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

Artificial night light and thyroid cancer

BACKGROUND

The occurrence of thyroid cancer (TC) has increased in recent decades. Exposure to outdoor artificial light at night (ALN) is associated with an increased risk of cancer.

AIM

To investigated the impact of ALN, as a significant environmental pollutant, on TC incidence worldwide.

METHODS

The assessment involved analyzing satellite ALN data in conjunction with TC incidence data [adjusted standardized rate (ASR)], while considering the quality of cancer registries (QCR), gross domestic product (GDP) per person, and health expenditure per person (HEP) for each country.

RESULTS

Results indicated a correlation between higher ASR and ALN exposure percentages, particularly in countries with higher GDP or HEP quartiles (all P< 0.05). Significant differences in ASR were observed across QCR levels, both high and low quality (all P < 0.05), but not in countries without registry activity. However, when evaluating ASR against ALN exposure percentages while considering GDP/HEP quartiles or QCR levels, no significant associations were found (all P > 0.10).

CONCLUSION

The findings suggest a potential link between higher GDP and adverse health conditions, serving as possible risk factors for TC, rather than a direct association with ALN. Limitations include the use of cross-sectional data, temporal misalignment, and reliance on ALN as a socioeconomic proxy. It is proposed that light pollution might be connected to a lifestyle conducive to carcinogenesis. Additionally, the presence of higher GDP/HEP could enhance access to diagnostic resources, potentially facilitating TC diagnosis and inclusion in cancer registries.

Geographic disparities in trends of thyroid cancer incidence and mortality from 1990 to 2019 and a projection to 2030 across income-classified countries and territories

Background

The rising incidence of thyroid cancer (TC) has generated growing concern globally; yet there are no studies examining whether this incidence was followed by a rise in related mortality. We aimed to comprehensively quantify current trends and future projections of TC incidence and mortality, and to explore the association between the TC burden and socioeconomic inequality in different income strata.

Methods

We obtained incidence and mortality data on TC and population from the 2019 Global Burden of Disease (GBD) study and the United Nations' World Population Prospects 2022. We applied an age-period-cohort (APC) model to estimate the overall annual percentage change (net drift) and age, period, and cohort effects from 1990 to 2019, and also constructed a Bayesian APC model to predict the TC burden through 2030.

Results

Over a third of global TC cases belonged to the high-income group. From 1990 to 2019, net drifts of TC incidence were >0 in all income groups, while a modest reduction (net drift <0) in mortality was observed in most income groups, except for the lower-middle-income group. Unfavourable age, period, and cohort effects were most notable in Vietnam, China, and Korea. The age-standardised incidence rate (ASIR) is predicted to increase whereas the age-standardized mortality rate (ASMR) is expected to decrease globally between 2020 and 2030, with geographic heterogeneity being detected across income groups. We observed a positive correlation between ASIR and universal health coverage index and health worker density, but a negative one between ASMR and the two indicators, primarily in upper-middle-income and high-income countries.

Conclusions

Opposite patterns in incidence and mortality of TC raise concerns about overdiagnosis, particularly in upper-middle-income and high-income countries. Discrepancies in the distribution of health service accessibility, including diagnostic techniques and therapeutic care, should be addressed by narrowing health inequalities in the TC burden across countries.

Diagnostic Scrutiny and Patterns of Elevated Cancer Risk: Uncovering Overdiagnosis Through Standardized Incidence Ratios

Certain medical diagnoses and environmental or occupational exposures may be associated with elevated risk of cancer diagnosis, either through causal mechanisms or via increased detection of a subclinical reservoir through increased diagnostic scrutiny (overdiagnosis). The present study aimed to investigate the distribution of elevated cancer risks associated with different diagnoses and exposures. A systematic literature search was conducted to identify studies published in the last 30 years that examined the standardized incidence ratio (SIR) associated with exposures and risk factors. Meta-SIRs for each cancer type were calculated. The distribution of elevated cancer risks was then compared between cancer types previously reported to be susceptible to overdiagnosis and those that have not been associated with overdiagnosis. The review of 108 studies identified four patterns: SIR generally elevated for 1) only overdiagnosis-susceptible cancer types, 2) both overdiagnosed and non-overdiagnosed cancer types, 3) select cancers in accordance with risk factor or exposure, and 4) SIRs that did not exhibit a distinct increase in any cancer type. The distribution of elevated cancer risks may serve as a signature of whether the underlying risk factor or exposure is a carcinogenic process or a mechanism of increased diagnostic scrutiny uncovering clinically occult diseases. The identification of increased cancer risk should be viewed with caution, and analyzing the pattern of elevated cancer risk distribution can potentially reveal conditions that appear to be cancer risk factors but are in fact the result of exposure to medical surveillance or other healthcare activities that lead to the detection of indolent tumors.

Determining the spatial non-stationarity underlying social and natural environment in thyroid cancer in China

BACKGROUND

Light at night (LAN) is a physiological environmental factor related to thyroid cancer (TC). The spatial relationship between the number of TC incident cases, LAN, air pollution and other macro social factors and stationarity needs to be further examined to provide evidence for regional control of TC.

METHODS

Spatial econometrics methods for spatial nonstationarity were used to explore the impacts of LAN, air pollutants, economic factors, and population size on the number of TC incident cases in 182 Chinese prefecture-level cities and the local coefficients were further tested for nonstationarity. Temporally weighted regression (TWR), geographically weighted regression (GWR), and geographically and temporally weighted regression (GTWR) were compared in this study for model selection.

RESULTS

Based on the ordinary least squares (OLS), LAN, air pollutants, and urbanization all significantly affected the number of TC incident cases. GWR had the best goodness of fit, and the coefficients of all the variables passed the nonstationarity test. The strong positive impact of LAN was mainly concentrated in North China, air pollutants in Central China and neighboring regions, and urbanization in the eastern coast of China.

