The thyroid cancer epidemic: is it the dark side of the CT revolution?

Exploring the advances of single-cell RNA sequencing in thyroid cancer: a narrative review

Thyroid cancer, a prevalent form of endocrine malignancy, has witnessed a substantial increase in occurrence in recent decades. To gain a comprehensive understanding of thyroid cancer at the single-cell level, this narrative review evaluates the applications of single-cell RNA sequencing (scRNA-seq) in thyroid cancer research. ScRNA-seq has revolutionised the identification and characterisation of distinct cell subpopulations, cell-to-cell communications, and receptor interactions, revealing unprecedented heterogeneity and shedding light on novel biomarkers for therapeutic discovery. These findings aid in the construction of predictive models on disease prognosis and therapeutic efficacy. Altogether, scRNA-seq has deepened our understanding of the tumour microenvironment immunologic insights, informing future studies in the development of effective personalised treatment for patients. Challenges and limitations of scRNA-seq, such as technical biases, financial barriers, and ethical concerns, are discussed. Advancements in computational methods, the advent of artificial intelligence (AI), machine learning (ML), and deep learning (DL), and the importance of single-cell data sharing and collaborative efforts are highlighted. Future directions of scRNA-seq in thyroid cancer research include investigating intra-tumoral heterogeneity, integrating with other omics technologies, exploring the non-coding RNA landscape, and studying rare subtypes. Overall, scRNA-seq has transformed thyroid cancer research and holds immense potential for advancing personalised therapies and improving patient outcomes. Efforts to make this technology more accessible and cost-effective will be crucial to ensuring its widespread utilisation in healthcare.

Risk Stratification of Differentiated Thyroid Cancer at King Abdullah Specialized Children's Hospital Endocrinology Clinic in Riyadh, Saudi Arabia

Background Papillary thyroid cancer (PTC), a well-differentiated form of cancer, accounts for the majority of thyroid malignancies, and the incidence of PTC is on the rise. While the rate of PTC recurrence is considered to be low, there are broad spectrums of clinical and biological behavior that can lead to disease recurrence. The American Thyroid Association (ATA) risk stratification system for differentiated thyroid cancer is used as a prognostic tool to guide decision-making and management strategies most likely to achieve a favorable outcome. Aim This study aimed to estimate the prevalence of PTC recurrence in each category of the ATA risk stratification system and determine the appropriate iodine dose to be administered at the King Abdulaziz Medical City Endocrinology Clinic in Riyadh, Saudi Arabia. Methods A cross-sectional retrospective chart review was conducted on adult patients with PTC who underwent thyroidectomy procedures at the King Abdullah Specialized Children's Hospital (KASCH) Endocrinology Clinic in Riyadh between 2015 and 2023. IBM SPSS (Statistical Package for the Social Sciences) version 25 (IBM Corp., Armonk, NY) was used for data analysis. Results Of the 697 patients included in the study, 82.4% were females. About 5% had suffered from PTC recurrence, and 54.4% had low-risk stratification. In addition, more than half (52.1%) had received radioactive iodine (RAI). The recurrence of PTC was significantly associated with age (P = 0.019), ATA risk stratification (P = 0.0001), RAI therapy (P = 0.001), and iodine dosage (P = 0.013). Conclusion Both low PTC recurrence rates and low-risk stratification were observed among the PTC patients. The risk factors relating to PTC recurrence included high-risk stratification, advanced age, RAI therapy, and the dosage of RAI administered.

Consumption of health resources in older people with differentiated thyroid carcinoma: a multicenter analysis

OBJECTIVE

There is hardly any information on the consumption of healthcare resources by older people with differentiated thyroid cancer (DTC). We analyzed these consumptions in older patients with DTC and compared patients 75 years and older with subjects aged 60-74 years.

METHODS

A multicenter, retrospective analysis was designed. We recorded three groups of health resources consumption (visits, diagnostic procedures, and therapeutic procedures) and identified a subgroup of patients with high consumption of resources. We compared patients aged between 60-74 years (group 1) with patients aged 75 and over (group 2).

RESULTS

We included 1654 patients (women, 74.4%), of whom 1388 (83.9%) belonged to group 1 and 266 (16.1%) to group 2. In group 2, we found a higher proportion of patients requiring emergency department visits (7.9 vs. 4.3%, P = 0.019) and imaging studies (24.1 vs. 17.3%; P = 0.012) compared to group 1. However, we did not find any significant difference between both groups in the consumption of other visits, diagnostic procedures, or therapeutic procedures. Overall, 340 patients (20.6%) were identified as high consumers of health resources, 270 (19.5%) in group 1 and 70 (26.3%) in group 2 (P = 0.013). Multivariate logistic regression analysis showed that the risk of recurrence and mortality, radioiodine treatment, tumor size, and vascular invasion were significantly related to the high global consumption of resources. However, the age was not significantly related to it.

CONCLUSION

In patients with DTC over 60 years of age, advanced age is not an independent determining factor in the consumption of health resources.

Risk of thyroid cancer in a lung cancer screening population of the National Lung Screening Trial according to the presence of incidental thyroid nodules detected on low-dose chest CT

PURPOSE

This study evaluated thyroid cancer risk in a lung cancer screening population according to the presence of an incidental thyroid nodule (ITN) detected on low-dose chest computed tomography (LDCT).

METHODS

Of 47,837 subjects who underwent LDCT, a lung cancer screening population according to the National Lung Screening Trial results was retrospectively enrolled. The prevalence of ITN on LDCT was calculated, and the ultrasonography (US)/fine-needle aspiration (FNA)-based risk of thyroid cancer according to the presence of ITN on LDCT was compared using the Fisher exact or Student t-test as appropriate.

RESULTS

Of the 2,329 subjects (female:male=44:2,285; mean age, 60.9±4.9 years), the prevalence of ITN on LDCT was 4.8% (111/2,329). The incidence of thyroid cancer was 0.8% (18/2,329, papillary thyroid microcarcinomas [PTMCs]) and was higher in the ITN-positive group than in the ITN-negative group (3.6% [4/111] vs. 0.6% [14/2,218], P=0.009). Among the 2,011 subjects who underwent both LDCT and thyroid US, all risks were higher (P<0.001) in the ITNpositive group than in the ITN-negative group: presence of thyroid nodule on US, 94.1% (95/101) vs. 48.6% (928/1,910); recommendation of FNA according to the American Thyroid Association guideline and Korean Thyroid Imaging Reporting and Data System guideline, 41.2% (42/101) vs. 2.4% (46/1,910) and 39.6% (40/101) vs. 1.9% (37/1,910), respectively.

