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Racial/Ethnic Disparities in Thyroid 
Cancer Stratified by Risk Factors: 
A Literature Review 
Kristiana Rood1,2,3,**, Ria T. Laxa1,**, Andrea Shields4, Hae-Soo Kim1,2, Salma Khan1,2,3,5,* 

1Division of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA. 2Division 
of Otolaryngology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA. 3Center for 
Health Disparities & Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, CA 
92350, USA. 4Department of Pathology & Human Anatomy, Loma Linda University School of Medicine, 
Loma Linda, CA 92350, USA. 5Department of Internal Medicine, Loma Linda University School of Medicine, 
Loma Linda, CA 92354, USA. Loma Linda University, Mortensen Hall, 11085 Campus St, Loma Linda, CA 
92350. 

*Corresponding author: Salma Khan: salmakhan@llu.edu. **Equally contributed. 

ABSTRACT 
In the United States, thyroid cancer incidence has increased dramatically within the last few decades. 
Recent research suggests that this incidence along with cancer stage and mortality vary by race/ethnicity, 
highlighting health disparities in the United States. There are several risk factors for thyroid cancer 
incidence that may contribute to these disparities. The goal of this literature review is to analyze whether 
these potential risk factors impact incidence and aggressiveness differently by race/ethnicity, implicating 
their possible role in influencing thyroid cancer disparities in the United States. Through PubMed searches, 
we have reviewed recent literature on U.S. populations. We found that chromosomal alterations/non-
hereditary conditions, autoimmunity, thyroid nodules, and socioeconomic differences potentially 
impacted thyroid cancer incidence and aggressiveness by race/ethnicity, whereas sex disparities did not. 
Several potential risk factors showed some variations by race/ethnicity but either did not specifically 
examine their relationship to thyroid cancer or did not impact thyroid cancer incidence and 
aggressiveness. Other potential risk factors have not yet been studied regarding their influence on thyroid 
cancer incidence and outcomes for racial/ethnic groups in the United States. Therefore, we identify a 
critical need for subsequent research to examine these potential risk factors for different racial/ethnic 
groups and contribute to our understanding of racial/ethnic health disparities in the United States. We 
also present several research areas relating to thyroid cancer health disparities that require further study. 
KEYWORDS: Thyroid cancer, health disparities, incidence, mortality. 

Citation: Rood K et al (2023) Racial/Ethnic Disparities in Thyroid Cancer Stratified by Risk Factors: A 
Literature Review. Cancer Health Disparities 7:e1-20. doi:10.9777/chd.2023.1004  

mailto:salmakhan@llu.edu


 
 
 
 
 

 
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1. Introduction 
Thyroid cancer incidence has increased dramatically 
over the last 30 years, and epidemiologists predict 
this cancer will become the fourth most prevalent 
cancer in the United States by 2030 (Krook et al., 
2015; La Vecchia et al., 2015; Rahib et al., 2014; 
Reitzel et al., 2014; Weeks et al., 2018). One study 
found that by 2008, thyroid cancer had already 
been one of the top five cancers in Asian 
Indian/Pakistani, Chinese, Filipina, Korean, and 
Vietnamese women (Gomez et al., 2013). 
Furthermore, recent research suggests that this 
incidence varies by race/ethnicity (Table 1) (Magreni 
et al., 2015; Suresh et al., 2015; Weeks et al., 2018). 

In the United States, thyroid cancer incidence rates 
are the highest in Non-Hispanic European 
Americans and the lowest in Non-Hispanic African 
Americans (Lim et al., 2017; Magreni et al., 2015; 
Reitzel et al., 2014; Tortolero-Luna et al., 2019; 
Weeks et al., 2018; Yu et al., 2010). However, when 
separating Asian Americans by subgroups, 
Vietnamese, Cambodian, and Filipino Americans 
are shown to have elevated thyroid cancer 
incidence rates; Filipino Americans, in particular, 
have higher thyroid cancer incidence rates than 
non-Filipino Asians and non-Hispanic European 
Americans (Gomez et al., 2013; Horn-Ross et al., 
2011; Jin et al., 2016; Megwalu et al., 2021; Nguyen 
et al., 2017). 

 

Table 1. Age-adjusted thyroid cancer incidence rates and 95% confidence intervals (CIs) by Asian subgroup 
and non-Hispanic (NH) Whites, 2009-2011* (Jin et al., 2016). 

 Chinese Filipino Japanese Korean South Asian Vietnamese Asian Total NH White 

N Rate 
(95% 
CI) 

N Rate 
(95% 
CI) 

N Rate 
(95% CI) 

N Rate 
(95% 
CI) 

N Rate 
(95% CI) 

N Rate 
(95% CI) 

N Rate 
(95% 
CI) 

N Rate 
(95% 
CI) 

Men 263 6.9 
(6.1-
7.8) 

271 9.7 
(8.5-
11.0) 

41 3.7 (2.6-
5.2) 

108 8.3 
(6.8-
10.1) 

186 5.8 (4.9-
6.8) 

75 5.3 (4.1-
6.7) 

974 6.8 
(6.4-
7.3) 

9,425 8.1 
(7.9-
8.3) 

Women 920 20.8 
(19.4-
22.2) 

1,108 28.5 
(26.8-
30.3) 

153 (11.6 
(9.7-
13.9) 

408 23.2 
(21.0-
25.6) 

624 19.9 
(18.3-
21.7) 

318 19.3 
(17.2-
21.7) 

3,670 21.5 
(20.8-
22.2) 

25,325 22.4 
(22.1-
22.7) 

*Rates are average annual per 100,000 age-standardized to the 2000 US population; the Number of cases may not add up to the 
total due to rounding. 

There are several risk factors for thyroid cancer 
incidence that may contribute to these disparities 
(Konturek et al., 2016; La Vecchia et al., 2015; Weeks 
et al., 2018). A recent study by Bogović et al. 
categorized the potential risk factors as either “high 
risk,” “low risk,” or “unclear” (Bogović Crnčić et al., 
2020). High-risk factors included external radiation 
exposure (especially during infancy and childhood), 
chromosomal alterations, and hereditary 
conditions. Low-risk factors included thyroid 
imaging with iodine, iodine deficiency, high thyroid-
stimulating hormone (TSH) level, autoimmunity, 

thyroid nodules, environmental pollutants, 
lifestyle/diet, and obesity/high BMI. The only 
unclear risk factor included was estrogen. Another 
recent study by Yildirim et al. mentioned metabolic 
syndrome and insulin resistance as important risk 
factors (Yildirim Simsir et al., 2020). Additionally, sex 
and socioeconomic status may also be considered 
risk factors. The goal of this literature review is to 
analyze whether these potential risk factors impact 
incidence and aggressiveness differently by 
race/ethnicity, implicating their possible role in 



 
 
 
 
 

 
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influencing thyroid cancer racial/ethnic disparities in 
the United States.  

2. Materials and Methods 
To review recent research, a PubMed search was 
used, including articles published since 2010. Each 
identified thyroid cancer risk factor, as informed by 
Bogović et al. (Bogović Crnčić et al., 2020) and 
Yildirim et al. (Yildirim Simsir et al., 2020), was used 
as a keyword: ‘radiation exposure’ or ‘ionizing 
radiation’, ‘chromosomal alterations’, ‘non-
hereditary conditions’, ‘hereditary conditions’, 
‘iodine’, ‘TSH’, ‘autoimmunity’, ‘thyroid nodules’, 
‘environmental pollutants’ and ‘geospatial’, ‘lifestyle 
and diet’, ‘BMI’, ‘metabolic syndrome’, ‘insulin 
resistance’, ‘sex’, and ‘socioeconomic’. Other 
keywords included: ‘effects of’, ‘thyroid’, ‘thyroid 
cancer’, ‘United States’, ‘health disparities’, ‘risk 
factors’, and ‘race and ethnicity’. Articles were 
selected after screening titles and abstracts for 
relevancy, with a particular focus on research done 
in the United States. Afterwards, the full text for 
each article was acquired. Some potential risk 
factors - such as radiation exposure, autoimmunity, 
chromosomal alterations/non-hereditary 
conditions, hereditary conditions, and thyroid 
nodules - included publications since 2000 as the 
findings for these risk factors are less likely to 
change significantly within the last 20 years 
compared to the others. Each potential risk factor 
was reviewed for whether they may impact thyroid 
cancer incidence and aggressiveness differently by 
racial/ethnic group, if no difference exists, or if 
further research is necessary to examine their 
relationship to health disparities.  

3. Risk factors potentially contributing 
to TC health disparities 
3.1. Genetic Factors 
Hereditary conditions influencing TC health 
disparities  

Although more than 90% of thyroid cancers are 
sporadic, thyroid cancer has been shown to have a 
significant hereditary component with many 
hereditary forms exhibiting more aggressive 
courses. Hereditary thyroid neoplasms are divided 
into those that arise from follicular cells, familial 
non-medullary thyroid carcinoma (FNMTC) and 
those arising from calcitonin-producing C cells, 
familial medullary thyroid carcinomas (FMTCs).  

FNMTCs are further divided into syndromes where 
non-thyroid tumors predominate, and those where 
non-medullary thyroid tumors predominate. The 
former includes familial adenomatous polyposis 
(FAP), Cowden Syndrome (CS), Carney complex 
(CNC), Werner syndrome (WS), McCune-Albright 
syndrome, Pendred syndrome, and DICER1 
syndrome. The latter group includes pure familial 
papillary thyroid carcinoma (fPTC), fPTC with 
multinodular goiter, and fPTC with papillary renal 
cell carcinoma (Guilmette and Nosé, 2018).  

Medullary thyroid cancer (MTC) is hereditary in 25% 
of cases, and commonly occurs as part of the 
multiple endocrine neoplasia II syndromes, 
although a heritable MTC-only syndrome is 
reported. Hereditary and sporadic MTC are both 
driven by mutations in the RET proto-oncogene; 
however, hereditary forms are more likely to 
present bilaterally and arise at an earlier age, with 
MENII carrying a near 100% lifetime risk of 
developing MTC (Guilmette and Nosé, 2018). 
Despite earlier presentation of hereditary MTC, one 
study found the overall 10-year survival to be 100% 
in hereditary MTC compared to 80% in sporadic 
MTC (Xu et al., 2012). Although hereditary MTC has 
been reported across varying ethnic groups, there 



 
 
 
 
 

 
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is little research investigating the racial distribution 
of hereditary MTC. 