CONCLUSIONS

The locational factors of the prefecture-level city influence the spatial pattern of the number of TC incident cases. Governments should pay attention to this influence, adhere to the Health in All Policies principle, and formulate region-specific policies based on regional characteristics, which this study provides updated evidence for.

Role of breast cancer screening in the overdiagnosis of thyroid cancer: results from a cross-sectional nationwide survey

BACKGROUND

South Korea has the highest incidence of thyroid cancer worldwide, raising questions regarding the possibility of overdiagnosis. Examining the factors affecting thyroid cancer screening is crucial in elucidating the reasons for this unusually high incidence of thyroid cancer. Therefore, in the present study, we investigated the association between breast cancer screening and thyroid cancer screening to determine the potential role of breast cancer screening in the overdiagnosis of thyroid cancer in South Korea.

METHODS

We analyzed the data of women aged > 30 years who were enrolled in the 2014 Korean National Cancer Screening Survey. Self-reported breast cancer screening behavior was categorized as follows: no screening, mammography only, ultrasonography only, and both ultrasonography and mammography. Thyroid cancer screening behavior was categorized as follows: those who had or had not undergone ultrasonography screening. Logistic regression analysis was used to examine the associations between breast and thyroid cancer screening behaviors.

RESULTS

Of the 2270 participants, a total of 569 (25.1%) were screened for thyroid cancer. Those who underwent only mammography, only ultrasonography, or both mammography and ultrasonography were more likely to be screened for thyroid cancer than those who did not undergo breast cancer screening (odds ratio [OR]: 1.47, 95% confidence interval [CI] 1.06-2.04; OR 2.71, 95% CI 1.83-4.02; OR 2.75, 95% CI 1.99-3.80, respectively).

CONCLUSIONS

Our findings indicate that thyroid cancer screening in Korea is likely to be performed on an opportunistic basis. Therefore, a nationwide public health and medical initiative is needed to curb the unnecessary use of thyroid screening in the asymptomatic general population.

Overdiagnosis and overuse of diagnostic and screening tests in low-income and middle-income countries: a scoping review

Objective

Overdiagnosis and overuse of healthcare services harm individuals, take resources that could be used to address underuse, and threaten the sustainability of health systems. These problems are attracting increasing attention in low-income and middle-income countries (LMICs). Unaware of any review of relevant evidence, we conducted a scoping review of the evidence around overdiagnosis and overuse of diagnostic and screening tests in LMICs.

Design

Scoping review.

Methods

We searched PubMed, Embase, PsycINFO, Global Index Medicus for relevant studies published until 24 May 2021, with no restrictions on date or language. We categorised included studies by major focus (overdiagnosis, overuse of tests, or both) and main themes (presence or estimates of extent; drivers; consequences and solutions).

Results

We identified 2763 unique records and included 162 articles reporting on 154 studies across 55 countries, involving over 2.8 million participants and/or requests for tests. Almost half the studies focused on overdiagnosis (70; 45.5%), one-third on overuse of tests (61; 39.6%) and one-fifth on both (23; 14.9%). Common overdiagnosed conditions included malaria (61; 39.6%) and thyroid cancer (25; 16.2%), estimated to be >70% in China. Overused tests included imaging (n=25 studies) such as CT and MRI; laboratory investigations (n=18) such as serological tests and tumour markers; and procedures (n=14) such as colonoscopy. Drivers included fear of conflict with patients and expanding disease definitions. Common consequences included unnecessary treatments such as antimalarials, and wasted resources, with costs of malaria overdiagnosis estimated at US$86 million in Sudan in 1 year alone. Only 9% of studies discussed solutions, which included addressing inappropriately lowered diagnostic thresholds and reforming test-ordering processes.

Conclusions

Overdiagnosis and overuse of tests are widespread in LMICs and generate significant harm and waste. Better understanding of the problems and robust evaluation of solutions is needed, informed by a new global alliance of researchers and policy-makers.

Longitudinal Content Analysis of the Characteristics and Expected Impact of Low-Value Services Identified in US Choosing Wisely Recommendations

IMPORTANCE

The US Choosing Wisely campaign has had substantial reach in mobilizing efforts to reduce low-value care, achieved largely by engaging physician specialty societies in stewardship. While some early recommendations were criticized for avoiding revenue-generating services, there is limited evidence of how the composition of recommendations shifted as more societies contributed.

OBJECTIVE

To analyze the characteristics and expected impact of Choosing Wisely recommendations.

DESIGN, SETTING, AND PARTICIPANTS

This qualitative study included content and trend analyses of all 626 Choosing Wisely recommendations by US physician societies as of March 1, 2021. Data were analyzed between March and May 2021.

MAIN OUTCOMES AND MEASURES

Primary outcomes were proportions of identified low-value services by characteristics (society type, service type, indication, do vs avoid, and clinical context) and expected impact (effect on the revenue of society members, cost, number of individuals at risk, direct harm potential, and cascade potential).

RESULTS

Low-value services identified in the 626 Choosing Wisely recommendations largely covered imaging (168 [26.8%]) and laboratory studies (156 [24.9%]) in the context of chronic conditions (169 [27.0%]) and healthy patients with risk factors alone (126 [20.1%]). Most of the identified low-value services were revenue neutral for the recommending society (402 [64.2%]) and the plurality were low cost (<$200; 284 [45.4%]); low-cost services represented a growing share of low-value services identified by Choosing Wisely recommendations (1.2 percentage points per year; P = .001). Nearly half (280 [44.7%]) of recommendations identified services with high direct harm potential, and 388 (62.0%) identified those with high potential for cascades (ie, triggering downstream services).

