Abstract
Background
The recruitment of underrepresented racial and ethnic groups in clinical trials remains a challenge.
Methods
The ClinicalTrials.gov database was queried for phase III trials related to non-Hodgkin lymphoma (NHL), leukemia, and multiple myeloma (MM). A reference population was sourced from the Surveillance, Epidemiology, and End Results (SEER) database.
Results
A total of 53,821 pooled participants from 119 phase III trials were included in the analyses. Race and ethnicity data were reported in 95.8% and 81.5% of trials, respectively. Globally, the majority of participants were predominantly White (77.3%), followed by Asian (8.2%), Black/African American (5.4%), American Indian/Alaska Native (0.4%), and Native Hawaiian/Other Pacific Islander (0.2%), while Hispanic/Latino individuals constituted 11.0% of trial participants. In comparison to data in SEER, the proportions were lower for Asian/Pacific Islander and Hispanic/Latino across all cancers, and for Black/African American and American Indian/Alaska Native in leukemia and MM in US only trials.
Conclusions
Despite progress, reporting and representation of non-White population remain insufficient in trials. Innovative strategies to enhance representation in trial enrollment are warranted, as well as the utilization of real-world data to establish recruitment goals by more effectively assessing the demographic and geographic distribution of target patient populations.
Keywords: Clinical trial, race, ethnicity, non-Hodgkin lymphoma, leukemia, multiple myeloma, SEER program
PLAIN LANGUAGE SUMMARY
It is very important to include people from different races and ethnicities in medical studies so that everyone can get fair and equal health care. Right now, most of these studies do not have enough diversity to match the real world. This study looked at 119 medical studies for certain blood cancers. It found that most of the people in the studies were White (77%). There were fewer Asian, Black, Native American, and Hispanic people. Over time, more people from different backgrounds started joining the studies, but it is still not enough. This shows that we need to find better ways to include a more diverse group of people in medical studies so that everyone is fairly represented.
ARTICLE HIGHLIGHTS
This is the first comprehensive analysis that systematically assessed the reporting and representation of race and ethnicity data in clinical trials for non-Hodgkin lymphoma, leukemia, and multiple myeloma.
Despite years of concerted efforts, the reporting of race and ethnicity data in trials continue to be insufficient and varies by disease.
The enrollment of non-White racial groups and Hispanic/Latino remains inadequate in clinical trials.
These findings underscore the necessity for innovative strategies to improve race and ethnicity reporting practice, as well as enhance representation in clinical trial enrollment.
Existing real-world data can be leveraged to develop evidence-based strategic recruitment objectives that are representative and improve recruitment efficiency.
Introduction
Racial and ethnic disparities in cancer incidence, mortality, and survival have been observed across racial and ethnic groups, shaped by a combination of genetics, behaviors, environments, socioeconomic status, and their interactions [1–4]. It is crucial for clinical trials to incorporate participants with various demographic characteristics, including race and ethnicity, in order to minimize biases and ensure the safety and efficacy of drugs for all individuals who will ultimately use them. However, most clinical trials for cancers have historically centered on White men [5]. And even now, clinical trials often still do not accurately represent disease prevalence or incidence among various racial and ethnic populations [6–8]. In June 2024, the US Food and Drug Administration (FDA) released a guidance titled “Diversity Action Plans to Improve Enrollment of Participants from Underrepresented Populations in Clinical Studies”. This guidance aims to enhance the enrollment of underrepresented populations in clinical trials both in the US and worldwide, ultimately strengthening and improving the generalizability of the evidence for the intended use population [9]. In this context, the current study sought to conduct a thorough review of the reporting and representation of race and ethnicity in contemporary trials, with the specifical focus on the most common site-specific hematological malignancies worldwide and in the US, namely non-Hodgkin lymphoma (NHL), leukemia, multiple myeloma (MM) [10,11].
