Explaining the increasing incidence of differentiated thyroid cancer

Demographic, clinical, and surgical features of patients undergoing thyroidectomy due to thyroid lesions in Southern Iran: A cross-sectional study

Background and Aims

The incidence of thyroid cancer has witnessed a significant global increase and stands as one of the most prevalent cancers in Iran. This surge is primarily attributed to the escalating incidence of papillary thyroid cancer (PTC), with overdiagnosis emerging as an equally noteworthy factor. Consequently, this study aims to ascertain the incidence of thyroid cancer, along with its clinical presentation, demographic characteristics, and surgical features in patients undergoing thyroid surgery.

Methods

This cross-sectional study involved the evaluation of patient files from referral centers in Shiraz spanning the years 2015-2020. Demographic and clinical information pertaining to thyroid cancer was extracted and subsequently analyzed using SPSS software.

Results

A total of 533 documented cases of thyroid cancer undergoing surgery revealed an annual rate of 89 cases in our location. The average age of the patients was 43.9 ± 13.4 years (ranging from 13 to 92), with females constituting 429 (83.5%) of the cases, and 278 (54.1%) being malignant. Conventional PTC emerged as the most prevalent pathology, accounting for 239 (45.0%) of the cases. Patients with thyromegaly exhibited significantly higher incidences of nonmalignant tumors (p = 0.01), while those with malignant tumors were notably younger than those with nonmalignant tumors (p = 0.001).

Conclusion

Our study revealed a progressive rise in the number of patients undergoing thyroidectomy over the years, with PTC constituting the majority of cases. Malignant cases were more frequently observed in younger patients, and in smaller lesion sizes, highlighting the importance of early screening and optimizing detection methods, especially in high-risk populations.

Management of thyroid cancer: results from a German and French patient survey

OBJECTIVE

Various national and international guidelines for the management of thyroid cancer exist. The aim of this survey was to evaluate whether patients experience differences regarding the management of thyroid cancer in Germany and in France.

METHODS

An online survey addressing diagnosis, treatment, aftercare, and information needs of thyroid cancer survivors was set up by the German and the French nationwide thyroid cancer self-help organizations. The survey consisted of up to 70 questions depending on the given answers. Descriptive statistics and univariate comparisons, if appropriate, for comparing thyroid cancer survivors in Germany and France were performed.

RESULTS

In total, 1254 thyroid cancer survivors took part in the survey, of whom 1005 were included in the analysis, 618 from Germany and 387 from France. Remarkable differences between the two countries were observed regarding waiting times, diagnostics, surgical complications, radioiodine treatment, and aftercare of the patients. A high disease burden and lack of information regarding the condition and its treatment were reported in both countries.

CONCLUSION

This large survey showed that despite various guidelines for the management of thyroid cancer, thyroid cancer survivors' experiences are noticeably different between two big European countries. Lack of information and unmet needs are still tasks to be addressed in order to optimize thyroid cancer care.

Bilateral axillo-breast approach robotic thyroidectomy: review of a single surgeon's consecutive 317 cases

Background

Bilateral axillo-breast approach robotic thyroidectomy (BABA RT) is one of the most popular remote-access approaches for thyroid surgery. This study aimed to evaluate the surgical outcomes of BABA RT.

Methods

Medical records of patients who underwent BABA RT between July 2008 and July 2016 were retrospectively reviewed. Surgeries were performed by one surgeon at one institution. Clinicopathological features and postoperative surgical outcomes were evaluated.

Results

A total of 317 patients were enrolled. The mean age was 40.0±9.7 years, and 287 (90.5%) were female. The mean tumor size was 1.02 cm. Papillary thyroid carcinoma (PTC) was most commonly seen (n=282, 88.8%), followed by benign nodules (n=33, 10.5%) and follicular thyroid carcinoma (n=2, 0.6%). Total thyroidectomy was performed in 202 (63.7%) patients, while unilateral lobectomy was performed in 113 (35.6%). Two patients (0.6%) had transient vocal cord palsy, but none showed permanent vocal cord palsy. Thirty-four (16.8%) patients developed hypoparathyroidism, 33 (16.3%) were transient and 1 (0.5%) was permanent. The mean operation time for total thyroidectomy and lobectomy was 264.9±52.4 and 203.4±47.6 min, respectively. A decrease in operation time in total thyroidectomy was observed in 49-51 cases (P=0.015). Four patients (1.4%) had local recurrence during the median follow-up of 61±23 months.

Conclusions

BABA RT can be performed safely in selected patients with thyroid nodules. The learning curve duration for BABA RT was 49-51 cases of total thyroidectomy.