CONCLUSIONS AND RELEVANCE

The results of this qualitative study suggest that the Choosing Wisely recommendations identified services with a range of expected impacts. Stakeholders could explicitly set priorities for future recommendations, while clinical leaders and payers might target intervention efforts on recommendations with the greatest potential for impact based on spending across populations, direct harms, and cascades.

Guideline Implementation on Fine-Needle Aspiration for Thyroid Nodules: Focusing on Micronodules

OBJECTIVE

We investigated patients who were referred to our institution after fine-needle aspiration (FNA) was performed at outside clinics to evaluate how many nodules satisfied the FNA indications of the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) and compare that to the number of thyroid nodules that satisfy the FNA indications of the American College of Radiology (ACR)-TIRADS and American Thyroid Association (ATA) guidelines.

METHODS

Between January 2018 and December 2018, 2,628 patients were included in our study. The included patients were those referred for thyroid surgery after having a suspicious thyroid nodule. We retrospectively applied the three guidelines to each thyroid nodule and determined whether each nodule satisfied the FNA indications. We compared the proportion of nodules satisfying the FNA indications of each guideline using a generalized linear model and generalized estimating equation.

RESULTS

The median size of the 2,628 thyroid nodules was 0.9 cm (range, 0.2 to 9.5 cm). We found that FNA was not indicated for 54.1%, 47.7%, and 19.1% of nodules and 87.3%, 99.0%, and 97.8% among them were micronodules (<1 cm) according to the ACR-TIRADS, ATA guideline, and K-TIRADS, respectively. The proportion of micronodules which satisfied the FNA indications was significantly higher for the K-TIRADS (65.1%) compared to the ACR TIRADS (12.1%) and ATA guideline (12.1%) (P<.001).

CONCLUSION

Among patients referred for thyroid surgery to our institutions, about 35% of the micronodules underwent FNA despite not being appropriate for indications by the K-TIRADS. Systematic training for physicians as well as modifications to increase the sensitivity of the guideline may be needed to reduce the overdiagnosis of thyroid cancers, especially for micronodules.

Thyroid Cancer Incidence in India Between 2006 and 2014 and Impact of Overdiagnosis

CONTEXT/OBJECTIVE

Increases of thyroid cancer (TC) incidence emerged in the past several decades in several countries. This study aimed to estimate time trends of TC incidence in India and the proportion of TC cases potentially attributable to overdiagnosis by sex, age, and area.

DESIGN

TC cases aged 0 to 74 years reported to Indian cancer registries during 2006 through 2014 were included. Age-standardized incidence rates (ASR) and TC overdiagnosis were estimated by sex, period, age, and area.

RESULTS

Between 2006 to 2008 and 2012 to 2014, the ASRs for TC in India increased from 2.5 to 3.5/100,000 women (+37%) and from 1.0 to 1.3/100,000 men (+27%). However, up to a 10-fold difference was found among regions in both sexes. Highest ASRs emerged in Thiruvananthapuram (14.6/100,000 women and 4.1/100,000 men in 2012-2014), with 93% increase in women and 64% in men compared with 2006 to 2008. No evidence of overdiagnosis was found in Indian men. Conversely, overdiagnosis accounted for 51% of TC in Indian women: 74% in those aged < 35 years, 50% at ages 35 to 54 years, and 30% at ages 55 to 64 years. In particular, 80% of TC overdiagnosis in women emerged in Thiruvananthapuram, whereas none or limited evidence of overdiagnosis emerged in Kamrup, Dibrugarh, Bhopal, or Sikkim.

CONCLUSIONS

Relatively high and increasing TC ASRs emerged in Indian regions where better access to health care was reported. In India, as elsewhere, new strategies are needed to discourage opportunistic screening practice, particularly in young women, and to avoid unnecessary and expensive treatments. Present results may serve as a warning also for other transitioning countries.

Thyroid cancer risk factors and Pakistani University students' awareness towards its preventive practice

OBJECTIVES

Thyroid Cancer is one of the rarest cancers but its prevalence has been increasing worldwide for the last couple of decades.

METHODS

The data collection tool was designed to assess knowledge, awareness, perception, and attitude towards preventive practices of thyroid cancer in Pakistani university students. The data were collected over a duration of six months and a total number of 3722 students participated.

RESULTS

The knowledge of risk factors of thyroid cancer was an important parameter of this study. The students who knew all the early signs of thyroid cancer were 28.7%. In this study, the independent variables such as age, gender, demographic location, and financial status were found to be highly significant with knowledge, attitude towards warning signs of cancer, and the perception of students about developing thyroid cancer.

CONCLUSIONS

The participants were found to have poor knowledge about early signs of thyroid cancer. The study participants perception, behavior, and attitude towards preventive practices of thyroid cancer were found inadequate and appropriate measures on a National level should be taken to enhance the knowledge about preventive practices of thyroid cancer. Increasing knowledge and awareness shall help decrease the overall morbidity and mortality linked with thyroid carcinomas and thyroid diseases.

Clinicopathological Significance of Overall Frequency of Allelic Loss (OFAL) in Lesions Derived from Thyroid Follicular Cell

Background

Loss of heterozygosity (LOH) and microsatellite instability (MSI) are frequent molecular events in thyroid tumor etiopathogenesis occurring in several chromosomal critical areas, including 3p12–25.3, 7q21–31, 10q22–24, and 15q11–13, with loci of tumor suppressor genes.

Objective

We evaluated the usefulness of LOH/MSI as a diagnostic/prognostic biomarker in lesions derived from thyroid follicular cells: follicular thyroid carcinoma (FTC); follicular adenoma (FA), papillary thyroid carcinoma (PTC), and nodular goiter (NG).

