Epidemiology and primary prevention of thyroid cancer

Cancer mortality and incidence in korean semiconductor workers

Objectives

The purpose of this study was to evaluate cancer risks in the Korean semiconductor industry.

Methods

A retrospective cohort study was performed in eight semiconductor factories between 1998 and 2008. The number of subjects was 113,443 for mortality and 108,443 for incidence. Standardized mortality ratios (SMR) and standardized incidence ratios (SIR) were calculated.

Results

The SMR of leukemia was 0.39 (95% Confidence Interval 0.08-1.14) in males (2 cases) and 1.37 (0.55-2.81) in females (7 cases). The SMR of non-Hodgkin's lymphoma (NHL) was 1.33 (0.43-3.09, 5 cases) in males and 2.5 (0.68-6.40, 4 cases) in females. The SIR of leukemia was 0.69 (0.30-1.37, 8 cases) in males and 1.28 (0.61-2.36, 10 cases) in females. The SIR of NHL in females was 2.31 (1.23-3.95, 13 cases) and that of thyroid cancer in males was 2.11 (1.49-2.89, 38 cases). The excess incidence of NHL was significant in female assembly operators [SIR=3.15 (1.02-7.36, 5 cases)], but not significant in fabrication workers. The SIR of NHL in the group working for 1-5 years was higher than the SIR of NHL for those working for more than five years. The excess incidence of male thyroid cancer was observed in both office and manufacturing workers.

Conclusion

There was no significant increase of leukemia in the Korean semiconductor industry. However, the incidence of NHL in females and thyroid cancer in males were significantly increased even though there was no definite association between work and those diseases in subgroup analysis according to work duration. This result should be interpreted cautiously, because the majority of the cohort was young and the number of cases was small.

Predictive value of cytologic atypia in indeterminate thyroid fine-needle aspirate biopsies

BACKGROUND

Fine-needle aspiration (FNA) biopsies are the most accurate method for diagnosis of thyroid nodules. Unfortunately, biopsies are indeterminate 15-30% of the time and surgery is thus required for a definitive diagnosis. We aimed to determine whether specific descriptors of cytologic atypia mentioned in indeterminate FNA reports were associated with malignancy on final histopathology.

METHODS

Retrospective review of 1000 surgery patients identified 466 indeterminate FNA lesions that underwent either a hemi- or total thyroidectomy between 1998 and 2009. We screened FNA reports for specific descriptors of nuclear atypia. Univariate and multivariate analyses were performed to evaluate the independent effect of cytologic atypia descriptors on the risk of malignancy.

RESULTS

Nuclear atypia on FNA conferred a risk of malignancy of 42% (P < 0.0001). Risk of malignancy increased from 17% for zero descriptors to 81.2% when four or more descriptors of atypia were described. Nuclear grooves and inclusions together conferred a risk of malignancy, specificity, and false positive rate of 79.3%, 98.2% and 1.8% respectively.

CONCLUSIONS

The presence of four or more descriptors of cytologic atypia or the presence of both nuclear inclusions and grooves together confers a high risk of malignancy on final histopathology and a low false positive rate. These findings should be taken into consideration when interpreting FNA reports and total thyroidectomy should be considered for those patients at higher risk.

Risks of papillary and follicular thyroid cancer among immigrants to Sweden

Previous studies have indicated that ionizing radiation, particularly during childhood, is the main established risk factor for thyroid cancer. History of benign nodules/adenoma, goiter, iodine deficiency or high-iodine intake might be other associated factors. We wanted to define the histology-specific thyroid cancer risk in the first-generation immigrants to Sweden. We used the 2010 update of the nation-wide Swedish Family-Cancer Database (>12 million individuals; 1.8 million immigrants; histology code in force since 1958) to calculate standardized incidence ratios (SIRs) for histology-specific thyroid cancer among immigrants compared to the native Swedes. The patient series covered 2,604 male and 6,406 female Swedes, and 247 and 863 immigrants. The median age at immigration was 29 years, and the median age at thyroid cancer diagnosis was 46 years. Increased risks for female papillary carcinoma were observed for Finns (SIR = 1.63), former Yugoslavians (2.36), Russians (2.34), other East Europeans (2.14), Turks (3.16), Iranians (2.68), Iraqis (2.77), East and Southeast Asians (2.92), other Asians (1.69) and South Americans (2.23). Male Iranians (2.85), East and Southeast Asians (3.57) and other Asians (2.26) had an increased risk for papillary carcinoma. Only male East and Southeast Asians (2.93) had an increased risk for follicular carcinoma. The data might suggest that immigrant populations in Sweden from areas of low or high-iodine intake are at risk of papillary carcinoma, implicating iodine imbalance as a contributing factor to our findings. The increased risk of thyroid cancer among Asian immigrants may confirm the role of childhood-ionizing radiation on thyroid cancer risk.

Prevalence of malignant tumors and adenomatous lesions detected by ultrasonographic screening in patients with autoimmune thyroid diseases

BACKGROUND

Thyroid ultrasonography (US) is the most sensitive method for detecting thyroid nodules, and US-guided aspiration biopsy is the most accurate diagnostic procedure for thyroid nodules. We performed this retrospective study to establish the prevalence of thyroid nodules in Graves' disease and patients with Hashimoto's thyroiditis at the time of their initial visit.

METHODS

We performed thyroid US as routine screening in 1652 patients with Graves' disease and 2036 Hashimoto's thyroiditis and performed US-guided fine-needle aspiration biopsy when the diameter of a nodule >1 cm or a nodule was suspected of being malignant.

RESULTS

The prevalence of papillary carcinoma in the patients with Hashimoto's thyroiditis was higher than in the patients with Graves' disease (1.77% vs. 0.97%), and two patients with Hashimoto's thyroiditis (0.098%) were found to have malignant lymphoma. Adenomatous lesions were observed more frequently in the patients with Hashimoto's thyroiditis than in the patients with Graves' disease. The prevalence of adenomatous lesions increased in an age-dependent manner in both the patients with Graves' disease and those with Hashimoto disease; and adenomatous lesions were more frequent in younger patients with Hashimoto' s thyroiditis than in those with Graves' disease.

