid, which might be more sensitive to mutagenic damage because of its unique biology related to iodine, which is a very reactive and strongly oxidizing agent. Different mechanisms could explain the specific carcinogenic effect of borderline/high environmental levels of metals on the thyroid, including (a) hormesis, the nonlinear response to chemicals causing important biological effects at low concentrations; (b) metal accumulation in the thyroid relative to other tissues; and (c) the specific effects of a mixture of different metals. Recent evidence related to all of these mechanisms is now available, and the data are compatible with a cause–effect relationship between increased metal levels in the environment and an increase in thyroid cancer incidence.

RORγt may Influence the Microenvironment of Thyroid Cancer Predicting Favorable Prognosis

We aimed to investigate the role of RORγt (Retinoic acid-related orphan receptor gamma) in the tumor microenvironment of differentiated thyroid carcinoma. We retrospectively analyzed 56 patients (48 papillary and 8 follicular thyroid carcinomas). Immunohistochemical expression of RORγt was compared to other immune markers previously investigated by our group, clinical and pathological information. All patients presented cytoplasmic expression of RORγt in thyroid tumor cells. Seven (12.5%) patients presented no nuclear expression of RORγt. Positivity was few (up to 10%) in 14 patients; 10 to 50% in 5 patients (8.9%); and more than 50% in 30 patients (53.6%). Nuclear RORγt positivity was associated with absence of distant metastasis at diagnosis (p = 0.013) and the need of less cumulative doses of radioactive iodine (p = 0.039). Patients whose tumors were positive for nuclear RORγt presented higher 10-years relapse-free survival rate than those patients who were negative for RORγt (p = 0.023). We classified the patients according to the clustering of immunological immunohistochemical markers. We were able to distinguish a subset (A) of 38 patients who presented high expression of nuclear RORγt and tended to be scarce in proinflammatory immune markers. Other 16 patients integrated a second subset (B) whose tumor microenvironment accumulated proinflammatory markers and presented low expression of nuclear nuclear RORγt. Distant metastasis at diagnosis were more frequent among patients from cluster B than from cluster A (p = 0.008). Our results reinforce that the expression of RORγt together with other immune markers might help predict the prognosis of patients with thyroid cancer and help individualize clinical management.

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.

Thyroid Cancer: The Quest for Genetic Susceptibility Involving DNA Repair Genes

The incidence of thyroid cancer (TC), particularly well-differentiated forms (DTC), has been rising and remains the highest among endocrine malignancies. Although ionizing radiation (IR) is well established on DTC aetiology, other environmental and genetic factors may also be involved. DNA repair single nucleotide polymorphisms (SNPs) could be among the former, helping in explaining the high incidence. To further clarify the role of DNA repair SNPs in DTC susceptibility, we analyzed 36 SNPs in 27 DNA repair genes in a population of 106 DTCs and corresponding controls with the aim of interpreting joint data from previously studied isolated SNPs in DNA repair genes. Significant associations with DTC susceptibility were observed for XRCC3 rs861539, XPC rs2228001, CCNH rs2230641, MSH6 rs1042821 and ERCC5 rs2227869 and for a haplotype block on chromosome 5q. From 595 SNP-SNP combinations tested and 114 showing relevance, 15 significant SNP combinations (p < 0.01) were detected on paired SNP analysis, most of which involving CCNH rs2230641 and mismatch repair variants. Overall, a gene-dosage effect between the number of risk genotypes and DTC predisposition was observed. In spite of the volume of data presented, new studies are sought to provide an interpretability of the role of SNPs in DNA repair genes and their combinations in DTC susceptibility.

Human exposure to bisphenol AF and diethylhexylphthalate increases susceptibility to develop differentiated thyroid cancer in patients with thyroid nodules