Materials and methods
A comprehensive review was conducted for eligible trials identified from the ClinicalTrials.gov database. The search terms “non-Hodgkin lymphoma”, “leukemia”, and “multiple myeloma” were employed. All phase III clinical trials for these three cancers that had results posted, with a primary completion date between 2017 and 2021 (as of July 24, 2024) and with any US site for enrollment were eligible for analyses. Data collect included trial start and trial end dates, geographic locations, sample size, and race and ethnicity of trial participants.
To correspond with the most frequently reported racial and ethnic groups and the minimum choices of race data required by the US FDA, racial categories were evaluated using categories such as White, Asian, Black or African American, American Indian or Alaska Native, Native Hawaiian or Other Pacific Islander, and other/unknown/more than one race. Ethnic categories included Hispanic/Latino, non-Hispanic/Latino, and not reported/unknown. The race and ethnicity categories reported in the trials were combined under the categories that they best corresponded to. The representation of each group was evaluated by calculating the proportion of trial participants in each category, relative to the total number of participants across all groups.
The representation of racial and ethnic groups over time was analyzed by categorizing trials into three periods based on the start date of trial enrollment: before 2013, 2013–2015, and 2016 or later. The percentage of participants in each category within each period was determined based on the total number of trial participants enrolled during that time frame. Counts and proportions by race and ethnicity groups within the cancer population in the US were evaluated utilizing data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) 22 registry database, which obtains information from cancer registries and encompasses approximately 50% of population in the US [12,13].
Results
In total, 53,821 participants pooled from 119 trials were included in this study (Table 1). Race and ethnicity data were reported in 114 (95.8%) and 97 (81.5%) trials, respectively. Specifically, race data were reported in 96.3% of NHL trials, 95.9% of leukemia trials, and 96.0% of MM trials, respectively, while ethnicity data were reported in 85.2% of NHL trials, 81.1% of leukemia trials, and 84.0% of MM trials, respectively. A total of 27 trials among 6,631 participants were conducted in the US exclusively, among which race and ethnicity data were reported in 96.3% and 74.1% of trials, respectively.
Table 1.
Descriptive statistics of analyzed phase III clinical trials for non-Hodgkin lymphoma, leukemia, and multiple myeloma on ClinicalTrials.gov.
| Trial information | Non-Hodgkin lymphoma |
Leukemia |
Multiple myeloma |
All combined |
||||
|---|---|---|---|---|---|---|---|---|
| Overall | US site only | Overall | US site only | Overall | US site only | Overall | US site only | |
| Total number of trials | 27 | 6 | 74 | 17 | 25 | 8 | 119 | 27 |
| Total number of trial participants | 19532 | 1543 | 36881 | 3491 | 10431 | 2528 | 53821 | 6631 |
| Earliest recruitment start year | 1998 | 1998 | 1998 | 1998 | 2004 | 2004 | 1998 | 1998 |
| Latest recruitment start year | 2018 | 2015 | 2021 | 2021 | 2018 | 2017 | 2021 | 2021 |
| Availability of race/ethnicity data | ||||||||
| Trials with available race data, n (%) | 26 (96.3) | 6 (100.0) | 71 (95.9) | 16 (94.1) | 24 (96.0) | 8 (100.0) | 114 (95.8) | 26 (96.3) |
| Trials with available ethnicity data, n (%) | 23 (85.2) | 6 (100.0) | 60 (81.1) | 12 (70.6) | 21 (84.0) | 8 (100.0) | 97 (81.5) | 20 (74.1) |
| Trial participants with available race data, n (%) | 19150 (98.0) | 1507 (97.7) | 35823 (97.1) | 3195 (91.5) | 10118 (97.0) | 2516 (99.5) | 52068 (96.7) | 6287 (94.8) |
| Trial participants with available ethnicity data, n (%) | 18719 (95.8) | 1507 (97.7) | 32871 (89.1) | 2633 (75.4) | 8851 (84.9) | 1556 (61.8) | 47418 (88.1) | 4765 (71.6) |
Seven trials were conducted involving multiple hematologic malignancies, resulting in overlap of clinical trials across different types of cancer.