Methods

We performed allelotyping (GeneMapper Software v. 4.0.) of ten microsatellite markers linked to the 1p31.2, 3p21.3, 3p24.2, 9p21.3, 11p15.5, and 16q22.1 region on DNA from 93 primary thyroid lesions then evaluated the LOH/MSI frequency and overall frequency of allelic loss (OFAL).

Results

We found regions with significantly increased frequency of LOH/MSI for specific histotypes: the 3p24.2 region for FA and 1p31.2 for FTC. LOH/MSI in 3p21.3 was significantly elevated in PTC and FTC. LOH/MSI in 3p21.3 was increased for small size tumors (T1a + T1b), tumors with no regional lymph node involvement (N0 + Nx), American Joint Committee on Cancer (AJCC) stage I tumors, and tumor diameter (Td) < 10 mm; in 1p31.2 for T2–3, N1, stage II–IV, and Td 10–30 mm; in 11p15.5 for T2–3, N1, stage II–IV, and Td > 30 mm. OFAL values were significantly higher in younger patients (< 40 years), in men, in those with T2–3 stage tumors, in those with increased Td, and in FA and FTC compared with NG and PTC.

Conclusions

We confirmed the occurrence of LOH/MSI in 3p21.3 at an early stage of tumorigenesis and mapped 1p31.2 and 11p15.5 as characteristic for advanced-stage tumors. The results of our study may enable consideration of OFAL, defined as LOH/MSI coincidence in various chromosomal regions, as a tumor progression marker. OFAL values were significantly higher in follicular neoplasms (FA and FTC) than in PTC or NG; hence, increased OFAL values can be regarded as a characteristic feature of the follicular phenotype.

Active surveillance for patients with very low-risk thyroid cancer

Over the past 30 years in the United States, increasing identification of small thyroid nodules has led to a dramatic rise in the detection of small thyroid cancers, many of which are unlikely to progress to overt clinical disease. Because autopsy studies reveal that up to 30% of people harbor clinically occult thyroid cancers, the growing use of diagnostic technologies has identified an increasing number of small, clinically low risk papillary thyroid cancers (PTCs). In recent years, clinical practice has evolved to de-intensify the treatment for PTCs, with fewer total thyroidectomy and nodal dissection procedures being performed, in favor of more limited operations. In addition, vigilant observation of selected low risk cancers has demonstrated outcomes comparable to those patients who undergo immediate surgical intervention. Active surveillance has emerged as a new option within the treatment algorithm of PTCs. There is now robust data from cancer centers in Japan and Korea which have reported excellent oncologic outcomes among patients undergoing active surveillance for PTC, as well as more recent, similar data from the United States. American Thyroid Association guidelines now include the option of active surveillance for appropriately selected patients with low-risk PTC. With active surveillance now one option within the standard of care for patients with certain thyroid cancers, surgeons have become critical to facilitating shared decision-making for patients facing this diagnosis.

Geographic influences in the global rise of thyroid cancer

The incidence of thyroid cancer is on the rise, and this disease is projected to become the fourth leading type of cancer across the globe. From 1990 to 2013, the global age-standardized incidence rate of thyroid cancer increased by 20%. This global rise in incidence has been attributed to several factors, including increased detection of early tumours, the elevated prevalence of modifiable individual risk factors (for example, obesity) and increased exposure to environmental risk factors (for example, iodine levels). In this Review, we explore proven and novel hypotheses for how modifiable risk factors and environmental exposures might be driving the worldwide increase in the incidence of thyroid cancer. Although overscreening and the increased diagnosis of possibly clinically insignificant disease might have a role in certain parts of the world, other areas could be experiencing a true increase in incidence due to elevated exposure risks. In the current era of personalized medicine, national and international registry data should be applied to identify populations who are at increased risk for the development of thyroid cancer.

Clinical behavior and outcome of papillary T1 thyroid cancers: South Korea vs. Turkey vs. Colombia in a cohort study analyzing oncological outcomes

BACKGROUND/PURPOSE

There has not been an international multicentric study to examine the relationship between thyroid cancer clinical outcomes and geographic location for South Korea, Colombia, and Turkey, whereas thyroid cancer is amongst the highest three cancer types seen in South Korea and Turkey. The aim of the study was to assess regional differences of T1 papillary thyroid cancer outcomes in Korea, Turkey and Colombia.

METHODS

This is an observational non-randomized study. A total of 2720 patients who have been operated for T1 papillary thyroid cancer between 2011 and 2014 and are on routine follow-up have been recruited. The mean follow-up was 46.4 ± 10.7 months. Data were collected in a commonly used database and analyses were conducted.

RESULTS

Patients participated in South Korea (88.2%), Turkey (9.1%) and Colombia (2.6%). Eighty percent were female. Female dominance tended to be higher in Colombia (p = 0.01). Mean age at diagnosis was 45.2 years. There was no mortality. Recurrence tended to be higher in Colombia (p < 0.001). Moreover, statistical analysis revealed differences among patients regarding symptoms (p < 0.001), family history (p < 0.001), euthyroidism (p < 0.001), anti-Tg and/or anti-TPO positivity (p < 0.001), FNAB results (p < 0.001), type of resection (p < 0.001), prophylactic central node dissection (p < 0.001), tumor size (p < 0.001), multifocality (p < 0.001), bilaterality (p < 0.001), tumor subtype (p < 0.001) and radioactive iodine treatment (p < 0.01).

CONCLUSION

Thyroid cancer is becoming more commonly diagnosed worldwide. This international multicentric study has identified differences in disease presentation, treatment approaches and outcome, which need to be investigated, especially by increasing the number of participating countries. Future comparisons will facilitate developments in treatment for the benefit of patient outcomes.