Pollutants represent potential threats to the human health, being ubiquitous in the environment and exerting toxicity even at low doses. This study aims at investigating the role of fifteen multiclass organic pollutants, assumed as markers of environmental pollution, most of which exerting endocrine-disrupting activity, in thyroid cancer development. The increasing incidence of differentiated thyroid cancer (DTC) may be related to the rising production and environmental dissemination of pollutants. Fifty-five patients, twenty-seven with diagnosis of benign thyroid nodules and twenty-eight suffering from differentiated thyroid cancer, were enrolled and the concentration levels of seven bisphenols, two phthalates (i.e. di(2-ethylhexyl) phthalate (DEHP) and its main metabolite, mono-(2-ethyl-hexyl) phthalate) (MEHP)), two chlorobenzenes, (1,4-dichlorobenzene and 1,2,4,5-tetrachlorobenzene), and 3 phenol derivatives (2-chlorophenol, 4- nonylphenol, and triclosan) were determined in their serum by using a validated analytical method based on high performance liquid chromatography with ultraviolet tandem fluorescence detection. A significant relationship was found between malignancy and the detection in the serum of both bisphenol AF and DEHP. Indeed, their presence confers a more than fourteen times higher risk of developing differentiated thyroid cancer. Relationship between these two pollutants and the risk of malignancy was dose-independent and not mediated by higher thyroid stimulating hormone levels. Even if a conclusive evidence cannot still be drawn and larger prospective studies are needed, the exposure to low doses of environmental endocrine-disrupting contaminants can be considered consistent with the development of thyroid cancer.

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.

Role of the Mechanisms of Detection in the Increased Risk of Thyroid Cancer: A Retrospective Cohort Study in an HMO in Buenos Aires

Background

Two hypotheses attempt to explain the increase of thyroid cancer (TC) incidence: overdetection by excessive diagnostic scrutiny and a true increase in new cases brought about by environmental factors. Changes in the mechanism of detection and the risk of incidentally diagnosed TC could result in an increase of TC incidence.

Methods

Retrospective cohort study. We identified incident cases of TC from the pathological reports of patients in a HMO and review of clinical records. The results were analyzed in two periods: 2003-2007 and 2008-2012. Incidence rates expressed per 100,000 person-years (with 95% CI) and relative risk of incidence rates of incidental and nonincidental TC were estimated.

Results

The relative risk of incidentally detecting a thyroid cancer in 2008-2012 compared to 2003-2007 was 6.06 (95%CI 1.84-20.04). Clinical evaluations detected 31 (75.6%) cancers in the period 2003-2007 and 70 (51.8%) cancers in the period 2008-2012 (p<0.007). Although tumor median size was significantly lower in the period 2008-2012 (10 vs. 14 mm, p<0.03), tumors greater than 40 mm (4.3%) were only present in 2008-2012. The female/male ratio decreased between analyzed periods from 8 (3-21) to 4 (3-7).

Conclusions

Our findings partially support the hypothesis of increased incidence due to overdetection but do not explain the changes in the increase of larger tumors and decrease in the female/male ratio, which could be secondary to the influence of unidentified environmental factors.

Mismatch repair single nucleotide polymorphisms and thyroid cancer susceptibility

Thyroid cancer (TC) is the most common endocrine malignancy and its incidence continues to rise worldwide. Ionizing radiation exposure is the best established etiological factor. Heritability is high; however, despite valuable contribution from recent genome-wide association studies, the current understanding of genetic susceptibility to TC remains limited. Several studies suggest that altered function or expression of the DNA mismatch repair (MMR) system may contribute to TC pathogenesis. Therefore, the present study aimed to evaluate the potential role of a panel of MMR single nucleotide polymorphisms (SNPs) on the individual susceptibility to well-differentiated TC (DTC). A case-control study was performed involving 106 DTC patients and 212 age- and gender-matched controls, who were all Caucasian Portuguese. Six SNPs present in distinct MMR genes (MLH1 rs1799977, MSH3 rs26279, MSH4 rs5745325, PMS1 rs5742933, MLH3 rs175080 and MSH6 rs1042821) were genotyped through TaqMan^® assays and genotype-associated risk estimates were calculated. An increased risk was observed in MSH6 rs1042821 variant homozygotes [adjusted odds ratio (OR)=3.42, 95% CI: 1.04-11.24, P=0.04, under the co-dominant model; adjusted OR=3.84, 95% CI: 1.18-12.44, P=0.03, under the recessive model]. The association was especially evident for the follicular histotype and female sex. The association was also apparent when MSH6 was analysed in combination with other MMR SNPs such as MSH3 rs26279. Interestingly, two other SNP combinations, both containing the MSH6 heterozygous genotype, were associated with a risk reduction, suggesting a protective effect for these genotype combinations. These data support the idea that MMR SNPs such as MSH6 rs1042821, alone or in combination, may contribute to DTC susceptibility. This is coherent with the limited evidence available. Nevertheless, further studies are needed to validate these findings and to establish the usefulness of these SNPs as genetic susceptibility biomarkers for DTC so that, in the near future, cancer prevention policies may be optimized under a personalized medicine perspective.