Epidemiology of Thyroid Cancer: A Review of the National Cancer Database, 2000-2013

Objective  To show the recent trends in thyroid cancer in the United States, elucidate the characteristics of stage IV thyroid cancer, and consider the effects of diagnostic testing on the rising incidence of thyroid cancer. Design  A retrospective population-based study conducted using the National Cancer Database from 2000-2013 (NCDB). Demographics of patients presenting with stage IV thyroid cancer were compared to patients presenting with all other stages using the chi-square testing. The incidence rates were examined with the trend graphs. Results  When compared to stages I-III, there was an increased incidence of stage IV thyroid cancer in: Medicare, lower level of education, lower income, advanced age, male sex, increased number of comorbidities, further distance from a treatment facility, and medullary/anaplastic histology. The incidence of thyroid cancer increased from 7.1 per 100,000 in 2000 to 17.6 per 100,000 in 2013. During this same time period, stage IV disease increased 1 per 100,000. The increase in the incidence of thyroid cancer was almost entirely due to an increase in papillary cancer. Conclusions  The United States has continued to see a rise in the incidence of thyroid cancer over the last decade, largely due to the detection of papillary cancers. During this same time, the incidence of stage IV thyroid cancer increased as well. Because early diagnosis and treatment of an increasing number of potentially lethal cancers should lead to a decrease in metastatic disease, we suggest that the increasing incidence of thyroid cancer in the United States is due to overdiagnosis and that more aggressive disease is not being removed by early detection.

The impact of BMI on clinical progress, response to treatment, and disease course in patients with differentiated thyroid cancer

Introduction

Obesity is a serious health problem worldwide, particularly in developed countries. It is a risk factor for many diseases, including thyroid cancer. The relationship between obesity and prognostic factors of thyroid cancer is unclear.

Aims

We sought to ascertain the relationship between body mass index (BMI) and clinicopathological features increasing the risk of poor clinical course, treatment response, and clinical outcome in patients with differentiated thyroid cancer (DTC).

Subjects & methods

The study included 1181 patients with DTC (88% women and 12% men) treated at a single center from 2000 to 2016. BMI before surgery and aggressive clinicopathological features, according to the American Thyroid Initial Risk stratification system, were analyzed. The relationship between BMI and initial risk, treatment response, and final status of the disease was evaluated, incorporating the revised 2015 American Thyroid Association guidelines and the 8^th edition of the American Joint Committee on Cancer/Tumor-Node-Metastasis (AJCC/TNM) staging system. Patients were stratified according to the World Health Organization classification of BMI. Statistical analysis was performed using univariate and multivariate logistic regression analysis.

Results

Median follow-up was 7.7 years (1–16 years). There were no significant associations between BMI and extrathyroidal extension (microscopic and gross), cervical lymph node metastasis, or distant metastasis in univariate and multivariate analyses. BMI did not affect initial risk, treatment response or disease outcome. Obesity was more prevalent in men (p = 0.035) and in patients ≥55 years old (p = 0.001). There was no statistically significant relationship between BMI and more advanced TNM stage in patients ≤55 years old (stage I vs. stage II) (p = 0.266) or in patients >55 years old (stage I–II vs. III–IV) (p = 0.877).

Conclusions

Obesity is not associated with more aggressive clinicopathological features of thyroid cancer. Obesity is not a risk factor for progression to more advanced stages of disease, nor is it a prognostic factor for poorer treatment response and clinical outcome.

Are thyroid nodules associated with sex-related hormones? A cross-sectional SPECT-China study

OBJECTIVE

Little is known about the association between thyroid nodules (TNs) and endogenous sex hormones. We aimed to investigate the relationship between TNs and sex-related hormones among men in China.

SETTING

The data were obtained from a cross-sectional study Survey on Prevalence in East China for Metabolic Diseases and Risk Factors (SPECT-China study, 2014-2015) based on the population.

PARTICIPANTS

In total, 4024 men over 18 years of age who were not using hormone replacement therapy and who underwent complete assays of the serum total testosterone (T), oestradiol (E₂), follicle-stimulating hormone (FSH), luteinising hormone (LH) and sex hormone-binding globulin (SHBG) levels as well as thyroid ultrasonography (US) enrolled in this study.

RESULTS

Of the 4024 participants (54.15±13.08 years old), 1667 participants (41.4%) had TNs. Men with TN(s) (TN(+) group) had significantly lower levels of total T and SHBG and higher E₂/T levels compared with the men without TN(s) (TN(-) group) (p<0.05). The TN prevalence decreased with the quartiles of the SHBG level (p<0.05). Binary logistic analysis showed that lower quartiles of SHBG had a greater risk of TN(s) (all p for trend <0.05). This association persisted in the fully adjusted model (p for trend=0.017), in which, for the lowest compared with the highest quartile of SHBG, the OR of TN(s) was 1.42 (95% CI 1.07 to 1.89). No statistically significant association was found between sex-related hormones and US characteristics associated with malignancy (nodule >10 mm, microcalcification and a 'taller' than 'wider' shape).

CONCLUSIONS

TNs are highly prevalent in men in China. A lower SHBG level was significantly associated with TN among men. The potential role of SHBG in the pathogenesis of the TN remains to be elucidated.

