Is residence in areas of endemic goiter a risk factor for thyroid cancer?

Clinicopathological profile and management of thyroid carcinoma: a Sub-Saharan country experience

BACKGROUND

In Sudan, there is limited knowledge on the epidemiology, clinical characteristics and pathological patterns of thyroid cancer. To address this shortcoming, we studied the clinical, pathological and treatment patterns of thyroid cancer at the National Cancer Institute ‒ University of Gezira (NCI-UG), Sudan.

METHODS

We performed a retrospective health facility-based study of patients with thyroid cancer who were treated at NCI-UG from January 2009 to December 2017.

RESULTS

A total of 139 patients with thyroid cancer were identified during the study period. Tumors were more common among women (69%). Goiter was the main presenting symptom (85%). The most common type of thyroid cancer was follicular carcinoma (41%), followed by papillary carcinoma (24%), then anaplastic carcinoma (20%). The mean age of the women was 56.3 years (SD ± 14.7), compared to 52.5 years (SD ± 16.6) for the men. The frequencies of stage I, II, III, and IV were 17%, 22%, 16%, and 45%, respectively. Different types of thyroidectomies were performed in 79% of the cases, lobectomy in 4%, and no surgery in 17%. Only 28% of the cases received radioactive iodine. Palliative chemotherapy and radiotherapy were prescribed to 17% and 37% of the cases, respectively.

CONCLUSION

Thyroid cancer is more prevalent among women and most patients present at later stages. The dominance of follicular type suggests that the majority of this population is iodine-deficient.

High Iodine Nutrition May Be a Risk Factor for Cervical Lymph Node Metastasis in Papillary Thyroid Cancer Patients

PURPOSE

The aim of this study was to retrospectively identify the effect of iodine on the papillary thyroid cancer (PTC) process and investigate the risk clinicopathologic characteristics of cervical lymph node metastasis (CLNM) for achieving a better preventive strategy of PTC.

METHODS

Totally 187 patients with CLNM and 279 without CLNM (NCLNM) were enrolled, and their urinary iodine concentration (UIC) and serum iodine concentration (SIC) were measured. Logistic regressions were used to reveal the effects of iodine nutrition on the CLNM status of PTC.

RESULTS

The levels of thyroid-stimulating hormone (TSH) and thyroglobulin (TG) were higher in the CLNM group than in the NCLNM group. UIC and SIC were positively correlated, and both of them were correlated with TSH, free thyroxine, and TG. The proportions of UIC >300 μg/L and of SIC >90 μg/L were higher in the CLNM than in the NCLNM. Logistic analysis showed that SIC >90 μg/L was an independent predictor for CLNM in PTC. Additionally, age ≥45, female, TG, multifocality, and diameter of cancer invasion >1 cm also affected CLNM status in PTC, and their logistic regression model showed a certain diagnostic accuracy (area under the receiver-operating characteristic curve = 0.72).

CONCLUSIONS

Relatively high iodine nutrition seemed to be a significant risk factor for the occurrence of CLNM in PTC and may promote lymphatic metastasis in PTC.

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.

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.

Case-Control Study of Anaplastic Thyroid Cancer

Aims and background

The aim of the present study was to test some hypothetical risk factors for anaplastic thyroid cancer.

Study design

A case-control study comprised 110 patients with histologically or cytologically verified anaplastic thyroid cancer and 110 hospital controls individually matched with cases by sex, age, place of residence and time of hospitalization. Univariate and multivariate logistic regressions were used for data analysis.

Results

According to the conditional logistic regression analysis, the following factors were significantly and independently related to anaplastic thyroid cancer: history of goiter or thyroid nodules (odds ratio, OR, 37.55; 95% confidence interval, CI, 4.86–290.11), history of residence in endemic goiter area (OR, 2.56; 95% CI, 1.05–6.22), history of previous malignant non-thyroid tumor (OR, 5.51; 95% CI, 1.04–29.25), diabetes mellitus (OR, 4.06; 95% CI, 1.29–12.81) and low educational level (OR, 2.44; 95% CI, 1.17–5.06).

Conclusions

The results are in line with the current knowledge on factors related to thyroid cancer, except for the association between thyroid cancer and diabetes mellitus, which as far as we know has not yet been reported.

Lack of Associations of the MDM4 rs4245739 Polymorphism with Risk of Thyroid Cancer among Iranian-Azeri Patients: a Case-Control Study

Background and Aim:

MDM4, a negative regulator of the p53 tumor suppression pathway, has been demonstrated to be overexpressed in a variety of human cancers. Research has revealed that the rs4245739 A>C polymorphism of MDM4 in the 3’-untranslated region makes it a miR-191 target site, leading to lower MDM4 expression. This study aimed to detect if the rs4245739 single nucleotide polymorphism (SNP) impacts on thyroid cancer (TC) development in Iranian-Azeri patients.