Circulating adipokines and metabolic setting in differentiated thyroid cancer

The associative link relating insulin resistance (IR) and adipokines to the occurrence and phenotype of differentiated thyroid cancer (DTC) is unknown. The aim of this study was to evaluate the relationship between IR and adipokines in DTC patients, as compared with carriers of benign thyroid diseases (BTD) and healthy controls. This observational study enrolled 77 subjects phenotyped as DTC (N = 30), BTD (N = 27) and healthy subjects (N = 20). Each subject underwent preoperative analysis of anthropometric parameters, thyroid function and autoimmunity, insulin resistance (HOMA-IR) and levels of unacylated (UAG) and acylated ghrelin (AG), obestatin, leptin and adiponectin. Multivariate regression models were used to test the predictive role of metabolic correlates on thyroid phenotypes and DTC extension. The three groups showed similar age, gender distribution, smoking habit, BMI and thyroid parameters. Obestatin was significantly higher in DTC group compared to BTD (P < 0.05) and control subjects (P < 0.0001). DTC and BTD groups showed higher levels of UAG (P < 0.01) and AG (P < 0.05). Leptin levels were comparable between groups, whereas adiponectin levels were lower in DTC compared to BTD group (P < 0.0001) and controls (P < 0.01). In parallel, HOMA-IR was higher in DTC than BTD (P < 0.05) and control group (P < 0.01). Stepwise multivariable regression analysis showed that obestatin and UAG were independent predictors of DTC (P = 0.01 for both). In an analysis restricted to the DTC group, obestatin levels were associated with the absence of lymph node metastases (P < 0.05). Our results highlight a potential association between metabolic setting, circulating adipokines and thyroid cancer phenotype.

Thyroid cancer "epidemic" also occurs in low- and middle-income countries

Thyroid cancer incidence varies greatly between and within high-income countries (HICs), and overdiagnosis likely plays a major role in these differences. Yet, little is known about the situation in low- and middle-income countries (LMICs). We compare up-to-date thyroid cancer incidence and mortality at national and subnational levels. 599,851 thyroid cancer cases in subjects aged 20-74 reported in Cancer Incidence in Five Continents volume XI from 55 countries with at least 0.5 million population, aged 20-74 years, covered by population-based cancer registration, and 22,179 deaths from the WHO Mortality Database for 36 of the selected countries, over 2008-2012, were included. Age-standardized rates were computed. National incidence rates varied 50-fold. Rates were 4 times higher among women than men, with similar patterns between countries. The highest rates (>25 cases per 100,000 women) were observed in the Republic of Korea, Israel, Canada, the United States, Italy, France, and LMICs such as Turkey, Costa Rica, Brazil, and Ecuador. Incidence rates were low (<8) in a few HICs (the Netherlands, the United Kingdom, and Denmark) and lowest (3-4) in some LMICs (such as Uganda and India). Within-country incidence rates varied up to 45-fold, with the largest differences recorded between rural and urban areas in Canada (HIC) and Brazil, India, and China (LMICs). National mortality rates were very low (<2) in all countries and in both sexes, and highest in LMICs. The very high thyroid cancer incidence and low mortality rates in some LMICs also strongly suggest a major role of overdiagnosis in these countries.

Incidence and mortality of thyroid cancer in China, 20082012

Objective

To analyze the incidence and mortality rates of thyroid cancer (TC) in China from 2008 to 2012.

Methods

Incident and death cases of TC were retrieved from the National Central Cancer Registry (NCCR) database collecting from 135 cancer registries in China during 2008-2012. The crude incidence and mortality rates of TC were calculated by area (urban/rural), region (eastern, middle, western), gender and age group (0, 1-4, 5-9, …, 85+). China census in 2000 and world Segi's population were applied for age-standardized rates. Joinpoint (Version 4.6.0.0) model was used for time-trend analysis.

Results

The crude incidence rate of TC was 7.56/100,000 which ranked the seventh in overall cancers. The age-standardized incidence rates by China population (ASIRC) and by World population (ASIRW) were 6.25/100,000 and 5.52/100,000, respectively. The crude mortality of TC in China was 0.52/100,000. The age-standardized mortality rates by Chinese standard population (ASMRC) and by world standard population (ASMRW) were 0.34/100,000 and 0.32/100,000, respectively. Incidence and mortality rates of TC were higher in females than in males and higher in urban areas than in rural areas. Eastern areas had the highest incidence followed by middle and western areas. TC incidence increased dramatically after age of 15 years, then peaked at 14.08/100,000 in the group of 50-54 years and finally decreased sharply after 55 years old. TC mortality increased with age in population, reaching the peak of 5.09/100,000 in sub-population aged 85 years or older. TC incidence increased by 4.73 times from 2.40/100,000 in 2003 to 13.75/100,000 in 2012 with an average annual increase of 20%, while TC mortality only increased slightly around 0.32/100,000 from 0.26/100,000 to 0.36/100,000.

Conclusions

Appropriate targeted prevention, early detection and treatment programs can be carried out to curb the rapid growth trend of TC and control the disease burden.