CONCLUSION

Despite a higher risk of thyroid cancer in the LDCT ITN-positive group than in the ITN-negative group in a lung cancer screening population, all cancers were PTMCs. A heavy smoking history may not necessitate thorough screening US for thyroid incidentalomas.

Thyroid cancer incidence and trends by demographic and tumor characteristics in Oran, Algeria: 1993-2013, a population-based analysis

OBJECTIVES

Incidence rates of thyroid cancer have dramatically increased over recent decades in many countries, particularly the papillary histotype and microcarcinomas. We examined thyroid cancer incidence and trends by demographic and tumor characteristics based on 1443 patients with thyroid cancer diagnosed between 1993 and 2013 in Oran district, in Northwest Algeria.

METHODS

All thyroid cancer cases were abstracted from medical records and pathology reports and classified according to the International Classification for Diseases in Oncology, third edition. Age-specific, age-standardized incidence rates per 100 000 person-years, and annual percent changes (APC) in the incidence were calculated.

RESULTS

Age-standardized incidence was 11.7 per 100 000 for women and 2.0 per 100 000 for men. Thyroid cancer incidence increased over time significantly in women (APC: +3.72%; P < 0.05), mostly due to an increased incidence of the papillary histotype (APC: +5.48%; P < 0.05), and microcarcinomas (APC: +17.34%; P < 0.05). During the same time period, the incidence of follicular thyroid carcinomas decreased (APC: -3.74%; P < 0.05).

CONCLUSIONS

The results of our study showing an upward trend of thyroid cancer incidence driven largely by increases in the papillary histotype are consistent with previous studies. The higher increase has coincided with the introduction of fine needle aspiration and thyroid ultrasound in the 1990s, and may have led to overdiagnosis. However, the increased papillary-to-follicular ratio observed over time is possibly a late effect of iodine supplementation implemented in Algeria in 1967 to combat endemic goiter. Further larger-scale population-based research is needed to gain insight into thyroid cancer etiology.

A Comparison of the Burden of Thyroid Cancer Among the European Union 15+ Countries, 1990-2019: Estimates From the Global Burden of Disease Study

Importance

The global incidence of thyroid cancer has been increasing rapidly, and this increase has had an attendant burden on health systems. However, it is unclear how the burden of this disease differs among the pre-2004 countries of the European Union (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, Netherlands, Portugal, Spain, Sweden, and the UK), US, Australia, Canada, and Norway (EU15+).

Objective

To assess the trends in mortality, incidence, and disability-adjusted life-years (DALYs) associated with thyroid cancer between 1990 and 2019 in EU15+ nations. Data analysis was conducted from July 11 to October 11, 2021.

Design, Setting, and Participants

Observational cross-sectional analysis of the incidence of thyroid cancer was conducted using data obtained from the Global Burden of Disease Study database. Nineteen countries of the EU15+ were included.

Exposures

Thyroid cancer.

Main Outcomes and Measures

Age-standardized incidence rates (ASIRs), age-standardized mortality rates (ASMRs) and DALYs were extracted for individual EU15+ countries per sex for each of the years from 1990 to 2019, and mortality-to-incidence indexes were computed. Joinpoint regression analysis was used to describe the trends.

Results

Thirteen of 19 countries (68%) showed an average annual percentage change increase in ASIR across the study period (range, 0.2%-2.5%). Joinpoint regression analysis revealed largely plateauing ASIR trends in recent years across most EU15+ nations since 1990. Between 2011 and 2019, the estimated annual percentage change in the US was 0. Australia, Denmark, and the US were the only countries with increasing ASMR trends with positive average annual percentage changes: Australia, 0.6 (95% CI, 0.2-1.0); Denmark, 1.0 (95% CI, 0.8-1.3); and US, 0.4 (95% CI, 0.4-0.5); the remaining 16 countries showed negative trends (range, -0.2 to -2.1). Disability-adjusted life-years decreased in all EU15+ countries except Australia, Denmark, and the US.

Conclusions and Relevance

This cross-sectional analysis found that overall, the burden of thyroid cancer across EU15+ countries appears to be decreasing, evidenced by plateauing incidence rates and reductions in mortality and DALYs over the 30-year study period. However, the US and Australia appear to have increasing ASMR and DALY trends. Ongoing observation is required to monitor how changes in international clinical practice guidelines affect thyroid cancer DALYs and mortality.

Trends in incidence and histological pattern of thyroid cancer in Ho Chi Minh City, Vietnam (1996-2015): a population-based study

BACKGROUND

The burden and trend of thyroid cancer in Vietnam have not been well documented. This study aimed to investigate the trends in incidence and histological pattern of thyroid cancer in Ho Chi Minh City from 1996 to 2015.

METHODS

A population-based study retrieved data from the Ho Chi Minh City Cancer Registry during 1996-2015. Trends in the incidence of thyroid cancer were investigated based on age, gender, and histology for each 5-year period. Annual percentage change (APC) in incidence rates was estimated using Joinpoint regression analysis.

RESULTS

In the study period, there were 5953 thyroid cancer cases (men-to-women ratio 1:4.5) newly diagnosed in Ho Chi Minh City with the mean age of 42.9 years (±14.9 years). The age-standardized incidence rate of thyroid cancer increased from 2.4 per 100,000 during 1996-2000 (95% confidence interval [95% CI]: 2.2-2.6) to 7.5 per 100,000 during 2011-2015 (95% CI: 7.3-7.9), corresponded to an overall APC of 8.7 (95% CI 7.6-9.9). The APC in men and women was 6.2 (95% CI: 4.2-8.2) and 9.2 (95% CI: 8.0-10.4), respectively. The incidence rate in the < 45 years age group was the highest diagnosed overall and increased significantly in both men (APC 11.0) and women (APC 10.1). Both genders shared similar distribution of subtype incidences, with papillary thyroid cancer constituted the most diagnosed (73.3% in men and 85.2% in women). The papillary thyroid cancer observed a markedly increase overall (APC of 10.7 (95% CI 9.3-12.0)).