Familial adenomatous polyposis (FAP) is an 
autosomal disorder caused by a germline mutation 
in the adenomatous polyposis coli (APC) gene. 
Around 2-12% of patients with FAP develop PTC, 
with a 160-fold greater risk of developing PTC than 
unaffected individuals. More than 90% of the cases 
have a histologic variant, called cribriform-morular 
PTC (CMV-PTC), and they are more likely to affect 
females and present bilaterally. Overall, the 
prognosis is good and only 10% of CMV-PTC cases 
are aggressive (Guilmette and Nosé, 2018). FAP has 
been described in all races but there is little research 
comparing the prevalence between different racial 
groups. One study investigated the racial variation 
in APC mutations and found that the overall APC 
mutation rate was higher in Asians and African 
Americans compared to Europeans (Inra et al., 
2015). Further research is indicated to evaluate 
whether the risk of thyroid cancer with FAP varies 
between racial/ethnic groups. 

 Out of all FNMTC, Cowden Syndrome (CS) is an 
autosomal dominant condition caused by a 
germline mutation in PTEN. Although other genes 
have also been implicated in CS, intact PTEN 
virtually excludes the diagnosis. Two-thirds of CS 
patients develop thyroid tumors, with the majority 
of follicular origin, including follicular adenoma and 
follicular carcinoma (Guilmette and Nosé, 2018). 
Although most of the patients with CS reported in 
the literature are European (Garofola et al., 2022), 
at present, the true racial distribution is not yet well 
described. 

Carney complex (CNC) is a rare autosomal 
dominant syndrome with the majority harboring 
mutations in the PRKAR1a gene. Up to 75% have 
multiple thyroid nodules but they are at minimal risk 
for developing thyroid malignancy. Thyroid 

neoplasms within CNC patients are more likely to 
be found in young females and both follicular 
thyroid carcinoma and PTC can be seen (Guilmette 
and Nosé, 2018). There have been more than 750 
reported cases with affected Europeans, Asians 
(from all continents), and African Americans 
described (Correa et al., 2015). 

Werner syndrome (WS) is an autosomal recessive 
syndrome caused by WRN mutations leading to 
defects in DNA repair and replication that leads to 
premature aging. Thyroid cancer typically presents 
in the third decade, with a lower female to male 
ratio (2:1). They carry a three-fold increased risk for 
follicular carcinoma and a six-fold increased risk for 
anaplastic thyroid carcinoma (Guilmette and Nosé, 
2018). There is a high prevalence of WS in Japan, 
where WS has been reported up to 1 in 20,000-
40,000 live births compared to 1 in 100,000 births 
worldwide. In the United States the prevalence is 
estimated to be even less as 1 in 200,000 live births 
(Sickles and Gross, 2022). Up to 18% of Japanese 
patients with WS also develop thyroid cancer and 
Europeans have an increased risk of PTC. The 
median life expectancy of WS patients is 
approximately 54 years, with thyroid cancers and 
cardiac diseases being the most common causes of 
death (Guilmette and Nosé, 2018).  

There are some cases of FNMTC in which genetics 
is not yet known. But it is believed that these cases 
are autosomal dominant and six potential 
chromosomal regions have been implicated. This 
category of FNMTC is diagnosed when three or 
more first-degree relatives have non-medullary 
thyroid cancer, usually PTC. The tumors are more 
likely to present at a younger age and have a more 
aggressive clinical course with a worse prognosis 
(Guilmette and Nosé, 2018). Further research is 
indicated on the racial distribution within all these 
various types of FNMTC. 



 
 
 
 
 

 
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3.2. Environmental Factors  
3.2.1. Radiation exposure in TC health disparities 

The radiosensitivity of the thyroid gland is well 
documented (Lubin et al., 2017). Radiation exposure 
in childhood is associated with a higher risk of 
thyroid cancer than radiation exposure in adults 
(Lee et al., 2019), and the risk increases from about 
5 years after exposure (Furukawa et al., 2013). 
Radiation exposure in children increases their 
likelihood of developing papillary thyroid cancer 
later in life, which is the most common type of 
thyroid cancer (Bogović Crnčić et al., 2020; Yildirim 
Simsir et al., 2020). Children and adolescents 
exposed to radioactive iodine from the Chernobyl 
fallout have also shown a higher risk of thyroid 
cancer (Furukawa et al., 2013). This trend has also 
been seen in animal models. It was reported that 
more radiation-induced thyroid tumors developed 
in 10-day-old infant rats than in adult rats (Matsuu-
Matsuyama et al., 2021). Another study 
demonstrated that the thyroids of 1-week-old 
neonatal rats are more sensitive to ionizing 
radiation at 12 Gy compared to those from adult 
rats (Matsuu-Matsuyama et al., 2021).  

Increase in the use of imaging in medicine, such as 
CT examinations, is believed to play a role in the 
increased incidence of thyroid cancer in the United 
States (Yildirim Simsir et al., 2020). This means that 
differences in access to healthcare between patients 
of different ethnic groups may affect the 
population’s exposure to radiation, and therefore 
incidence of thyroid cancer. For example, in the 
1970s and 80s, there were many medical 
professionals who came to the United States from 
the Philippines. This group most likely had better 
access to CT examinations and had additional 
occupational exposure to ionizing radiation. In fact, 
one study reported that highly educated Filipinos 
had higher proportionate mortality due to thyroid 
cancer than less educated Filipinos (Nguyen et al., 

2017). On the other hand, in a single hospital study 
of 1,024 female nurses and 2,631 non-nurse females 
with both groups receiving their annual health 
examinations over a period of two years, generally 
no difference was found in incidence of thyroid 
cancer between the two groups (Kim and Woo, 
2016). This suggests more research is needed to 
determine if this increased incidence among 
Filipinos is due to job or socioeconomic status-
related radiation exposure or if it is largely due to 
inherent biological factors within the Filipina 
population. 

3.2.2. Iodine deficiency in TC health disparities 

The thyroid gland uses iodine to make thyroid 
hormones. When the body is low on iodine and 
there is a decrease in the level of thyroid hormones, 
the pituitary gland produces more TSH to 
compensate. However, TSH is a growth stimulating 
factor for thyroid follicular cells. This suggests that 
diets with insufficient intake of iodine could play a 
role in follicular thyroid cancer (Bogović Crnčić et 
al., 2020). However, low iodine diets are necessary 
prior to radioactive iodine (RAI) treatment for 
thyroid cancer patients with a thyroidectomy 
(Nguyen et al., 2017). Studies showed that thyroid 
cancer patients on low-iodine diets before 
radioactive iodine (RAI) treatment experienced 
enhanced uptake and maximized destruction of 
thyroid cancer cells (Li et al., 2016; Nguyen et al., 
2017). However, in Filipino Americans who have a 
higher intake of iodine-rich foods - such as seafood, 
dairy, grains, and eggs - treatment was less effective 
compared to other patients preparing for RAI 
treatment (Herrick et al., 2018; Nguyen et al., 2017). 
Another study analyzed the median urinary iodine 
concentration (mUIC) of individuals in the United 
States as a measure of dietary iodine (Herrick et al., 
2018). Non-Hispanic Asian women of reproductive 
age had low mUIC, and therefore mild iodine 
deficiency, compared to non-Hispanic African 



 
 
 
 
 

 
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American women of reproductive age despite both 
populations consuming similar amounts of dairy 
and grains (Herrick et al., 2018). When looking at the 
total population of individuals ages 6 years and 
above, non-Hispanic Asians consumed more 
amounts of dairy and grains compared to non-
Hispanic African Americans but continued to have 
lower mUIC (Herrick et al., 2018). Since Asian 
individuals tend to consume more rice than other 
racial groups, it is possible that differences in the 
type of grain consumed by ethnic groups could 
influence iodine levels (Herrick et al., 2018). 
Additionally, this study found that non-Hispanic 
Asians consumed higher amounts of soy products 
compared to other racial groups and suggests that 
substances in these soy products could inhibit 
iodine uptake by the thyroid (Herrick et al., 2018). 
These data suggest that differences in diet among 
racial/ethnic groups may impact dietary iodine 
levels and, therefore, RAI treatment outcome. 

3.2.3. Environmental pollutants influencing TC 
health disparities 

Populations are exposed to varying levels of 
harmful chemicals in the environment through 
water, air, food, or soil (Yildirim Simsir et al., 2020). 
A few of these chemicals – such as benzene, 
formaldehyde, and pesticides – have been linked to 
goiter and nodular goiter formation as well as 
papillary thyroid cancer (Bogović Crnčić et al., 2020; 
Yildirim Simsir et al., 2020). Another set of 
chemicals, nitrates, are commonly found in ready-
made foods and, when at above-average levels, 
can affect iodine uptake and increase the risk of 
thyroid cancer (Bogović Crnčić et al., 2020). 
Additionally, polybrominated diphenyl ethers 
(PBDEs) found in many industrial materials may 
induce abnormal thyroid cell proliferation leading 
to a risk of thyroid cancer (Bogović Crnčić et al., 
2020).  

Considering residential segregation and 
racial/ethnic diversity by geographic level in the 
United States, a geospatial approach to cancer 
research could allow for a better understanding of 
whether environmental pollutants differentially 
impact certain racial/ethnic groups (Korycinski et al., 
2018; Sahar et al., 2019). An example of this 
approach includes the application of geographic 
information science (GIScience) to cancer research. 
This allows researchers to analyze spatial data, 
visualize cancer and risk factor data on a map, and 
investigate geographic disease patterns and 
clusters (Sahar et al., 2019). Most geospatial cancer 
research studies have been published after 2010 
and are affiliated with NCI-designated Cancer 
Centers (Korycinski et al., 2018). Additionally, 
despite this recently growing area of research, most 
of these studies have looked at other cancer types 
besides thyroid cancer – such as breast, prostate, 
and colorectal cancers (Korycinski et al., 2018). One 
study done in Vermont found no correlation 
between thyroid cancer incidence and proximity to 
tertiary healthcare centers or socioeconomic status 
(Hanley et al., 2015). However, the researchers note 
that Vermont has a population that is >95% 
European American and has >92% healthcare 
insurance coverage, providing little evidence for 
racial/ethnic minority groups (Hanley et al., 2015). 
Another study done in California found that 
disadvantaged communities, or DACs, had higher 
amounts of nitrate well contamination as well as a 
significant correlation between well contamination 
per square mile and thyroid cancer incidence (Tariqi 
and Naughton, 2021). In particular, there was a two 
times greater thyroid cancer incidence compared to 
non-DACs (Tariqi and Naughton, 2021). DACs tend 
to have a higher population density and amount of 
people per well, exposing a larger number of 
people to contaminated drinking water and 
suggesting that certain populations are 
disproportionately affected by environmental 



 
 
 
 
 

 
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factors (Tariqi and Naughton, 2021). These studies 
highlight the importance of further geospatial 
research on thyroid cancer to address geographic 
and racial/ethnic cancer disparities in the United 
States.  