In trials with available race data, the majority of participants were White (77.3%). Only 8.2%, 5.4%, 0.4%, and 0.2% of participants were reported as Asian, Black/African American, American Indian/Alaska Native, and Native Hawaiian or Other Pacific Islander, respectively (Table 2). In comparison to leukemia and MM, NHL trials included the highest percentage of non-White racial groups, comprising 9.0% Asian, 5.8% Black/African American, 0.7% American Indian/Alaska Native, and 0.4% Native Hawaiian/Other Pacific Islander. Conversely, MM trials included the lowest percentage of non-White racial groups, with 8.1% Asian, 6.4% Black/African American, 0.1% American Indian/Alaska Native, and 0.1% Native Hawaiian/Other Pacific Islander. In trials with enrollment exclusively in the US across three cancer sites, the overall representation of participants was reported as 81.5% White, 2.0% Asian, 11.9% Black/African American, 0.2% American Indian/Alaska Native, and 0.1% Native Hawaiian/Other Pacific Islander. In these US trials, the proportion of non-White racial groups was highest in trials for MM (23.8%), and lowest in trials for leukemia (13.0%).
Table 2.
Distribution of racial groups in phase III clinical trials for non-Hodgkin lymphoma, leukemia, and multiple myeloma on ClinicalTrials.gov.
| Study site | Type of cancer | Race |
|||||
|---|---|---|---|---|---|---|---|
| Asian, n (%) | Native Hawaiian or other pacific islander, n (%) | Black/ African American, n (%) | White, n (%) | American Indian/ Alaska native, n (%) | Other/ unknown/ more than one race, n (%) | ||
| Overall | All combined | 4274 (8.2) | 127 (0.2) | 2822 (5.4) | 40227 (77.3) | 196 (0.4) | 4422 (8.5) |
| Non-Hodgkin lymphoma | 1716 (9.0) | 73 (0.4) | 1111 (5.8) | 13931 (72.7) | 133 (0.7) | 2186 (11.4) | |
| Leukemia | 2329 (6.5) | 112 (0.3) | 2004 (5.6) | 27663 (77.2) | 169 (0.5) | 3546 (9.9) | |
| Multiple myeloma | 817 (8.1) | 10 (0.1) | 648 (6.4) | 8258 (81.6) | 6 (0.1) | 379 (3.7) | |
| US site only | All combined | 123 (2.0) | 5 (0.1) | 747 (11.9) | 5123 (81.5) | 11 (0.2) | 278 (4.4) |
| Non-Hodgkin lymphoma | 48 (3.2) | 2 (0.1) | 174 (11.5) | 1237 (82.1) | 10 (0.7) | 36 (2.4) | |
| Leukemia | 61 (1.9) | 2 (0.1) | 232 (7.3) | 2781 (87.0) | 7 (0.2) | 112 (3.5) | |
| Multiple myeloma | 41 (1.6) | 2 (0.1) | 416 (16.5) | 1916 (76.2) | 0 (0) | 141 (5.6) | |
Six trials were conducted involving multiple hematologic malignancies, resulting in overlap of clinical trials across different types of cancer.
The predominant majority of trial participants were White in the SEER database, representing between 71.9% and 83.8% across three cancers. Nonetheless, compared with the trials in the US only, larger proportions of non-White individuals were noted in MM and leukemia. Specifically, 4.9–5.0% of participants were reported as non-Hispanic Asian/Pacific Islander (including Native Hawaiian/Other Pacific Islander), 8.6–21.2% as Black, and 0.3% as non-Hispanic American Indian/Alaska Native, respectively (Supplementary Table 1). The proportions for Asian/Pacific Islander in all cancers, as well as for Black/African American and American Indian/Alaska Native in MM and leukemia from the SEER database, were higher than those reported in the US only trials.
In trials with available ethnicity data, 11.0% of participants were reported as Hispanic/Latino globally, compared with 5.8% in the US only trials (Table 3). The proportion in the US was lower than those observed from the SEER database, where they ranged between 14.4% and 15.5% (Supplementary Table 1).