CONCLUSIONS

There were appreciable increases in the age-standardized incidence rate of thyroid cancer in both genders, mainly contributed by the papillary subtype. The age of patients at diagnosis decreased gradually. The widespread utilization of advanced diagnostic techniques and healthcare accessibility improvement might play a potential role in these trends. Further investigations are needed to comprehend the risk factors and trends fully.

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

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

Incidental versus clinically diagnosed differentiated thyroid cancer in both adult and elderly subjects: histological characteristics and follow-up in a retrospective analysis from a single institution

PURPOSE

Most thyroid cancer are incidentally diagnosed. However, little is known on the different modalities of incidental diagnosis in adult versus older patients.

METHODS

We retrospectively analyzed data from 440 patients consecutively diagnosed with differentiated thyroid cancer (DTC) in a single institution. Modalities of diagnosis were categorized as follows: (A) clinically diagnosed, nonincidental cases; (B) incidental during carotid power-duplex (CPD); (C) incidental during neck imaging other than carotid power-duplex; (D) incidental during imaging workup of thyroid dysfunction or at histological examination after thyroidectomy for benign lesions. Demographics, histology and follow-up were compared between adult (<65 years) and older (≥65 years) patients according to the different modalities of diagnosis.

RESULTS

A total of 363 and 67 cases were recorded in adult and older patients, respectively with incidental proportions of 79% and 85%, respectively. A P < 0.001 significant difference in the modality of diagnosis was found between adult and older subjects, the latter presenting with a higher prevalence of Group B. In the nonincidental group, papillary histotype, larger size, and extrathyroidal invasion were more frequently observed in older subjects. Disease-free survival was comparable between adult and older subjects in the incidental cases, whereas it was reduced, though not significantly, in older subjects.

CONCLUSION

Incidental cases of DTC are more frequently diagnosed in the old subjects and are mainly due to CPD. Disease-free survival is comparable between adult and older subjects in both incidental and nonincidental cases, although it may be slightly reduced in nonincidentally diagnosed older patients.

Risk Factors for Thyroid Cancer: What Do We Know So Far?

Thyroid cancer (TC) is the most common endocrine cancer today. The rising incidence of the differentiated papillary type cannot be entirely explained by early and meticulous diagnosis, since a proportion of large tumors has also been reported. In this review, we present the results of numerous investigations focused on possible factors causing increased TC incidence, such as chromosomal and genetic alterations, iodine intake, TSH level, autoimmune thyroid disease, gender, estrogen, obesity, lifestyle changes, and environmental pollutants. Up to now, only childhood exposure to ionizing radiation has been fully recognized as a risk factor. There is also a possibility that yet undiscovered carcinogens, especially during intrauterine life or early childhood, might be responsible for increased TC incidence as well as epigenetic changes. Therefore, more studies are necessary in order to further investigate the potential risk factors for TC and their mechanisms of action.

Cost for treatment and follow-up of thyroid cancer increases according to the severity of disease

BACKGROUND

The aim of this study was to provide an analysis of thyroid cancer-related health care costs over a 5-year period, according to the extent of thyroid surgery.

METHODS

The study included 33 patients from our institutional database who underwent thyroid cancer surgery in 2010. Patients were divided into four groups based on surgical extent: (1) hemithyroidectomy, (2) total thyroidectomy, (3) total thyroidectomy with ipsilateral radical neck dissection, and (4) total thyroidectomy with bilateral radical neck dissection and mediastinal dissection. Costs for admission and outpatient follow-up for 5 years were analyzed.

RESULTS

Costs for outpatient follow-up and admission, and overall cost increased with increasing stage of disease and increasing extent of thyroid surgery. Patients who underwent only hemithyroidectomy had the lowest costs for outpatient follow-up and admission, as well as the lowest overall cost.

CONCLUSION

Over the 5-year follow-up period, surgery performed at an early disease stage was the most cost-effective.

Interactions between life expectancy and the incidence and mortality rates of cancer in China: a population-based cluster analysis

BACKGROUND

The relationship between cancer and life expectancy is well established in both developed and developing countries. China is a vast country with significant geographical differences in population structure and healthcare, and thus provides a unique opportunity to analyze the complex relationship between life expectancy and cancer incidence and mortality rates.

METHODS

Cancer data were extracted for a total of 255 units (cities or counties) from the 2013 National Central Cancer Registry. Life expectancy data at the unit level were obtained from the National Centers for Disease Control and Prevention. Linear regression analysis was used to analyze the relationship between life expectancy and crude incidence and mortality rates of cancer. In a separate analysis, life expectancy was rated as low (< 76.0 years), middle (76-80 years), or high (> 80 years).

RESULTS

Overall, the cancer incidence and mortality rates positively correlated with life expectancy in both sexes (R at 0.37 and 0.50, P < 0.001). The correlation was significant for the following cancers: lung, colorectal, prostate, bladder and pancreas, as well as for lymphoma in men (R 0.36-0.58, P < 0.001), lung, breast, colorectal, thyroid, uterus, and ovary in women (R 0.18-0.51, P < 0.001). We failed to observe an association between upper gastrointestinal cancer and life expectancy. The number of cities/counties with low, middle and high life expectancy levels were 110, 101 and 44, respectively. The highest age-standardized cancer incidence rate was observed in areas with a high life expectancy level (192.83/100,000). The highest age-standardized mortality rate was in areas with the lowest life expectancy (118.44/100,000). Cancers of the stomach, liver and esophagus are major cancer types in areas with low and middle life expectancy. In contrast, areas with high life expectancy had high incidence and mortality rates of colorectal cancer, breast cancer in women and prostate cancer in men.

CONCLUSIONS

Longer life expectancy is associated with higher overall cancer incidence and mortality in China. The cancer pattern also varies substantially across areas with different life expectancy levels. Life expectancy levels must be considered when developing strategies to prevent and treat cancers.