Estimation of the medical need for carbon-ion radiotherapy in Korea

The Korea Heavy Ion Medical Accelerator project focuses on the development of medical accelerator facilities for delivering carbon-ion beams to cancer patients. The purpose of the present study was to estimate the clinical need for carbon-ion therapy in Korea. Seven tumor sites, namely head and neck, liver, lung, colon and rectum, prostate, bone and soft tissue, and pancreas were selected as eligible sites for receiving carbon-ion radiotherapy (RT) by radiation oncologists of the Korea Institute of Radiological and Medical Sciences. Cancer incidence data for the selected tumor sites were obtained from the Korea National Cancer Incidence Database in order to estimate the potential medical need for carbon-ion RT. The carbon-ion RT adaption rate was assessed based on the clinical experience of other carbon-ion therapy facilities. An estimation model was constructed for estimating the medical need for carbon-ion RT, and from this, 25 606 patients were deemed to be potential candidates for carbon-ion RT. This estimated potential need corresponded to 10% of newly diagnosed cancer patients in Korea. The realistic estimation was calculated as ranging between 4000 and 6300 patients, depending on the carbon-ion RT adaptation rate. This estimated medical need corresponded to 2-3% of newly diagnosed cancer patients in Korea. Taken together, our findings suggest that there is a clear medical need for carbon-ion RT in Korea, with at least 4000 potential patients per year.

Overdiagnosis in primary care: framing the problem and finding solutions

Overdiagnosis, is defined as the diagnosis of a condition that, if unrecognized, would not cause symptoms or harm a patient during his or her lifetime, and it is increasingly acknowledged as a consequence of screening for cancer and other conditions. Because preventive care is a crucial component of primary care, which is delivered to the broad population, overdiagnosis in primary care is an important problem from a public health perspective and has far reaching implications. The scope of overdiagnosis as a result of services delivered in primary care is unclear, though overdiagnosis of indolent breast, prostate, thyroid, and lung cancers is well described and overdiagnosis of chronic kidney disease, depression, and attention-deficit/hyperactivity disorder is also recognized. However, overdiagnosis is a known consequence of all screening and can be assumed to occur in many more clinical contexts. Overdiagnosis can harm patients by leading to overtreatment (with associated potential toxicities), diagnosis related anxiety or depression, and labeling, or through financial burden. Many entrenched factors facilitate overdiagnosis, including the growing use of advanced diagnostic technology, financial incentives, a medical culture that encourages greater use of tests and treatments, limitations in the evidence that obscure the understanding of diagnostic utility, use of non-beneficial screening tests, and the broadening of disease definitions. Efforts to reduce overdiagnosis are hindered by physicians' and patients' lack of awareness of the problem and by confusion about terminology, with overdiagnosis often conflated with related concepts. Clarity of terminology would facilitate physicians' understanding of the problem and the growth in evidence regarding its prevalence and downstream consequences in primary care. It is hoped that international coordination regarding diagnostic standards for disease definitions will also help minimize overdiagnosis in the future.

Refractory thyroid carcinoma: which systemic treatment to use?

The incidence of thyroid cancer has increased markedly in recent decades, but has been stable in terms of mortality rates. For the most part, these cancers are treated with surgery, which may or may not be followed by radioactive iodine depending on the tumor subtype. Still, many of these cancers will recur and may be treated with radioactive iodine or another surgery. It is unclear what treatment is best for cases of locally advanced or metastatic thyroid cancer that are refractory to radioactive iodine. Chemotherapy has a very low response rate. However, in the past few years, several systemic therapies, primarily targeted, have emerged to improve the overall survival of these patients. Alternative treatments are also of interest, namely peptide receptor radionuclide therapy or immunotherapy.

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.

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

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

Systematic Review of Trends in the Incidence Rates of Thyroid Cancer

BACKGROUND

A large proportion of global increase in thyroid cancer (TC) incidence has been attributed to increased detection of papillary thyroid cancer (PTC). Nonetheless, some reports support a real increase in incidence. This study aimed to perform a systematic review to evaluate the changing trends in TC incidence and summarize potential risk factors predisposing to this trend.

METHODS

Literature published in the English language between 1980 and August 2014 was searched via PubMed (MEDLINE) and OvidSP (EMBASE). Original studies on changes in TC incidence in defined geographic areas that described clear methods of case selection and population estimates were included. Data on incidence rates and risk factors were collected.

RESULTS

Of 4719 manuscripts, 60 studies were included, of which 31 were from Europe, 13 from North America, and the rest from Asia (n = 9), Oceania (n = 4), and South America (n = 3). Fifty-three articles reported a significant increase in incidence (highest was a 10-fold increase in South Korea), six reported stable rates, and one noted a decrease. PTC was the commonest type reported to have increased in incidence (in 10 studies with relevant data). Follicular TC increased in incidence (in four studies), albeit at a lower rate compared with PTC. Data on risk factors were sparse; factors discussed included ionizing radiation, iodine deficiency, and supplementation.

CONCLUSION

This systematic review strongly supports a widespread and persistent increase in TC incidence. Evidence for over-detection of PTC as the predominant influence includes increased numbers of smaller size tumors and improved or unchanged survival.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY DISEASE STATE CLINICAL REVIEW: THE INCREASING INCIDENCE OF THYROID CANCER

OBJECTIVE

(1) Describe current epidemiology of thyroid cancer in the United States; (2) evaluate hypothesized causes of the increased incidence of thyroid cancer; and (3) suggest next steps in research and clinical action.

METHODS

Analysis of data from Surveillance, Epidemiology and End Results System and the National Center for Vital Statistics. Literature review of published English-language articles through December 31, 2013.

RESULTS

The incidence of thyroid cancer has tripled over the past 30 years, whereas mortality is stable. The increase is mainly comprised of smaller tumors. These facts together suggest the major reason for the increased incidence is detection of subclinical, nonlethal disease. This has likely occurred through: health care system access, incidental detection on imaging, more frequent biopsy, greater volumes of and extent of surgery, and changes in pathology practices. Because larger-size tumors have increased in incidence also, it is possible that there is a concomitant true rise in thyroid cancer incidence. The only clearly identifiable contributor is radiation exposure, which has likely resulted in a few additional cases annually. The contribution of the following causes to the increasing incidence is unclear: iodine excess or insufficiency, diabetes and obesity, and molecular disruptions. The following mechanisms do not currently have strong evidence to support a link with the development of thyroid cancer: estrogen, dietary nitrate, and autoimmune thyroid disease.

