Disparities Research in Thyroid Cancer: Challenges and Strategies for Improvement

Abstract

Until recently, thyroid cancer was one of the most rapidly increasing cancers in the United States. Disparities exist in many aspects of thyroid cancer care as a result of the multifactorial interplay of systemic, patient, and physician factors. To better understand the management of thyroid cancer in populations at risk for health disparities and subsequently implement changes that will lead to health equity for all patients with thyroid cancer, health services research with innovative approaches is necessary.

Introduction

There has been increasing attention on disparities in health and health care among physicians, policy experts, and the federal government. The National Institute of Health defines populations at risk for health disparities to include blacks/African Americans, Hispanics/Latinos, American Indians/Alaska natives, Asian Americans, native Hawaiians and other Pacific Islanders, socioeconomically disadvantaged populations, underserved rural populations, and sexual and gender minorities (1).

Based on data from the United States census bureau, these groups at risk for health disparities make up a significant part of the U.S. population. About 40% of the U.S. population self-identify as non-white (13.4% self-identify as black or African American, 18.3% as Hispanic or Latino, 1.3% as American Indian and Alaska native, 5.9% as Asian, and 0.2% as Native Hawaiian and other Pacific Islander), and about 19% of the U.S. population live in rural areas (2). In 2018, 34% of the U.S. population had public insurance and 8.5% did not have health insurance at some point during the year (2). Furthermore, about 3.8% of adults in the United States identify as lesbian, gay, bisexual, or transgender (3).

Disparities in health and health care exist in many aspects of thyroid cancer care in the United States, but thyroid cancer in populations at risk for health disparities remains understudied. As a result, research findings are limited in its generalizability to racial and ethnic as well as to sexual minority populations. Additionally, there is a need for more thyroid cancer research that will inform interventions and policies focused on reducing disparities in care. As we strive to reduce disparities in thyroid cancer care and provide more equitable treatment to all patients, it is imperative that we recognize the existing thyroid cancer literature in populations at risk for health disparities, acknowledge factors that contribute to these disparities, and consider strategies to optimize thyroid cancer disparities research.

Disparities in Thyroid Cancer Care

Racial and ethnic minorities with thyroid cancer are more likely to be diagnosed with more advanced disease and receive suboptimal treatment compared with their white counterparts (4–7). In a retrospective cohort study of 25,945 patients with well-differentiated thyroid cancer, Harari et al. noted that a higher percentage of black, Hispanic, and Asian-Pacific Islander patients presented with metastatic disease compared with white patients (7). In terms of surgical treatment, black and Hispanic patients continue to be at a disadvantage. In a cross-sectional analysis of 16,878 patients who underwent thyroid procedures, Sosa et al. demonstrated that the majority of black and Hispanic patients had surgery by the lowest-volume surgeons (one to nine cases per year) compared with white patients; and that black patients experienced a longer mean length of stay and higher in-hospital mortality compared with white patients (8). In a separate cross-sectional analysis of patients who underwent thyroidectomy, Sosa et al. highlighted the importance of surgeon experience with the highest-volume surgeons (more than 100 cases per year) having the shortest length of stay and lowest complication rate (9).

Post-thyroidectomy, black, Hispanic, and Asian patients had a higher likelihood of undertreatment with radioactive iodine (RAI) therapy compared with their white counterparts (4,10). At two to four years after the diagnosis of thyroid cancer, race/ethnicity continued to influence patients' experience. Among low-risk thyroid cancer patients, Papaleontiou et al. demonstrated that cancer-related worry was associated with being Hispanic and Asian (11), and Chen et al. demonstrated that Hispanic ethnicity was associated with overestimating recurrence risk (12).

Socioeconomically disadvantaged populations, which includes individuals with low income or low levels of education, or who are uninsured or underinsured, are also at risk for being diagnosed with more advanced disease and receiving suboptimal treatment for thyroid cancer (6,7,10,13). In a retrospective cohort analysis of 9011 patients with papillary thyroid cancer, Zevallos et al. demonstrated that low socioeconomic status is associated with more advanced disease at time of diagnosis and a lower rate of adjuvant RAI therapy after thyroidectomy (14). In this study, Zevallos et al. calculated a composite socioeconomic status score based on cost-of-living-adjusted median household income, proportion of residents with at least a high school education, and percentage of population with health insurance.