Heavy metals in the volcanic environment and thyroid cancer

In the last two decades thyroid cancer incidence has increased worldwide more than any other cancer. Overdiagnosis of subclinical microcarcinomas has certainly contributed to this increase but many evidences indicate that a true increase, possibly due to environmental factors, has also occurred. Thyroid cancer incidence is markedly increased in volcanic areas. Thus, the volcanic environment is a good model to investigate the possible factors favoring thyroid cancer. In the volcanic area of Mt. Etna in Sicily, as well as in other volcanic areas, a non-anthropogenic pollution with heavy metals has been documented, a consequence of gas, ash and lava emission. Soil, water and atmosphere contamination, via the food chain, biocontaminate the residents as documented by high levels in the urines and the scalp hair compared to individuals living in adjacent non-volcanic areas. Trace amounts of metals are essential nutrients but, at higher concentrations, can be toxic for living cells. Metals can behave both as endocrine disruptors, perturbing the hormonal system, and as carcinogens, promoting malignant transformation. Similarly to other carcinogens, the transforming effect of heavy metals is higher in developing organisms as the fetus (contaminated via the mother) and individuals in early childhood. In the last decades environment metal pollution has greatly increased in industrialized countries. Although still within the "normal" limits for each single metal the hormesis effect (heavy metal activity at very low concentration because of biphasic, non linear cell response) and the possible potentiation effect resulting from the mixture of different metals acting synergistically can explain cell damage at very low concentrations. The effect of metals on the human thyroid is poorly studied: for some heavy metals no data are available. The scarce studies that have been performed mainly focus on metal effect as thyroid endocrine disruptors. The metal concentration in tissues has been rarely measured in the thyroid. Heavy metal accumulation and metabolism in the thyroid or the carcinogenic activity of different doses and different speciation of metals has not been investigated. These studies are now warranted to better understand thyroid biology and heavy metal role in human thyroid carcinogenesis.

Incidence of Cancer in Shenzhen, Guangdong Province during 2001-2015: A Retrospective Population-Based Study

Cancer is a serious public health issue and the leading cause of death around the world. This article aimed to estimate the cancer incidence and the trend in standardized cancer incidence in Shenzhen, Guangdong province, South China during 2001–2015 by analyzing the cancer data of the population-based cancer registry in Shenzhen. Data were collected from the cancer registry in Shenzhen, which was conducted during 2001–2015. In this registry, the crude incidence rates, age-specific incidence rates, age-standardized incidence rates and cumulative incidence rates were calculated in every five years. Trends for standardized incidence rates of cancers were analyzed by using the joinpoint regression analysis. In total, 33,374.3 thousand person-years (17,593.9 thousand for males and 15,780.4 thousand for females) were monitored over this time period. The number of new cancer cases during 2001–2015 was 59,218 (30,144 and 29,074 for males and females, respectively). The crude incidence during 2001–2005 was 136.44 per 100,000 persons, while the age-standardized rates by Chinese standard population (ASR-China) and by world standard population (ASR-world) were 165.13 and 212.48 per 100,000 persons, respectively. The crude incidence during 2006–2010 was 179.01 per 100,000 persons, while the ASR-China and ASR-world were 168.08 and 214.44 per 100,000 persons, respectively. The crude incidence during 2011–2015 was 196.53 per 100,000 persons, while the ASR-China and ASR-world were 171.44 and 219.99 per 100,000 persons, respectively. During 2001 and 2015, the joinpoint regression analysis showed that the ASR-China of cancer had an overall increase of 0.96% per year and 0.84% per year for males and females respectively, although both of these values (males and females) were non-significant increases. The leading cancer types during 2011–2015 were lung, colorectal, thyroid gland, breast, liver, stomach, cervix, nasopharynx, leukemia and lymphoma. For males, the top five common cancers were lung, liver, colorectal, stomach and thyroid gland. For females, the top five common cancers were breast, thyroid gland, lung, colorectal and cervix. The results of this study showed a heavy cancer burden among the population of Shenzhen, China. Future researches of the etiology and prevention of cancers should be planned in order to reduce the incidence associated with cancers in the future.