Thyroid cancer burden in Central and South America

RATIONALE AND OBJECTIVE

Incidence of thyroid cancer (TC) is rapidly increasing worldwide, but little is known about the TC burden in Central and South America (CSA). We describe the geographic patterns and trends of TC by sex in CSA.

METHODS

We obtained regional- and national-level incidence data from 48 population-based cancer registries in 13 countries and nationwide cancer deaths from the WHO mortality database for 18 countries. We estimated world population age-standardized incidence rates (ASRs) and age-standardized mortality rates (ASMRs) per 100,000 person-years. We calculated ASRs by histological subtype. We estimated the annual percentage change (EAPC) to describe time trends.

RESULTS

Between CSA countries, TC incidence and mortality rates varied from 8-fold to 12-fold and from 2-fold to 5-fold, respectively. In 2003-2007, the highest TC ASRs in females and males were in Ecuador (16.0 and 3.5, respectively), Brazil (14.4 and 3.4), Costa Rica (12.6 and 2.1) and Colombia (10.7 and 2.5). The highest ASMRs were in Ecuador, Colombia, Mexico, Peru and Panama (0.68-0.91 in females and 0.41-0.48 in males). Papillary TC was the most commonly diagnosed histological subtype, following the same incidence pattern as overall TC. In Argentinean, Brazilian, Chilean and Costa Rican females TC incidence increased by 2.2-17.9% annually, and papillary TC increased by 9.1-15.0% annually, while mortality remained stable between 1997 and 2008. In males, trends in TC were stable.

CONCLUSION

TC occurred more frequently in females than in males. The overall high incidence and low mortality of TC suggest identification of subclinical disease due to improved detection methods.

Cancer patterns and trends in Central and South America

RATIONALE AND OBJECTIVE

Cancer burden is increasing in Central and South America (CSA). We describe the current burden of cancer in CSA.

METHODS

We obtained regional and national-level cancer incidence data from 48 population-based registries (13 countries) and nation-wide cancer mortality data from the WHO (18 countries). We estimated world population age-standardized incidence and mortality rates per 100,000 person-years.

RESULTS

The leading cancers diagnosed were prostate, lung, breast, cervix, colorectal, and stomach, which were also the primary causes of cancer mortality. Countries of high/very high human development index (HDI) in the region experienced a high burden of prostate and breast cancer while medium HDI countries had a high burden of stomach and cervical cancers. Between countries, incidence and mortality from all cancers combined varied by 2-3-fold. French Guyana, Brazil, Uruguay, and Argentina had the highest incidence of all cancers while Uruguay, Cuba, Argentina, and Chile had the highest mortality. Incidence of colorectum, prostate and thyroid cancers increased in Argentina, Brazil, Chile and Costa Rica from 1997 to 2008, while lung, stomach and cervical cancers decreased.

CONCLUSION

CSA carries a double-burden of cancer, with elevated rates of infection- and lifestyle-related cancers. Encountered variation in cancer rates between countries may reflect differences in registration practices, healthcare access, and public awareness. Resource-dependent interventions to prevent, early diagnose, and treat cancer remain an urgent priority. There is an overwhelming need to improve the quality and coverage of cancer registration to guide and evaluate future cancer control policies and programs.

Different Radioiodine Dose for Remnant Thyroid Ablation in Patients With Differentiated Thyroid Cancer: A Meta-analysis

OBJECTIVE

Remnant thyroid ablation is crucial in the management of patients with differentiated thyroid cancer. However, the optimal dose of radioactive I for ablation is still controversial. This study aimed to compare the success rate of different activities of I for postoperative remnant ablation in randomized controlled trials (RCTs) and to determine the optimal dose.

PATIENTS AND METHODS

Sources were retrieved from the Cochrane Library, Medline, Embase, Scopus, and Google Scholar until March 2014. All RCTs that assessed the efficacy of different doses of I for ablation were selected. After data extraction, statistics were performed by Review Manager 5.2 software.

RESULTS

Seventeen RCTs were considered eligible, involving 3737 patients. The overall methodological quality of the studies was good. The rate of successful remnant ablation of low versus moderate I activities (risk ratio [RR], 0.89; 95% confidence interval [CI], 0.80-1.00; P = 0.06) and moderate versus high I activities (RR, 0.94; 95% CI, 0.89-1.00; P = 0.05) showed no significant differences. However, high I activities had 11% higher successful ablation rate than low activities with an RR of 0.89 (95% CI, 0.81-0.97; P = 0.008), which was significant.

CONCLUSIONS

We summarized all available randomized evidence to demonstrate that high dose of I was significantly better than low dose to achieve successful remnant thyroid ablation.

Do US thyroid cancer incidence rates increase with socioeconomic status among people with health insurance? An observational study using SEER population-based data

OBJECTIVES

The US thyroid cancer incidence rates are rising while mortality remains stable. Trends are driven by papillary thyroid cancer (PTC), the predominant cancer subtype which has a very good prognosis. We hypothesised that health insurance and high census tract socioeconomic status (SES) are associated with PTC risk.