Another area of consideration regarding 
environmental pollutants and their possible 
contribution to thyroid cancer racial/ethnic 
disparities is birthplace. One study – although 
limited by birthplace data – has looked at whether 
birthplace alters incidence rates of thyroid cancer 
among Asians (Horn-Ross et al., 2011). Researchers 
found that US-born Chinese women had higher 
papillary thyroid cancer incidence rates than China-
born Chinese women, and a reverse trend was 
observed among Filipino American and Japanese 
American women (Horn-Ross et al., 2011). Another 
study of five Asian female subgroups in California 
from 1988 to 2004 showed that Japan-born 
Japanese women had a significantly higher papillary 
thyroid cancer incidence rate compared to US-born 
Japanese women, and a reverse trend was 
observed among Chinese and Filipina American 
women (Horn-Ross et al., 2011). This study also 
found that foreign-born Chinese, Korean, 
Vietnamese, and Filipina American women had 
papillary thyroid cancer incidence rates that peaked 
at 70 years of age, whereas their US-born Asian 
subgroup counterparts peaked during reproductive 
and menopausal years (Horn-Ross et al., 2011). 
Overall, these findings suggest that exposures 
related to immigration and acculturation of these 
ethnic groups may have impacted their risk of 
thyroid cancer (Horn-Ross et al., 2011)(21). Further 
research is needed that includes other racial/ethnic 
groups and analyzes how these factors could affect 
thyroid cancer incidence. 

3.3. Socioeconomic Factors 
3.3.1. Radioiodine treatment  

Within the last few decades, the use of RAI 
treatment for thyroid cancer has increased (Pasqual 
et al.). One study found that patients who had a 
thyroidectomy for low-risk papillary thyroid cancer 
were more likely to undergo RAI treatment if they 
had lower healthcare access (Marti et al., 2015). This 
includes those that are uninsured, in poverty, 
attained only a high school education, are non-
English speaking, or unemployed. Additionally, 
racial/ethnic minority populations are more likely to 
be uninsured and have decreased access to high-
quality care, whether due to geographic area or 
stereotyping by healthcare providers (Artiga S, 
2021; National Research Council Panel on Race and 
Health in Later, 2004). This suggests that some 
racial/ethnic minority populations of the United 
States may experience inappropriate use of RAI 
treatment, an aggressive therapy for low-risk PTC 
(Marti et al., 2015). 

When using RAI for differentiated thyroid cancer 
(DTC) treatment, one recent study found that RAI 
treatment increased the risk of leukemia and several 
types of solid cancer such as breast cancer, 
regardless of racial/ethnic group (Pasqual et al.). 
However, RAI treatment for DTC did not increase 
the risk of second thyroid cancer (Pasqual et al.). 
This indicates that RAI treatment may not be a risk 
factor for thyroid cancer which differentially impacts 
certain racial/ethnic groups. Further studies could 
examine the racial/ethnic variations in RAI 
treatment sensitivity or resistance to determine if 
these contribute to thyroid cancer health disparities. 

3.3.2. Diagnostic differences in TC health 
disparities 

Many literature suggest that thyroid cancer’s 
racial/ethnic differences could be related to 
socioeconomic status and insurance coverage 
impacting dissimilar access to US-guided FNA and 



 
 
 
 
 

 
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computed tomography (CT) (Brown et al., 2010; 
Keegan et al., 2015; Morris et al., 2013; Reitzel et al., 
2014; Roche et al., 2016; Stroup et al., 2012; Weeks 
et al., 2018; Zevallos et al., 2015). While thyroid 
cancer incidence has been increasing over time 
irrespective of socioeconomic status, a study in 
Texas reports a difference in the rate of increase 
between low and high socioeconomic status ethnic 
groups (Reitzel et al., 2014). In particular, the study 
found a low thyroid cancer incidence rate among 
low socioeconomic status Non-Hispanic African 
Americans and Hispanic Americans and a high 
thyroid cancer incidence rate among high 
socioeconomic status Non-Hispanic African 
Americans and Hispanic Americans (Reitzel et al., 
2014). Similarly, a study in North Dakota found that 
counties with higher median income levels had 
increasing incidence rates, likely due to detection 
bias associated with increased access to physicians 
(Schwartz and Klug, 2019). Studies have also shown 
that among thyroid cancer patients, European 
Americans (vs. non- European Americans) have 
greater odds of having tumors <40mm, and this 
variability in diagnosis is likely due to differences 
between races in their access to medical care to 
detect these tumors; particularly, European 
Americans tend to have and seek more access to 
medical care than racial/ethnic minority patients 
(National Research Council Panel on Race and 
Health in Later, 2004; Weeks et al., 2018). However, 
once tumors increase to a size ≥40mm in other 
races/ethnicities, they become palpable, thus 
leading patients to seek medical attention similarly 
(Weeks et al., 2018). 

Regarding insurance coverage, it has been found 
that insured patients were 45% more likely to be 
diagnosed with small tumors compared to the 
uninsured (Weeks et al., 2018). A study found that 
adolescent and young adult patients who were 
diagnosed between 2001 and 2010 had a worse 
overall survival if they had no medical insurance 

(Keegan et al., 2015). Another study found that age-
adjusted thyroid cancer incidence rates were 2-3 
times greater in uninsured Hispanic Americans than 
in uninsured European Americans (Weeks et al., 
2018). The reverse incidence rate was found in 
insured Hispanic Americans compared to insured 
Non-Hispanic European Americans (Weeks et al., 
2018). As mentioned previously, racial/ethnic 
minority populations are more likely to be 
uninsured (Artiga S, 2021; National Research 
Council Panel on Race and Health in Later, 2004), 
therefore these findings suggest that access to 
medical care and insurance could influence 
incidence rates among racial/ethnic groups 
differentially. 

3.4. Metabolic Factors 
Obesity, metabolic syndrome, and insulin 
resistance in TC health disparities 

While there has been a rise in thyroid cancer 
incidence, the Centers for Disease Control and 
Prevention (CDC) reports that there has also been 
a rise in obesity in the United States; obesity 
prevalence has increased from 30.5% to 42.4% 
from 1999-2000 through 2017-2018, and the 
prevalence of severe obesity has increased from 
4.7% to 9.2% (https://www.cdc.gov/obesity/data/ 
adult.html). Besides being associated with a number 
of chronic diseases, such as diabetes mellitus and 
cardiovascular disease, studies have also shown 
that obesity puts individuals at a higher risk of 
thyroid cancer compared to those with normal 
weight (Bogović Crnčić et al., 2020; Clinckspoor et 
al., 2011; Franchini et al., 2022; Hales et al., 2020; 
Kushchayeva et al., 2022; Ma et al., 2022; Zhao et 
al., 2019). Studies found that high BMI was 
significantly associated with the risk of papillary, 
follicular, and anaplastic, but not medullary, thyroid 
cancers (Kitahara et al., 2016; Zhao et al., 2019). 
Furthermore, studies have shown that high BMI was 
associated with larger tumor size, multifocality, and 

https://www.cdc.gov/obesity/data/adult.html
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advanced tumor-node-metastasis (TNM) stage (Ma 
et al., 2022; Zhao et al., 2019). In addition to high 
BMI, a waist circumference ≥109 cm has also been 
found as a strong predictor of thyroid cancer (Lubin 
et al., 2017; Ma et al., 2022). While one cohort study 
found that higher BMI was not associated with more 
aggressive tumor features and recurrence or 
persistence, this study looked at a 93% European 
American population at a single institution, 
therefore, the results may have been limited by the 
lack of racial/ethnic and socioeconomic diversity 
(Paes et al., 2010).  

In these ongoing studies, it is important to 
recognize that obesity impacts some ethnic/racial 
groups more than others. In particular, non-
Hispanic African American adults have the highest 
prevalence of obesity (defined as a BMI of greater 
than or equal to 30) and severe obesity (defined as 
a BMI greater than or equal to 40) compared to 
other ethnic/racial groups (Hales et al., 2020). By 
contrast, non-Hispanic Asian adults have the lowest 
prevalence of obesity (Hales et al., 2020). Despite 
having lower BMI’s than other racial/ethnic groups, 
Asian Americans tend to have high prevalence rates 
of metabolic syndrome, especially amongst 
Filipinos and Asian Indians (Palaniappan et al., 2011). 
Filipinos and Asian Indians also tend to have a 
higher prevalence of obesity than non-Hispanic 
European Americans (Palaniappan et al., 2011). This 
is particularly interesting considering the 
disproportionate impact Filipinos face from thyroid 
cancer as well. Therefore, further research is 
necessary to determine whether some factors which 
may impact obesity for a certain ethnic/racial group 
could impact that group’s risk for thyroid cancer. 

3.5. Behavioral Factors 
Lifestyle and diet in TC health disparities 

With the growing evidence that obesity may be 
associated with an increased risk of thyroid cancer, 
it is advised that individuals adopt a lifestyle that 

includes at least 60 min/day of moderate physical 
activity to reduce the incidence of obesity-related 
thyroid cancer (Franchini et al., 2022; Ma et al., 
2022). Some studies in the United States have found 
that higher levels of physical activity could reduce 
the risk of some cancers (bladder, breast, colon, 
endometrial, esophageal adenocarcinoma, and 
gastric cardia) while increasing the risk for some 
other cancers (lung, ovarian, pancreatic, and renal 
cancer) (Friedenreich et al., 2021). However, these 
studies have not looked at the relationship between 
thyroid cancer, specifically, and physical activity 
(Friedenreich et al., 2021). Some research has been 
done to examine this relationship in Korea; less 
physical activity in women was associated with a 
decreased risk of thyroid cancer, and a positive 
correlation was found between physical exercise 
and thyroid cancer (Kim et al., 2021; Lee et al., 2020). 
Further research is needed to examine the 
relationship between physical activity and thyroid 
cancer among populations in the United States, 
especially since physical activity in the United States 
varies between racial/ethnic groups which could 
impact thyroid cancer outcomes. In particular, the 
CDC reports that Hispanic adults have the lowest 
physical activity outside of work and Non-Hispanic 
Asian adults have the highest.   