CONCLUSIONS

The prevalence of both thyroid papillary cancer and adenomatous lesions was greater in the patients with Hashimoto's thyroiditis than in those with Graves' disease; and adenomatous lesions were more frequent in younger patients with Hashimoto's thyroiditis. We recommend performing US at the time of the initial visit in patients with autoimmune thyroid disease, who have a high prevalence of thyroid papillary carcinoma, to detect malignant thyroid tumors and adenomatous lesions.

Role of PTPRJ genotype in papillary thyroid carcinoma risk

The strong genetic predisposition to papillary thyroid carcinoma (PTC) might be due to a combination of low-penetrance susceptibility variants. Thus, the research into gene variants involved in the increase of susceptibility to PTC is a relevant field of investigation. The gene coding for the receptor-type tyrosine phosphatase PTPRJ has been proposed as a cancer susceptibility gene, and its role as a tumor suppressor gene is well established in thyroid carcinogenesis. In this study, we want to ascertain the role of PTPRJ genotype in the risk for PTC. We performed a case-control study in which we determined the PTPRJ genotype for the non-synonymous Gln276Pro and Asp872Glu polymorphisms by PCR amplification and sequencing. We calculated allele and genotype frequencies for the considered polymorphisms of PTPRJ in a total sample of 299 cases (PTC patients) and 339 controls (healthy subjects) selected from Caucasian populations. We observed a significantly higher frequency of homozygotes for the Asp872 allele in the group of PTC patients than in the control group (odds ratio=1.61, 95% confidence interval 1.15-2.25, P=0.0053). We observed a non-significant increased frequency of homozygotes for Gln276Pro polymorphism in PTC cases in two distinct Caucasian populations. Therefore, the results reported here show that the homozygous genotype for Asp872 of PTPRJ is associated with an increased risk to develop PTC.

[Thyroid cancers in Madagascar]

This is a retrospective study, conducted on thyroid cancer observed for 13 months (from June 1(st) 2004 to June 30(th) 2005). Data were collected from four main surgical pathology laboratories in Antananarivo, Madagascar. Among 6,036 surgical samples, 179 were of thyroid gland, a rate that is near 3% of the total. Among them were found 40 cases of thyroid cancer, which is 0.66% of all screened samples, and 22.32% of all examined thyroid samples. In the studied population was observed a female preponderance (82%) with a mean age of 43.9 years when diagnosis was confirmed. It was evidenced a 50 % of papillary carcinoma and 45% of follicular carcinoma, with a rate of 2.5% respectively for the medullar and anaplastic carcinoma. Metastases were seen in 20%, originated from papillary type for the lymph node involvement and from the follicular type for the bone involvement. In Antananarivo, thyroid cancer is seen mainly in people from the surrounding Highlands, supposed to be sites of endemic goiter related to iodine deficiency. Despite its limits, this study may be used as reference about thyroid cancer in Madagascar. Further studies are required to find out other factors involved in the development of this disease.

Prevalence of previous extracranial malignancies in a series of 1228 patients presenting with meningioma

OBJECT

The study of patients with multiple neoplasms can yield valuable insight into the common pathogenesis of both diseases, as well as identify more subtle risk factors that might not be as readily apparent otherwise. The authors present an analysis of the prevalence of previously diagnosed extracranial malignancies at the time of meningioma diagnosis in 1228 patients evaluated at a single institution.

METHODS

All patients who underwent evaluation and/or treatment for meningioma between 1991 and 2007 at the authors' institution were identified. The intake history and physical were assessed for any history of extracranial malignancy. Using the National Cancer Institute data, the authors calculated an expected cancer prevalence for their meningioma patient population, and compared this derived value to the observed rate of these cancers in this population.

RESULTS

There were 1228 patients included in this study. A total of 50 patients (4.1%) with newly diagnosed meningioma had a history of an extracranial malignant tumor at the time of their initial meningioma diagnosis. In general, most malignancies did not differ in prevalence from their expected frequency in the population in the present study. Notable exceptions were acute leukemia (p < 0.0001), and papillary thyroid carcinoma, which had a prevalence 2.5 times that expected in this population (p < 0.05).

CONCLUSIONS

The data support a growing body of evidence suggesting an epidemiological link between papillary carcinoma of the thyroid and meningioma. Although the link between these tumors is not immediately apparent, it is possible that further exploration will yield interesting insight into the pathogenesis of both diseases.

[Time trends in the geographic variation of thyroid cancer incidence by tumor size from 1983 to 2000 in France]

BACKGROUND

The aim of this investigation was to study geographic time trends of thyroid cancer incidence according to tumor size in France, 1983 to 2000.

METHODS

Incidence data were provided from six French registries over the period 1983-2000 covering seven administrative districts. Five tumor size groups were distinguished: < 10mm, 10-20mm, 20-40mm, > 40mm and unknown size. Papillary cancers diagnosed in women were analyzed according to tumor size in each geographic area. World age standardized rates were calculated and annual percent change rates were estimated for each tumor size group in each geographic area. Loglinear Poisson regression models were used to study geographic discrepancies in time trends incidences.

RESULTS

The six French registries included 2222 papillary thyroid cancers in women between 1983 et 2000. Thyroid cancer incidence was increasing in the six geographic areas. Geographical variations in time trends incidence between registries reflected geographical variations in time trends incidence of small sized tumors (less than 10mm).

CONCLUSION

Wide geographic variations in thyroid cancer incidence were noticed for small size tumors, which may be correlated with geographic variations in medical practices.

The Prevalence of Vitamin D Deficiency Is Similar between Thyroid Nodule and Thyroid Cancer Patients

Introduction. There are reported associations between vitamin D deficiency and breast, prostate, and colon cancer, but the relationship in thyroid cancer has not been evaluated. Methods. We evaluated serum calcium, creatinine, albumin, and 25-hydroxy vitamin D (25-OH-D) in 42 thyroid nodule, 45 thyroid cancer in remission, and 24 active thyroid cancer patients. Results. 25-OH-D was not different between groups. The percent with 25-OH-D levels <75 nmol/L was not significantly different between groups and was not affected by season of measurement, age, or cancer stage. Multivariate regression showed a BMI of >/=30 kg/m(2) to be the only significant predictor of vitamin D deficiency. Conclusions. Rates of vitamin D deficiency are similar in thyroid nodules and thyroid cancer, although higher than the general population. This is different than previous studies for other cancers, which show higher rates of vitamin D deficiency. BMI was the only predictor of vitamin D deficiency.