Materials and Method:

Blood samples were taken from 232 healthy controls and 130 TC patients of Iranian-Azeri ethnicity. For genotyping, Tetra-ARMS PCR was performed. SPSS for Windows (version 22.0, IBM SPSS Inc., USA) and the SHEsis online software were used for data analysis.

Results:

Alleles of MDM4 rs4245739 SNP demonstrated no significant different in frequencies between patients and controls (p>0.05). Additionally, genotypes of MDM4 rs4245739 SNP did not increase or decrease TC risk in patients compared with healthy subjects.

Conclusion:

Considering the lack of any observed association between the MDM4 rs4245739 polymorphism and TC, we conclude no significant role in the pathophysiology of the disease.

FOXE1 Polymorphism Interacts with Dietary Iodine Intake in Differentiated Thyroid Cancer Risk in the Cuban Population

BACKGROUND

The incidence of differentiated thyroid cancer (DTC) is low in Cuba, and the contribution of dietary factors to DTC in this population has not been investigated so far. The aim of this study was to evaluate the relationship between dietary iodine intake and DTC with regard to the interaction with environmental factors or some common single nucleotide polymorphisms (SNPs), based on a case-control study carried out in Cuba.

METHODS

A total of 203 cases and 212 controls from the general population were interviewed face-to-face using the dietary intake questionnaire and the photo booklet from the E3N cohort. A specific food composition table was constructed for this study. For each parameter studied, the odds ratio (OR) was stratified on age group and sex, and further adjusted for dietary energy, smoking status, ethnic group, level of education, number of pregnancies, and body surface area.

RESULTS

The risk of DTC was significantly reduced with increasing consumption of fish (p = 0.04), but no association between total dietary iodine intake and DTC risk was evident (p = 0.7). This lack of significant association was true whatever the age, the smoking status, the dietary selenium intake, and the ethnicity (p > 0.05). DTC risk was positively and strongly associated with the number of copies in the minor allele (A) for SNP rs965513 near FOXE1 among people who consumed less iodine than the median (p = 0.005).

CONCLUSION

Overall, the majority of the studied population had an optimal dietary iodine intake. DTC risk was inversely associated with high fish consumption. Furthermore, DTC risk was positively associated with the number of copies in the minor allele (A) of rs965513 among people who consumed less iodine than the median. Because these findings are based on post-diagnostic measures, studies with pre-diagnostic dietary iodine are needed for confirmation.

Iodine deficiency and thyroid cancer trends in three regions of Thailand, 1990-2009

BACKGROUND

Iodine deficiency may play a role in thyroid cancer carcinogenesis. Because Thailand has region-specific historical iodine deficiency, it is ideal to evaluate the potential impact of recent national iodine supplementation policies on thyroid cancer incidence trends.

METHODS

We examined thyroid cancer trends in Thailand from 1990 to 2009 in three geographically separated populations (Songkhla Province [south], Chiang Mai Province [north], and Khon Kaen Province [northeast]), each with a different historical prevalence of iodine deficiency. We used Joinpoint analysis and age-period-cohort (APC) models to investigate trends in thyroid cancer incidence.

RESULTS

Pooled incidence of papillary cancers significantly increased (Males APC: 2.0, p<0.05; Females APC: 7.3 [1990-2001, p<0.05], -2.1 [2001-2009]) and incidence of follicular cancers significantly decreased (Males APC: -5.2, p<0.05; Females APC: -4.3 [1990-1998, p<0.05], 12.3 [1998-2001], -17.0 [2001-2005, p<0.05], 8.2 [2005-2009]) in both males and females between 1990 and 2009. The largest increases in papillary cancer incidence, and the largest decreases in follicular cancer incidence, occurred in historically iodine-deficient regions. Interestingly, the significant histological changes coincided with Thailand's most recent national iodination policy. The thyroid cancer trends in females were better explained by period effects than cohort effects.

CONCLUSIONS

This study adds to the research indicating that papillary carcinoma incidence increases, and follicular carcinoma incidence decreases, as population-level iodine deficiency declines, and suggests that iodine exposure may affect late stages of thyroid carcinogenesis. However, our findings are limited by the ecological study design and lack of data prior to iodine supplementation.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Undifferentiated (anaplastic) thyroid carcinoma and iodine intake in Salta, Argentina