DESIGN

Relationships between thyroid cancer incidence, insurance and census tract SES during 2007-2010 were examined in population-based cancer registries. Cases were stratified by tumour histology, size and demography.

SETTING

Surveillance, Epidemiology, and End Results (SEER) registries covering 30% of the US population.

RESULTS

PTCs accounted for 88% of incident thyroid cancer cases. Small PTCs (≤ 2 cm) accounted for 60% of cases. Unlike non-PTC cases, the majority of those diagnosed with PTC were <50 years of age and had ≤ 2 cm tumours. Rate ratios (RR) of PTC diagnoses increased monotonically with SES among fully insured cases. The effect was strongest for small PTCs, high-SES versus low-SES quintile RR=2.7, 95% CI 2.6 to 2.9, two-sided trend test p<0.0001. For small PTC cases with insurance, the monotonic increase in incidence rates with rising SES persisted among cases younger than 50 years of age (RR=3.3, 95% CI 3.0 to 3.5), women (RR=2.6, 95% CI 2.5 to 2.8) and Caucasians (RR=2.5, 95% CI 2.4 to 2.7). Among the less than fully insured, rates generally decreased with increasing SES.

CONCLUSIONS

The >2.5-fold increase in risk of PTC diagnosis among insured individuals associated with high SES may be informative with respect to the contemporary issue of PTC overdiagnosis.

Analysis of pattern of occurrence of thyroid carcinoma between 2001 and 2010

INTRODUCTION

An ongoing discussion is found in medical literature about the reasons for changes in thyroid carcinoma incidence patterns over the last decades.

OBJECTIVE

To analyze the clinical and pathological characteristics of thyroid carcinoma cases over a decade.

METHODS

Cross-sectional study over an historical cohort. Medical records of 628 thyroid cancer cases in a single center were reviewed. 597 patients were included. Microcarcinoma cases were selected for a qualitative analysis phase, in which medical records were reviewed for better understanding of thyroid nodule and thyroid cancer diagnosis process.

RESULTS

An increase in the proportion of cases with thyroid cancer diagnosis was observed throughout the decade; new cases were predominantly tumors of less than 2 cm, with histopathological signs of low aggressiveness. There was an increase in proportion of cases with malignant cytological results among microcarcinomas.

CONCLUSION

There is a trend for increase in thyroidectomies due to cancer in this institution, with proportional increment of cases with histopathological characteristics indicative of early disease. Among microcarcinomas, there is an increasing group represented by cancer cases that were not incidentally diagnosed, related to an enhancement in preoperative diagnostic methods.

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

Most epidemiological studies concerning differentiated thyroid cancers (DTC) indicate an increasing incidence over the last two decades. This increase might be partially explained by the better access to health services worldwide, but clinicopathological analyses do not fully support this hypothesis, indicating that there are carcinogenetic factors behind this noticeable increasing incidence. Although we have undoubtedly understood the biology and molecular pathways underlying thyroid carcinogenesis in a better way, we have made very little progresses in identifying a risk profile for DTC, and our knowledge of risk factors is very similar to what we knew 30-40 years ago. In addition to ionizing radiation exposure, the most documented and established risk factor for DTC, we also investigated the role of other factors, including eating habits, tobacco smoking, living in a volcanic area, xenobiotics, and viruses, which could be involved in thyroid carcinogenesis, thus, contributing to the increase in DTC incidence rates observed.

Obesity and thyroid cancer: epidemiologic associations and underlying mechanisms

The incidence of thyroid cancer has been rising over the past few decades along with a parallel increase in obesity. Observational studies have provided evidence for a potential association between the two. By contrast, clinical data for a link between type 2 diabetes mellitus, a condition strongly associated with obesity, and thyroid cancer are limited and largely not supportive of such an association. Obesity leads to hypoadiponectinemia, a pro-inflammatory state, and insulin resistance, which, in turn, leads to high circulating insulin and insulin-like growth factor-1 levels, thereby possibly increasing the risk for thyroid cancer. Thus, insulin resistance possibly plays a pivotal role in underlying the observed association between obesity and thyroid cancer, potentially leading to the development and/or progression of thyroid cancer, through its interconnections with other factors including insulin-like growth factor-1, adipocytokines/cytokines and thyroid-stimulating hormone. In this review, epidemiological and clinical evidence and potential mechanisms underlying the proposed association between obesity and thyroid cancer risk are reviewed. If the association between obesity and thyroid cancer demonstrated in observational studies proves to be causal, targeting obesity (and/or downstream mediators of risk) could be of importance in the prevention and management of thyroid cancer.

Changing patterns in thyroid cancer incidence and mortality in the Slovak Republic by histological type and age

BACKGROUND

Thyroid cancer (TC) is the most common malignant disease of the endocrine system; however, in the Slovak Republic (SR), time trends of incidence and mortality according to histological type and age of patients have never been reported.