Geographic variation in U.S. thyroid cancer incidence and a cluster near nuclear reactors in New Jersey, New York, and Pennsylvania

In the United States, thyroid cancer incidence (along with liver cancer) is increasing more rapidly than any other malignancy, rising nearly threefold from 1980 to 2006. Improved diagnosis has been proposed by some as the major reason for this change, while others contend that additional factors also account for the increase. Among U.S. states, 2001-2005 age-adjusted thyroid cancer incidence rates vary from 5.4 to 12.8 per 100,000. County-specific incidence data, available for the first time, document that most U.S. counties with the highest thyroid cancer incidence are in a contiguous area of eastern Pennsylvania, New Jersey, and southern New York State. Exposures to radioactive iodine emissions from 16 nuclear power reactors within a 90-mile radius in this area indicate that these emissions are a likely etiological factor in rising thyroid cancer incidence rates.

Time trends for thyroid cancer in northwestern Spain: true rise in the incidence of micro and larger forms of papillary thyroid carcinoma

BACKGROUND

Thyroid cancer incidence is increasing throughout the world. Most studies attribute this rise entirely to the increase in papillary carcinoma, the most common thyroid malignancy in iodine-sufficient areas. A variety of nonetiological factors such as changes in clinical practice may affect the incidence of thyroid cancer and some researchers have suggested that this rise is only apparent due to an increase in diagnostic activity. Since data on the epidemiology of thyroid cancer in Spain are scarce, the main goal of this study was to analyze changes in thyroid cancer presentation, incidence, and prevalence in Vigo (northwestern Spain) between 1978 and 2001, and to investigate the relationship between the incidence rates and trends in tumor size and thyroid surgery.

METHODS

In this descriptive epidemiologic study, an analysis was carried out on new thyroid cancer cases obtained from the Pathology Registry of the University Hospital of Vigo (500,000 inhabitants). Trends in age, sex, thyroid surgery, histological type, tumor size, and incidence rates were calculated. The prevalence of thyroid cancer was determined in three cross-sectional surveys.

RESULTS

The rate of population undergoing thyroid surgery significantly increased over time. Out of 322 new primary thyroid cancers, papillary thyroid cancer (PTC) was the predominant type (76%). The age-standardized incidence rate shows a significant increase in females: 1.56 per 100,000 year (1978 to 1985) to 3.83 (1986 to 1993) and 8.23 (1994 to 2001); and in males: 0.33, 1.19, and 2.65, respectively. PTC was mainly responsible for this pattern and was the result of both the increase in micropapillary thyroid carcinoma (MPTC) incidence and in PTC measuring more than 1 cm. Besides MPTC cases, no significant variations were observed in tumor size over time.

CONCLUSIONS

In northwestern Spain, the incidence of thyroid cancer is increasing. These data should be taken into account when planning health resources for these patients. Our results may reflect the contribution that other factors, besides increased diagnostic activity, have made to the rise in thyroid cancer incidence in our region. Additional studies are needed to explain the rise in PTC incidence throughout the world and to search for potential risk factors that are currently unrecognized.

Sex disparities in cancer incidence by period and age

BACKGROUND

Cancer epidemiology articles often point out that cancer rates tend to be higher among males than females yet rarely is this theme the subject of investigation.

METHODS

We used the Surveillance, Epidemiology and End Results program data to compute age-adjusted (2000 U.S. standard population) sex-specific incidence rates and male-to-female incidence rate ratios (IRR) for specific cancer sites and histologies for the period 1975 to 2004.

RESULTS

The 10 cancers with the largest male-to-female IRR were Kaposi sarcoma (28.73), lip (7.16), larynx (5.17), mesothelioma (4.88), hypopharynx (4.13), urinary bladder (3.92), esophagus (3.49), tonsil (3.07), oropharynx (3.06), and other urinary organs (2.92). Only 5 cancers had a higher incidence in females compared with males: breast (0.01), peritoneum, omentum, and mesentery (0.18), thyroid (0.39), gallbladder (0.57), and anus, anal canal, and anorectum (0.81). Between 1975 and 2004, the largest consistent increases in male-to-female IRR were for cancers of the tonsil, oropharynx, skin excluding basal and squamous, and esophagus, whereas the largest consistent decreases in IRR were for cancers of the lip and lung and bronchus. Male-to-female IRRs varied considerably by age, the largest increases of which were for ages 40 to 59 years for tonsil cancer and hepatocellular carcinoma. The largest decreases in male-to-female IRR by age, meanwhile, were for ages 30 to 49 years for thyroid cancer, ages >70 years for esophageal squamous cell carcinoma, and ages >30 years for lung and bronchus cancer.

CONCLUSION

These observations emphasize the importance of sex in cancer etiopathogenesis and may suggest novel avenues of investigation.

Role of B-Raf(V600E) in differentiated thyroid cancer and preclinical validation of compounds against B-Raf(V600E)

B-Raf(V600E), an oncogenic protein kinase, is the most frequent genetic alteration in papillary thyroid carcinomas (PTC). PTC represents 80-90% of all thyroid cancers and over the past five years, more than 200 manuscripts have been published about the relationship between "B-Raf(V600E) and thyroid cancer". B-Raf(V600E) genetically arises from a transversion point mutation (valine-to-glutamate substitution at amino acid residue-600, V600E) and leads to over activation of the mitogen-activated protein kinases (MAPK) signaling pathway. The MAPK pathway is essential for transmitting proliferation signals generated by cell surface receptors and cytoplasmic signaling elements to the nucleus. In many cancers, including thyroid cancer, B-Raf(V600E) appears to play a crucial role in cell proliferation, survival and de-differentiation. In thyroid cancer, the V600E mutation occurs with greater frequently in aggressive subtypes of PTC, and in individuals that present at advanced stages of disease with extra-thyroidal extension and/or lymph node metastases. B-Raf(V600E) is considered a marker of aggressive disease in both PTC (>1 cm) and micro-PTC (</=1 cm), and interestingly, is associated with both loss of I-131 avidity and PTC recurrence. Though treatment of patients with thyroid cancer is usually successful and most patients are rendered disease-free, to date there are no effective therapies for patients with invasive, non-radioiodine sensitive tumors or metastatic disease. In this article we will review the relation between B-Raf(V600E) and PTC, as well as both non-selective and selective pharmacological agents currently under investigation for treatment of B-Raf(V600E) positive PTC.