CONCLUSION

Research should focus on illuminating which thyroid cancers need treatment. Patients should be advised of the benefits as well as harms that can occur with treatment of incidentally identified, small, asymptomatic thyroid cancers.

The clinical utilization of radiation therapy in Korea between 2009 and 2013

Purpose:

The purpose of this study was to estimate the clinical utilization of radiation therapy (RT) in Korea between 2009 and 2013.

Materials and Methods:

We analyzed open claims data from the Health Insurance Review and Assessment Service. The subjects were patients who had diagnostic codes C00-C97 or D00-D48 according to the 10th revision of the International Classification of Diseases, with procedure codes indicating RT treatment.

Results:

The total number of patients who received RT in 2009, 2010, 2011, 2012, and 2013 were 45,571, 49,593, 54,671, 59,172, and 61,485, respectively. Among them, the total numbers of male and female patients were 20,780/24,791 in 2009, 22,711/26,882 in 2010, 24,872/29,799 in 2011, 27,101/32,071 in 2012, and 27,941/33,544 in 2013. The five cancers that were most frequently treated with RT between 2009 and 2012 were breast, lung, colorectal, liver, and uterine cervical cancers. However, the fifth most common cancer treated with RT that replaced uterine cervical cancer in 2013 was prostate cancer. The three leading types of cancer among the male patients were lung, colorectal, and liver cancers, whereas in female patients, they were breast, uterine cervical, and lung cancers. The type of cancer most commonly treated by RT was cancer of the central nervous system in patients aged 20 years or less, breast cancer in patients aged 30–50 years, and lung cancer in patients aged 60 years or more.

Conclusion:

Data from this study provided the clinical utilization of RT in Korea between 2009 and 2013.

Role of hemithyroidectomy in differentiated thyroid cancer

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

The Clinical Status of Radiation Therapy in Korea in 2009 and 2013

Purpose

The purpose of this study is to estimate the clinical status of radiation therapy (RT) in Korea.

Materials and Methods

We analyzed open claims data from the Health Insurance Review and Assessment Service (HIRA). The subjects were patients with malignant neoplasms who had procedure codes concerning RT in 2009 and 2013.

Results

The total numbers of patients who underwent RT in 2009 and 2013 were 42,483 and 56,850, respectively. The numbers of men and women were 20,012 and 22,471 in 2009 and 26,936 and 29,914 in 2013, respectively. The five most frequent RT sites were metastatic, breast, gastrointestinal, thoracic, and gynecologic cancers in 2009, and metastatic, breast, gastrointestinal, thoracic and head and neck cancers in 2013. The three leading types of cancer among men were metastatic, gastrointestinal, and thoracic, and breast, metastatic, and gynecologic among women. According to age, the most common treatment site was the central nervous system for those aged 20 years or less, the breast for those in their 30s to 50s, and metastatic sites for those in their 60s or older.

Conclusion

Data from this study provide an overview of the clinical status of RT in Korea.

Overdiagnosis of thyroid cancer: answers to five key questions

Thyroid cancer fulfills the criteria for overdiagnosis by having a reservoir of indolent cancers and practice patterns leading to the diagnosis of incidental cancers from the reservoir. The occurrence of overdiagnosis is also supported by population-based data showing an alarming rise in thyroid cancer incidence without change in mortality. Because one of the activities leading to overdiagnosis is the workup of incidental thyroid nodules detected on imaging, it is critical that radiologists understand the issue of overdiagnosis and their role in the problem and solution. This article addresses 1) essential thyroid cancer facts, 2) the evidence supporting overdiagnosis, 3) the role of radiology in overdiagnosis, 4) harms of overdiagnosis, and 5) steps radiologists can take to minimize the problem.

Increasing diagnosis of subclinical thyroid cancers leads to spurious improvements in survival rates

BACKGROUND

Survival rates are commonly used to measure success in treating cancer, but can be misleading. Modern diagnostic practices can lead to the appearance of improving cancer survival, as tumors are diagnosed earlier (lead-time bias) or as an increasing proportion are slow-growing (length bias), whereas the actual burden of cancer deaths is unchanged. Increasingly, more subclinical thyroid cancers are being diagnosed. The objective of the current study was to determine whether thyroid cancer survival rates have been affected by this phenomenon.

METHODS

The authors analyzed survival data from patients with thyroid cancer who were treated at Memorial Sloan Kettering Cancer Center (MSKCC) from 1950 to 2005, and United States population-based incidence, prevalence, and survival data from 1973 to 2009 in the Surveillance, Epidemiology, and End Results data set.

RESULTS

US thyroid cancer incidence has increased 3-fold from 1975 to 2009. Over time, the proportion of thyroid cancers that are subcentimeter in size has increased from 23% (1983) to 36% (2009). At MSKCC, this percentage rose from 20% (1950) to 35% (2005). The incidence rates of large tumors (>6 cm) and distant metastasis have not changed. In the United States, 10-year relative survival improved from 95.4% to 98.6% (1983-1999). At MSKCC, 10-year disease-specific survival improved from 91.1% to 96.1% (1950-2005). However, when stratified by tumor size and stage, no changes in survival outcomes were observed. US thyroid cancer mortality rates have remained stable (1975-2009).

CONCLUSIONS

Modern medical practices increasingly uncover small, asymptomatic thyroid cancers. Survival rates appear improved, but this finding is spurious, attributable instead to shifts in the characteristics of disease being diagnosed. Relying on survival rates to measure success in treating thyroid cancer may reinforce inappropriately aggressive management. Treatment decisions in thyroid cancer should be made based on mortality, not survival data.