MATERIALS AND METHODS

Long-term (1968-2007) trends from the National Cancer Registry data of overall, histology and age-specific incidence and mortality in the SR have been calculated using join-point regression and other descriptive characteristics.

RESULTS

Age-standardized overall incidence rates increased significantly in females by an estimated annual percentage change (APC) of 3.6 %, and in males by 2.2 %. Overall mortality decreased by APC -2.1 % in females and -0.9 % in males. The mean ages of female and male TC patients at the time of diagnosis significantly decreased; ages at the time of death significantly increased. The incidence of papillary carcinoma rose significantly in females by 8.9 %, compared with 6.1 % in males; follicular carcinoma in males and females was stable. Medullary carcinoma was stable in females; in males, it rose by 5.2 %. Poorly differentiated TC was stable in females; undifferentiated/anaplastic carcinomas decreased in both sexes.

CONCLUSIONS

The incidence of TC, especially of selected histological types, is dramatically rising in the SR in both genders, while mortality is decreasing. Patients diagnosed in recent years are younger and died at a greater age than those reported in older national data. These trends seem to be affected by more intensive diagnosis in the most recent years.

Evolution of thyroid cancer mortality in adults in Brazil

OBJECTIVE: To assess the trend of thyroid cancer mortality in Brazil between 1980 and 2010. MATERIALS AND METHODS: An ecological study of time series. Mortality rates for thyroid cancer adjusted by age according to gender were calculated between 1980 and 2010. Data were analyzed by three distinct strategies: polynomial regression, joinpoint analysis, and moving averages. RESULTS: Over 70% of deaths occur in the elderly, regardless of sex. Among young adults, the mortality rate is low, with no difference between men and women. Among mature adults and elderly, mortality is increasing, and significantly, for women. There is a trend of decreasing mortality in all female adults and overall population, and in males and 40-59 years and overall population, both excluding the elderly, with statistical significance. CONCLUSION: Knowledge about trends allows setting priorities and allocating resources toward positive changes in this scenario in the Brazilian population.

High versus low radioiodine activity in patients with differentiated thyroid cancer: a meta-analysis

BACKGROUND

The purpose of the meta-analysis was to estimate the effectiveness and toxicity of low activity radioiodine ablation versus high activity in patients with differentiated thyroid cancer (DTC).

DESIGN

A systematic review and meta-analysis was performed by including all randomized trials of low activity versus high activity radioiodine ablation after thyroidectomy. Standard meta-analytic procedures were used to analyze the study outcomes.

RESULTS

Ten trials were considered eligible and were further analyzed. The pooled risk ratio (RR) of having a successful ablation for an activity of 1100 MBq versus 3700 MBq (seven trials, 1772 patients) was 0.94 (95% CI 0.85-1.04, p-value = 0.21). The RR for successful ablation when only thyroid hormone withdrawal was used (five trials, 1116 patients) was 0.87 (95% CI 0.72-1.06, p-value = 0.17) and it was comparable to RR when only recombinant-human TSH (rec-hTSH) (two trials, 812 patients) was used (1.00, 95% CI 0.93-1.07, p-value = 0.92). Salivary dysfunction, nausea, and neck pain were significantly more frequent among patients with higher dose for ablation.

CONCLUSION

Our meta-analysis provides some evidence from randomized trials that a lower activity of radioiodine ablation is as effective as higher dose after surgery in patients with DTC with lower toxicity.

Descriptive epidemiology of human thyroid cancer: experience from a regional registry and the "volcanic factor"

Thyroid cancer (TC), the most common endocrine tumor, has steadily increased worldwide due to the increase of the papillary histotype. The reasons for this spread have not been established. In addition to more sensitive thyroid nodule screening, the effect of environmental factors cannot be excluded. Because high incidences of TC were found in volcanic areas (Hawaii and Iceland), a volcanic environment may play a role in the pathogenesis of TC. In January 2002, the Regional Register for TC was instituted in Sicily. With a population of approximately five million inhabitants with similar genetic and lifestyle features, the coexistence in Sicily of rural, urban, industrial, moderate-to-low iodine intake, and volcanic areas provides a conducive setting for assessing the environmental influences on the etiology of TC. In Sicily, between 2002 and 2004, 1,950 new cases of TC were identified, with an age-standardized rate (world) ASR(w) = 17.8/10(5) in females and 3.7/10(5) in males and a high female/male ratio (4.3:1.0). The incidence of TC was heterogeneous within Sicily. There were 2.3 times more cases in the Catania province (where most of the inhabitants live in the volcanic area of Mt. Etna): ASR(w) = 31.7/10(5) in females and 6.4/10(5) in males vs. 14.1 in females and 3.0 in males in the rest of Sicily. Multivariate analysis documented that residents in the volcanic area of Mt. Etna had a higher risk of TC, compared to the residents in urban, industrial, and iodine deficient areas of Sicily. An abnormally high concentration of several chemicals was found in the drinking water of the Mt. Etna aquifer, which provides water to most of the residents in the Catania province. Our data suggest that environmental carcinogen(s) of volcanic origin may promote papillary TC. Additional analyses, including cancer biological and molecular features, will allow a better understanding of risk factors and etiopathogenetic mechanisms.