Rising incidence of thyroid cancer in Singapore not solely due to micropapillary subtype

Introduction The annual incidence of thyroid cancer is known to vary with geographic area, age and gender. The increasing incidence of thyroid cancer has been attributed to increase in detection of micropapillary subtype, among other factors. The aim of the study was to investigate time trends in the incidence of thyroid cancer in Singapore, an iodine-sufficient area. Materials and methods Data retrieved from the Singapore National Cancer Registry on all thyroid cancers that were diagnosed from 1974 to 2013 were reviewed. We studied the time trends of thyroid cancer based on gender, race, pathology and treatment modalities where available. Results The age-standardised incidence rate of thyroid cancer increased to 5.6/100,000 in 2013 from 2.5/100,000 in 1974. Thyroid cancer appeared to be more common in women, with a higher incidence in Chinese and Malays compared with Indians. Papillary carcinoma is the most common subtype. The percentage of papillary microcarcinoma has remained relatively stable at around 38% of all papillary cancers between 2007 and 2013. Although the incidence of thyroid cancer has increased since 1974, the mortality rate has remained stable. Conclusion This trend of increase in incidence of thyroid cancer in Singapore compares with other published series; however, the rise seen was not solely due to micropapillary type. Thyroid cancer was also more common in Chinese and Malays compared with Indians for reasons that needs to be studied further.

The role of microRNAs in different types of thyroid carcinoma: a comprehensive analysis to find new miRNA supplementary therapies

The most common endocrine malignancy is thyroid cancer, and researchers have made a great deal of progress in deciphering its molecular mechanisms in the recent years. Many of molecular changes observed in thyroid cancer can be used as biomarkers for diagnosis, prognosis, and therapeutic targets for treatment. MicroRNAs (miRNAs) are important parts in biological and metabolic pathways such as regulation of developmental stages, signal transduction, cell maintenance, and differentiation. Therefore, their dysregulation can expose individuals to malignancies. It has been proved that miRNA expression is dysregulated in different types of tumors, like thyroid cancers, and can be the cause of tumor initiation and progression. In this paper, we have reviewed the available data on miRNA dysregulation in different thyroid tumors including papillary, follicular, anaplastic, and medullary thyroid carcinomas aiming to introduce the last updates in miRNAs-thyroid cancer relation.

Trends in thyroid cancer incidence and mortality in Portugal

The objective was to quantify thyroid cancer incidence and mortality trends in Portugal. The number of thyroid cancer cases and incidence rates were retrieved from the Regional Cancer Registries for the period 1989-2011. The number of deaths and mortality rates were obtained from the WHO cancer mortality database (1988-2003 and 2007-2012) and Statistics Portugal (2004-2006; 1988-2012 by region). Joinpoint regression of the standardized incidence and mortality rates was performed. A significant, rapid and continued increase in incidence was observed for both sexes in each of the Regional Cancer Registries, with annual per cent changes (APCs) ranging between 2 and 9. Incidence in Portuguese women is higher than estimates for the world and Europe. Mortality decreased for women (APC: -1.5), with the greatest decrease in the North, and increased marginally for men (APC: +0.2), with a greater increase in the South. The significant increases in incidence in Portugal are predominantly because of the increase in incidence among women from the North. These trends, combined with an overall low mortality and high 5-year relative survival, raise concerns on the extent to which overdiagnosis may be taking place. Further research is needed, quantifying the importance of the most likely determinants of these trends as well as the extent and potentially deleterious effects of overdiagnosis and overtreatment in the Portuguese setting.

Diagnostic X-Ray Exposure and Thyroid Cancer Risk: Systematic Review and Meta-Analysis

BACKGROUND

Radiation exposure is a well-known risk factor for thyroid cancer. However, the specific effects of diagnostic radiation exposure on thyroid cancer risk are controversial. The purpose of this study was to perform a systematic review and meta-analysis to assess the effects of diagnostic radiation exposure on thyroid cancer risk.

METHODS

The PubMed and EMBASE databases were searched to identify eligible studies. Summary odds ratio (OR) estimates and confidence intervals (CIs) were used to compute the risk of thyroid cancer using fixed- and random-effects models. Subgroup and sensitivity analyses were performed to evaluate the potential heterogeneity.

RESULTS

Nine studies from 12 publications were included in the meta-analysis. Overall exposure to diagnostic radiation exposure was associated with a significantly increased thyroid cancer risk (OR = 1.52 [CI 1.13-2.04]). The subgroup and sensitivity analyses revealed similar results. By type of exposure, exposure to computed tomography scans (OR = 1.46 [CI 1.27-1.68]) or dental x-rays (OR = 1.69 [CI 1.17-2.44]) were associated with an increased thyroid cancer risk. Head and neck (OR = 1.31 [CI 1.02-1.69]) and chest (OR = 1.71 [CI 1.09-2.69]) exposure to diagnostic radiation was associated with an increased thyroid cancer risk.

CONCLUSIONS

The results of this meta-analysis indicate that diagnostic radiation exposure is associated with an increased thyroid cancer risk. Therefore, to the extent that it will not compromise the information being sought, radiation exposure to the thyroid should be minimized during diagnostic examinations.

Growing incidence of thyroid carcinoma in recent years: Factors underlying overdiagnosis

There is an increasing incidence of well-differentiated thyroid cancer worldwide. Much of the increase is secondary to increased detection of small, low-risk tumors, with questionable clinical significance. This review addresses the factors that contribute to the increasing incidence and considers environmental, and patient-based and clinician-led influences. Articles addressing the causes of the increased incidence were critically reviewed. A complex interplay of environmental, medical, and social pressures has resulted in increased awareness of the thyroid disease risk, increased screening of thyroid cancers, and increased diagnosis of thyroid cancers. Although there is evidence to suggest that the true disease incidence may be changing slightly, most of the increase is related to factors that promote early diagnosis of low-risk lesions, which is resulting in a significant phenomenon of overdiagnosis. An improved understanding of these pressures at a global level will enable healthcare policymakers to react appropriately to this challenge in the future.