This study was conducted to investigate the natural history of undifferentiated thyroid carcinoma (UTC) in the iodine-deficient province of Salta, Argentina, in relation to salt iodization and health care standards. Five hundred ninety-three thyroid cancers diagnosed from 1958 to2012 were reviewed based mainly on the WHO classification and grouped into three periods, one before and two after iodine prophylaxis. The incidence of UTC was analyzed in relation to changing concentrations of potassium iodide (KI) in salt during the prophylaxis period (from 40 to 33.3 mg KI/kg salt), establishment of primary health care centers throughout the region, and use of fine needle aspiration (FNA) cytology. Twenty-nine UTCs were found in the whole series. The frequency of UTC decreased from 15.2 % (9/59 cases) in the first period to 2.6 % (10/381 cases) well after salt iodination (x (2) Fisher's test, p < 0.0002), and the incidence from 1.4/10(6)/year to 0.1/10(6)/year (Student's t test, p < 0.06), respectively. The decline of UTC after iodine prophylaxis occurred even after decreasing concentrations of KI in salt and timely coincided with the establishment of primary health care centers throughout the region and routine use of FNA. The lower rate of UTC after iodine prophylaxis in the province of Salta is mostly related to earlier detection of more differentiated thyroid tumors rather than higher salt iodization.

Follicular thyroid cancer incidence patterns in the United States, 1980-2009

BACKGROUND

The increases in thyroid cancer overall and in the predominant papillary type have been well documented, but trends for follicular thyroid cancer, a less common but more aggressive variant, have not been as well characterized. In this study, we determined the incidence patterns for follicular thyroid cancer and compared trends between the follicular and papillary thyroid cancers in the United States.

METHODS

We used the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program to examine incidence in the United States during 1980-2009, stratified by demographic and tumor characteristics. Incidence rates (IR) were calculated, relative risks were expressed as incidence rate ratios (IRR), and temporal trends were expressed as percentage changes and plotted.

RESULTS

Overall we observed a modest increase in age-adjusted follicular thyroid cancer rates among women (31.89%) and men (35.88%). Rates increased most dramatically for regional stage tumors compared to localized tumors in women, whereas the rates for all tumor sizes rose. These findings reveal increases in more aggressive tumors in women in addition to small and localized tumors. The trends for males were different from those among females. Among males, the largest increase was observed for regional and smaller size tumors. The papillary-to-follicular IRR overall was 7.07 [95% confidence interval 6.91-7.24], which varied from 7.37 among Whites to 3.86 among Blacks (SEER race/ethnicity categories), and increased significantly from 3.98 during 1980-1984 to 9.88 during 2005-2009.

CONCLUSION

The different trends for follicular and papillary types of thyroid cancer illustrate that thyroid cancer is a heterogeneous disease. Our results do not support the hypothesis that increasing thyroid cancer rates are largely due to improvements in detection, and suggest the importance of evaluating thyroid cancer types separately in future studies.

Dietary iodine and thyroid cancer risk in French Polynesia: a case-control study

BACKGROUND

French Polynesia has one of the world's highest thyroid cancer incidence rates. Iodine is suspected to play a role in this high incidence. The objective of this study was to assess whether low dietary iodine is related to a higher risk of thyroid cancer in the French Polynesian population.

METHODS

A case-control study was performed among native residents of French Polynesia. It included 229 cases of differentiated thyroid cancer diagnosed between 1979 and 2004 (203 women, 26 men) matched with 371 population controls (324 women, 47 men) on the date of birth. The current study is focused on dietary iodine intake and fish consumption (food rich in iodine) and analyzed by conditional logistic regression.

RESULTS

Daily dietary iodine intake was insufficient (<150 μg/day) in 60% of both cases and controls. A decreased risk of thyroid cancer was observed with a higher consumption of fish (p(trend)=0.008) and shellfish (p(trend)=0.002), and also with a higher dietary iodine intake (p(trend)=0.03). There was no significant interaction between the effects of the thyroid radiation dose and the dietary iodine intake (p=0.2).

CONCLUSION

French Polynesia is a mild iodine deficiency area in which a higher consumption of food from the sea and a higher dietary iodine intake are significantly associated with a decreased risk of thyroid cancer. The quantification of this reduction requires specific investigation of iodine intake in traditional Polynesian food.

Role of GST and NAT2 polymorphisms in thyroid cancer

Genetic polymorphisms have shown to be susceptibility factors playing an important role in the development of most cancers. Nevertheless, as far as we know, only few studies have been conducted linking thyroid cancer incidence and GST polymorphisms, and no data are available on the possible association between NAT2 polymorphisms and thyroid cancer risk. The possible relationship between polymorphism at the GSTM1, GSTT1, GSTP1, and NAT2 genes and increased susceptibility to thyroid cancer has been evaluated in 176 thyroid cancer patients and 167 healthy controls, all from the urban district of Barcelona (Spain). The results indicate a clear role of the C481T change, present in several NAT2*5 alleles [odds ratio (OR)=0.58; 95% confidence interval (95% CI)=0.35-0.98]. Thus, those individuals carrying this change are less prone to develop thyroid cancer, mainly of the papillary type. In addition, there is a tendency towards the over-representation of the GSTM1 null genotype among thyroid cancer patients, particularly in those patients with papillary type tumor. The same is observed for the GSTM1 and GSTT1 null genotypes combination, and for other combinations with different NAT2 polymorphisms. The combinations involving the NAT2*6 and NAT2*7 genotypes showed the most important effect, and individuals carrying both alleles present a higher risk of thyroid cancer (OR=7.36; 95% CI=0.85-63.47), mainly for the follicular type (OR=17.94; 95% CI=1.34-238.70). The combination of NAT2*5 with NAT2*7 was also found to increase 5.26 (95% CI=1.07-25.76) times the risk of thyroid cancer. In conclusion, our results show that NAT2 polymorphisms play a significant role in thyroid cancer risk modulation.