Intake of Boron, Cadmium, and Molybdenum enhances rat thyroid cell transformation

Background

Epidemiologic data in volcanic areas suggest that environmental factors might be involved in the increase of thyroid cancer (TC) incidence. Recent reports indicate that several heavy metals and metalloids are increased in volcanic areas. This study aims to evaluate the combined effect of three of these elements Boron (B), Cadmium (Cd), and Molybdenum (Mo) - all increased in the volcanic area of Mt. Etna, in Italy - on thyroid tumorigenesis in the rat.

Methods

Female Wistar rats prone to develop thyroid tumors by low-iodine diet and methimazole treatment received ad libitum drinking water supplemented with B, Cd, and Mo at concentrations in the range found in the urine samples of residents of the volcanic area. At 5 and 10 months animals were euthanized, and their thyroid analysed. Statistical analysis was performed with a 2-way unpaired t-test.

Results

No toxic effect of the three elements on the growth of the animals was observed. A significant increase of histological features of transformation was observed in thyroid follicular cells of rats treated with B, Cd, and Mo compared with those of control group. These abnormalities were associated with decreased iodine content in the thyroid.

Conclusions

This study provides the evidence that slightly increased environmental concentrations of B, Cd, and Mo can accelerate the appearance of transformation marks in the thyroid gland of hypothyroid rats.

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.

How do etiological factors can explain the different clinical features of patients with differentiated thyroid cancer and their histopathological findings?

The aim was to retrospectively analyse the clinical-histopathological characteristics of patients with newly diagnosis of differentiated thyroid cancer (DTC) referred to two Italian centres, one in Northern and the other in Southern Italy, between 2000 and 2013. 1081 patients were included and subdivided into two groups: group A (474 patients from Novara) and group B (607 patients from Naples). The group A came from the industrial area of Novara, while the Group B came from the areas around Vesuvius and Campi Flegrei. The two groups were comparable for iodine levels, body mass index, diagnostic timing and clinical procedures. For all patients, demographic and clinical data were collected. No difference was found in gender, whereas the age at diagnosis was later in the group A (group A 53.1 ± 15.16 years, group B 41.9 ± 14.25 years, p < 0.001). In both groups, the most frequent histotype was papillary thyroid cancer (PTC) with prevalence of follicular variant in group A (p < 0.0001) and classical variant in group B (p < 0.0001). Aggressive histological features were mainly seen in group A (bilaterality p < 0.0001, multifocality p < 0.0001 and thyroid capsular invasion p < 0.0001). Microcarcinomas were more frequent in group A (p < 0.0001) but mostly characterized by bilaterality (p < 0.001) and multifocality (p < 0.04). In both groups, tumour-associated thyroiditis showed a significant increase over the years (group A p < 0.05, group B p < 0.04). Environmental factors could justify the differences found in our study. These preliminary data should stimulate the need for an Italian Cancer Registry of DTC in order to allow an epidemiological characterization, allowing the identification of specific etiological factors and an improvement in the management of the disease.

Interleukin 10 expression is related to aggressiveness and poor prognosis of patients with thyroid cancer

Most patients with thyroid cancer will evolve very well with current therapies. However, 10-30% of these patients will present recurrent disease and some of them will eventually die. IL-10 is an anti-inflammatory and immunosuppressive cytokine that can contribute to the immune escape of neoplastic cells. We aimed to investigate IL-10 as a molecular marker to improve the clinical management of patients with thyroid cancer. We retrospectively studied 162 patients with follicular cell-derived thyroid cancer who attended to our institution, including 63 classic papillary thyroid carcinomas, 46 follicular variant of papillary thyroid carcinomas, 11 poorly differentiated thyroid carcinomas and 42 follicular thyroid carcinomas. Patients were treated according to current guidelines and followed-up for 1-150 months. Additionally, we studied 96 samples of non-malignant tissues. We investigated the expression of IL-10 in tumor cells by semiquantitative and quantitative methods. Malignant tissues presented higher positivity (0.773 ± 0.140) than non-malignant samples (0.623 ± 0.190; p < 0.001). Tumors with extrathyroidal invasion at diagnosis presented higher levels of positivity for IL-10 (0.802 ± 0.125) than tumors without extrathyroidal invasion (0.731 ± 0.147; p = 0.004). We observed a positive correlation between tumor size and IL-10 positivity (correlation coefficient = 0.407; p < 0.001). Patients with IL-10 positivity above the median presented lower relapse-free survival rate compared to those patients whose tumors presented IL-10 positivity below the median. We suggest that a simple IL-10 IHC analysis could help selecting patients who would benefit from a more intensive approach.