The role of fragile sites in sporadic papillary thyroid carcinoma

The incidence of thyroid cancer is increasing, especially papillary thyroid carcinoma (PTC), making it currently the fastest-growing cancer among women. Reasons for this increase remain unclear, but several risk factors including radiation exposure and improved detection techniques have been suggested. Recently, the induction of chromosomal fragile site breakage was found to result in the formation of RET/PTC1 rearrangements, a common cause of PTC. Chromosomal fragile sites are regions of the genome with a high susceptibility to forming DNA breaks and are often associated with cancer. Exposure to a variety of external agents can induce fragile site breakage, which may account for some of the observed increase in PTC. This paper discusses the role of fragile site breakage in PTC development, external fragile site-inducing agents that may be potential risk factors for PTC, and how these factors are especially targeting women.

Thyroid cancer incidence among active duty U.S. military personnel, 1990-2004

BACKGROUND

Increases in thyroid papillary carcinoma incidence rates have largely been attributed to heightened medical surveillance and improved diagnostics. We examined papillary carcinoma incidence in an equal-access health care system by demographics that are related to incidence.

METHODS

Incidence rates during 1990-2004 among white and black individuals aged 20 to 49 years in the military, and the general U.S. population were compared using data from the Department of Defense's Automated Central Tumor Registry and the National Cancer Institute's Surveillance Epidemiology and End Results (SEER-9) program.

RESULTS

Incidence was significantly higher in the military than in the general population among white women [incidence rate ratio (IRR) = 1.42; 95% confidence interval (CI), 1.25-1.61], black women (IRR = 2.31; 95% CI, 1.70-2.99), and black men (IRR = 1.69, 95% CI, 1.10-2.50). Among whites, differences between the two populations were confined to rates of localized tumors (women: IRR = 1.73, 95% CI, 1.47-2.00; men: IRR = 1.51, 95% CI, 1.30-1.75), which may partially be due to variation in staging classification. Among white women, rates were significantly higher in the military regardless of tumor size and rates rose significantly over time both for tumors ≤ 2 cm (military: IRR = 1.64, 95% CI, 1.18-2.28; general population: IRR = 1.55, 95% CI, 1.45-1.66) and > 2 cm (military: IRR = 1.74, 95% CI, 1.07-2.81; general population: IRR = 1.48, 95% CI, 1.27-1.72). Among white men, rates increased significantly only in the general population. Incidence also varied by military service branch.

CONCLUSIONS

Heightened medical surveillance does not appear to fully explain the differences between the two populations or the temporal increases in either population.

IMPACT

These findings suggest the importance of future research into thyroid cancer etiology.

XRCC1 polymorphisms and risk of papillary thyroid carcinoma in a Korean sample

Polymorphisms of DNA repair genes, X-ray repair cross-complementing group 1 (XRCC1) might contribute to individual susceptibility to different types of cancers. We analyzed the relationship between XRCC1 polymorphisms and the risk of papillary thyroid carcinoma in a Korean sample. A hospital-based case-control study was performed in 111 papillary thyroid carcinoma patients and 100 normal control subjects. XRCC1 Arg194Trp and Arg399Gln single nucleotide polymorphisms (SNPs) were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The XRCC1 Arg194Trp Arg/Trp genotype was significantly associated with a decreased risk of papillary thyroid carcinoma compared to that of Arg/Arg genotype (odds ratio [95% confidence intervals]; 0.550 [0.308-0.983]). There was no significant association between XRCC1 Arg399Gln genotypes and risk of papillary thyroid carcinoma. Based on these results, the XRCC1 Arg194Trp Arg/Trp genotype could be used as a useful molecular biomarker to predict genetic susceptibility for papillary thyroid carcinoma in Koreans.

Estimates of thyroid cancer incidence in Brazil: an approach using polynomial models

This study aimed to estimate thyroid cancer incidence in Brazil in 2006 using polynomial models that take age and birth cohort effects into account in the estimation process. Estimates were based on new cases of thyroid cancer in nine Brazilian cities (Manaus, Palmas, Natal, Recife, Cuiabá, Belo Horizonte, São Paulo, Porto Alegre, and Curitiba) and the Federal District from 1997 to 2001. We estimated 6,066 new cases, of which 1,065 in men and 5,001 in women. The incidence rates were, respectively, 1.16 and 5.27 per 100,000 inhabitants. Rates increased with age in both genders, especially after 30 years. The size and profile of rates according to age and gender indicate that the method yields plausible estimates.