Table 3.
Distribution of ethnic groups in phase III clinical trials for non-Hodgkin lymphoma, leukemia, and multiple myeloma on ClinicalTrials.gov.
| Study site | Type of cancer | Ethnicity |
||
|---|---|---|---|---|
| Hispanic/ Latino, n (%) | Non-Hispanic or Latino, n (%) | Not reported/ unknown, n (%) | ||
| Overall | All combined | 5230 (11.0) | 38864 (82.0) | 3324 (7.0) |
| Non-Hodgkin lymphoma | 3004 (16.0) | 14934 (79.8) | 781 (4.2) | |
| Leukemia | 4455 (13.6) | 26347 (80.2) | 2069 (6.3) | |
| Multiple myeloma | 390 (4.4) | 7407 (83.7) | 1054 (11.9) | |
| US site only | All combined | 277 (5.8) | 4296 (90.2) | 192 (4.0) |
| Non-Hodgkin lymphoma | 94 (6.2) | 1379 (91.5) | 34 (2.3) | |
| Leukemia | 161 (6.1) | 2420 (91.9) | 52 (2.0) | |
| Multiple myeloma | 76 (4.9) | 1370 (88.0) | 110 (7.1) | |
Regarding the trend over time, the percentage of non-White racial groups in trials across all three cancers increased slightly, from 22.9% for trials started before 2013 to 24.7% after 2015 (Table 4). The trend was primarily influenced by the rapid growth of the Asian population in trials (3.6% before 2013, 10.7% during 2013–2015, and 14.4% in 2016 or later). In trials enrolled in the US only, however, the proportion of non-White racial groups remained relatively stable—19.8% before 2013, 14.4% during 2013–2015, and 18.5% in 2016 or later. A downward trend was noted in the proportion of Hispanic/Latino participants globally over time, with proportions of 15.5%, 7.9%, and 5.4%. However, this trend was not observed in the US trials, where the percentages were 6.3%, 4.6%, and 7.2% (Table 5).
Table 4.
Distribution of racial groups by the year of study start in phase III clinical trials for non-Hodgkin lymphoma, leukemia, and multiple myeloma on ClinicalTrials.gov.
| Study site | Year of study start | Race |
|||||
|---|---|---|---|---|---|---|---|
| Asian, n (%) | Native Hawaiian or other pacific islander, n (%) | Black/ African American, n (%) | White, n (%) | American Indian/ Alaska native, n (%) | Other/ unknown/ more than one race, n (%) | ||
| Overall | Before 2013 | 832 (3.6) | 89 (0.4) | 1894 (8.1) | 18051 (77.1) | 133 (0.6) | 2420 (10.3) |
| 2013–2015 | 1960 (10.7) | 26 (0.1) | 699 (3.8) | 14444 (78.6) | 45 (0.2) | 1208 (6.6) | |
| 2016 or later | 1482 (14.4) | 12 (0.1) | 229 (2.2) | 7732 (75.3) | 18 (0.2) | 794 (7.7) | |
| US site only | Before 2013 | 86 (1.9) | 5 (0.1) | 591 (12.7) | 3723 (80.2) | 10 (0.2) | 227 (4.9) |
| 2013–2015 | 34 (2.4) | 0 (0) | 128 (8.9) | 1237 (85.6) | 1 (0.1) | 45 (3.1) | |
| 2016 or later | 3 (1.5) | 0 (0) | 28 (14.0) | 163 (81.5) | 0 (0) | 6 (3.0) | |
Table 5.