Incidence of differentiated thyroid cancer in Canada by City of residence

Background

Thyroid cancer incidence in Canada is increased in high socioeconomic groups, and in urban compared with rural areas. The objective of this study was to analyze patterns in thyroid cancer incidence across Canada, particularly with respect to the major urban areas across the country, to identify whether there are any discrepancies in thyroid cancer incidence between Canadian cities.

Methods

Cases were drawn from the Canadian Cancer Registry. Demographic and socioeconomic information were extracted from the Canadian Census of Population data. We linked cases to income quintiles (InQs) by patients’ postal codes, and categorized residence by census metropolitan area ((CMA), population >100,000). Within the Toronto CMA we further classified by census subdivision (CSD).

Results

There were a total of 33 CMAs across the country. After controlling for demographic and socio-economic factors, we found that the Toronto CMA had an IRR of thyroid cancer that was significantly higher than all other CMAs across the country. For 70 % of CMAs and CAs across Canada, the IRR for thyroid cancer was less than half of the IRR for thyroid cancer in the Toronto CMA.

As Toronto is one of the largest CMAs, we then subdivided the Toronto area into CSDs to examine how incidence of thyroid cancer varies within this large area. The Toronto City core was used as the reference category and all other areas were compared directly to it. In doing so, we found that a contiguous area of three CSDs North of Toronto had higher IRRs compared with the Toronto city core: Markham, Vaughan and Richmond Hill.

Conclusions

After controlling for demographic and socioeconomic factors, we found that the Toronto CMA has the highest incidence of thyroid cancer nationwide. Several explanations could account for this discrepancy including increased detection due to increased access to imaging, differences in ethnicity or environmental exposures.

Increasing thyroid cancer rate and the extent of thyroid surgery in Korea

BACKGROUND

It is evident that the rate of thyroid cancer is increasing throughout the world. One reason is increased detection of preclinical small cancers. However, it is not clear whether the increase in thyroid cancer rate is reducing the extent of thyroid surgeries. The purpose of this study was to evaluate the thyroid cancer rate and analyze recent changes in the extent of thyroid cancer surgeries in Korea.

METHODS

An observational study was conducted using data from Korea's Health Insurance Review and Assessment Service (HIRAS) for thyroidectomy with/without neck dissection, with 228,051 registered patients between 2007 and 2011. Data were categorized by the extent of surgery: unilateral thyroidectomy without neck dissection (UT), bilateral thyroidectomy or radical thyroidectomy without neck dissection (TT), any thyroidectomy with unilateral selective neck dissection (SND), any thyroidectomy with unilateral modified radical neck dissection (MRND), any thyroidectomy with unilateral radical neck dissection (RND), and any thyroidectomy with bilateral neck dissection (BND). Annual rate difference for each surgery was analyzed with a linear by linear association.

RESULTS

The absolute numbers of total thyroid surgeries (UT+TT+SND+MRND+RND+BND) were increased from 28539 to 61481. The proportion of patients who underwent only thyroidectomy without neck dissection (UT+TT) decreased from 67.30% to 60.50%, whereas the proportion of patients who underwent neck dissection (SND+MRND+RND+BND) increased from 32.70% to 39.50% during the 5-year study period.

CONCLUSION

Despite the increase in rate of thyroid cancer due to earlier detection, increased rate of neck dissection was noted.

Thyroid cancer mortality and incidence: a global overview

In most areas of the world, thyroid cancer incidence has been appreciably increasing over the last few decades, whereas mortality has steadily declined. We updated global trends in thyroid cancer mortality and incidence using official mortality data from the World Health Organization (1970-2012) and incidence data from the Cancer Incidence in Five Continents (1960-2007). Male mortality declined in all the major countries considered, with annual percent changes around -2/-3% over the last decades. Only in the United States mortality declined up to the mid 1980s and increased thereafter. Similarly, in women mortality declined in most countries considered, with APCs around -2/-5% over the last decades, with the exception of the UK, the United States and Australia, where mortality has been declining up to the late 1980s/late 1990s to level off (or increase) thereafter. In 2008-2012, most countries had mortality rates (age-standardized, world population) between 0.20 and 0.40/100,000 men and 0.20 and 0.60/100,000 women, the highest rates being in Latvia, Hungary, the Republic of Moldova and Israel (over 0.40/100,000) for men and in Ecuador, Colombia and Israel (over 0.60/100,000) for women. In most countries, a steady increase in the incidence of thyroid cancer (mainly papillary carcinomas) was observed in both sexes. The declines in thyroid cancer mortality reflect both variations in risk factor exposure and changes in the diagnosis and treatment of the disease, while the increases in the incidence are likely due to the increase in the detection of this neoplasm over the last few decades.

The communication of the radiation risk from CT in relation to its clinical benefit in the era of personalized medicine: part 1: the radiation risk from CT

The theory of radiation carcinogenesis has been debated for decades. Most estimates of the radiation risks from CT have been based on extrapolations from the lifespan follow-up study of atomic bomb survivors and on follow-up studies after therapeutic radiation, using the linear no-threshold theory. Based on this, many population-based projections of induction of future cancers by CT have been published that should not be used to estimate the risk to an individual because of their large margin of error. This has changed recently with the publication of three large international cohort follow-up studies, which link observed cancers to CT scans received in childhood. A fourth ongoing multi-country study in Europe is expected to have enough statistical power to address the limitations of the prior studies. The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) report released in 2013 specifically addresses variability in response of the pediatric population exposed to ionizing radiation. Most authorities now conclude that there is enough evidence to link future cancers to the radiation exposure from a single CT scan in childhood but that cancer risk estimates for individuals must be based on the specifics of exposure, age at exposure and absorbed dose to certain tissues. Generalizations are not appropriate, and the communication of the CT risk to individuals should be conducted within the framework of personalized medicine.

Trends in thyroid cancer incidence in Texas from 1995 to 2008 by socioeconomic status and race/ethnicity

BACKGROUND

Thyroid cancer incidence is increasing, potentially due to enhanced diagnostic practices. However, access to healthcare may be dependent on socioeconomic status (SES) and race/ethnicity. Consequently, certain segments of the population may experience thyroid cancer overdiagnosis as a result of greater access to and use of enhanced diagnostic technology. The current study examined trends by SES in thyroid cancer incidence at the census tract level from 1995 to 2008 for the population of Texas, as well as by racial/ethnic subgroup.