Increasing incidence of thyroid cancer in the Nordic countries with main focus on Swedish data

BACKGROUND

Radiofrequency radiation in the frequency range 30 kHz-300 GHz was evaluated to be Group 2B, i.e. 'possibly' carcinogenic to humans, by the International Agency for Research on Cancer (IARC) at WHO in May 2011. Among the evaluated devices were mobile and cordless phones, since they emit radiofrequency electromagnetic fields (RF-EMF). In addition to the brain, another organ, the thyroid gland, also receives high exposure. The incidence of thyroid cancer is increasing in many countries, especially the papillary type that is the most radiosensitive type.

METHODS

We used the Swedish Cancer Register to study the incidence of thyroid cancer during 1970-2013 using joinpoint regression analysis.

RESULTS

In women, the incidence increased statistically significantly during the whole study period; average annual percentage change (AAPC) +1.19 % (95 % confidence interval (CI) +0.56, +1.83 %). Two joinpoints were detected, 1979 and 2001, with a high increase of the incidence during the last period 2001-2013 with an annual percentage change (APC) of +5.34 % (95 % CI +3.93, +6.77 %). AAPC for all men during 1970-2013 was +0.77 % (95 % CI -0.03, +1.58 %). One joinpoint was detected in 2005 with a statistically significant increase in incidence during 2005-2013; APC +7.56 % (95 % CI +3.34, +11.96 %). Based on NORDCAN data, there was a statistically significant increase in the incidence of thyroid cancer in the Nordic countries during the same time period. In both women and men a joinpoint was detected in 2006. The incidence increased during 2006-2013 in women; APC +6.16 % (95 % CI +3.94, +8.42 %) and in men; APC +6.84 % (95 % CI +3.69, +10.08 %), thus showing similar results as the Swedish Cancer Register. Analyses based on data from the Cancer Register showed that the increasing trend in Sweden was mainly caused by thyroid cancer of the papillary type.

CONCLUSIONS

We postulate that the whole increase cannot be attributed to better diagnostic procedures. Increasing exposure to ionizing radiation, e.g. medical computed tomography (CT) scans, and to RF-EMF (non-ionizing radiation) should be further studied. The design of our study does not permit conclusions regarding causality.

Role of hemithyroidectomy in differentiated thyroid cancer

PURPOSE OF REVIEW

The incidence of differentiated thyroid cancer (DTC), especially among small tumors, is increasing worldwide, despite the fact that the mortality rate from thyroid cancer remains stable. Total thyroidectomy with or without radioiodine therapy is actually the standard treatment. In the last 2 decades, several studies have shown that lobectomy could be an alternative to total thyroidectomy in low-risk DTC without compromising overall survival. The aim of this article was to assess the role of conservative surgery (hemithyroidectomy) in DTC reviewing the literature data.

RECENT FINDINGS

Recent advances in diagnostic techniques allow treatment to be tailored to patients' needs. The latest consensus guidelines suggest that patients with high-risk tumors should undergo total thyroidectomy, whereas patients with small, low-risk, node-negative DTC may be candidates for conservative surgery. Careful risk evaluation and stratification makes it possible to individualize treatment, avoid overtreatment and guarantee a good long-term prognosis with low recurrence risk. Excellent prognosis of DTC would require large sample sizes and long-term follow-up for prospective trials comparing the outcomes of total thyroidectomy vs. lobectomy; however, there are several remarkable retrospective studies.

SUMMARY

Based on current clinical data, a conservative surgery might be appropriate for patients with low-risk DTC.