Diets can vary by racial/ethnic group due to social 
and cultural differences between populations (Satia, 
2009). Variations in iodine intake among 
racial/ethnic groups could be from differences in 
the consumption of seafood, dairy, grains, and eggs 
(Bogović Crnčić et al., 2020; Herrick et al., 2018; 
Nguyen et al., 2017). Nitrate/nitrite intake can vary 
among racial/ethnic groups due to consumption of 
processed foods and meats, which is more 
common in certain racial/ethnic groups than others 
(Said Abasse et al., 2022). In particular, one study 
found that Non-Hispanic European Americans were 
more likely than other racial/ethnic groups to 
consume excess processed meats (Gudenkauf and 



 
 
 
 
 

 
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Thrift, 2021). This study also found that Non-
Hispanic African Americans had more cancer types 
attributable to processed meat consumption 
(Gudenkauf and Thrift, 2021). However, this study 
focused on Non-Hispanic European Americans, 
Non-Hispanic African Americans, and Hispanics 
while grouping all other racial/ethnic groups 
together. Further research is needed to examine 
differences in diet practices and nutrient intake 
among racial/ethnic subgroups since certain 
subgroups, such as Filipino Americans within the 
Asian American population, tend to have high 
consumption of processed foods. Social and 
cultural differences in diet could, therefore, place 
some racial/ethnic groups at a higher risk of thyroid 
cancer. It is worth noting that socioeconomic 
differences can play a role in access to ingredients 
and types of foods as well as how much physical 
activity individuals can realistically engage in due to 
barriers such as cost and time, placing minority 
populations at particular risk of thyroid cancer. 

Some other lifestyle practices, such as smoking and 
alcohol consumption, could affect one’s risk of 
thyroid cancer. In the United States, one study 
examining smoking found that e-cigarette users 
had a higher prevalence of several cancer types - 
including thyroid cancer - compared to traditional 
smokers (Chidharla et al., 2022). Smoking and 
alcohol consumption habits vary by racial/ethnic 
group, as well, and could be due to social and 
cultural factors. According to the CDC, cigarette 
smoking prevalence is the highest in Native 
Americans and Alaska Natives and lowest among 
Asian Americans - although within Asian 
subgroups, Koreans and Vietnamese have high 
smoking prevalence (Chartier and Caetano, 2010). 
Alcohol consumption tends to be most common in 
European Americans, lowest in Asian Americans, 
and similar amongst Native Americans, Hispanics, 
and African Americans; however Native Americans 
tend to have the highest prevalence of heavy and 

binge drinking (Chartier and Caetano, 2010). These 
variations in smoking and alcohol consumption 
habits could contribute to the thyroid cancer health 
disparities seen between racial/ethnic groups in the 
United States, however, further research is needed 
to examine these relationships.  

3.6. Biological Factors 
3.6.1. Thyroid-stimulating hormone (TSH) level in 
TC health disparities 

Research suggests that thyroid stimulating 
hormone (TSH), also known as thyrotropin, 
mediates thyroid cell growth factors, such as IGF-I 
and insulin (Bogović Crnčić et al., 2020). Therefore, 
high levels of TSH may lead to an enlarged thyroid 
gland, or goiter (Bogović Crnčić et al., 2020; Yildirim 
Simsir et al., 2020). One study has found that higher 
levels of TSH is associated with a fourfold increase 
of thyroid cancer and a higher risk of advanced 
stage differentiated thyroid cancer (Bogović Crnčić 
et al., 2020). Another study has found that even 
minimal elevations of serum TSH over time could 
lead to increased thyroid volume and goiter 
(Yildirim Simsir et al., 2020). Obese individuals are 
at a higher risk of increased TSH levels and the 
development of goiter and papillary thyroid cancer 
(Yildirim Simsir et al., 2020). Therefore, it is not 
surprising that TSH suppression therapy following 
radioiodine treatment can reduce the recurrence 
rate of differentiated thyroid cancer (Bartenstein et 
al., 2014; Kim et al., 2014; Wang et al., 2022). 
However, further research is needed to look at 
whether levels of TSH vary by race/ethnicity in the 
United States. 

3.6.2. Sex in TC health disparities 

Thyroid cancer is one of the most rapidly increasing 
types of cancer in both women and men (Lim et al., 
2017; Rahbari et al., 2010; Tortolero-Luna et al., 
2019; Weeks et al., 2018). It is known that women 
are about three times more likely to be diagnosed 
with thyroid cancer than men, particularly through 



 
 
 
 
 

 
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the finding of small tumors (<40mm) (Rahbari et al., 
2010; Weeks et al., 2018). This places thyroid cancer 
as one of the top ten most diagnosed cancers in 
women as of 2018 (Rahbari et al., 2010; Weeks et al., 
2018). Furthermore, follicular and papillary thyroid 
cancers make up approximately 80% of thyroid 
cancer cases in women, and papillary thyroid cancer 
is three times more common in women than in men 
(Horn-Ross et al., 2011; Rahbari et al., 2010). 
However, it is also known that men have a higher 
mortality rate compared to women (Keegan et al., 
2015; Rahbari et al., 2010; Tortolero-Luna et al., 
2019). Additionally, men are more likely to have 
regional/distant stages of disease upon diagnosis, 
unfavorable clinicopathological characteristics such 
as angioinvasion, and a higher risk for recurrence of 
well-differentiated thyroid cancer (Gajowiec et al., 
2021; Keegan et al., 2015; Zahedi et al., 2020). While 
some studies have been looking at differences 
between men and women in hormonal regulation, 
androgen receptor gene expression, and certain 
somatic mutations, further research is needed to 
find if there are any strong associations with thyroid 
cancer (Asban et al., 2019; Chou et al., 2020; 
Megwalu et al., 2021; O'Connell et al., 2021; Rahbari 
et al., 2010).  

When looking at whether sex as a risk factor for 
thyroid cancer varies by race/ethnicity, one study 
found a ratio of female to male incidence rates of 
3:1 to 4:1 across racial/ethnic groups, including 
European Americans, Hispanics, Asians, African 
Americans, and Native Americans (Weeks et al., 
2018). It is likely that this higher incidence among 
women and the size of tumors upon diagnosis 
could be due to differences in access to medical 
care and women receiving more regular check-ups 
than men (Rahbari et al., 2010; Weeks et al., 2018). 
Generally, however, there is a uniform 3:1 ratio of 
sex disparities across all ethnicities, suggesting that 
sex is a risk factor for thyroid cancer that does not 
differentially impact certain racial/ethnic groups. 

Based on these findings, it is of interest to 
investigate differences in sex hormone levels 
among racial/ethnic groups. For example, a study 
found that African American men had higher sex 
hormone binding globulin (SHBG) concentration 
and serum estradiol levels than Hispanic American 
and European American men (Rohrmann et al., 
2007). Serum testosterone levels did not differ 
between African American men and European 
American men, however Hispanic American men 
had higher serum testosterone levels than the other 
racial/ethnic groups (Rohrmann et al., 2007). 
Another study looked at variations in hormone 
levels among overweight, glucose-intolerant, 
postmenopausal women (Kim et al., 2012). This 
study found that, among women not using 
estrogen, Non-Hispanic European Americans had 
higher baseline total and bioavailable estradiol and 
testosterone levels than Hispanics, as well as higher 
baseline bioavailable estradiol and lower levels of 
SHBG than African Americans (Kim et al., 2012). 
Therefore, while sex differences exist across all 
racial/ethnic groups, it is still possible that variations 
in androgen and androgen receptor levels between 
racial/ethnic groups could contribute to the 
racial/ethnic disparity in thyroid cancer. Future 
studies are required to investigate the correlation 
between androgen and thyroid cancer health 
disparities. 

3.6.3. Autoimmunity in TC health disparities 

Autoimmune diseases (AD) are caused by 
inflammation of organs due to production of 
antibodies against self-structures and cytotoxic 
action of T cells (Fröhlich and Wahl, 2017). AD is 
prevalent in the population and is more common in 
women (≥85%) than in men. Additionally, 
autoimmune thyroid disease (AITD) is one of the 
most common types (Fröhlich and Wahl, 2017). 
Graves’ disease and Hashimoto’s thyroiditis (HT) are 



 
 
 
 
 

 
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examples of thyroid autoimmune diseases (Umar et 
al., 2010).  

In Graves’ disease, hyperthyroidism (low TSH and 
elevated free T4 concentrations) is caused by 
thyroid-stimulating autoantibodies to the TSH 
receptor (TSHR) , which may lead to hyperfunction 
of the thyroid gland (Umar et al., 2010). After 
delivering a baby, some patients may develop 
forms of autoimmune thyroid dysfunction, such as 
Graves’ disease (Inaba and Akamizu, 2000). 
Another is postpartum thyroiditis, which is also 
believed to be an autoimmune disorder, and its 
prevalence ranges from 3 to 8 percent of all 
pregnancies (Inaba and Akamizu, 2000). It is 
painless and occurs within 6 months after 
pregnancy, with a return to normal thyroid function 
typically within a year, although some patients 
develop permanent hypothyroidism as a result 
(Inaba and Akamizu, 2000). It is characterized by 
transient thyrotoxicosis followed by hypothyroidism 
or by one or the other occurring in the first year 
after parturition (Inaba and Akamizu, 2000). 
Diagnostic tests reveal that serum TSH is 
suppressed, associated with an increase in serum 
FT3 and FT4 levels (Inaba and Akamizu, 2000). 

In HT, hypothyroidism (elevated TSH and low free 
T4 concentrations) is associated with thyroid 
peroxidase and thyroglobulin autoantibodies 
(McLachlan et al., 2007), and is thought to be 
caused by a TSH stimulation-blocking antibody 
(TSBAb) which blocks the action of the TSH 
hormone causing damage to the thyroid gland 
(Umar et al., 2010). Retrospective pathological 

studies and FNA cytological studies have shown an 
association between HT and papillary thyroid 
carcinoma (PTC) (Boi et al., 2017). Most pathological 
studies showed high prevalence of PTC in HT (Boi 
et al., 2017). In most FNAC studies, increased 
thyroid-stimulating hormone (TSH) levels were the 
main risk factor for malignancy (Boi et al., 2017). 