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.

Is there really an increased incidence of thyroid cancer?

PURPOSE OF REVIEW

Between 1975 and 2009, the incidence of thyroid cancer has increased from 4.9 to 14.3 cases per 100 000 individuals, with a more pronounced increase in women (from 6.5 to 21.4 cases per 100 000 women). In the USA, in 2013, there are now more cases of thyroid cancer than all leukemias, pancreas and liver cancers combined. This review assesses the current evidence around the hypothesis that thyroid cancer is overdiagnosed: cancers are being detected that were never destined to cause a patient harm.

RECENT FINDINGS

There is a large reservoir of slow or nonprogressing thyroid cancers; up to one-third of the population may unknowingly harbor a thyroid cancer. At least two activities have contributed to the detection of this reservoir of thyroid cancer: the increasing use of advanced imaging modalities in the recent years (i.e., computed tomography and MRI) and increased rates of thyroid surgery coupled with more aggressive evaluation of excised thyroid glands. Despite the increased incidence of thyroid cancer, mortality has not changed over the last 4 decades. This mismatch between incidence and mortality is most consistent with increased identification of nonlethal disease (overdiagnosis).

SUMMARY

Thyroid cancer incidence is increasing, although mortality is stable. The major cause of the increased incidence is detection of subclinical disease - overdiagnosis. Patients are still treated aggressively and are exposed to side-effects of treatment without any certainty of benefit. Strategies to avoid unnecessary intervention and to explicitly involve patients in decision-making should be pursued. Research is needed to help predict which cancers are likely to become problematic.

Differentiated thyroid cancer-personalized therapies to prevent overtreatment

The concept of individualized therapy is rapidly gaining recognition in the management of patients with differentiated thyroid cancer (DTC). This Review provides an overview of the most important elements of this paradigm shift in DTC management and discusses the implications for clinical practice. In the majority of patients with DTC who have an inherently good prognosis, the extent of surgery, the dosage of (131)I therapy and the use of levothyroxine therapy are all aspects suitable for individualization, on the basis of both the stage of disease and the response to treatment. In individuals with advanced disease, newer imaging techniques, advances in (131)I therapy and the use of targeted molecular therapies (such as multitargeted kinase inhibitors) have provided new options for the personalized care of patients, for whom until recently no effective therapies were available. Individualized therapies could reduce adverse effects, including the sometimes debilitating hypothyroidism that used to be required before initiation of (131)I treatment, and major salivary gland damage, a common and unpleasant side effect of (131)I therapy. Highly individualized interdisciplinary treatment of patients with DTC might lead to improved outcomes with reduced severity and frequency of complications and adverse effects. However, in spite of ongoing research, personalized therapies remain in their infancy.

Thyroid cancer in 2013: Advances in our understanding of differentiated thyroid cancer

Studies published in 2013 have addressed the question of whether the rising incidence of differentiated thyroid cancer is actually the result of overdiagnosis. Advances have also been made in the treatment of differentiated thyroid cancer, including improvements in radioiodine therapy.

The association between the socioeconomic status and thyroid cancer prevalence; based on the Korean National Health and Nutrition Examination Survey 2010-2011

The incidence of thyroid cancer has recently increased in most industrialized countries, including Korea. To date, few studies have examined the association between thyroid cancer and socioeconomic status (SES). The current study was based on data collected from a total of 12,276 subjects (5,277 men and 6,999 women) by the Korean National Health and Nutrition Examination Survey (KNHANES) between 2010 and 2011. Univariate and multivariate logistic regression analysis revealed that older age (odds ration [OR], 1.03; 95% confidence interval [CI], 1.00-1.05), being female (OR, 8.16; 95%CI, 2.99-22.24), being overweight (OR, 1.04; 95%CI, 1.01-1.06), monthly household income (OR, 3.27; 95%CI, 1.16-9.20 for medium-highest household income vs lowest household income; OR, 3.30; 95%CI, 1.16-9.34 for highest household income vs lowest household income), educational level (OR, 2.74; 95%CI, 1.16-6.46 for 10-12 yr vs < 7 yr) and alcohol consumption (OR, 1.89; 95%CI 1.08-3.32) were significant risk factors for thyroid cancer. Our results indicate that the recent increase in thyroid cancer is attributable to better early detection rather than to any increase in actual prevalence.

Thyroid cancer is the most common cancer in women, based on the data from population-based cancer registries, South Korea

Similar to worldwide trends, the incidence of thyroid cancer in South Korea has increased steadily in recent decades. We examined the trends in thyroid cancer incidence in Gwangju and Jeonnam provinces between 1996 and 2010, and identified 19 881 cases (men 3282/16.5%; women 16 599/83.5%) from the Gwangju Cancer Registry and Jeonnam Cancer Registry databases, which are population-based cancer registries. Age-standardized incidence rates per 100 000 persons, using hypothetical world standard population (Segi), increased from 1.9 in 1996 to 27.0 in 2010 in men, and from 10.6 to 111.3 in women, respectively. The estimated annual percentage changes (95% confidence interval) of age-standardized incidence rates were 27.1% (24.6-29.6) and 19.7% (16.4-23.2) for men and women, respectively, during the same period. The proportion of papillary-type thyroid cancer increased from 74.2 and 75.4% in 1996 to 97.9 and 98.3% in 2010 for men and women, respectively. We found the most prominent increasing trends and the highest incidence rate of thyroid cancer among those that have ever been reported. Thyroid cancer has been the leading cancer in women since 2003 and is now the fifth most common cancer in men in Gwangju and Jeonnam, South Korea.