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

Iodine is a trace element that is essential for the synthesis of thyroid hormone. Both chronic iodine deficiency and iodine excess have been associated with hypertrophy and hyperplasia of follicular cells, attributed to excessive secretion of TSH. This may be associated to thyroid cancer risk, particularly in women. Experimental studies have documented thyroid cancer induction by elevation of endogenous TSH, although in a small number of animals. Iodine deficiency associated with carcinogenic agents and chemical mutagens will result in a higher incidence of thyroid malignancy. Inadequate low iodine intake will result in increased TSH stimulation, increased thyroid cell responsiveness to TSH, increased thyroid cell EGF-induced proliferation, decreased TGFbeta 1 production and increased angiogenesis, all phenomena related to promotion of tumor growth. Epidemiological studies associating iodine intake and thyroid cancer led to controversial and conflicting results. There is no doubt that introduction of universal iodine prophylaxis in population previously in chronic iodine-deficiency leads to a changing pattern of more prevalent papillary thyroid cancer and declining of follicular thyroid cancer. Also anaplastic thyroid cancer is practically not seen after years of iodine supplementation. Iodine excess has also been indicated as a possible nutritional factor in the prevalence of differentiated thyroid cancer in Iceland, Hawaii and, more recently, in China.

IN CONCLUSION

available evidence from animal experiments, epidemiological studies and iodine prophylaxis has demonstrated a shift towards a rise in papillary carcinoma, but no clear relationship between overall thyroid cancer incidence and iodine intake.

Smoking and environmental iodine as risk factors for thyroiditis among parous women

OBJECTIVE

To elucidate whether exposure to some environmental factors, i.e. cigarette smoking and iodine deficiency influence the risk of thyroiditis.

METHODS

We identified a cohort of 874, 507 parous women with self-reported information on smoking during pregnancy registered in the Swedish Medical Birth Registry from September 1983 through December 1997. Hospital diagnoses of thyroiditis (n = 286) and hypothyroidism (n = 690) following entry into the cohort were identified by record-linkage with the national Inpatient Registry. The hazard ratio (HR) of smokers compared to non-smokers and the corresponding 95% confidence limits (CL) were estimated by Cox regression.

RESULTS

Smoking was inversely associated with risk of overt thyroiditis (adjusted HR = 0.72; CL = 0.54-0.95), even when diagnoses of primary hypothyroidism were included. However, a diagnosis of thyroiditis within 6 months from a childbirth was positively associated with smoking (adjusted HR = 1.88; CL = 0.94-3.76). Being born in areas of endemic goiter was not associated to hospital admission for thyroiditis. Thyroiditis patients who were smokers had more often than non-smokers a co-morbidity with other autoimmune disorders.

CONCLUSIONS

Smoking may increase the risk of thyroiditis occurring in the post-partum period and influence the clinical expression of other thyroiditis, especially when occurring as part of a polymorphic autoimmune disease.

Municipal mortality due to thyroid cancer in Spain

Background

Thyroid cancer is a tumor with a low but growing incidence in Spain. This study sought to depict its spatial municipal mortality pattern, using the classic model proposed by Besag, York and Mollié.

Methods

It was possible to compile and ascertain the posterior distribution of relative risk on the basis of a single Bayesian spatial model covering all of Spain's 8077 municipal areas. Maps were plotted depicting standardized mortality ratios, smoothed relative risk (RR) estimates, and the posterior probability that RR > 1.

Results

From 1989 to 1998 a total of 2,538 thyroid cancer deaths were registered in 1,041 municipalities. The highest relative risks were mostly situated in the Canary Islands, the province of Lugo, the east of La Coruña (Corunna) and western areas of Asturias and Orense.

Conclusion

The observed mortality pattern coincides with areas in Spain where goiter has been declared endemic. The higher frequency in these same areas of undifferentiated, more aggressive carcinomas could be reflected in the mortality figures. Other unknown genetic or environmental factors could also play a role in the etiology of this tumor.