Incidental thyroid "PETomas": clinical significance and novel description of the self-resolving variant of focal FDG-PET thyroid uptake

BACKGROUND

Recent series of incidental thyroid activity on fluorodeoxyglucose positron emission tomography (FDG-PET) in patients evaluated for nonthyroidal malignancy, which we refer to as a "PEToma," have suggested that such lesions are associated with a significant incidence of primary thyroid cancer.

METHODS

We retrospectively reviewed 6457 FDG-PET scans performed on 4726 patients from May 2004 to March 2007. We reviewed the cases of patients whose PET or computed tomography (CT) radiology reports described PET uptake within the thyroid to identify incidence and malignant potential of PETomas and evaluate their clinical and histopathologic features.

RESULTS

We found that 160 patients (3.4%) had incidental, abnormal FDG uptake in the thyroid gland, 103 of whom had focal uptake (the PEToma group). Of these patients, 50 (48%) underwent further investigations, including ultrasonography in 48, fine-needle aspiration cytology in 38 and computed tomography in 3. Ten patients underwent surgery, and papillary thyroid cancer was identified in 9. The remaining 53 patients with PETomas underwent no further investigation. Interestingly, 5 patients who had focal uptake within the thyroid showed either spontaneous resolution on repeat FDG-PET (self-resolving) or no focal lesion on subsequent ultrasonography (false-positive).

CONCLUSION

The incidence of papillary thyroid cancer in the present series is similar to that in the literature. Although some patients will show self-resolving or false-positive focal thyroid uptake on FDG-PET, we believe that, if the patient's clinical status permits, the evaluation of patients with incidental thyroid PEToma should include ultrasonographic confirmation and fine-needle aspiration cytology.

The most commonly occurring papillary thyroid cancer in the United States is now a microcarcinoma in a patient older than 45 years

BACKGROUND

The incidence of papillary thyroid cancer (PTC) is growing at a faster rate than any other malignancy. However, it is unknown what effect age is having on the changing PTC incidence rates. With the goal of understanding the role of age in thyroid cancer incidence, this study analyzes the changing demographics of patients with PTC over the past three decades.

METHODS

This was a retrospective evaluation of the incidence rates of PTC from 1973 to 2006 reported by the National Cancer Institute's Surveillance, Epidemiology, and End Results database.

RESULTS

From 1973-2006 the age group most commonly found to have PTC has shifted from patients in their 30s to patients in the 40-50-year-old age group. In 1973 60% of PTC cases were found in patients younger than 45, and the majority of cases continued to occur in younger patients until 1999. After 1999 PTC became more common in patients older than 45 years, and in 2006, 61% of PTC cases were in patients older than 45 years. From 1988 to 2003 there has been an increasing incidence of all sizes of PTC in all age groups with the largest increase in tumors <1 cm in patients older than 45. Forty-three percent of tumors in patients older than 45 are now <1 cm, whereas only 34% are <1 cm in patients younger than 45. Of the nearly 20,000 thyroid cancer cases in 2003, 24% were microcarcinomas in patients over the age of 45.

CONCLUSIONS

The incidence of PTC is increasing disproportionally in patients older than 45 years. The number of PTC tumors smaller than 1 cm is increasing in all age groups, and now the most commonly found PTC tumor in the United States is a microcarcinoma in a patient older than 45 years. These changing patterns relating age and incidence have important prognostic and treatment implications for patients with PTC.

Incidence of thyroid cancer in Italy, 1991-2005: time trends and age-period-cohort effects

BACKGROUND

In Italy, some of the highest incidence rates (IRs) of thyroid cancer (TC) worldwide have been reported.

PATIENTS AND METHODS

TC cases <85 years of age reported to Italian cancer registries during 1991-2005 were included. Age-standardized IRs were computed for all TC and age-period-cohort effects were estimated for papillary TC.

RESULTS

IRs of TC were twofold higher in 2001-2005 than in 1991-1995 (18 and 8 per 100,000 women, 6 and 3 per 100,000 men, respectively). Increases were similar in the two sexes and nearly exclusively due to papillary TC. Increases of papillary TC by birth cohort were found in both sexes and among all age groups between 20 and 79 years. Age-period-cohort models showed a strong period effect in both sexes (rate ratio for 2001-2009 versus 1991-1995 = 2.5 in women and 2.3 in men), although IRs peaked at an earlier age in women (45-49 years) than men (65-69 years).

CONCLUSION

The strength of the period effect in both sexes and the earlier onset in women than men strongly implicated increased medical surveillance in the upward trends of papillary TC incidence in Italy. The consequences of the current intense search for TC on morbidity and possible overtreatment, especially among young women, should be carefully evaluated.

Papillary microcarcinoma of the thyroid among atomic bomb survivors: tumor characteristics and radiation risk

BACKGROUND

: Radiation exposure is an established cause of clinical thyroid cancer, but little is known about radiation effects on papillary microcarcinoma (PMC) of the thyroid, a relatively common subclinical thyroid malignancy. Because the incidence of these small thyroid cancers has been increasing, it is important to better understand them and their relation to radiation.