Distribution of ethnic groups by the year of study start in phase III clinical trials for non-Hodgkin lymphoma, leukemia, and multiple myeloma on ClinicalTrials.gov.
| Study site | Year of study start | Ethnicity |
||
|---|---|---|---|---|
| Hispanic/ Latino, n (%) | Non-Hispanic or Latino, n (%) | Not reported/ unknown, n (%) | ||
| Overall | Before 2013 | 3414 (15.5) | 17090 (77.5) | 1553 (7.0) |
| 2013–2015 | 1404 (7.9) | 15379 (86.7) | 954 (5.4) | |
| 2016 or later | 412 (5.4) | 6395 (83.9) | 817 (10.7) | |
| US site only | Before 2013 | 205 (6.3) | 2944 (90.6) | 99 (3.0) |
| 2013–2015 | 67 (4.6) | 1329 (92.0) | 49 (3.4) | |
| 2016 or later | 5 (7.2) | 23 (33.3) | 41 (59.4) | |
Discussion
Various policies and guidelines have been issued regarding the reporting of race and ethnicity data for the US National Institutes of Health (NIH)-funded trial participants since 1990s [14]. This effort has been supported by multiple academic and governmental initiatives [14]. In 2016, the NIH introduced a final rule requiring the registration and submission of results information for clinical trials, which mandates that demographic characteristics, including race and ethnicity, be reported in ClinicalTrials.gov [15]. Despite these policies and guidelines in place for decades, the reporting of race and ethnicity data in clinical trials remains insufficient, and enforcement and compliance have been inconsistent. Some sponsors and researchers may lack accountability or resources to adhere strictly to reporting standards. Trial participants may be reluctant to disclose their sensitive personal information, including race and ethnicity data, given data security and privacy concerns [16]. Variations in race and ethnicity definition and collection across studies can also contribute to incomplete or non-standardized data collection. Additionally, guidelines and regulations concerning racial and ethnic reporting may vary by country, institution, or even within the same trial. Thus in June 2024, the US FDA released a guidance to enhance the enrollment of underrepresented populations in clinical trials [9].
Nowadays it remains a significant challenge to achieve adequate representation of each racial and ethnic population in trials [17]. Our previous research found that non-White racial and ethnic minorities were underrepresented in clinical trials for solid tumors [18]. In our current study, a similar pattern was observed—a substantial majority of participants in trials for hematological malignancies were White (76.3%), while smaller proportions were reported for Black/African American, American Indian/Alaska Native, Asian, and Native Hawaiian/Other Pacific Islander, which also aligns with earlier findings in this area [6,19–22]. For instance, an evaluation of participant characteristics across 15 Cancer and Leukemia Group B/Alliance cooperative group adult acute leukemia clinical trials during 1998–2013 showed White patients had higher enrollment likelihood than their Asian, Black/African Americans, or Hispanic counterparts, with odds ratios of 0.75, 0.48, and 0.44, respectively (all p < 0.01) [19]. A systematic review of 304 publications concerning phase III trials for cancers in general showed that 83% of participants identified as White [6]. In a recent pooled analysis of 19 MM therapeutic related trials submitted to the FDA between 2006 and 2019, White, Asian, and Black patients comprised 84%, 7%, and 4% of the study population, respectively [22]. A cohort study involving patients from approximately 280 cancer clinics in the US found that clinical trial participation rates were significantly lower among Black/African American (4.4%) and Latinx patients (4.2%) compared to White patients (7.2%) [21]. Notably, consistent with previous publications, our findings revealed a decreasing trend in the proportion of Black/African American participants over time, which dropped from 8% in trials initiated before 2013 to just 2% in those starting after 2015 [6,7,23,24].