Geographical analysis of thyroid cancer in young people from northern England: evidence for a sustained excess in females in Cumbria

A previous study found a thyroid cancer excess in Cumbria following the Chernobyl explosion, but did not analyse sex-specific effects. This study examines sex differences in the incidence of thyroid cancer. Ninety-five primary thyroid carcinomas (69 females, 26 males) diagnosed in those aged 0-24 during 1968-2005 were identified from the Northern Region Young Persons' Malignant Disease Registry. Age-standardised incidence rates (ASRs), rate ratios (RRs) and 95% confidence intervals (CIs) were calculated. For males, the ASR was 0.6 per million person-years during the pre-Chernobyl period (1968-1986), and was 1.8 per million person-years during the post-Chernobyl period (1987-2005). For females, the ASR was 2.4 pre-Chernobyl and was 3.9 post-Chernobyl. The previously noted excess in Cumbria was entirely confined to females (Cumbrian females: RR for post-Chernobyl compared with pre-Chernobyl=10.8; 95% CI: 1.4-85.3). These findings may be consistent with sex-specific differences in susceptibility to an environmental exposure, such as fallout from the Chernobyl nuclear accident.

Multiplex analysis of cytokines as biomarkers that differentiate benign and malignant thyroid diseases

Thyroid cancer incidence is increasing, and its diagnosis can be challenging. Fine needle biopsy, the principal clinical tool to make a tissue diagnosis, leads to inconclusive diagnoses in up to 30% of the cases, leading to surgery. Advances in proteomics are improving abilities to diagnose malignant conditions using small samples of tissue or body fluids. We hypothesized that analysis of serum growth factors would uncover diagnostically informative differences between benign and malignant thyroid conditions. Using xMAP profiling, we evaluated concentrations of 19 cytokines, chemokines, and growth factors. We used sera from 23 patients with cancer (Malignant group), 24 patients with benign nodular thyroid disease (Benign group), and 23 healthy subjects (Normal group). In univariate analysis, five factors (epithelial growth factor, hepatocyte growth factor, Interleukins-5 and -8, and regulated upon activation, normally T-expressed and presumably secreted (RANTES) distinguished subjects with thyroid disease from the Normal group. In multivariate analysis, the set {Interleukin-8, hepatocyte growth factor, monocyte-induced γ interferon, interleukin-12 p40} achieved noteworthy discrimination between Benign and Malignant groups (area under the receiver operating characteristics curve was 0.81 (95% confidence interval: 0.65-0.90)). Multiplex panels of serum biomarkers may be promising tools to diagnose cancer in patients presenting with evidence of nodular thyroid disease.

Risk factors for thyroid cancer: an epidemiological review focused on nutritional factors

OBJECTIVES

The present review summarizes epidemiological evidence on risk factors for thyroid cancer (TC), in particular, nutritional factors.

METHODS

Searches of articles on the issue were conducted using MEDLINE.

RESULTS

Exposure to ionizing radiation, particularly during childhood, is the best-established risk factor for TC. There is also a strong association with history of benign nodules/adenoma or goiter. Iodine deficiency may induce an increasing incidence of benign thyroid conditions, but very high iodine intake also affects thyroid function and, possibly, TC risk. Among dietary factors, fish-the major natural source of iodine in human diet-is not consistently related to TC risk. High intake of cruciferous vegetables shows a weak inverse association with TC. Among other food groups, vegetables other than cruciferous are the only food group showing a favorable effect on TC, with an approximate 20% reduction in risk for subjects with the highest consumption. No effect on TC risk of alcohol, coffee, or other food-groups/nutrients emerged. Height and weight at diagnosis show a moderate positive association with TC risk.

CONCLUSION

At present, the only recognized measures for reducing TC risk is to avoid ionizing radiation and iodine deficiency, particularly in childhood and young women, and to increase vegetable consumption.

Molecular phenotyping of thyroid tumors identifies a marker panel for differentiated thyroid cancer diagnosis

BACKGROUND

Currently, a large proportion of individuals undergo thyroidectomy as a diagnostic procedure for cancer. The objective of this work was to evaluate the molecular phenotype of differentiated thyroid cancer (DTC) and benign thyroid lesions to identify molecular markers that allow for accurate thyroid cancer diagnosis.

METHODS

Tissue microarrays consisting of 100 benign and 105 malignant thyroid lesions, plus 24 lymph node samples, were stained for a panel of 57 molecular markers. Significant associations between marker staining and tumor pathology (DTC versus benign) were determined using contingency table and Mann-Whitney U (MU) tests. A Random Forests classifier algorithm was also used to identify useful/important molecular classifiers.

RESULTS

Of the 57 diagnostic markers evaluated 35 (61%) were significantly associated with a DTC diagnosis after multiple testing correction. Of these, in DTC compared with benign thyroid tumors, 8 markers were downregulated and 27 upregulated. The most significant markers for DTC diagnosis were: Galectin-3, Cytokeratin 19, Vascular Endothelial Growth Factor, Androgen Receptor, p16, Aurora-A, and HBME-1. Using the entire molecular marker panel, a Random Forests algorithm was able to classify tumors as DTC or benign with an estimated sensitivity of 87.9%, specificity of 94.0%, and an accuracy of 91.0%.

CONCLUSION

Evaluation of the DTC and benign thyroid tumor molecular phenotype has allowed for identification of a marker panel, composed of both established and novel markers, useful for thyroid cancer diagnosis. These results suggest that further study of the molecular profile of thyroid tumors is warranted, and a diagnostic molecular marker panel may potentially improve patient selection for thyroid surgery.