Additionally, several studies have shown an 
association between chronic inflammation and 
increased risk of developing differentiated thyroid 
cancers (DTCs) (Pagano et al., 2018). This suggests 
that the inflammatory microenvironment is essential 
in cellular transformation and tumor progression 
(Pagano et al., 2018). It has been demonstrated that 
inflammatory cells within the cancer site and 
activation of oncoprotein-mediated signaling in 
epithelial cancer cells influence thyroid cancer 
progression (Pagano et al., 2018). 

Racial disparities have been noted in autoimmune 
thyroid conditions (Table 2). A study has shown that 
African Americans and Asians are much more likely 
to develop Graves’ disease than European 
Americans (McLeod et al., 2014). On the other hand, 
European Americans have a greater risk of 
developing HT compared to other ethnic groups 
(McLeod et al., 2014). When evaluating thyroid 
function and autoimmunity in African American and 
European American women during pregnancy and 
the postpartum period, another study found that 
African American women always had lower TSH 
values than European American women (Walker et 
al., 2005). These findings provide awareness of 
racial disparities in thyroid autoimmune disorders. 

 

 

 

Table 2. Racial Disparities in Autoimmune Thyroiditis. 



 
 
 
 
 

 
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 European Americans (EA) African Americans (AA) Asian Americans 

Graves’ Disease (McLeod 
et al., 2014) 

Less susceptible More susceptible More susceptible 

Hashimoto Thyroiditis 
(McLeod et al., 2014) 

More susceptible Less susceptible Less susceptible 

Pregnancy/Postpartum 
(Walker et al., 2005) 

Higher TSH values 
compared to AAs 

Lower TSH values 
compared to EAs 

- 

 

3.6.4. Thyroid nodule size in TC health disparities 

It is proposed that the dramatic increase in thyroid 
cancer incidence rates within the last few decades 
could be due to improved diagnostic techniques 
and the introduction of ultrasound-guided fine-
needle aspiration (US-guided FNA) into the United 
States healthcare system in the 1990s, which aids in 
detecting tumors that are not easily discovered by 
palpation (La Vecchia et al., 2015; Lim et al., 2017; 
Tortolero-Luna et al., 2019; Weeks et al., 2018; 
Zevallos et al., 2015). More sensitive diagnostic 
procedures, such as CT or MRI scans (done for 
other medical problems), can detect nonpalpable, 
incidental thyroid nodules (ITNs) that might not 
otherwise have been found in the past (Fisher and 
Perrier, 2018). Imaging studies can detect up to 10 
times more nodules than by palpation, most of 
which are benign (Fisher and Perrier, 2018). 

Approximately 5 to 15% of nodules are found to be 
malignant (Alexander et al., 2012). For diagnostic 
purposes, nodules 1cm or larger in diameter 
prompt diagnostic US-guided FNA, which is the 
only method routinely used for thyroid nodule 
evaluation (Alexander et al., 2012; Yoon et al., 2014). 
However, about 15 to 30% of thyroid nodules 
evaluated by FNA are indeterminate, so it is unclear 
whether they are benign or malignant (Alexander et 
al., 2012). Indeterminate nodules are often referred 
for diagnostic surgery, though most of these 
nodules are shown to be benign (Alexander et al., 
2012). This exposes these patients to a 2 to 10% risk 
of serious surgical complications, and they could 

require thyroid hormone replacement therapy for 
life to overcome hypothyroidism (Alexander et al., 
2012). Future work is needed for better diagnostic 
tools in preoperative diagnosis of thyroid cancer.  

Autopsy studies estimate that thyroid nodules may 
be present in up to 50% to 60% of all adults (Fisher 
and Perrier, 2018). Women are more frequently 
affected than men (4:1), and the prevalence of 
thyroid nodules in women increases with age 
(Fisher and Perrier, 2018). Studies have been done 
exploring ethnicities affected. Zheng et al. showed 
that thyroid nodules in African Americans had 
consistently lower rates of harboring malignancy 
compared to other groups (Zheng et al., 2022). 
Among different ethnic groups represented in the 
study, the prevalence of thyroid malignancy was 
24.0% of African Americans, 52.1% of Caucasian 
Americans, 58.7% of Hispanic Americans, and 71.7% 
of Asian Americans (Zheng et al., 2022). Iwata et al. 
noted that African Americans have a much lower 
incidence of thyroid cancer than other ethnic 
groups despite presenting with larger nodules, and 
European Americans have a greater risk (Iwata et 
al., 2018). This study aimed to see if there was a true 
difference in the thyroid cancer rates between these 
ethnicities, or if socioeconomic status perhaps 
played a role (Iwata et al., 2018). They found that 
European Americans have a higher incidence not 
only due to diagnostic bias, but also due to a true 
difference in cancer prevalence (Iwata et al., 2018). 
Another study aimed to determine whether patients 
of Filipino descent are at increased risk of thyroid 



 
 
 
 
 

 
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cancer compared to matched controls (Clark et al., 
2006). This group found that Filipino patients with 
thyroid nodules are at significantly increased risk. 
Thus, suspicion for malignancy should be high 
when evaluating these patients. Recently, we 
showed a differential expression of vitamin D 
binding protein (DBP) in two different ethnic 
groups, which was related to advanced stage 
thyroid cancer in Filipino Americans compared to 
European Americans (Mull et al., 2021); higher DBP 
expression in European Americans correlated to 
better prognosis. We further demonstrated that 
differential small non-coding RNAs may potentially 
influence the poor prognosis in Filipino Americans 
versus European Americans (Rood et al., 2021). 

3.6.5. Chromosomal alterations/non-hereditary 
conditions influencing TC health disparities 

Although germline mutations are very rare, somatic 
mutations play an important role in thyroid cancer 
oncogenesis. Several genetic alterations have been 
implicated in the development of thyroid cancer, 
including activation of signaling pathways by either 
recombination events or point mutations, with 
some mutations associated with more aggressive 
forms (Bogović Crnčić et al., 2020; Yildirim Simsir et 
al., 2020). 

Somatic mutations can cause dysregulation of 
mitogen-activated protein kinases (MAPK), 
phosphoinositide 2 kinase-AKT (PI3K-AKT), and 
wingless-related integration site (WNT) cell 
signaling pathways (Singh et al., 2021). They are 
some of the most common pathways associated 
with thyroid cancer (Singh et al., 2021). Both MAPK 
and PI3K-AKT pathways are coupled to the cell 
membrane receptor tyrosine kinase (RTK), which 
leads to downstream intracellular signaling and 
ultimately activation and deactivation of genes 
related to cell growth, proliferation, and survival 
(Xing et al., 2013). The WNT pathway similarly leads 
to disordered cellular growth by preventing 

degradation of β-catenin, thus allowing its 
localization into the nucleus and subsequent 
activation of transcription factors involved in cellular 
proliferation and cell-cell adhesion (Pai et al., 2017). 
Activating point mutations of RAS and BRAF and 
rearrangements of RET/PTC and NTRK genes within 
the MAPK pathway, are common drivers of papillary 
thyroid cancer (PTC). In contrast, follicular thyroid 
cancer (FTC) frequently has alterations of the PI3K-
AKT pathway such as activating mutations of 
PIK3CA, RAS, and AKT1, and deactivating mutations 
of PTEN. Other mutations such as p53 and TERT 
promoter mutations, and WNT/β-catenin pathway 
alterations have been implicated in thyroid cancer 
disease progression and dedifferentiation (Prete et 
al., 2020).   

There are few studies comparing the prevalence of 
these mutations across different racial/ethnic 
groups. One study evaluated radioiodine refractory 
thyroid (RAIR) cancers and found that European 
race/ethnicity was associated with a reduced odds 
ratio of radioiodine refractoriness (Shobab et al., 
2019). Additionally, 50% of patients with RAIR had 
mutations in the RAS/RAF pathway; however, the 
prevalence of RAS/RAF mutation within Europeans 
was not directly measured (Shobab et al., 2019). 
Another study performed whole-genome 
genotyping on European and African American 
patients with RAIR and found that the thyroglobulin, 
BRCA1, and the NSMCE2 haplotypes were uniquely 
associated with African Americans (Hurst et al., 
2019). Differences in mutation can explain the 
established differences in the incidence of thyroid 
cancer among racial/ethnic groups. Different 
mutations also carry varying prognoses. Therefore, 
differences in chromosomal alterations between 
races/ethnicities can potentially contribute to the 
varying disease outcomes seen across racial/ethnic 
groups. Additional studies are indicated to further 
explore the demographics and other racial/ethnic 
groups with common thyroid cancer mutations. 



 
 
 
 
 

 
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4. Conclusions 
Through this literature review, several risk factors 
are found to potentially impact thyroid cancer 
incidence and aggressiveness differently by 
racial/ethnic groups. Chromosomal 
alterations/non-hereditary conditions, 
autoimmunity, thyroid nodules, and socioeconomic 
differences are identified as factors that vary by 
racial/ethnic group and influence thyroid cancer 
incidence and outcomes. Some of these potential 
risk factors require further research to incorporate 
more racial/ethnic groups. The only risk factor that 
does not vary by racial/ethnic group is sex 
disparities. However, differences found in sex 
hormone levels between racial/ethnic groups may 
suggest their possible influence on thyroid cancer 
health disparities and necessitates further research. 
Some studies on iodine deficiency, environmental 
pollutants, obesity/metabolic syndrome/insulin 
resistance, and lifestyle/diet as risk factors for 
thyroid cancer suggest that certain racial/ethnic 
groups could be differentially impacted. Further 
research, however, is needed to specifically 
examine their relation to thyroid cancer or to clarify 
whether certain racial/ethnic groups are 
differentially impacted in the United States. 
Additionally, while some racial/ethnic disparities 
exist in regards to the use of RAI treatment, recent 
research suggests that this is not a risk factor for 
secondary thyroid cancer. Other potential risk 
factors - including radiation exposure, hereditary 
conditions, and TSH level - have not yet been 
studied regarding their potential influence on 
thyroid cancer incidence and outcomes for different 
racial/ethnic groups in the United States. These 
should be given priority in future research work. 

5. Limitations 
A limitation of our literature review is that we did 
not perform a meta-analysis of potential factors 
contributing to thyroid cancer health disparities. 