Recruiting underrepresented participants in clinical trials presents complex and multifaceted challenges. These barriers disproportionately influence underrepresented populations [25–27]. Lack of awareness and understanding of potential benefits, together with past unethical studies, has fostered deep mistrust, especially among racial and ethnic minorities, which can lead to reluctance or refusal to participate in current clinical trials [28–39]. Other contributing factors include a lack of adequate health insurance, cultural and language barriers, limited opportunities to engage in trials, having comorbidities that render them ineligible for enrollment, lack of community engagement, structural inequities in healthcare access and disparities in provider-patient relationships, and participant requirements based on tumor stage or positive results of unique biomarkers that is less prevalent in certain racial or ethnic groups [28–39]. Socioeconomic status also plays a crucial role in access to trials [40]. Specifically, for cancer patients living in the rural area, various barriers have been reported, including lack of awareness and fear or unease about clinical trials, mistrust of medical science, cost concerns, limited healthcare infrastructure and access to trials, transportation challenges, comorbid conditions that reduce trial eligibility, and a lack of support or incentives for oncology professionals to participate in clinical research within underserved settings [41–44]. Despite these challenges, recent patient navigation programs and enhancements to institutional clinical trial infrastructure have shown promise in increasing underrepresented patient participation in trials [45,46].
This represents the first study examining the reporting and representation of race and ethnicity data in phase III clinical trials for NHL, leukemia, and MM. The data sourced from ClinicalTrials.gov provides a more comprehensive and reliable perspective than previously published studies, which may be subject to publication bias. However, it is essential to consider our findings in light of limitations. Our analysis was restricted to studies that reported results, potentially excluding non-compliant studies or those that failed to reach full enrollment. Moreover, inconsistencies in the reporting of race and ethnicity data present an additional challenge. Many clinical trials only provide information for White, Black/African American, Asian, American Indian or Alaska Native, and Native Hawaiian or Other Pacific Islander groups to align with the minimum choices of race data required by the US FDA. Limited data availability makes it difficult to perform more detailed subgroup analyses within these racial categories. We also acknowledge that some of racial groups mentioned above may not be applicable to non-US regions, for example, American Indian or Alaska Native, and Native Hawaiian or Other Pacific Islander. Some trials resorted to using the “other” category to capture data that did not fit into predefined classifications. The absence of data regarding multiracial or multiethnic individuals further limits our understanding, as it overlooks patients who identify with multiple racial backgrounds. We also recognize the limitations posed by excluding trials without enrollment in the US, which may affect the generalizability of our conclusions. Also, although different subtypes of hematological malignancies vary in disease characteristics, progression, and prognosis, conducting subgroup analyses for each subtype proved challenging due to the limited number of eligible trials for individual subtype on ClinicalTrials.gov, especially those conducted solely in the US. Finally, using the US SEER data as the benchmark for our global analysis may introduce bias, as patient demographics, socioeconomic status, healthcare access, and treatment patterns differ greatly from one country to another. However, currently population-based global data of the actual disease distribution in selected hematological malignancies by race and ethnicity groups are not available. Given all eligible trials included in the current study required at least one US site for enrollment, thus the SEER data were used to estimate the expected distribution of race and ethnicity data in the US.
Conclusions
Compared with the actual disease distribution in real-world data, the enrollment of non-White racial groups and Hispanic/Latino remains inadequate in oncology clinical trials, albeit showing slow progress. All pertinent stakeholders should adopt innovative strategies focused on improving race and ethnicity data standardized collection and enhancing the representation of clinical trial participants to guarantee modern medical advancements are effectively and safely accessible to the entire cancer community. Strategies may include conducting worldwide clinical trials, selecting trial sites that represent a diverse pool of potential participants, collaborating with community organizations, media, and patient advocacy groups, and providing clear, understandable information about clinical trials in multiple languages. Furthermore, real-world data can be a powerful tool to inform and shape strategic recruitment objectives in clinical trials by evaluating demographics in target patient population. Real-world data can also be used in creating tailored strategies to overcome barriers faced by underrepresented populations and improve recruitment efficiency, by gaining deeper insights into patient preferences, identifying disparities in healthcare access, comorbidities, and treatment patterns, assessing the effectiveness of recruitment channels, optimizing site selection and outreach efforts, forecasting patient enrollment rates and facilitating continuous monitoring and adjustment of recruitment strategies. Ultimately, these initiatives will support the enhancement of racial and ethnic representation in trial population.