Thyroid cancer in the Middle Eastern population of California

OBJECTIVE

To describe and compare the epidemiology of thyroid cancer in the rapidly growing Middle Eastern (ME) population and the non-Hispanic, non-Middle Eastern White (NHNMW) residents of California. Population with ME heritage that is officially not recognized as a distinct ethnicity has rarely been studied in the past.

METHODS

ME cases in the California cancer registry files for 1988-2004 were identified by surname recognition. ME population was estimated by ancestry from census data.

RESULTS

Thyroid cancer in ME group, 869 cases and 56 deaths were compared with 19,182 cases and 1,327 deaths in the NHNMW population. Age-adjusted rate ratio (RR) for incidence was 1.5 (95% CI 1.3-1.7) in men and 1.5 (95% CI 1.4-1.7) in women. RR for mortality was 1.4 (95% CI 0.9-2.4) in men and 2.3 (95% CI 1.4-3.9) in women. Papillary tumors comprised over 80% of all cases and their pattern correlated with the rapid increase in thyroid cancer in recent years. Five-year observed survival in ME men was significantly higher than in NHNMW men, but similar in women.

CONCLUSIONS

Eighty-five percent of ME cases identified in this study were born in the Middle East. The higher incidence of thyroid cancer in this immigrant population may largely reflect a combination of sequels of radiation treatment for fungal diseases of the scalp that was common in the area in early 1950s, benign proliferative thyroid disease that is common in the area due to dietary iodine imbalance, and possibly genetic predisposition.

Fas single nucleotide polymorphisms and risk of thyroid and salivary gland carcinomas: A case-control analysis

BACKGROUND

The purpose of this study was to examine the association between 4 Fas single nucleotide polymorphisms (SNPs) and risk of differentiated thyroid carcinoma (DTC) and salivary gland carcinoma (SGC).

METHODS

We conducted a case-control study including 279 DTC cases, 165 benign thyroid disease (BTD) cases, 154 SGC cases, 61 benign salivary gland disease (BSGD) cases, and 510 controls.

RESULTS

The A744G SNP genotype distribution was significantly different between subjects with SGC or BSGD and controls, while that of the A18272G SNP was significantly different between subjects with DTC or SGC and controls. Risk of SGC was significantly elevated for the 22628 heterozygous CT genotype (odds ratio [OR] = 1.5, p = .050), and risk of BSGD was elevated for the 22628 homozygous TT genotype (OR = 2.9, p = .023).

CONCLUSION

Fas C22628T SNP may be associated with risk of SGC and BSGD, but none of the investigated Fas SNPs was associated with risk of DTC.

Papillary thyroid cancer: monitoring and therapy

The last 10 years have seen a major paradigm shift in the management of thyroid cancer, with greater reliance on serum thyroglobulin and neck ultrasonography, and less emphasis on routine diagnostic whole-body radioactive iodine scanning for detection of recurrent disease. As our follow-up tests become more sensitive for detection of recurrent disease, we are finding many asymptomatic patients who have low-level persistent disease many years after initial therapy that may or may not benefit from additional testing and therapy. These difficult issues have been addressed by at least five different sets of guidelines published recently by various thyroid specialty organizations around the world. In this article, the authors compare and contrast the recommendations from the various guidelines in an attempt to define areas of consensus and explore possible reasons for differing recommendations.

Baseline chromosome aberrations in children

Field studies conducted in children exposed to ionizing radiation and industrial chemicals have consistently reported increased frequencies of chromosome aberrations in those environmentally exposed than in referent subjects. Exposure(s) occurring during childhood--as well as in utero--may continue for several years, become chronic, and eventually play a relevant role in the etiology of childhood as well as adulthood cancers. Indeed the statistical association between CA frequency in peripheral blood lymphocytes and cancer risk detected in occupationally exposed adults supports the hypothesis that CA is a predictor of cancer. These facts suggest the usefulness of including CA as biomarkers of genetic damage in epidemiologic studies of children exposed to environmental pollutants. As reported for other cytogenetic biomarkers, CA frequency may vary with gender and age in children as well as in adults. Estimates of the baseline frequency of CA in a pediatric population is a prerequisite in planning epidemiologic investigations of children exposed to low level of environmental genotoxic agents. The CA baseline levels were estimated from 16 published epidemiologic studies and from a large sample of Czech children aged 7-16 years (n=1214) and 206 newborns, all serving as referents (not exposed individuals). For the whole referent population (age range 0-19 years) the mean CA frequency estimated from the published findings was 1.24% (95%CI=1.05-1.47). Similar baseline levels were found for chromosome breaks frequency in boys and girls: 1.22% (95%CI=1.12-1.32) and 1.21% (95%CI=1.10-1.31), respectively. Among newborns CA baseline frequency was 1.14% (95%CI=0.96-1.32). Based on the reviewed studies and the reanalysed data, CA baseline levels were similar in boys and girls and failed to show any increase with age.

Sonographic detection of thyroid cancer in breast cancer patients

The purpose of our study was to analyze the incidence of incidental thyroid cancers which were detected by simultaneous sonographic examination of breast and thyroid glands. Between January 2001 and March 2004, 518 patients were diagnosed with breast cancer after modified radical mastectomy (n=369) or breast conserving surgery (n=149). We screened thyroid glands when we examined breast for diagnosis and follow-up after surgery. If we found the sonographic finding of suspicious for malignancy in thyroid, we immediately performed ultrasound-guided fine needle aspiration biopsy (FNAB). Forty-two cases showed suspicious sonographic findings and of those, 18 cases (42.9%) were determined to have suspicious malignant cytology by ultrasound guided FNAB. Among 518 breast cancers, total 13 cases (2.5%) were diagnosed with papillary carcinoma after thyroidectomy. The mean longest diameter of the thyroid masses was 9.9 mm (range 1-30 mm). Six cases (6/13, 46.2%) were diagnosed as simultaneous breast and thyroid cancers, and the rest of the thyroid cancers were detected after 6 to 33 months (mean 16.5 months) after surgery. In conclusion, the patients with breast cancer had a high incidence (2.5%) of thyroid cancer. Sonographic screening is useful for the early detection of thyroid cancer.