Thyroid nodules and thyroid autoimmunity in the context of environmental pollution

Evidence suggests that in most industrialized countries autoimmune disorders, including chronic lymphocytic thyroiditis, are increasing. This increase parallels the one regarding differentiated thyroid cancer, the increment of which is mainly due to the papillary histotype. A number of studies have pointed to an association between chronic lymphocytic thyroiditis and differentiated thyroid cancer. The upward trend of these two thyroid diseases is sustained by certain environmental factors, such as polluting substances acting as endocrine disrupting chemicals. Herein we will review the experimental and clinical literature that highlights the effects of environmental and occupational exposure to polluting chemicals in the development of autoimmune thyroid disease or differentiated thyroid cancer. Stakeholders, starting from policymarkers, should become more sensitive to the consequences for the thyroid resulting from exposure to EDC. Indeed, the economic burden resulting from such consequences has not been quantified thus far.

The changing epidemiology of thyroid cancer: why is incidence increasing?

PURPOSE OF REVIEW

Thyroid cancer incidence is increasing worldwide. Causes are highly debated.

RECENT FINDINGS

Thyroid cancer increase has been associated to socioeconomic status, better access to healthcare and rising use of thyroid imaging. Therefore, the rise could be apparent because of the useless identification of a large reservoir of subclinical papillary lesions that will never affect patient health (overdiagnosis).However, not all epidemiological and clinical data support this hypothesis. The increasing number of large tumors, the increasing thyroid cancer-related mortality in spite of earlier treatment and the changes in thyroid cancer molecular profile suggest a true increase. Recently increased and thyroid-specific environmental carcinogens could be responsible, such as radiation (mostly medical radiation), increased iodine intake and chronic lymphocytic thyroiditis and environmental pollutants such as nitrates, heavy metals and other compounds largely used in the industrialized society. Possible mechanisms await further investigation.

SUMMARY

The increased incidence of thyroid cancer is the likely result of two coexisting processes: increased detection (apparent increase) and increased number of cases (true increase) due to unrecognized thyroid-specific carcinogens.To identify causal factors and to differentiate stationary cancers from those that will progress are major urgent requirements for both clinical and scientific purposes.

Break-apart interphase fluorescence in situ hybridization assay in papillary thyroid carcinoma: on the road to optimizing the cut-off level for RET/PTC rearrangements

OBJECTIVE

Chromosomal rearrangements of the RET proto-oncogene is one of the most common molecular events in papillary thyroid carcinoma (PTC). However, their pathogenic role and clinical significance are still debated. This study aimed to investigate the prevalence of RET/PTC rearrangement in a cohort of BRAF WT PTCs by fluorescence in situ hybridization (FISH) and to search a reliable cut-off level in order to distinguish clonal or non-clonal RET changes.

DESIGN

Forty BRAF WT PTCs were analyzed by FISH for RET rearrangements. As controls, six BRAFV600E mutated PTCs, 13 follicular adenomas (FA), and ten normal thyroid parenchyma were also analyzed.

METHODS

We performed FISH analysis on formalin-fixed, paraffin-embedded tissue using a commercially available RET break-apart probe. A cut-off level equivalent to 10.2% of aberrant cells was accepted as significant. To validate FISH results, we analyzed the study cohort by qRT-PCR.

RESULTS

Split RET signals above the cut-off level were observed in 25% (10/40) of PTCs, harboring a percentage of positive cells ranging from 12 to 50%, and in one spontaneous FA (1/13, 7.7%). Overall, the data obtained by FISH matched well with qRT-PCR results. Challenging findings were observed in five cases showing a frequency of rearrangement very close to the cut-off.

CONCLUSIONS

FISH approach represents a powerful tool to estimate the ratio between broken and non-broken RET tumor cells. Establishing a precise FISH cut-off may be useful in the interpretation of the presence of RET rearrangement, primarily when this strategy is used for cytological evaluation or for targeted therapy.