METHODS

Joinpoint regressions were used to examine incidence trends over time by SES for the study population, and for the non-Hispanic white, non-Hispanic black, and Hispanic subgroups separately. Other race/ethnicities were not adequately represented for subgroup analyses.

RESULTS

There were 22,390 incident thyroid cancer cases (65.0% white, 6.7% black, 24.3% Hispanic, 4.1% Asian/other races; 85.9% papillary histology). The low SES group experienced a steady increase in incidence since 1995 (6.7% per year, p<0.05), whereas incidence among the high SES group has increased at a rate of 8.6% per year since 1999 (p<0.05). The joinpoint projected incidence trends for the low and high SES groups were significantly different (p=0.047). Whites experienced a steady increase in incidence over time among both high and low SES groups (7.6% per year p<0.05), whereas blacks and Hispanics of higher SES had a much more pronounced increase in incidence over time relative to their lower SES counterparts (blacks=12.8% vs. 4.1%; Hispanics=11.2% vs. 8.3%, p<0.05). For blacks and Hispanics, joinpoint projected incidence trends for the low and high SES groups were significantly different from one another (p<0.001-0.004).

CONCLUSIONS

These results identify groups experiencing the greatest problem of increasing thyroid cancer incidence, and raise concern that greater access to healthcare may be accompanied by thyroid cancer overdiagnosis. A dual focus on delineating and preventing disease-related causal factors and focusing clinical attention on avoiding overdiagnosis among certain populations (e.g., high SES) may be advisable to address thyroid cancer in Texas. Clinicians are encouraged to adhere to ATA/NCCN guidelines when choosing patients for thyroid ultrasound, selecting which nodules to examine, and deciding which patients should proceed to biopsy.

Access, excess, and overdiagnosis: the case for thyroid cancer

The incidence of thyroid cancer in women is increasing at an epidemic rate. Numerous studies have proposed that the cause is increasing detection due to availability and use of medical diagnostic ultrasound. Our objective was to compare rates of diagnosis across different health-care regions to rates of diagnostic tests and to features of both health and access of the regional populations. This is a population-based retrospective ecological observational study of 12,959 patients with thyroid cancer between January 1, 2000 and December 31, 2008 in Ontario Canada based on the health-care utilization regions (Local Health Integration Networks) of the province of Ontario Canada. We found that some regions of Ontario had four times the rates of diagnosis of thyroid cancer compared to other regions. The regions with the highest use of discretionary medical tests (pelvic ultrasound, abdominal ultrasound, neck ultrasound, echocardiogram, resting electrocardiogram, cardiac nuclear perfusion tests, and bone scan), highest population density, and better education had the highest rates of thyroid cancer diagnoses. Differences in the rates of the ordering of discretionary diagnostic medical tests, such as diagnostic ultrasound, in different geographic regions of Ontario lead to differences in the rates of diagnosis of thyroid cancer.

Breast cancer causes and treatment: where are we going wrong?

This discussion paper seeks to provoke thoughts about cancer research in general, and why breast cancer in particular is not yet "curable". It asks the question - are we looking at the disease in the right way? Should we regard cancer as a progressive state, which is part of aging? Should we tailor treatment to "reset" the system or slow progression rather than try using toxic and aggressive therapy to kill every cancer cell (and sometimes also the patient)? The thesis is presented that we need to revisit our fundamental beliefs about the disease and then ask why we cling to beliefs that clearly are no longer valid. The paper also questions the role of ethics boards in hampering research and discusses the concept that breast cancer is an industry with vested interests involving profiteering by preventive, diagnostic, and therapeutic players. Finally, the paper suggests some ways forward based on emerging concepts in system biology and epigenetics.

New developments in the diagnosis and treatment of thyroid cancer

Thyroid cancer exists in several forms. Differentiated thyroid cancers include those with papillary and follicular histologies. These tumors exist along a spectrum of differentiation, and their incidence continues to climb. A number of advances in the diagnosis and treatment of differentiated thyroid cancers now exist. These include molecular diagnostics and more advanced strategies for risk stratification. Medullary cancer arises from the parafollicular cells and not the follicular cells. Therefore, diagnosis and treatment differs from those of differentiated thyroid tumors. Genetic testing and newer adjuvant therapies have changed the diagnosis and treatment of medullary thyroid cancer. This review will focus on the epidemiology, diagnosis, workup, and treatment of both differentiated and medullary thyroid cancers, focusing specifically on newer developments in the field.

Very high prevalence of ultrasound thyroid scan abnormalities in healthy volunteers in Modena, Italy

BACKGROUND

Italy is characterized by high prevalence of goiter. To date, only limited data about the prevalence of goiter in the Italian adult population are available.

AIM

To investigate the prevalence of thyroid ultrasound abnormalities in adults unaware of any thyroid disease and evaluate the rate of differentiated thyroid cancer (DTC) obtained by this intervention.

METHODS

Ultrasound (US) thyroid scan was performed in adult volunteers recruited by advertisement in Modena, Italy. One hundred and thirty-five women and 66 men (no.= 201), unaware of any thyroid disease (mean age of 46 ± 10.7 yr) underwent their first thyroid US scan.

RESULTS

US thyroid abnormalities were found in 101 subjects (50.3%): 91 nodular goiters (45.2%) and 13 US-thyroiditis (6.5%) associated with positive auto-antibodies in 11 of them. Seventeen subjects (18%) with nodules underwent US-fine needle aspiration biopsy with the following cytological class (C) outcome: 14 patients C2 (82%), 1 patient C3 (6%), 2 patients had C4 (12%), the latter received histological confirmation.

CONCLUSIONS

The prevalence of thyroid abnormalities is very high in subjects unaware of any thyroid disease. DTC was found in 1% of subjects and in 2% of those affected by nodular goiter. Compared to the detection rate of the well-established screening programs for breast (0.45%) and colorectal (0.27%) cancer, the prevalence of DTC seems to be much higher. Thyroid US screening could allow the detection of DTC in asymptomatic subjects and this diagnosis often includes DTC at an advanced stage. Thus, US screening not necessarily results in the over-diagnosis of clinically not relevant thyroid diseases.