Patterns of cancer incidence among US Hispanics/Latinos, 1995-2000

OBJECTIVE

Current and comprehensive data on cancer incidence in US Latinos has been limited.

METHODS

Using a standardized approach to uniformly assign Hispanic/Latino race/ethnicity to cancer records, data from 15 central cancer registries, representing more than 85% of the US Latino population, were included in the analysis. Average annual age-adjusted incidence rates and standard errors were calculated for Hispanic, non-Hispanic white and non-Hispanic black males and females. To compare cancer incidence among Hispanic and non-Hispanic populations, standardized incidence ratios (SIRs) also were calculated.

RESULTS

Latino populations had overall lower incidence for all cancers combined and the four leading cancers (breast, prostate, lung and colorectal) than non-Hispanic populations, however, cancers of lesser impact in non-Hispanic populations (liver, gallbladder, stomach, penis and cervix) were more commonly diagnosed among Latinos.

CONCLUSIONS

Understanding the patterns of cancer incidence in this diverse racial/ethnic minority group can serve to both stimulate research into the unique behaviors, exposures and genetics that drive cancer risk among Latinos and to direct prevention and control efforts tailored to this population.

Concomitância da tireoidite de Hashimoto e o carcinoma diferenciado da tireóide

OBJETIVO: Avaliar a associação da tireoidite auto-imune e o carcinoma diferenciado da tireóide na Santa Casa de Misericórdia de Goiânia-Goiás. MÉTODO: De 1395 tireoidectomias realizadas de 1994 a 2003, foram selecionadas 120 carcinomas diferenciados (27 foliculares e 93 papilíferos). Foram avaliadas as variáveis clínicas (idade e sexo) com apresentação de freqüências e de sumários de medidas-resumo na descrição estatística. Para aferir a associação de tireoidite auto-imune e carcinoma diferenciado da tireóide em função dos achados histopatológicos, utilizou-se tabelas de contingência e análise pelo teste não paramétrico do quiquadrado de Pearson. Em todos os testes estatísticos foi adotado um nível de significância de 5% (p<0,05). RESULTADOS: 11,1% dos carcinomas foliculares e 18,3% dos carcinomas papilíferos estão associados à tireoidite auto-imune. Existe uma relação de freqüências quatro vezes maior da tireoidite auto-imune com o carcinoma diferenciado da tireóide em comparação com outras doenças tireoideanas (16,7% X 3,6%). CONCLUSÕES: Tais resultados permitem inferir que a associação entre a tireoidite auto-imune e o carcinoma diferenciado da tireóide é mais que casual, exigindo uma observação clínico-laboratorial cuidadosa nos portadores da doença auto-imune.

Incidental Thyroid Carcinoma in Thyrotoxic Patients Treated by Surgery

BACKGROUND AND AIMS

Thyroid malignancy detected incidentally in patients who are operated for thyrotoxicosis has been reported at different rates. The aim of this study was to investigate the rate of incidental thyroid carcinoma in thyrotoxic patients managed with surgery in our institution.

METHODS

Of the 375 thyrotoxic patients who had thyroid surgery between the years of 1997-2004, 70.7% were females and 29.3% were males. Among thyrotoxic patients 65.3% (n=245) had toxic multinodular goiter (TMG), 16.8% (n=63) had toxic adenoma (TA) and 17.9% (n=67) had Graves' disease.

RESULTS

Twenty-six (6.9%) of all thyrotoxic patients had thyroid carcinoma. Eighteen (7.3%) of TMG, 4 (6.3%) of TA and 4 (6%) of Graves' disease patients had thyroid carcinoma. Histologic examination revealed 18 papillary (9 microscopic), 5 follicular, 2 hurthle cell and 1 anaplastic carcinoma.

CONCLUSION

In our study, incidental thyroid carcinoma was found in 6.9% of subjects with thyrotoxicosis. Papillary thyroid microcarcinomas constituted 34.6% (26/9) of these newly diagnosed thyroid carcinomas. The incidence of thyroid carcinoma was not higher in subjects with Graves' disease compared to TMG and TA. The rate of incidental thyroid carcinoma in subjects with thyrotoxicosis treated with surgery was similar to previous studies reported from different countries.

Time trends of incidence rates of thyroid cancer in Israel: what might explain the sharp increase

BACKGROUND

Worldwide changes in the incidence, histological type, and prognosis of thyroid cancer (TC) have been observed. Regional differences in the spectrum of TC may be related to genetic factors, ionizing radiation, lifestyle, and nutritional iodine, as well as to the availability of medical services.

METHODS

Analysis of records of 5864 TC patients (diagnosed between 1982 and 2001), retrieved from the Israel National Cancer Registry.

RESULTS

The age-standardized incidence rate (ASR per 100,000 persons) of TC among Jewish women in 2001 was 12.45 (higher than generally reported in the world) and 3.68 among Jewish men. There was a significant increase in the ASR for TC between 1982 and 2001 in the Jewish population (by 101% among women and by 25% among men, p < 0.01 for both), mainly due to papillary carcinoma. TC incidence increased in the non-Jewish population from 2.33 to 6.02 in women (p < 0.05) and from 1.13 to 2.49 in men (p > 0.05). TC incidence was similar among immigrants from Europe and America arriving in Israel before 1990 or after 1990 for both genders. An improved 5-year survival was noted in patients diagnosed between 1992 and 1996 in comparison to patients diagnosed earlier: 1982-1986 (86% versus 78%, p < 0.01).

CONCLUSIONS

A marked increase in TC incidence over the last two decades (mainly due to papillary carcinoma) has been noted in different Israeli subpopulations, being the highest in Jewish women. The increase trends were similar regardless of gender or ethnicity. The reasons for this rise in TC incidence and improvement in the survival are probably multifactorial and may relate partly to increased diagnostic vigilance and changes in clinical practice.