[Clinical guideline for management of patients with low risk differentiated thyroid carcinoma]

Incidence of thyroid cancer is increasing in Spain and worldwide. Overall thyroid cancer survival is very high, and stratification systems to reliably identify patients with worse prognosis have been developed. However, marked differences exist between the different specialists in clinical management of low-risk patients with thyroid carcinoma. Almost half of all papillary thyroid carcinomas are microcarcinomas, and 90% are tumors < 2 cm that have a particularly good prognosis. However, they are usually treated more aggressively than needed, despite the lack of adequate scientific support. Surgery remains the gold standard treatment for these tumors. However, lobectomy may be adequate in most patients, without the need for total thyroidectomy. Similarly, prophylactic lymph node dissection of the central compartment is not required in most cases. This more conservative approach prevents postoperative complications such as hypoparathyroidism or recurrent laryngeal nerve injury. Postoperative radioiodine remnant ablation and strict suppression of serum thyrotropin, although effective for the more aggressive forms of thyroid cancer, have not been shown to be beneficial for the treatment of low risk patients, and may impair their quality of life. This guideline provides recommendations from the task force on thyroid cancer of the Spanish Society of Endocrinology and Nutrition for adequate management of patients with low-risk thyroid cancer.

Protocol of a thyroid cancer longitudinal study (T-CALOS): a prospective, clinical and epidemiological study in Korea

INTRODUCTION

Thyroid cancer incidence in Korea is the highest in the world and has recently increased steeply. However, factors contributing to this sudden increase have not been fully elucidated, and few studies have explored the postoperative prognosis. The Thyroid Cancer Longitudinal Study (T-CALOS) was initiated with three aims: (1) to identify factors predicting quality of life, recurrence, and incidence of other diseases after thyroid cancer treatments; (2) to investigate environmental exposure to radiation, toxicants and molecular factors in relation to tumour aggressiveness; and (3) to evaluate gene-environment interactions that increase thyroid cancer in comparison with healthy participants from a pool of nationwide population-based healthy examinees.

METHODS AND ANALYSIS

T-CALOS enrols patients with incident thyroid cancer from three general hospitals, Seoul National University Hospital, Seoul National University Bundang Hospital and National Medical Center, Korea. The study is an ongoing project expecting to investigate 5000 patients with thyroid cancer up until 2017. Healthy examinees with a normal thyroid confirmed by sonography have been enrolled at the Healthy Examination Center at Seoul National University Hospital. We are also performing individual matching using two nationwide databases that are open to the public. Follow-up information is obtained at patients' clinical visits and by linkage to the national database. For statistical analysis, we will use conditional logistic regression models and a Cox proportional hazard regression model. A number of stratifications and sensitivity analyses will be performed to confirm the results.

ETHICS AND DISSEMINATION

Based on a large sample size, a prospective study design, comprehensive data collection and biobank, T-CALOS has been independently peer-reviewed and approved by the three hospitals and two funding sources (National Research Foundation of Korea and Korean Foundation for Cancer Research). The results of T-CALOS will be published according to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) criteria.

Time trends and age-period-cohort analyses on incidence rates of thyroid cancer in Shanghai and Hong Kong

Background

Increasing incidence rates of thyroid cancer have been noted worldwide, while the underlying reasons remain unclear.

Methods

Using data from population-based cancer registries, we examined the time trends of thyroid cancer incidence in two largest cities in China, Shanghai and Hong Kong, during the periods 1973–2009 and 1983–2011, respectively. We further performed age-period-cohort analyses to address the possible underlying reasons for the observed temporal trends.

Results

We observed continuous increases in the incidence rates of thyroid cancer in Shanghai and Hong Kong, since the 1980s, in addition to higher incidence rates in the 1970s in both sexes in Shanghai. The age-standardized incidence rate of thyroid cancer increased by 3.1% [95% confidence interval (CI): 1.0%, 5.1%] and 3.8% (95% CI: 1.9%, 5.7%) per year on average, respectively, in Shanghai men and women during the period 1973–2009, while it increased by 2.2% (95% CI: 1.5%, 2.8%) and 2.7% (1.6%, 3.8%) per year on average, respectively, in Hong Kong men and women during the period 1983–2011. We observed global changes in trends across all age groups in similar ways, in addition to varied trends across different generations (birth cohorts).

Conclusions

The increased incidence rates of thyroid cancer in these two Chinese populations during recent decades may be contributable to a combination of the introduction of more sensitive diagnostic techniques and the increasing prevalence of environmental exposures in the populations.