Newborn screening for congenital hypothyroidism

Most neonates born with congenital hypothyroidism (CH) have normal appearance and no detectable physical signs. Hypothyroidism in the newborn period is almost always overlooked and delayed diagnosis leads to the most severe outcome of CH, mental retardation, emphasizing the importance of neonatal screening. Blood spot T4 or TSH or both can be used in neonatal screening for CH. The latter, which is more sensitive, is not cost effective, so the first two are used in different programs in the world. TSH screening was shown to be more specific in the diagnosis of CH; T4 screening is more sensitive in detecting newborns especially with rare hypothalamic-pituitary hypothyroidism, but less specific with a high frequency of false positives mainly in low birth weight and premature infants. The time at which the sample is taken may vary between centers, with the majority taking blood from a heel prick after 24 hours of age to minimize the false positive high TSH due to the physiological neonatal TSH surge that elevates TSH levels and causes dynamic T4 and T3 changes in the first 1 or 2 days after birth. Early discharge of mothers postpartum has increased the ratio of false positive TSH elevations. Although transient hypothyroidism may occur frequently, all suspected infants should be treated as having CH for the first 3 years of life, taking into account the risks of mental retardation. A reevaluation after 3 years is needed in such patients. The goal of initial therapy in CH is to minimize neonatal central nervous system exposure to hypothyroidism by normalizing thyroid function, as reflected by T4 and TSH levels, as rapidly as possible. Iodine deficiency is the most important cause of CH worldwide. Iodine is essential for thyroid hormone synthesis and is present in soil, water and air. Prevention of iodine deficiency can be by iodized salt, iodized oil, iodized bread or iodine tablets.

Iodine intake and incidence of thyroid cancer in Denmark

OBJECTIVE

Iodine intake is suspected to be a risk factor for thyroid cancer. Eastern Denmark is characterized by mild and western Denmark by moderate iodine deficiency, and this difference is associated with a 50% difference in the occurrence of goitre and thyrotoxicosis. The objective of the study was to determine whether the incidence of thyroid cancer differs between these two regions, as any difference would have important safety implications for the national iodine supplementation programme.

DESIGN AND METHODS

We studied all thyroid cancers notified to the Danish Cancer Registry in the period 1973-1997, focusing on the four most frequent subtypes: papillary, follicular, anaplastic and medullary thyroid cancer. A Poisson regression model was used with models of goodness-of-fit for age, period, sex.

RESULTS

No regional difference was found in the overall incidence of follicular (0.3% 100 000 person-years) or papillary (0.7% 100 000 person-years) thyroid cancer. A slight but nonsignificant increase in total incidence, resulting mainly from a significant increase in the incidence for the papillary subtype, was observed in both regions.

CONCLUSION

The results suggest that modest differences in iodine intake do not affect thyroid cancer incidence or the distribution of subtypes.

Basal and induced micronucleus frequencies in human lymphocytes with different GST and NAT2 genetic backgrounds

Basal and induced frequencies of genetic damage can be modulated by different host factors, including genes involved in phase II metabolism. Since polymorphic variants in the glutathione S-transferase (GST) and N-acetyl transferase (NAT) genes have been associated with cancer risk, we explored the possible links between GSTM1, GSTP1, GSTT1 and NAT2 variants and the frequency of micronuclei (MN) in human lymphocytes. This exploratory study was carried out in 30 thyroid cancer patients, before and after receiving an average dose of 109.9+/-1.3 mCi radioactive iodine as a co-adjuvant therapy. The results indicate that none of the polymorphisms studied show any kind of association with the basal level of micronuclei. When the same patients were followed after radioiodine exposure, a significant increase in the frequency of MN was observed in practically all of them (28/30), indicating the genotoxic activity of the ionising radiation exposure. The increase in MN frequency was not associated with any of the GST polymorphisms evaluated. Nevertheless, the presence of slow acetylator phenotypes and, in particular, the presence of the NAT2*7 allele was significantly associated with a lower increase of the MN frequency after radioiodine treatment.

Cigarette smoking and the risk of goitre and thyroid nodules amongst parous women

OBJECTIVES

To clarify the mechanisms by which smoking is associated to toxic and nontoxic goitre and thyroid nodules.

DESIGN

Cohort study.

SETTING

Sweden.

SUBJECTS

A cohort of 874,507 parous women identified through the Medical Birth Registry, with smoking behaviour assessed through self-reported information at the first pre-natal visit, and follow-up between 1983 and 1997.

MAIN OUTCOME MEASURES

Hospital diagnoses of toxic and nontoxic goitre and thyroid nodules, identified by record-linkage with the national Inpatient Registry. Cox regression was employed to estimate the hazard ratio (HR) of smokers compared with nonsmokers and the corresponding 95% confidence limits (CL).

RESULTS

There was a significantly increased risk of goitre and nodules amongst smokers. The positive association was stronger for toxic (age adjusted HR = 1.94, CL = 1.74-2.16) than for nontoxic goitre and nodules (age-adjusted HR = 1.26; CL = 1.14-1.38). There was generally no clear risk trend with regard to amount smoked (below and above 10 cigarettes per day). Elevated body mass attenuated these associations, whilst being born in Swedish areas of endemic goitre enhanced the association with nontoxic goitre and nodules.