Analysis of chromosome damage in circulating lymphocytes of radiological workers affected by thyroid nodules

The aim of our study was to assess whether or not thyroid nodularity in combination with occupational exposure to low levels of ionising radiation would be correlated with chromosome damage in peripheral lymphocytes. Conventional chromosome-aberration analysis was performed on a group of 92 hospital workers with or without thyroid nodules. On the basis of measurements of their exposure levels, the workers were classified into a low (mean total level=0.03 mSv), medium (mean total level=1.04 mSv) or high (mean total level=8.60 mSv) exposure category. Our results indicate that among workers with thyroid nodules, the high-exposed workers showed significantly higher levels of both total (2.35+/-0.34 per 100 cells) and chromosome-type aberrations (1.46+/-0.20 per 100 cells) than medium-exposed (0.98+/-0.42 and 0.68+/-0.25 per 100 cells, respectively) or low-exposed workers (1.11+/-0.29 and 0.58+/-0.17 per 100 cells, respectively). Workers without thyroid nodules had comparable frequencies of chromosome aberrations among the three exposure categories. To our knowledge, this is the first study revealing a slight, but significant increase of chromosome damage in peripheral lymphocytes from hospital workers who developed thyroid nodules under conditions of occupational exposure to radiation well below the threshold limit for the workplace. The existence of a possible association between chromosome aberrations and development of thyroid nodularity will be discussed.

Thyroid cancer in Luxembourg: a national population-based data report (1983-1999)

BACKGROUND

Twenty years after the nuclear accident in Chernobyl (Eastern Europe), there is still a controversial debate concerning a possible effect of the radioactive iodines, especially I-131, on the increase of thyroid carcinomas (TCs) in Western Europe. Time trends in incidence rates of TC in Luxembourg in comparison with other European countries and its descriptive epidemiology were investigated.

METHODS

The population-based data of the national Morphologic Tumour Registry collecting new thyroid cancers diagnosed between 1983 and 1999 at a nation-wide level in the central division of pathology were reviewed and focused on incidence rates of TC. Data from 1990 to 1999 were used to evaluate the distribution by gender, age, histological type, tumour size and the outcome.

RESULTS

Out of 310 new thyroid carcinomas diagnosed between 1990 and 1999, 304 differentiated carcinomas (A: 80% papillary; B: 14.5% follicular; C: 3.5% medullary) and 6 anaplastic/undifferentiated TCs (D: 2%) were evaluated. The M/F-ratio was 1:3.2, the mean age 48.3 years (range: 13-92). The overall age-standardized (world population) incidence rates over the two 5-year periods 1990-1994 and 1995-1999 increased from 7.4 per 100,000 to 10.1 per 100,000 in females, from 2.3 per 100,000 to 3.6 per 100,000 in males. Only 3 patients were children or adolescents (1%), the majority of the patients (50%) were between 45 and 69 years of age. The percentage of microcarcinomas (<1 cm) was A: 46.4%, (115/248); B: 13.3%, (6/45); C: 27.3%, (3/11). The unexpected increase of TCs in 1997 was mainly due to the rise in the number of microcarcinomas. The observed 5-year survival rates for both genders were A: 96.0+/-2%; B: 88.9%; C: 90.9%; D: 0%. Prognosis was good in younger patients, worse in males and elderly, and extremely poor for undifferentiated TCs.

CONCLUSION

The increasing incidence rates of TC, especially of the papillary type, seem mainly due to a rise in diagnosed microcarcinomas due to some extent to a change in histologic criteria and to more efficient diagnostic tools. This rise appears to be independent of the number of surgical treatments, the immigration rate, and the Chernobyl fallout as the incidence of TC in children remained stable.

Unexpected additional increase in the incidence of thyroid cancer among a recent birth cohort in Switzerland

Data collected by the Swiss Cancer Registries Network (ASRT/VSKR) have been used to analyse trends in thyroid cancer during the last available 20 years, to make within-country geographical comparisons for current incidence rates. Age-standardized (European population) incidence rates per 100,000 for all morphologies combined ranges from 1.62 to 2.99 among males and from 2.13 to 8.09 among females in Switzerland. Regression analyses for both sexes combined detected an increase in time for papillary cases and a decrease for other types. Age-period-cohort analyses revealed that the youngest cohorts of men and women born after 1940 had an increased risk of all types of thyroid cancer while the cohort of people born between 1920 and 1939 were at increased risk of the papillary subtype. Assuming a higher sensitivity to ionizing radiation among the youngest people, a Chernobyl effect cannot be definitively excluded and continuous study of this topic should be encouraged.

Reproductive history, occupational exposures, and thyroid cancer risk among women textile workers in Shanghai, China

OBJECTIVES

Thyroid cancer risk has been previously associated with increased age at first pregnancy and history of miscarriage. Occupational risk factors for thyroid cancer, with the exception of radioactive iodine, have not been well investigated. We conducted a case-cohort study nested in a cohort of 267,400 female textile workers in Shanghai, China, who had been followed for cancer incidence during 1989-1998.

METHODS

The analysis included 130 incident thyroid cases and 3,187 subcohort non-cases. Reproductive history was determined by questionnaire at baseline. Historical exposures were reconstructed from work history and information on factory processes and exposures. Cox proportional hazards analysis was performed to estimate hazard ratios (HR) for reproductive factors and occupational exposures.

RESULTS

Associations were observed between thyroid cancer and employment in jobs with 10 or more years of benzene exposure (HR 6.43, 95% CI: 1.08, 38) and formaldehyde exposure (HR 8.33, 95% CI: 1.16, 60). Administration workers also had an increased risk (HR 1.56, 95% CI: 1.08, 2.25). No associations between examined reproductive factors and thyroid cancer were observed in this study.

CONCLUSIONS

Despite statistically imprecise risk estimates, the findings suggest potential associations with some occupational chemical exposures in this cohort of textile workers.

Molecular pathogenesis of euthyroid and toxic multinodular goiter

The purpose of this review is to summarize current knowledge of the etiology of euthyroid and toxic multinodular goiter (MNG) with respect to the epidemiology, clinical characteristics, and molecular pathology. In reconstructing the line of events from early thyroid hyperplasia to MNG we will argue the predominant neoplastic character of nodular structures, the nature of known somatic mutations, and the importance of mutagenesis. Furthermore, we outline direct and indirect consequences of these somatic mutations for thyroid pathophysiology and summarize information concerning a possible genetic background of euthyroid goiter. Finally, we discuss uncertainties and open questions in differential diagnosis and therapy of euthyroid and toxic MNG.