However, we are currently gathering insight into the 
factors that may contribute to the differences in the 
genetic and epigenetic pathways of health 
disparities. Additionally, the findings of our 
literature review are limited by the racial/ethnic 
groups that have been studied by the articles 
reviewed. In particular, some studies focused on 
two racial/ethnic populations only or may have 
grouped some racial/ethnic populations together. 
Therefore, it is possible that variations in the 
potential thyroid cancer risk factors between 
racial/ethnic groups may have been limited by the 
lack of diversity in some of these studies.  

6. Future Directions 
There are several areas of research which need to 
be addressed regarding thyroid cancer health 
disparities, as highlighted by this literature review. 
One such area of interest for our lab is the sex 
hormone-induced immune pathway in cancer cells. 
In future work, we will examine this pathway in 
relation to racial/ethnic groups in the United States 
to understand why Filipino Americans have higher 
TC incidence rates. Additionally, although biologic 
differences were thought to be responsible for the 
difference in the severity and progression of thyroid 
cancer, no genetic or molecular level differences 
were reported so far. This literature review 
contributes to our knowledge of the several factors 
that may be correlated to the differential miRNA 
expression we observe within ethnic groups. Future 
work may include taking these factors into account 
in our statistical analysis in a larger cohort of 
patients. 

Acknowledgements 
The authors would like to thank Dr. Reinhard 
Schulte, MD; Dr. Mia Perez, MD; Celina R. 
Yamauchi, BS; and Dr. Qudus Lawal, MD for 
contributing through conceptualization, reviewing, 
and editing of the manuscript.  



 
 
 
 
 

 
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Funding 
This research was supported by the Department of 
Otolaryngology and the National Institute on 
Minority Health and Health Disparities (NIMHD) 
[grant number P20MD001632] (PI: DeLeon) from 
Center for Health Disparities & Molecular Medicine, 
Loma Linda University School of Medicine. This 
work was also supported by NIMHD Grant [grant 
number 5U54MD007592]. 

Author’s contribution 
Conceptualization, KR, RL, SK; writing—original 
draft preparation, RL, KR, AS, HSK, SK; writing—
review and editing, RL, KR, AS, HSK, SK; supervision, 
SK; funding acquisition, SK. All authors have read 
and agreed to the published version of the 
manuscript. 

Conflicts of interest 
The authors declare that there is no conflict of 
interest regarding the publication of this article. 

Consent 
All co-authors approve the submission of this 
manuscript. 

Confirmation 
Content of this manuscript has not been submitted 
for publication elsewhere, and is not under 
consideration for publication by any other journal. 

References 
Autoimmune Thyroiditis. ARUP Consult®. 

Alexander, E.K., Kennedy, G.C., Baloch, Z.W., Cibas, E.S., 
Chudova, D., Diggans, J., Friedman, L., Kloos, R.T., LiVolsi, 
V.A., Mandel, S.J., et al. (2012). Preoperative Diagnosis of 
Benign Thyroid Nodules with Indeterminate Cytology.  
367, 705-715. 

Artiga S, H.L., Orgera K, Damico A (2021). Health Coverage by 
Race and Ethnicity, 2010-2019. KFF. 

Asban, A., Chung, S.K., Xie, R., Lindeman, B.M., Balentine, C.J., 
Kirklin, J.K., and Chen, H. (2019). Gender and Racial 
Disparities in Survival After Surgery Among Papillary and 
Patients With Follicular Thyroid Cancer: A 45-Year 

Experience. Clin Med Insights Endocrinol Diabetes 12, 
1179551419866196. 

Bartenstein, P., Calabuig, E.C., Maini, C.L., Mazzarotto, R., 
Muros de Fuentes, M.A., Petrich, T., Rodrigues, F.J., Vallejo 
Casas, J.A., Vianello, F., Basso, M., et al. (2014). High-risk 
patients with differentiated thyroid cancer T4 primary 
tumors achieve remnant ablation equally well using rhTSH 
or thyroid hormone withdrawal. Thyroid 24, 480-487. 

Bogović Crnčić, T., Ilić Tomaš, M., Girotto, N., and Grbac 
Ivanković, S. (2020). Risk Factors for Thyroid Cancer: What 
Do We Know So Far? Acta Clin Croat 59, 66-72. 

Boi, F., Pani, F., and Mariotti, S. (2017). Thyroid Autoimmunity 
and Thyroid Cancer: Review Focused on Cytological 
Studies. Eur Thyroid J 6, 178-186. 

Brown, S.R., Lee, S., Brown, T.A., and Waddell, B.E. (2010). Effect 
of race on thyroid cancer care in an equal access 
healthcare system. Am J Surg 199, 685-689. 

Chartier, K., and Caetano, R. (2010). Ethnicity and health 
disparities in alcohol research. Alcohol Res Health 33, 152-
160. 

Chidharla, A., Agarwal, K., Abdelwahed, S., Bhandari, R., Singh, 
A., Rabbani, R., Patel, K., Singh, P., Mehta, D., Manaktala, 
P.S., et al. (2022). Cancer Prevalence in E-Cigarette Users: 
A Retrospective Cross-Sectional NHANES Study. World J 
Oncol 13, 20-26. 

Chou, C.K., Chi, S.Y., Chou, F.F., Huang, S.C., Wang, J.H., Chen, 
C.C., and Kang, H.Y. (2020). Aberrant Expression of 
Androgen Receptor Associated with High Cancer Risk and 
Extrathyroidal Extension in Papillary Thyroid Carcinoma. 
Cancers (Basel) 12. 

Clark, J.R., Eski, S.J., and Freeman, J.L. (2006). Risk of malignancy 
in Filipinos with thyroid nodules--a matched pair analysis. 
Head Neck 28, 427-431. 

Clinckspoor, I., Verlinden, L., Overbergh, L., Korch, C., Bouillon, 
R., Mathieu, C., Verstuyf, A., and Decallonne, B. (2011). 
1,25-dihydroxyvitamin D3 and a superagonistic analog in 
combination with paclitaxel or suberoylanilide hydroxamic 
acid have potent antiproliferative effects on anaplastic 
thyroid cancer. J Steroid Biochem Mol Biol 124, 1-9. 

Correa, R., Salpea, P., and Stratakis, C.A. (2015). Carney 
complex: an update. Eur J Endocrinol 173, M85-97. 

Fisher, S.B., and Perrier, N.D. (2018). The incidental thyroid 
nodule. CA Cancer J Clin 68, 97-105. 

Franchini, F., Palatucci, G., Colao, A., Ungaro, P., Macchia, P.E., 
and Nettore, I.C. (2022). Obesity and Thyroid Cancer Risk: 
An Update. Int J Environ Res Public Health 19. 

Friedenreich, C.M., Ryder-Burbidge, C., and McNeil, J. (2021). 
Physical activity, obesity and sedentary behavior in cancer 
etiology: epidemiologic evidence and biologic 
mechanisms. Mol Oncol 15, 790-800. 



 
 
 
 
 

 
www.companyofscientists.com/index.php/chd e17 Cancer Health Disparities 

RESEARCH 

Fröhlich, E., and Wahl, R. (2017). Thyroid Autoimmunity: Role of 
Anti-thyroid Antibodies in Thyroid and Extra-Thyroidal 
Diseases. Front Immunol 8, 521. 

Furukawa, K., Preston, D., Funamoto, S., Yonehara, S., Ito, M., 
Tokuoka, S., Sugiyama, H., Soda, M., Ozasa, K., and 
Mabuchi, K. (2013). Long-term trend of thyroid cancer risk 
among Japanese atomic-bomb survivors: 60 years after 
exposure. Int J Cancer 132, 1222-1226. 

Gajowiec, A., Chromik, A., Furga, K., Skuza, A., Gąsior-Perczak, 
D., Walczyk, A., Pałyga, I., Trybek, T., Mikina, E., Szymonek, 
M., et al. (2021). Is Male Sex A Prognostic Factor in Papillary 
Thyroid Cancer? J Clin Med 10. 

Garofola, C., Jamal, Z., and Gross, G.P. (2022). Cowden Disease. 
In StatPearls (Treasure Island (FL): StatPearls Publishing 

Copyright © 2022, StatPearls Publishing LLC.). 

Gomez, S.L., Noone, A.M., Lichtensztajn, D.Y., Scoppa, S., 
Gibson, J.T., Liu, L., Morris, C., Kwong, S., Fish, K., Wilkens, 
L.R., et al. (2013). Cancer incidence trends among Asian 
American populations in the United States, 1990-2008. 
Journal of the National Cancer Institute 105, 1096-1110. 

Gudenkauf, F.J., and Thrift, A.P. (2021). Preventable causes of 
cancer in Texas by Race/Ethnicity: Inadequate diet Prev 
Med Rep 24, 101637. 

Guilmette, J., and Nosé, V. (2018). Hereditary and familial 
thyroid tumours. Histopathology 72, 70-81. 

Hales, C.M., Carroll, M.D., Fryar, C.D., and Ogden, C.L. (2020). 
Prevalence of Obesity and Severe Obesity Among Adults: 
United States, 2017-2018. NCHS Data Brief, 1-8. 

Hanley, J.P., Jackson, E., Morrissey, L.A., Rizzo, D.M., Sprague, 
B.L., Sarkar, I.N., and Carr, F.E. (2015). Geospatial and 
Temporal Analysis of Thyroid Cancer Incidence in a Rural 
Population. Thyroid 25, 812-822. 

Herrick, K.A., Perrine, C.G., Aoki, Y., and Caldwell, K.L. (2018). 
Iodine Status and Consumption of Key Iodine Sources in 
the U.S. Population with Special Attention to Reproductive 
Age Women. Nutrients 10. 

Horn-Ross, P.L., McClure, L.A., Chang, E.T., Clarke, C.A., 
Keegan, T.H., Rull, R.P., Quach, T., and Gomez, S.L. (2011). 
Papillary thyroid cancer incidence rates vary significantly 
by birthplace in Asian American women. Cancer Causes 
Control 22, 479-485. 

Hurst, Z., Liyanarachchi, S., He, H., Brock, P., Sipos, J., Nabhan, 
F., Kebebew, E., Green, P., Cote, G.J., Sherman, S., et al. 
(2019). Risk Haplotypes Uniquely Associated with 
Radioiodine-Refractory Thyroid Cancer Patients of High 
African Ancestry. Thyroid 29, 530-539. 

Inaba, H., and Akamizu, T. (2000). Postpartum Thyroiditis. In 
Endotext, K.R. Feingold, B. Anawalt, A. Boyce, G. Chrousos, 
W.W. de Herder, K. Dhatariya, K. Dungan, J.M. Hershman, 
J. Hofland, S. Kalra, et al., eds. (South Dartmouth (MA): 
MDText.com, Inc. 