Similarly, Ullmann et al. demonstrated that insurance status has a significant impact on care such that patients with private insurance, compared with no insurance, were less likely to have thyroid cancer with high-risk features at diagnosis and more likely to receive more extensive surgical and adjuvant treatment (15). Even among patients with high-risk papillary thyroid cancer, patients without insurance or with Medicaid insurance had lower odds of receiving RAI therapy compared with patients with private insurance or Medicare (16). At two to four years after diagnosis of low-risk thyroid cancer, lower education was found to be associated with more cancer-related worry and with overestimating disease recurrence and mortality risk (11,12).

In the thyroid cancer literature, studies on rural populations and on sexual and gender minorities are scarce. While some studies have demonstrated a lower incidence of thyroid cancer in rural areas compared with urban areas, there is limited information beyond data from cancer registries (17,18).

Similarly, lesbian, gay, bisexual, transgender, and intersex (LGBTI) individuals are an understudied group in thyroid cancer research (19). This is likely due to the methodology of most health services research in its utilization of large administrative databases in which details about sexual orientation and gender identity are not available. Although both sexuality and gender are nonbinary constructs, this information has historically not been systematically collected in cancer registries with much of the available data focused on biologic sex and minimal information available on gender (20,21). Furthermore, federal funding opportunities for research focused on better understanding the health needs and challenges of sexual and gender minorities are relatively new (19,22,23). Recruitment of participants to achieve an adequate sample size to protect the nonidentifiable nature of the data is an additional barrier in thyroid cancer health services research focused on LGBTI individuals.

Factors Contributing to Existing Disparities

The reasons that disparities exist in thyroid cancer care are multifactorial and include systemic barriers as well as patient and physician factors. In the United States, health insurance significantly influences patients' access to and utilization of health care services including physician office visits and imaging studies. With the trend of patients becoming financially responsible for increasing health care costs, obtaining medical treatment for thyroid cancer can become cost prohibitive (24,25). Furthermore, it can be a challenge for some patients to receive optimal thyroid cancer care if they need to travel a long distance for treatment and/or if there are a limited number of practicing physicians in the region who are comfortable managing thyroid cancer (26).

Patient factors such as illness perceptions, level of acculturation, health literacy, and physician distrust may influence how patients select physicians and the medical care that they receive for their thyroid cancer. Physician factors including conscious and unconscious biases, cultural competency, knowledge of and experience with thyroid cancer management, and communication styles may impact the patient populations that they care for and how they manage thyroid cancer (27,28).

Differential use of thyroid ultrasound, a known driver of thyroid cancer incidence (29–31), may contribute to disparities in cancer stage at time of diagnosis. While greater ultrasound use has contributed to the incidental detection of low-risk thyroid cancers, the increase in thyroid cancer incidence has not been equal across all populations. Based on Surveillance, Epidemiology, and End Results data from 1992 through 2010, Magreni et al. demonstrated that the increase in age-adjusted thyroid cancer incidence for Asians/Pacific Islanders was significantly lower than that for whites and blacks, and that non-Hispanics experienced a larger increase in incidence than Hispanics (32). Similarly, Miller et al. noted a higher incidence rate of thyroid cancer among non-Hispanic whites compared with Hispanics from 2011 through 2015 (33). Among Hispanic and black populations, Kotwal et al. noted stable mortality rates despite a rising incidence of thyroid cancer after 2009, suggesting that overdiagnosis may have a role in the observed trends (34).