CONCLUSIONS

Smoking enhances the risk of thyroid goitre and nodules requiring hospital admission. Iodine deficiency and body weight are likely to be important modifiers of the risk of thyroid hyperplastic diseases amongst smokers.

Geographic pathology revisited: development of an atlas of cancer in India

Information on 217,174 microscopically diagnosed cancers diagnosed in 2001-2002 was collected from pathology laboratories in 68 districts across India. Data collection took place primarily via the Internet. Average annual age-adjusted incidence rates for microscopically diagnosed cases (MAAR) by gender and site were calculated for each of the 593 districts in the country. The rates were compared to those from established population based cancer registries (PBCR). In 82 districts, the MAAR for 'all cancer sites' was above a "completeness" threshold of 36.2/100,000 (based on results of a rural PBCR). The results confirmed some known features of the geography of cancer in India, and brought to light new ones. Cancers of the mouth and tongue are particularly frequent in both genders in the southern states. Very high rates of nasopharynx cancer were found in the northeastern states (Nagaland, Manipur). There was clear geographic correlation between the rates of cervical and penile cancer, and a high rate of stomach and lung cancer (in both genders) in many districts of Mizoram State. The area of high risk for gallbladder cancer seems larger than suspected previously, involving a wide band of northern India. There is a belt of high incidence of thyroid cancer in females in southwest coastal districts. Other than identifying possible existence of high-risk areas of specific cancers, our study has recognized places where PBCR could be established. The study was remarkably cost-effective and the electronic data-capture methodology provides a model for health informatics in the setting of a developing country.

Expression profile of malignant and non-malignant diseases of the thyroid gland reveals altered expression of a common set of genes in goiter and papillary carcinomas

Using cDNA microarrays with 3800 cDNA fragments, we determined the expression profile of normal thyroid tissue, goiter, adenoma and papillary carcinoma (10 samples from each class). After background correction and statistical analysis, we identified a set of 160 genes as being differentially expressed in all pair-wise comparisons. Here we demonstrate that, at least on the basis of these differentially expressed genes, a positive correlation between goiter and papillary carcinomas could be observed. We identified a common set of genes whose expression is diminished in both goiter and papillary carcinomas as compared to normal thyroid tissue. Moreover, no genes with inverse correlation in samples from goiter and papillary carcinomas could be detected. Using Real-Time PCR and/or tissue microarrays, we confirmed the altered expression of some of the identified genes. Of notice, we demonstrate that the reduced mRNA levels of p27(kip1) observed in papillary carcinomas as compared to either goiter or normal thyroid tissues (P<0.001) is accompanied by an altered protein distribution within the cell. In papillary carcinomas, P27(KIP1) is preferentially cytoplasmic as opposed to goiter or normal thyroid tissue, where P27(KIP1) is preferentially located in the nucleus. The exploitation of the data presented here could contribute to the understanding of the molecular events related to thyroid diseases and gives support to the notion that common molecular events might be related to the frequent observation of areas of papillary carcinomas in the gland of patients with goiter.

Risk factors for malignancy in multinodular goitres

BACKGROUND

Multinodular goitre (MNG) is quite often associated with thyroid carcinoma, but the risk factors for malignancy are not well known. The aim is to analyse patients with thyroid carcinoma associated with MNG to determine the clinical risk factors for malignancy.

METHOD

From a series of 672 MNGs we analysed a subgroup of 59 patients presenting with an associated thyroid carcinoma. The variables analysed were age, sex, family history, cervical radiation therapy, residence in areas of endemic goitre, prior thyroid surgery, time of evolution, asymptomatic status, hyperthyroidism, compressive syndromes, intrathoracic prolongation, goitre consistency and cervical adenopathies. These were compared to MNGs not developing malignancy using the Chi-squared test, Student's t test and a logistic regression test.

RESULTS

Of the 59 cases, 37 corresponded to a microcarcinoma (< or =1 cm). The most common histological type was papillary (n=48), followed by follicular (n=6). In 20 cases the carcinoma was multifocal, and capsular involvement was noted in 16 patients, lymph node involvement in five and vascular involvement in another five. The multivariate analysis confirmed the following as independent variables associated with the presence of carcinoma: family history of thyroid pathology (RR=1.6), history of cervical radiation therapy (RR=1.8), recurrent goitre (RR=2.1) and presence of adenopathies on physical exploration (RR=1.6).

CONCLUSION

The risk factors for carcinoma associated with MNG are family history of thyroid pathology, personal history of cervical radiation therapy, prior surgery and presence of cervical adenopathies.