Epidemiology of thyroid microcarcinoma found in autopsy series conducted in areas of different iodine intake

The prevalence of thyroid microcarcinomas found at autopsies is 100-1000 times higher than in clinical cancer. The epidemiological and histological characteristics of thyroid microcarcinomas in consecutive series of autopsies performed in two areas of different iodine intake were investigated. Iodine deficient (ID) area: n = 222 (M = 109, F = 113), median age: 74-76 years, median iodine excretion (MIE) of nursing home residents from this area: 70 microg/g creatinine. Iodine sufficient (IS) area: n = 221 (M = 132, F = 89), median age: 68 years, MIE: 500 microg/g creatinine. When compared to the IS area, the results obtained in the ID area showed a higher thyroid weight (mean 27.75 g +/- 18.43 g vs. 16.5 g +/- 9.6 g, p < 0.0001) and a larger number of goitrous glands (50/222 vs. 5/221, p < 0.0001). Altogether 21 microcarcinomas were found (4.74%) with no iodine intake- or gender-related difference: ID n = 11 (4.95%), M/F = 8/3; IS n = 10 (4.52%), M/F = 6/4. Microcarcinomas seemed to be more prevalent in the 40-59-year age group. All microcarcinomas were of the papillary type. In conclusion, compared to clinical cancer, thyroid microcarcinomas are characterized by a two-scale higher prevalence, are not related to iodine intake, gender or nodularity, are most exclusively of the papillary type.

Opportunities for cancer epidemiology in developing countries

Most cancer epidemiology studies involve people living in North America and Europe, which represent only a fraction of the global population. The wide variety of dietary, lifestyle and environmental exposures, as well as the genetic variation among people in developing countries can provide valuable new information on factors that contribute to cancer or that protect against it. What are the challenges and advantages to performing large epidemiological studies in developing nations?

Evidence of increased chromosomal abnormalities in French Polynesian thyroid cancer patients

PURPOSE

The aim of this study was to evaluate the frequency of chromosomal abnormalities in thyroid cancer patients before and after radioactive iodine administration in order to assess cytogenetic particularity in Polynesian thyroid cancer patients.

METHODS

Chromosomal abnormalities were studied in 30 Polynesian patients with differentiated thyroid cancer, prior to and 4 days after 131I administration. Unstable chromosomal abnormalities were counted in peripheral blood lymphocytes using a conventional cytogenetic method. Peripheral blood was irradiated in vitro at different doses (0.5, 1 and 2 Gy) in order to establish the dose-response of the lymphocytes. Control groups were composed of 50 European thyroid cancer patients before and after first administration of 131I, and of ten European healthy donors. In addition, in vitro irradiation assays were performed at different doses (0.5, 1 and 2 Gy).

RESULTS

The relative risk of spontaneous dicentrics before any radiation treatment was 2.9 (95% CI 1.7-5.1) times higher among Polynesian thyroid patients than among European thyroid cancer patients. After in vitro irradiation, the rise in frequency of dicentrics was similar in the Polynesian thyroid cancer group and the European thyroid patients and healthy donors. Four days after administration of 3.7 GBq 131I, the relative risk for a dicentric per cell was 1.3 (95% CI 1.0-1.5) times higher in Polynesian than in European patients. This can be explained by higher 131I retention in Polynesian compared with European patients. The results obtained revealed an increased frequency of cytogenetic abnormalities in Polynesian thyroid cancer patients compared with European control patients.

CONCLUSION

These preliminary findings are compatible with possible previous environmental aggression and therefore imply a need for further investigations on larger series including, in particular, French Polynesian healthy donors. In addition to French Polynesians, Maori and Hawaiian control groups could be useful.

Second malignancies in pediatric patients: imaging findings and differential diagnosis

Therapeutic advances in the treatment of pediatric neoplasms have improved the prognosis but have also increased the risk of developing rare second malignant neoplasms (SMNs). Primary neoplasms that are often associated with SMNs include lymphoma, retinoblastoma, medulloblastoma, neuroblastoma, and leukemia. The most common SMNs are central nervous system (CNS) tumors, sarcomas, thyroid and parotid gland carcinomas, and leukemia, particularly acute myeloblastic leukemia. Genetic predisposition, chemotherapy, and especially radiation therapy are implicated as pathogenic factors in SMN. All survivors of childhood cancer should have lifelong follow-up, preferably with magnetic resonance imaging, which does not require ionizing radiation and provides greater anatomic detail and resolution in the head and neck region and the CNS. A new or progressive lesion may represent recurrence of the primitive neoplastic process, late radiation injury, or, more infrequently, an SMN. Differential diagnosis can be very difficult, and outcome is often fatal. Treatment protocols should be modified to reduce the risk for SMN without compromising the effectiveness of initial therapy. Clinicians should individualize treatment for patients who are genetically predisposed to SMN. In addition, radiologists should be familiar with the long-term consequences of antineoplastic therapy to facilitate diagnosis and anticipate adverse outcomes.

Differentiated thyroid cancer: Growth factors, oncogenes and environmental influences

The present data of growth factors, oncogenes, tumor-suppressor-genes and environmental factors can be summarized in thus: thyrotropin, growth factors and other hormones do increase thyrocyte growth and specific mutations of growth factor receptors (thyrotropin receptor [TSH-R], alpha subunit of hetero-trimeric transducer protein [GSP]) cause autonomously functioning thyroid tissue and differentiated thyroid carcinoma. In the thyroid, as in other organs, genes that are found to be differentially expressed between normal thyroid tissue and thyroid carcinomas can be used as targets for molecular-based diagnosis and therapy. Deregulation of tumor suppressor gene p53, however, parallels dedifferentiation of papillary and follicular thyroid cancer but has been found in few cases only. Iodide inhibiting thyrocyte growth will have to be investigated more intensively after sodium-iodide-symporter (NIS) has been cloned, and studies may now be available that could lead to form of conservative treatment in especially dedifferentiated thyroid cancer.