METHODS

: PMCs were identified in a subset of 7659 members of the Life Span Study of atomic bomb survivors who had archived autopsy or surgical materials. We conducted a pathology review of these specimens and evaluated the histological features of the tumors and the association between PMCs and thyroid radiation dose.

RESULTS

: From 1958 to 1995, 458 PMCs were detected among 313 study subjects. The majority of cancers exhibited pathologic features of papillary thyroid cancers. Overall, 81% of the PMCs were of the sclerosing variant and 91% were nonencapsulated, psammoma bodies that occurred in 13% and calcification was observed in 23%. Over 95% had papillary or papillary-follicular architecture and most displayed nuclear overlap, clear nuclei, and nuclear grooves. Several of these features increased with increasing tumor size, but no association was found with radiation dose. A significant radiation-dose response was found for the prevalence of PMCs (estimated excess odds ratio/Gy = 0.57; 95% confidence interval, 0.01-1.55), with the excess risk observed primarily among women.

CONCLUSIONS

: Exposure to low-to-moderate doses of ionizing radiation appears to increase the risk of thyroid PMCs, even when exposure occurs during adulthood. Cancer 2010. (c) 2010 American Cancer Society.

[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.

Is BRAF mutation screening useful for preoperative risk stratification in papillary thyroid cancer?

Evaluation of: Xing M, Clark D, Guan H et al.: BRAF mutation testing of thyroid fine-needle aspiration biopsy specimens for preoperative risk stratification in papillary thyroid cancer. J. Clin. Oncol. 27(18), 2977–2982 (2009). Although the majority of patients with papillary thyroid cancer are effectively treated with thyroidectomy and selective use of postoperative 131I therapy, disease persistence/recurrence can afflict a proportion of patients after the initial treatments. BRAF mutations, present in a large proportion of papillary thyroid cancers, illustrate one of the most impressive examples of phenotype–genotype correlation in human pathology. In this study, the authors propose that preoperative BRAF mutation testing of fine-needle aspiration biopsy specimens provides a novel tool for a preoperative risk stratification strategy for predicting the extent of initial disease and subsequent clinical outcomes.

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.

Rising thyroid cancer incidence in the United States by demographic and tumor characteristics, 1980-2005

Thyroid cancer incidence has been rising in the United States, and this trend has often been attributed to heightened medical surveillance and the use of improved diagnostics. Thyroid cancer incidence varies by sex and race/ethnicity, and these factors also influence access to and utilization of healthcare. We therefore examined thyroid cancer incidence rates by demographic and tumor characteristics based on 48,403 thyroid cancer patients diagnosed during 1980-2005 from the Surveillance, Epidemiology and End Results program of the National Cancer Institute. The rates varied by histologic type, sex, and race/ethnicity. Papillary carcinoma was the only histologic type for which incidence rates increased consistently among all racial/ethnic groups. Subsequent analyses focused on the 39,706 papillary thyroid cancers diagnosed during this period. Papillary carcinoma rates increased most rapidly among females. Between 1992-1995 and 2003-2005, they increased nearly 100% among White non-Hispanics and Black females but only 20% to 50% among White Hispanics, Asian/Pacific Islanders, and Black males. The increases were most rapid for localized stage and small tumors; however, rates also increased for large tumors and tumors of regional and distant stage. Since 1992-1995, half the overall increase in papillary carcinoma rates was due to increasing rates of very small (<or=1.0 cm) cancers, 30% to cancers 1.1 to 2 cm, and 20% to cancers>2 cm. Among White females, the rate of increase for cancers>5 cm almost equaled that for the smallest cancers. Medical surveillance and more sensitive diagnostic procedures cannot completely explain the observed increases in papillary thyroid cancer rates. Thus, other possible explanations should be explored.

Inadvertent thyroid irradiation in protocol-driven trauma CT: a survey of hospital ERs

Given the well-recognized association of radiation and thyroid cancer, the objective of this study was to assess the frequency of radiation overlap at the level of the thyroid gland as part of standard protocols for computed tomography (CT) assessment of trauma, incorporating both cervical spine and chest images. A survey was sent to physician members of the American Society of Emergency Radiology. Among other questions, the respondents were asked to indicate their CT protocol with respect to the lower boundary of their cervical spine series and the upper boundary of their chest CT series. Forty-one surveys were returned. Of these, 83% reported overlap of the contiguous margins of the two CT studies resulting in partial or total double radiation deposition to the thyroid gland, which typically extends from vertebral levels C5 to T1. Sixty-one percent reported overlapping at T1 only, 15% at C7 to T1, 4.9% at C6 to T1, and 2.4% at C5 to T1. These data reveal that the predominant practice among the respondents is to include the thyroid gland in coincident CT studies of the cervical spine and chest in trauma protocols.