Copyright © 2000-2022, MDText.com, Inc.). 

Inra, J.A., Steyerberg, E.W., Grover, S., McFarland, A., Syngal, S., 
and Kastrinos, F. (2015). Racial variation in frequency and 
phenotypes of APC and MUTYH mutations in 6,169 
individuals undergoing genetic testing. Genet Med 17, 
815-821. 

Iwata, A.J., Bhan, A., Lahiri, S., Williams, A.M., Burmeister, C., 
Chang, S.S., and Singer, M.C. (2018). INCIDENTAL 
THYROID NODULES: RACE/ETHNICITY DISPARITIES AND 
OUTCOMES. Endocr Pract 24, 941-947. 

Jin, H., Pinheiro, P.S., Xu, J., and Amei, A. (2016). Cancer 
incidence among Asian American populations in the 
United States, 2009-2011. Int J Cancer 138, 2136-2145. 

Keegan, T.H., Grogan, R.H., Parsons, H.M., Tao, L., White, M.G., 
Onel, K., and Horn-Ross, P.L. (2015). Sociodemographic 
disparities in differentiated thyroid cancer survival among 
adolescents and young adults in California. Thyroid 25, 
635-648. 

Kim, C., Golden, S.H., Mather, K.J., Laughlin, G.A., Kong, S., Nan, 
B., Barrett-Connor, E., and Randolph, J.F., Jr. (2012). 
Racial/ethnic differences in sex hormone levels among 
postmenopausal women in the diabetes prevention 
program. J Clin Endocrinol Metab 97, 4051-4060. 

Kim, K.H., and Woo, S.H. (2016). An Occupational Study in 
Nurses: Prevalence of Thyroid Nodules and Cancer in 
Comparison to Health Check-up Female. Clin Exp 
Otorhinolaryngol 9, 252-256. 

Kim, S.Y., Yoo, D.M., Min, C., and Choi, H.G. (2021). Association 
between Coffee Consumption/Physical Exercise and 
Gastric, Hepatic, Colon, Breast, Uterine Cervix, Lung, 
Thyroid, Prostate, and Bladder Cancer. Nutrients 13. 

Kim, T.Y., Kim, W.G., Kim, W.B., and Shong, Y.K. (2014). Current 
status and future perspectives in differentiated thyroid 
cancer. Endocrinology and metabolism (Seoul, Korea) 29, 
217-225. 

Kitahara, C.M., McCullough, M.L., Franceschi, S., Rinaldi, S., 
Wolk, A., Neta, G., Olov Adami, H., Anderson, K., 
Andreotti, G., Beane Freeman, L.E., et al. (2016). 
Anthropometric Factors and Thyroid Cancer Risk by 
Histological Subtype: Pooled Analysis of 22 Prospective 
Studies. Thyroid 26, 306-318. 

Konturek, A., Barczyński, M., Stopa, M., and Nowak, W. (2016). 
Trends in Prevalence of Thyroid Cancer Over Three 
Decades: A Retrospective Cohort Study of 17,526 Surgical 
Patients. World journal of surgery 40, 538-544. 

Korycinski, R.W., Tennant, B.L., Cawley, M.A., Bloodgood, B., 
Oh, A.Y., and Berrigan, D. (2018). Geospatial approaches 
to cancer control and population sciences at the United 
States cancer centers. Cancer Causes Control 29, 371-377. 

Krook, K.A., Fedewa, S.A., and Chen, A.Y. (2015). Prognostic 
indicators in well-differentiated thyroid carcinoma when 



 
 
 
 
 

 
www.companyofscientists.com/index.php/chd e18 Cancer Health Disparities 

RESEARCH 

controlling for stage and treatment. The Laryngoscope 
125, 1021-1027. 

Kushchayeva, Y., Kushchayev, S., Jensen, K., and Brown, R.J. 
(2022). Impaired Glucose Metabolism, Anti-Diabetes 
Medications, and Risk of Thyroid Cancer. Cancers (Basel) 
14. 

La Vecchia, C., Malvezzi, M., Bosetti, C., Garavello, W., 
Bertuccio, P., Levi, F., and Negri, E. (2015). Thyroid cancer 
mortality and incidence: a global overview. International 
journal of cancer 136, 2187-2195. 

Lee, J.H., Youn, S., Jung, S., Kim, K., Chai, Y.J., Chung, Y.S., Park, 
W.S., Lee, K.E., and Yi, K.H. (2020). A national database 
analysis for factors associated with thyroid cancer 
occurrence. Sci Rep 10, 17791. 

Lee, W.J., Preston, D.L., Cha, E.S., Ko, S., and Lim, H. (2019). 
Thyroid cancer risks among medical radiation workers in 
South Korea, 1996-2015. Environ Health 18, 19. 

Li, J.H., He, Z.H., Bansal, V., and Hennessey, J.V. (2016). Low 
iodine diet in differentiated thyroid cancer: a review. Clin 
Endocrinol (Oxf) 84, 3-12. 

Lim, H., Devesa, S.S., Sosa, J.A., Check, D., and Kitahara, C.M. 
(2017). Trends in Thyroid Cancer Incidence and Mortality 
in the United States, 1974-2013. Jama 317, 1338-1348. 

Lubin, J.H., Adams, M.J., Shore, R., Holmberg, E., Schneider, 
A.B., Hawkins, M.M., Robison, L.L., Inskip, P.D., Lundell, M., 
Johansson, R., et al. (2017). Thyroid Cancer Following 
Childhood Low-Dose Radiation Exposure: A Pooled 
Analysis of Nine Cohorts. J Clin Endocrinol Metab 102, 
2575-2583. 

Ma, X.N., Ma, C.X., Hou, L.J., and Fu, S.B. (2022). The association 
of obesity with thyroid carcinoma risk. Cancer Med 11, 
1136-1144. 

Magreni, A., Bann, D.V., Schubart, J.R., and Goldenberg, D. 
(2015). The effects of race and ethnicity on thyroid cancer 
incidence. JAMA otolaryngology-- head & neck surgery 
141, 319-323. 

Marti, J.L., Davies, L., Haymart, M.R., Roman, B.R., Tuttle, R.M., 
and Morris, L.G. (2015). Inappropriate Use of Radioactive 
Iodine for Low-Risk Papillary Thyroid Cancer Is Most 
Common in Regions with Poor Access to Healthcare. 
Thyroid 25, 865-866. 

Matsuu-Matsuyama, M., Shichijo, K., Matsuda, K., Fujimoto, N., 
Kondo, H., Miura, S., Kurashige, T., Nagayama, Y., and 
Nakashima, M. (2021). Age-dependent effects on 
radiation-induced carcinogenesis in the rat thyroid. Sci 
Rep 11, 19096. 

McLachlan, S.M., Nagayama, Y., Pichurin, P.N., Mizutori, Y., 
Chen, C.-R., Misharin, A., Aliesky, H.A., and Rapoport, B. 
(2007). The Link between Graves’ Disease and Hashimoto’s 
Thyroiditis: A Role for Regulatory T Cells. Endocrinology 
148, 5724-5733. 

McLeod, D.S., Caturegli, P., Cooper, D.S., Matos, P.G., and 
Hutfless, S. (2014). Variation in rates of autoimmune 
thyroid disease by race/ethnicity in US military personnel. 
Jama 311, 1563-1565. 

Megwalu, U.C., Ma, Y., Osazuwa-Peters, N., and Orloff, L.A. 
(2021). Clinical presentation and survival outcomes of well-
differentiated thyroid cancer in Filipinos. Cancer Med. 

Morris, L.G., Sikora, A.G., Tosteson, T.D., and Davies, L. (2013). 
The increasing incidence of thyroid cancer: the influence 
of access to care. Thyroid 23, 885-891. 

Mull, B., Davis, R., Munir, I., Perez, M.C., Simental, A.A., and 
Khan, S. (2021). Differential expression of Vitamin D 
binding protein in thyroid cancer health disparities. 
Oncotarget 12, 596-607. 

National Research Council Panel on Race, E., and Health in 
Later, L. (2004). The National Academies Collection: 
Reports funded by National Institutes of Health. In Critical 
Perspectives on Racial and Ethnic Differences in Health in 
Late Life, N.B. Anderson, R.A. Bulatao, and B. Cohen, eds. 
(Washington (DC): National Academies Press (US) 

Copyright © 2004, National Academy of Sciences.). 

Nguyen, M.T., Hu, J., Hastings, K.G., Daza, E.J., Cullen, M.R., 
Orloff, L.A., and Palaniappan, L.P. (2017). Thyroid cancer 
mortality is higher in Filipinos in the United States: An 
analysis using national mortality records from 2003 
through 2012. Cancer 123, 4860-4867. 

O'Connell, T.J., Dadafarin, S., Jones, M., Rodríguez, T., Gupta, 
A., Shin, E., Moscatello, A., Iacob, C., Islam, H., Tiwari, R.K., 
et al. (2021). Androgen Activity Is Associated With PD-L1 
Downregulation in Thyroid Cancer. Front Cell Dev Biol 9, 
663130. 

Paes, J.E., Hua, K., Nagy, R., Kloos, R.T., Jarjoura, D., and Ringel, 
M.D. (2010). The relationship between body mass index 
and thyroid cancer pathology features and outcomes: a 
clinicopathological cohort study. J Clin Endocrinol Metab 
95, 4244-4250. 

Pagano, L., Mele, C., Sama, M.T., Zavattaro, M., Caputo, M., De 
Marchi, L., Paggi, S., Prodam, F., Aimaretti, G., and 
Marzullo, P. (2018). Thyroid cancer phenotypes in relation 
to inflammation and autoimmunity. Front Biosci 
(Landmark Ed) 23, 2267-2282. 

Pai, S.G., Carneiro, B.A., Mota, J.M., Costa, R., Leite, C.A., 
Barroso-Sousa, R., Kaplan, J.B., Chae, Y.K., and Giles, F.J. 
(2017). Wnt/beta-catenin pathway: modulating anticancer 
immune response. J Hematol Oncol 10, 101. 

Palaniappan, L.P., Wong, E.C., Shin, J.J., Fortmann, S.P., and 
Lauderdale, D.S. (2011). Asian Americans have greater 
prevalence of metabolic syndrome despite lower body 
mass index. Int J Obes (Lond) 35, 393-400. 