Changing trends of incidence and prognosis of thyroid carcinoma in lower Franconia, Germany, from 1981-1995

BACKGROUND

A population-based registry (PBR) in Lower Frankonia in southern Germany was conducted to evaluate the changes of incidence and prognosis of thyroid carcinoma (TC) in this area.

METHODS

The study comprised 476 patients with differentiated thyroid carcinoma (DTC) from Lower Franconia (1.3 x 10(6) inhabitants) registered between 1981 and 1995 at the Regional Tumor Center. The incidence was assessed with respect to gender, age, histology, tumor stage, lymph node involvement and distant metastases in 5-year intervals (1981-1985, 1986-1990, and 1991-1995).

RESULTS

An increasing rate of papillary thyroid carcinoma PTC and a decreasing rate of follicular thyroid carcinoma (FTC) were observed over the three time periods (1981-1985, 1986-1990, and 1991-1995). The overall incidence revealed no significant change with time for both females from 3.22 to 3.25 and 3.73 and males (1.07 to 1.54 and 1.69) between the three time periods. There was a significant improvement in outcome of patients with DTC with respect to life expectancy.

CONCLUSIONS

Iodine prophylaxis does influence the distribution of the histologic types of thyroid cancer and leads to an increase in the ratio of papillary versus follicular carcinoma. Our study supports the hypothesis that the benefits of correcting iodine deficency outweigh the risks of iodine supplementation.

Cancer: a single disease with a multitude of manifestions?

The relationships of critical nutrients such as plant phenolics, vitamins, minerals and lipids are considered with respect to the incidence of a variety of cancers, and analyzed in terms of how these nutrient deficiencies alter immune function, DNA integrity and cell proliferation. With a significant correlation found between cancer and these nutrient deficiencies, the hypothesis is presented here that nutrition could provide a unifying perception of cancer and recast it as a single disease. This further suggests that a coordinated administration of specific, critical nutrients to cancer patients could lead to the reversal of the disease. It is also proposed that the concurrent presence of a variety of nutritional deficiencies in cancer patients requires a multilevel, systemic approach to this disease as opposed to the single active therapeutic agent approach that is the cornerstone of contemporary research and pharmacology.

Glutathione S-transferase polymorphisms in thyroid cancer patients

Glutathione S-transferases (GST) are enzymes involved in the metabolism of many carcinogens and mutagens, also acting as important free-radical scavengers. The existence of different genetic polymorphisms in human populations has proven to be a susceptibility factor for different tumours. Nevertheless, as far as we know, for thyroid cancer no study has been conducted until now linking its incidence to genetic susceptibility biomarkers. The present investigation has been conducted to detect the possible association between polymorphism at the GSTM1, GSTT1 and GSTP1 genes and thyroid cancer incidence. Thus, 134 thyroid cancer patients and 116 controls, all from the urban district of Barcelona (Spain), have been included in this study. The results indicate that, according to the calculated odds ratio, the frequencies of the different genotypes found in the group of cancer patients do not significantly differ from those values obtained in the controls. This is true for the overall data as well as for the tumour characterization as follicular and papillar types. In addition, none of the possible combinations of mutant genotypes were shown to be risk factors. Finally, when the sex of the patients, the age of tumour onset, and life-style habits were also taken into account, no influence was observed related to the different genotypes. In conclusion, the results obtained in this study clearly suggest that those susceptibility factors related to the different GST polymorphic enzymes are not a predisposing factor in thyroid cancer disease.

Cancer incidence among a cohort of female farm residents in New York State

A retrospective cohort study of cancer incidence among 6,310 female farm residents who were New York Farm Bureau members, or members' spouses or relatives, was conducted from 1980 through 1993. Similar to the previous findings for New York State male farmers, the female farm resident cohort experienced significantly lower cancer rates for all cancers combined, and for lung cancer, compared with rural nonfarm female residents. In addition, significantly low rates for colorectal cancer and ovarian cancer were found among the female cohort members. Nonsignificant excesses were found for thyroid and liver cancers. The findings suggest that female farm residents in this cohort might have experienced some of the same cancer-protective factors as male farmers.

Cohort study of thyroid cancer in a San Francisco Bay area population

Using data from a large health plan, we performed a cohort study of thyroid cancer among 204,964 persons (aged 10--89 at baseline in 1964--1973, 54% female) followed for a median of 20 years. There were 196 incident thyroid cancers (73 in men, 123 in women). Risk was independently and positively related to female gender [relative risk (RR) = 1.56, 95% confidence interval (CI) = 1.12--2.19], Asian race (RR = 2.86, 95% CI = 1.76--4.65), completed college or post-graduate education (RR = 1.76, 95% CI = 1.20--2.59), history of goiter (RR = 3.36, 95% CI = 1.82--6.20), radiation of the neck region (RR = 2.33, 95% CI = 1.28--4.23) and family history of thyroid disease (RR = 2.18, 95% CI = 1.17--4.05). An inverse association was found for black race (RR = 0.55, 95% CI = 0.33--0.91). Cigarette smoking, alcohol consumption, personal history of hyperthyroidism, hypothyroidism, overweight or obesity, weight gain since age 20, height, occupational exposures, reproductive factors, oral contraceptives and hormone use did not show statistically significant relations to thyroid cancer. These results provide further evidence for a role of female gender, radiation, goiter, Asian race, high educational attainment and family history of thyroid disease in the etiology of thyroid cancer.