Worldwide increasing incidence of thyroid cancer: update on epidemiology and risk factors

Background. In the last decades, thyroid cancer incidence has continuously and sharply increased all over the world. This review analyzes the possible reasons of this increase. Summary. Many experts believe that the increased incidence of thyroid cancer is apparent, because of the increased detection of small cancers in the preclinical stage. However, a true increase is also possible, as suggested by the observation that large tumors have also increased and gender differences and birth cohort effects are present. Moreover, thyroid cancer mortality, in spite of earlier diagnosis and better treatment, has not decreased but is rather increasing. Therefore, some environmental carcinogens in the industrialized lifestyle may have specifically affected the thyroid. Among potential carcinogens, the increased exposure to medical radiations is the most likely risk factor. Other factors specific for the thyroid like increased iodine intake and increased prevalence of chronic autoimmune thyroiditis cannot be excluded, while other factors like the increasing prevalence of obesity are not specific for the thyroid. Conclusions. The increased incidence of thyroid cancer is most likely due to a combination of an apparent increase due to more sensitive diagnostic procedures and of a true increase, a possible consequence of increased population exposure to radiation and to other still unrecognized carcinogens.

The incidence of thyroid cancer is affected by the characteristics of a healthcare system

The aim of this study was to investigate the associations between the incidence of thyroid cancer and the characteristics of healthcare systems in OECD countries and to demonstrate that the increasing incidence of thyroid cancer is mainly due to overdiagnosis. We used a random effects panel model to regress the incidence of thyroid cancer on the characteristics of healthcare systems (i.e., share of public expenditure on health, mode of health financing, existence of referral system to secondary care, mode of payment to primary care physicians), controlling for macro context variables (i.e., GDP per capita, educational level) on a country level. Data were derived from 34 OECD countries for 2002 and 2008. The share of public expenditure on health was negatively associated with the incidence of thyroid cancer. However, it had no statistically significant effect on the mortality of thyroid cancer and on the incidence of stomach and lung cancer. In the case of colorectal cancer, it had a positive effect on the incidence rate. The upward trend of the incidence of thyroid cancer is closely related to the healthcare system that permits overdiagnosis. Increases in the proportion of public financing may help reduce the overdiagnosis of thyroid cancer.

Comparison of exposures among Arab American and non-Hispanic White female thyroid cancer cases in metropolitan Detroit

Arab American (ArA) women may be at greater risk for thyroid cancer (TC) than White women. This case-case comparison explored differences in known and proposed risk factors of TC among ArA and non-Hispanic White (NHW) female TC cases in metropolitan Detroit. Cases of invasive TC identified from a population-based registry responded to a telephone survey regarding potential TC risk factors. Thirty ArA women (response rate 52%) and 70 NHW women (67%) participated. NHW women reported significantly more prior thyroid disease (TD), family history of TD, hormone use, cumulative years of hormone use, cigarette and alcohol consumption. In adjusted logistic regression analysis, ArA women had significantly higher odds of exposure to dental x-rays (OR = 3.48, CI 1.01-12.00) and medical radiation (OR = 13.58, CI 1.49-124.04) than NHW women. Risk factors for TC may differ among ArA women and their NHW counterparts.

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.

Analysis of the rising incidence of thyroid cancer using the Surveillance, Epidemiology and End Results national cancer data registry

BACKGROUND

The incidence of thyroid cancer has more than doubled in recent decades. Debate continues on whether the increasing incidence is a result of an increased detection of small neoplasms or other factors.

METHODS

Using the Surveillance, Epidemiology and End Results database, we examined the overall incidence of thyroid cancer with variations based on tumor pathology, size, and stage, as well as the current surgical and adjuvant therapy of thyroid carcinoma.

RESULTS

Thyroid cancer incidence increased 2.6-fold from 1973 to 2006. This change can be attributed primarily to an increase in papillary thyroid carcinoma, which increased 3.2-fold (P < .0001). The increase in papillary thyroid carcinoma also was examined based on tumor size. Tumors ≤ 1 cm increased the most at a total of 441% between 1983 and 2006 or by 19.2% per year, the incidence of papillary thyroid carcinoma also increased at 12.3%/year in 1.1-2-cm tumors, 10.3%/year in 2.1-5-cm tumors, and 12.0%/year for > 5-cm tumors (all P < .0001 by Cochran-Armitage trend test). We also demonstrated a positive correlation between papillary thyroid carcinoma tumor size and stage of disease (Spearman, r = 0.285, P < .0001). Operative treatment for thyroid cancer also has shifted with total thyroidectomy replacing partial thyroidectomy as the most common surgical procedure.

CONCLUSION

Contrary to other studies, our data indicate that the increasing incidence of thyroid cancer cannot be accounted for fully by an increased detection of small neoplasms. Other possible explanations for the increase in clinically significant (> 1 cm) well-differentiated thyroid carcinomas should be explored.

Thyroid cancer risk 40+ years after irradiation for an enlarged thymus: an update of the Hempelmann cohort

Although ionizing radiation is a known carcinogen, the long-term risk from relatively higher-dose diagnostic procedures during childhood is less well known. We evaluated this risk indirectly by assessing thyroid cancer incidence in a cohort treated with "lower-dose" chest radiotherapy more than 55 years ago. Between 2004 and 2008, we re-surveyed a population-based cohort of subjects treated with radiation for an enlarged thymus during infancy between 1926 and 1957 and their unexposed siblings. Thyroid cancer occurred in 50 irradiated subjects (mean thyroid dose, 1.29 Gy) and in 13 nonirradiated siblings during 334,347 person-years of follow-up. After adjusting for attained age, Jewish religion, sex and history of goiter, the rate ratio for thyroid cancer was 5.6 (95% CI: 3.1-10.8). The adjusted excess relative risk per gray was 3.2 (95% CI: 1.5-6.6). The adjusted excess absolute risk per gray was 2.2 cases (95% CI: 1.4-3.2) per 10,000 person-years. Cumulative thyroid cancer incidence remains elevated in this cohort after a median 57.5 years of follow-up and is dose-dependent. Although the incidence appeared to decrease after 40 years, increased risk remains a lifelong concern in those exposed to lower doses of medical radiation during early childhood.