The method of thyroid cancer diagnosis (i.e., incidental finding on an imaging test or clinically palpable thyroid nodule) is in part influenced by where patients go for their medical care. In a retrospective chart review of 473 patients with well-differentiated thyroid cancer after thyroid surgery in two adjacent hospital, Zagzag et al. demonstrated that private university hospital patients were more likely to have thyroid cancer detected by imaging and have smaller tumors compared with public hospital patients (35). Notably, the demographics of the patient cohort at the two hospitals were significantly different: the private hospital group was composed of 90% white, 2% black, 2% Hispanic, and 6% Asian patients compared with the public hospital group, which was composed of 5% white, 10% black, 30% Hispanic, and 56% Asian patients.

Strategies to Improve Disparities Research

To expand our understanding of thyroid cancer in populations at risk for health disparities, it is necessary to improve the breadth and depth of the data collected (Table 1). First, ideally, large administrative databases should be revised to include additional patient information such as method of thyroid cancer diagnosis, income adjusted for household size, access to public transportation, proximity to a tertiary care medical center, sexual orientation and gender identity, and more classification options for race/ethnicity. For example, the race classification of Asian should be expanded to include culturally distinct ethnic subgroups such as Chinese, Korean, Japanese, etc. Aggregating Asian subgroups into a single undifferentiated race group ignores important variations that exist.

Table 1.

Strategies to Improve Thyroid Cancer Disparities Research, and the Predicted Impact That These Strategies Will Have on the Study Cohort and Data

	Improve diversity of the cohort	Improve breadth of the data	Improve depth of the data
Administrative databases to include
Method of thyroid cancer diagnosis			X
Income adjusted for household size		X
Access to public transportation		X
Proximity to tertiary care medical center		X
Sexual orientation and gender identity	X	X
More specific race/ethnicity categories	X	X
Use of surveys and patient interviews
Sampling strategy to include diverse cohort	X
Information on illness perception		X	X
Assessment of communication and decision-making preferences		X	X
Use of traditional of folk therapies		X	X
Evaluation of acculturation		X	X
Evaluation of health literacy		X	X
Use of informational sources		X	X
Details about health insurance coverage		X	X
Barriers to care from high-volume surgeons		X	X
Involvement of researchers from populations at risk for health disparities	X	X	X
Involvement of community physicians	X	X	X

Second, there is a role for both qualitative and quantitative research. The utilization of surveys and patient interviews, in addition to information gathered from administrative databases, will provide more granular data about the management of thyroid cancer in populations at risk for health disparities. Sampling strategies to identify participants for surveys and interviews should strive to incorporate a diverse patient cohort. The additional data obtained could include information on patients' illness perceptions and communication styles, decision-making preferences, use of traditional or folk therapies, level of acculturation, health literacy, and use of informational sources as well as more granular data on health insurance coverage. In addition, surveys and interviews may provide insight into potential barriers for patients to obtain surgery from high-volume surgeons such as scheduling difficulties, availability of a translator at the office visit, and community perception of care provided to minority groups by the hospital.

Third, collaboration with physicians who work in community practices or who belong to one of the populations at risk for health disparities may be meaningful because patients may choose physicians who are concordant in terms of race/ethnicity, sexual orientation, or gender identity. The implementation of these strategies could be feasible through funding opportunities for disparities research and research involving diverse patient cohorts such as those available through the American Cancer Society, the National Institute on Minority Health and Health Disparities, and the Association of American Medical Colleges (1,36,37).

Conclusions

Until recently, thyroid cancer was one of the most rapidly increasing cancers in the United States, with 52,890 new cases of thyroid cancer estimated in 2020 (38). Disparities in thyroid cancer exist as a result of the multifactorial interplay of systemic, patient, and physician factors. To better understand the management of thyroid cancer in populations at risk for health disparities and subsequently implement changes that will lead to health equity for all patients with thyroid cancer, health services research with innovative approaches is necessary.

Author Disclosure Statement

No competing financial interests exist.

Funding Information

This work is supported by the National Cancer Institute (NCI) grant no. R01 CA201198 to Principal Investigator (M.R.H). M.R.H. also receives funding from R01 HS024512 from the Agency for Healthcare Research and Quality (AHRQ). D.W.C. receives support from grant T32DK07245 from the National Institutes of Diabetes and Digestive and Kidney Diseases.