Pasqual, E.A.-O., Schonfeld, S.A.-O., Morton, L.A.-O., Villoing, 
D.A.-O., Lee, C.A.-O., Berrington de Gonzalez, A.A.-O., 



 
 
 
 
 

 
www.companyofscientists.com/index.php/chd e19 Cancer Health Disparities 

RESEARCH 

and Kitahara, C.A.-O. Association Between Radioactive 
Iodine Treatment for Pediatric and Young Adulthood 
Differentiated Thyroid Cancer and Risk of Second Primary 
Malignancies. 

Prete, A., Borges de Souza, P., Censi, S., Muzza, M., Nucci, N., 
and Sponziello, M. (2020). Update on Fundamental 
Mechanisms of Thyroid Cancer. Front Endocrinol 
(Lausanne) 11, 102. 

Rahbari, R., Zhang, L., and Kebebew, E. (2010). Thyroid cancer 
gender disparity. Future oncology (London, England) 6, 
1771-1779. 

Rahib, L., Smith, B.D., Aizenberg, R., Rosenzweig, A.B., 
Fleshman, J.M., and Matrisian, L.M. (2014). Projecting 
cancer incidence and deaths to 2030: the unexpected 
burden of thyroid, liver, and pancreas cancers in the 
United States. Cancer research 74, 2913-2921. 

Reitzel, L.R., Nguyen, N., Li, N., Xu, L., Regan, S.D., and Sturgis, 
E.M. (2014). Trends in thyroid cancer incidence in Texas 
from 1995 to 2008 by socioeconomic status and 
race/ethnicity. Thyroid 24, 556-567. 

Roche, A.M., Fedewa, S.A., and Chen, A.Y. (2016). Association 
of Socioeconomic Status and Race/Ethnicity With 
Treatment and Survival in Patients With Medullary Thyroid 
Cancer. JAMA Otolaryngol Head Neck Surg 142, 763-771. 

Rohrmann, S., Nelson, W.G., Rifai, N., Brown, T.R., Dobs, A., 
Kanarek, N., Yager, J.D., and Platz, E.A. (2007). Serum 
estrogen, but not testosterone, levels differ between black 
and white men in a nationally representative sample of 
Americans. J Clin Endocrinol Metab 92, 2519-2525. 

Rood, K., Begum, K., Wang, H., Wangworawat, Y.C., Davis, R., 
Yamauchi, C.R., Perez, M.C., Simental, A.A., Laxa, R.T., 
Wang, C., et al. (2021). Differential Expression of Non-
Coding RNA Signatures in Thyroid Cancer between Two 
Ethnic Groups.  28, 3610-3628. 

Sahar, L., Foster, S.L., Sherman, R.L., Henry, K.A., Goldberg, 
D.W., Stinchcomb, D.G., and Bauer, J.E. (2019). GIScience 
and cancer: State of the art and trends for cancer 
surveillance and epidemiology. Cancer 125, 2544-2560. 

Said Abasse, K., Essien, E.E., Abbas, M., Yu, X., Xie, W., Sun, J., 
Akter, L., and Cote, A. (2022). Association between Dietary 
Nitrate, Nitrite Intake, and Site-Specific Cancer Risk: A 
Systematic Review and Meta-Analysis. Nutrients 14. 

Satia, J.A. (2009). Diet-related disparities: understanding the 
problem and accelerating solutions. J Am Diet Assoc 109, 
610-615. 

Schwartz, G.G., and Klug, M.G. (2019). Thyroid Cancer Incidence 
Rates in North Dakota are Associated with Land and Water 
Use. Int J Environ Res Public Health 16. 

Shobab, L., Gomes-Lima, C., Zeymo, A., Feldman, R., Jonklaas, 
J., Wartofsky, L., and Burman, K.D. (2019). Clinical, 
Pathological, and Molecular Profiling of Radioactive Iodine 

Refractory Differentiated Thyroid Cancer. Thyroid 29, 
1262-1268. 

Sickles, C.K., and Gross, G.P. (2022). Progeria. In StatPearls 
(Treasure Island (FL): StatPearls Publishing 

Copyright © 2022, StatPearls Publishing LLC.). 

Singh, A., Ham, J., Po, J.W., Niles, N., Roberts, T., and Lee, C.S. 
(2021). The Genomic Landscape of Thyroid Cancer 
Tumourigenesis and Implications for Immunotherapy. 
Cells 10. 

Stroup, A.M., Harrell, C.J., and Herget, K.A. (2012). Long-term 
survival in young women: hazards and competing risks 
after thyroid cancer. J Cancer Epidemiol 2012, 641372. 

Suresh, R., Sethi, S., Ali, S., Giorgadze, T., and Sarkar, F.H. (2015). 
Differential Expression of MicroRNAs in Papillary Thyroid 
Carcinoma and Their Role in Racial Disparity. Journal of 
cancer science & therapy 7, 145-154. 

Tariqi, A.Q., and Naughton, C.C. (2021). Water, Health, and 
Environmental Justice in California: Geospatial Analysis of 
Nitrate Contamination and Thyroid Cancer. Environ Eng 
Sci 38, 377-388. 

Tortolero-Luna, G., Torres-Cintrón, C.R., Alvarado-Ortiz, M., 
Ortiz-Ortiz, K.J., Zavala-Zegarra, D.E., and Mora-Piñero, E. 
(2019). Incidence of thyroid cancer in Puerto Rico and the 
US by racial/ethnic group, 2011-2015. BMC cancer 19, 637. 

Umar, H., Muallima, N., Adam, J.M., and Sanusi, H. (2010). 
Hashimoto's thyroiditis following Graves' disease. Acta 
Med Indones 42, 31-35. 

Walker, J.A., Illions, E.H., Huddleston, J.F., and Smallridge, R.C. 
(2005). Racial comparisons of thyroid function and 
autoimmunity during pregnancy and the postpartum 
period. Obstet Gynecol 106, 1365-1371. 

Wang, X., Teng, R., Liu, F., Liu, P., and Yang, Y. (2022). Effect of 
thyrotropin suppressive therapy on lumbar bone mineral 
density in patients with differentiated thyroid cancer: a 
retrospective cohort study. Gland Surg 11, 432-441. 

Weeks, K.S., Kahl, A.R., Lynch, C.F., and Charlton, M.E. (2018). 
Racial/ethnic differences in thyroid cancer incidence in the 
United States, 2007-2014. Cancer 124, 1483-1491. 

Xing, M., Haugen, B.R., and Schlumberger, M. (2013). Progress 
in molecular-based management of differentiated thyroid 
cancer. Lancet 381, 1058-1069. 

Xu, L., Zhao, Y.P., Wang, W.B., Zhang, T.P., Liao, Q., Chen, G., 
Zhou, L., and Shu, H. (2012). Clinical characteristics of 
hereditary and sporadic medullary thyroid carcinoma. 
Zhongguo Yi Xue Ke Xue Yuan Xue Bao 34, 401-404. 

Yildirim Simsir, I., Cetinkalp, S., and Kabalak, T. (2020). Review 
of Factors Contributing to Nodular Goiter and Thyroid 
Carcinoma. Med Princ Pract 29, 1-5. 

Yoon, J.H., Kim, E.K., Kwak, J.Y., Moon, H.J., and Kim, G.R. (2014). 
Sonographic features and ultrasonography-guided fine-



 
 
 
 
 

 
www.companyofscientists.com/index.php/chd e20 Cancer Health Disparities 

RESEARCH 

needle aspiration of metastases to the thyroid gland. 
Ultrasonography (Seoul, Korea) 33, 40-48. 

Yu, G.P., Li, J.C., Branovan, D., McCormick, S., and Schantz, S.P. 
(2010). Thyroid cancer incidence and survival in the 
national cancer institute surveillance, epidemiology, and 
end results race/ethnicity groups. Thyroid 20, 465-473. 

Zahedi, A., Bondaz, L., Rajaraman, M., Leslie, W.D., Jefford, C., 
Young, J.E., Pathak, K.A., Bureau, Y., Rachinsky, I., 
Badreddine, M., et al. (2020). Risk for Thyroid Cancer 
Recurrence Is Higher in Men Than in Women Independent 
of Disease Stage at Presentation. Thyroid 30, 871-877. 

Zevallos, J.P., Hartman, C.M., Kramer, J.R., Sturgis, E.M., and 
Chiao, E.Y. (2015). Increased thyroid cancer incidence 
corresponds to increased use of thyroid ultrasound and 
fine-needle aspiration: a study of the Veterans Affairs 
health care system. Cancer 121, 741-746. 

Zhao, S., Jia, X., Fan, X., Zhao, L., Pang, P., Wang, Y., Luo, Y., 
Wang, F., Yang, G., Wang, X., et al. (2019). Association of 
obesity with the clinicopathological features of thyroid 
cancer in a large, operative population: A retrospective 
case-control study. Medicine 98, e18213. 

Zheng, H., Lai, V., Lu, J., Kang, J.K., Felger, E.A., Carroll, N.M., 
Burman, K.D., Wartofsky, L., and Rosen, J.E. (2022). 
Comparing the rate and extent of malignancy in surgically 
excised thyroid nodules across race and ethnicity. The 
American Journal of Surgery 223, 617-623. 

 

 


	1. Introduction
	2. Materials and Methods
	3. Risk factors potentially contributing to TC health disparities
	3.1. Genetic Factors
	Hereditary conditions influencing TC health disparities

	3.2. Environmental Factors
	3.2.1. Radiation exposure in TC health disparities
	3.2.2. Iodine deficiency in TC health disparities
	3.2.3. Environmental pollutants influencing TC health disparities

	3.3. Socioeconomic Factors
	3.3.1. Radioiodine treatment
	3.3.2. Diagnostic differences in TC health disparities

	3.4. Metabolic Factors
	Obesity, metabolic syndrome, and insulin resistance in TC health disparities

	3.5. Behavioral Factors
	Lifestyle and diet in TC health disparities

	3.6. Biological Factors
	3.6.1. Thyroid-stimulating hormone (TSH) level in TC health disparities
	3.6.2. Sex in TC health disparities
	3.6.3. Autoimmunity in TC health disparities
	3.6.4. Thyroid nodule size in TC health disparities
	3.6.5. Chromosomal alterations/non-hereditary conditions influencing TC health disparities


	4. Conclusions
	5. Limitations
	6. Future Directions
	Acknowledgements
	Funding
	Author’s contribution
	Conflicts of interest
	Consent
	Confirmation