Exposing the thyroid to radiation: a review of its current extent, risks, and implications

Radiation exposure of the thyroid at a young age is a recognized risk factor for the development of differentiated thyroid cancer lasting for four decades and probably for a lifetime after exposure. Medical radiation exposure, however, occurs frequently, including among the pediatric population, which is especially sensitive to the effects of radiation. In the past, the treatment of benign medical conditions with external radiation represented the most significant thyroid radiation exposures. Today, diagnostic medical radiation represents the largest source of man-made radiation exposure. Radiation exposure related to the use of computerized tomography is rising exponentially, particularly in the pediatric population. There is direct epidemiological evidence of a small but significant increased risk of cancer at radiation doses equivalent to computerized tomography doses used today. Paralleling the increasing use of medical radiation is an increase in the incidence of papillary thyroid cancer. At present, it is unclear how much of this increase is related to increased detection of subclinical disease from the increased utilization of ultrasonography and fine-needle aspiration, how much is due to a true increase in thyroid cancer, and how much, if any, can be ascribed to medical radiation exposure. Fortunately, the amount of radiation exposure from medical sources can be reduced. In this article we review the sources of thyroid radiation exposure, radiation risks to the thyroid gland, strategies for reducing radiation exposure to the thyroid, and ways that endocrinologists can participate in this effort. Finally, we provide some suggestions for future research directions.

Thyroid cancer epidemiology and prognostic variables

Thyroid cancer comprises a broad spectrum of diseases with variable prognoses. Although most patients with this disease have excellent overall survival, there are some who do not fare so well. With the worldwide increase in incidence, the need to identify which tumours pose the greatest risk to patients is more acute than ever. This paper will discuss this rising trend in incidence with an analysis of the possible reasons for the increase. In addition, the paper will explore the factors that portend a worse prognosis for the individual patient. Finally, the limitations of the current staging systems will be discussed, with particular emphasis on why they are not as informative in the management of patients with thyroid cancer.

[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.

Metachronous testicular teratoma, testicular seminoma and papillary thyroid carcinoma occurring in a single individual: a report of two unrelated cases

We describe two unrelated men who both developed teratomas in one testis followed by seminomas in the contralateral testis followed by papillary thyroid carcinomas. Neither man had a family history of cancers. Although random occurrence is possible, genetic predisposition and/or environmental influence would seem a likely explanation for this previously unreported combination of tumours.

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.

Expression of opioid growth factor (OGF)-OGF receptor (OGFr) axis in human nonmedullary thyroid cancer

BACKGROUND

Although thyroid cancers are readily treatable with surgery and radioactive iodine, there are problems in managing recurring, as well as locally advanced, thyroid cancer. The opioid growth factor (OGF) and its receptor, OGF receptor (OGFr), form a tonically active, autocrine-paracrine loop that serves to inhibit cell proliferation in a wide variety of normal and abnormal cells and tissues. In the present study we examined the presence and distribution of OGF and OGFr in nonmedullary thyroid cancer, including papillary, follicular, and anaplastic, as well as thyroid tissue from patients with nonmalignant disease.

METHODS

Patient samples of thyroid cancers and goiter were collected at the time of resection and processed for immunohistochemistry of OGF and OGFr, as well as pharmacological binding assays for OGFr.

RESULTS

Both peptide and receptor were detected in the cytoplasm and nucleus of all nonmedullary thyroid cancers, as well as in goiter. Specific and saturable binding of OGFr was found in all thyroid samples.

CONCLUSIONS

The finding that a potent negative growth regulator and its receptor are present in nonmedullary thyroid cancers and thyroid tissues from patients with nonmalignant disease lead us to suggest that the OGF-OGFr axis serves as a regulator of cell proliferation in these tissues. Moreover, modulation of this biological system may be used to treat progression of nonmedullary thyroid neoplasias.

Thyroid cancer incidence and socioeconomic indicators of health care access

OBJECTIVE

It has been hypothesized that changes in diagnostic practices have driven the dramatic rise in thyroid cancer incidence over the past two decades. This study investigated the relation between the incidence of thyroid cancer and socioeconomic indicators of health care access.

METHODS

We examined thyroid cancer incidence trends in Wisconsin, USA, between 1980 and 2004, according to patient and tumor characteristics. Ecologic analyses were conducted by county to examine the relation between thyroid cancer incidence and education, income, and health insurance coverage.

RESULTS

The incidence of thyroid cancer nearly doubled in Wisconsin between 1980 and 2004, with almost all of the increase occurring between 1990 and 2004, during which an annual change of 4.0% (95% CI: 3.3-4.6) was observed. The bulk of the increase consisted of small, localized cancers of papillary histology. Ecologic analyses indicated moderate correlations by county between thyroid cancer incidence and median household income (r = 0.25), percent of residents with a college degree (r = 0.24), and percent of residents with health insurance (r = 0.41).

CONCLUSIONS

The association between thyroid cancer incidence and socioeconomic indicators of health care access is consistent with the hypothesis that the rising incidence trend is attributable to utilization of new diagnostic practices.

The thyroid dose burden in medical imaging A re-examination

Radiation is the best defined causative factor in thyroid cancer. The thyroid is especially susceptible to injury from radiation to which it may be exposed in a variety of circumstances in addition to natural background: radiotherapy, including, historically, therapy of such benign conditions as ring worm and haemangiomata, radiation exposure in nuclear accidents and fallout from nuclear bomb tests, and diagnostic exposures, particularly in the relatively high dose CT examination of head and neck. Both use of CT and the incidence of thyroid cancer appear to be increasing worldwide and it has been suggested that there may be a causative relationship between the two. It has been further posited that the iodine content of the thyroid might play a role in increasing the radiation dose absorption. Indeed, on the same basis, iodine administered in the form of an X-ray contrast-enhancing agent might also be expected to play some role in increasing thyroid radiation absorption resulting in a yet higher dose burden in any give circumstances than is generally assumed. In view of the importance of these ideas we have performed some calculations to estimate the magnitude of the iodine effects. We conclude that they are not great enough to cause concern.