Incidence and clinical characteristics of thyroid carcinoma after iodine prophylaxis in an endemic goiter country

Iodized salt prophylaxis has been performed in Austria since 1963. Through this approach, mean urinary iodine excretion has been normalized to 144+/-23.5 microg/g creatinine per day. Thus Tyrol is no longer an endemic goiter area. We have analyzed the impact of iodized salt prophylaxis on thyroid cancer (TC) comparing data from the early 1960s with those corresponding to the period 1986 to 1995, when iodine supply was normalized. The study included 439 patients from Tyrol and Southern Tyrol. The incidence of TC in Tyrol has risen during the past decades from 3.07 between in 1957 and 1970 to 7.8 between 1990 and 1994 (CR/100000/year). We observed a rise in the percentage of differentiated adenocarcinomas (56% to 91.5%) with a predominance of papillary TC (54.4%) along with a decrease of anaplastic TC. In addition to these histological features, a shift to less advanced TNM stages, eg, T1-3, N0-1a, M0, was obvious, increasing from 29% to 72.2%, whereas advanced tumors, ie, T4 or N1b or M1, decreased from 71% to 28%. These changes have significantly improved prognosis. The current 5-year survival rate is 90.7% as compared with a rate of 73% in the 1960s; the values for 7-year survival are 89% and 48%, respectively. The marked effects of age, tumor stages, and histology on prognosis were confirmed with the Kaplan-Meier method. We conclude that together with normalization of iodine supply in an endemic goiter region the epidemiological profile of TC has changed. Even though the incidence of TC has risen, prognosis has significantly improved due to a shift towards differentiated forms of TC that are diagnosed at earlier stages.

Parental cancer and risk of papillary and follicular thyroid carcinoma

In a population-based case-control study in the Uppsala-Orebro Health Care Region of Sweden, the histories of cancer among parents of 517 histologically confirmed cases of papillary and follicular carcinoma and of a similar number of sex- and age-matched controls were compared. The parental history of cancer was compiled through information from death certificates and from the nationwide Cancer Register. The incidence of malignancies in a cohort of parents of cases of thyroid cancer was also compared with the incidence in the whole Swedish population. A maternal history of cancer was more common among women with follicular carcinoma than among their controls (OR 2.11, 95% CI 0.96-4.67). Parents of probands with papillary carcinoma had an increased risk of thyroid cancer (OR 4.25, 95% CI 1.16-10.89), and mothers of probands with follicular carcinoma had an increased risk of stomach cancer (OR 3.65, 95% CI 0.99-9.35) compared with the general population. Cancer of the lung, breast, and pancreas were less common than in the general population. Familial cases of thyroid cancer were not limited to the papillary type. An inheritable pattern of carcinogenesis is possible for certain differentiated non-medullary thyroid cancers, but shared environmental exposures may also explain the parent-child associations of cancer in this study.

Time trend and age-period-cohort effect on incidence of thyroid cancer in Connecticut, 1935-1992

Recent studies from Europe suggest a continuing increase in thyroid cancer, but it is unclear whether this trend also applies to the United States. The current study examined the long-term trend of thyroid cancer in Connecticut. Our results show that the overall age-adjusted incidence rate of thyroid cancer has been increasing in Connecticut, from 1.30/100,000 in 1935-1939 to 5.78/100,000 in 1990-1992 in females, and from 0.30/100,000 in 1935-1939 to 2.77/100,000 in 1990-1992 in males. The increase mainly comes from papillary carcinoma of the thyroid. The birth cohort analyses indicate that the increase in thyroid cancer occurred among cohorts born between 1915 and 1945, which experienced an increase of 31.4% every 5 years in males and 17.3% in females over the period 1960-1979. For those born since the 1945 cohort, the incidence has been decreasing, at rates of 9.3% and 8.3% every 5 years over the period 1975-1992 in males and females, respectively. Age-period-cohort modeling results also suggest a strong birth cohort effect on the observed time trend in both sexes, which closely follows the introduction of radiation treatment of benign childhood conditions in the head and neck between 1920 and the 1950s in the United States. Our results are consistent with the suggested radiation hypothesis, indicating that radiation treatment of benign childhood conditions in the head and neck is largely responsible for the observed increase of thyroid cancer in Connecticut.