Supplementary Material
Author contribution statement
Tianyi Wang conceptualized the study, designed the methodology, conducted data extraction and data analysis, and drafted the manuscript. Dina Gifkins assisted in study design and result interpretation. All authors reviewed and provided critical revisions to the manuscript.
Disclosure statement
All authors are employed by Johnson & Johnson.
Ethical approval
This study performed a secondary analysis utilizing publicly available data, specifically the clinicaltrials.gov database and the Surveillance, Epidemiology, and End Results (SEER) database, both of which are fully de-identified. Consequently, a full ethical review and approval from the Institutional Review Board (IRB) is not required.
Data availability statement
The data sources utilized by this study are publicly available at https://clinicaltrials.gov/ and https://seer.cancer.gov/. The data that support the findings of this study are available from the corresponding author upon reasonable request.
References
Papers of special note have been highlighted as either of interest (*) or of considerable interest (**) to readers.
* This guidance aims to enhance the enrollment of underrepresented populations in clinical trials both in the US and worldwide, ultimately strengthening and improving the generalizability of the evidence for the intended use population. It also provides the context for our current study, which aimed to better understand how race and ethnicity were reported and represented among patients with hematological malignancies in recent clinical trials.
** These previous studies provided background information, and findings in these studies are consistent with ours, i.e., despite of the implementation of various policies and guidelines since 1990s, the majority of participants in clinical trials were still non-Hispanic White.
- 1.Daly B, Olopade OI.. A perfect storm: How tumor biology, genomics, and health care delivery patterns collide to create a racial survival disparity in breast cancer and propo sed interventions for change. CA Cancer J Clin. 2015;65(3):221–238. doi: 10.3322/caac.21271 [DOI] [PubMed] [Google Scholar]
- 2.Wallace TA, Martin DN, Ambs S.. Interactions among genes, tumor biology and the environment in cancer health disparities: examining the evidence on a national and global scale. Carcinogenesis. 2011;32(8):1107–1121. doi: 10.1093/carcin/bgr066 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Elledge RM, Clark GM, Chamness GC, et al. Tumor biologic factors and breast cancer prognosis among white, Hispanic, and black women in the United States. J Natl Cancer Inst. 1994;86(9):705–712. doi: 10.1093/jnci/86.9.705 [DOI] [PubMed] [Google Scholar]
- 4.Zavala VA, Bracci PM, Carethers JM, et al. Cancer health disparities in racial/ethnic minorities in the United States. Br J Cancer. 2021;124(2):315–332. doi: 10.1038/s41416-020-01038-6 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Swanson GM, Bailar JC. 3rd.. Selection and description of cancer clinical trials participants–science or happenstance? Cancer. 2002;95(5):950–959. doi: 10.1002/cncr.10785 [DOI] [PubMed] [Google Scholar]
- 6.** Kwiatkowski K, Coe K, Bailar JC, et al. Inclusion of minorities and women in cancer clinical trials, a decade later: Have we improved? Cancer. 2013;119(16):2956–2963. doi: 10.1002/cncr.28168 [DOI] [PubMed] [Google Scholar]
- 7.Murthy VH, Krumholz HM, Gross CP.. Participation in cancer clinical trials: race-, sex-, and age-based disparities. JAMA. 2004;291(22):2720–2726. doi: 10.1001/jama.291.22.2720 [DOI] [PubMed] [Google Scholar]
- 8.Aldrighetti CM, Niemierko A, Van Allen E, et al. Racial and ethnic disparities among participants in precision oncology clinical studies. JAMA Netw Open. 2021;4(11):e2133205. doi: 10.1001/jamanetworkopen.2021.33205 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.* Diversity action plans to improve enrollment of participants from underrepresented populations in clinical studies—draft guidance for industry. 2024. Available from: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/diversity-action-plans-improve-enrollment-participants-underrepresented-populations-clinical-studies
- 10.Ferlay J, Ervik M, Lam F, et al. Global Cancer Observatory: Cancer Today (version 1.1). 2024. [2025 Feb 25]. Available from: https://gco.iarc.who.int/today
- 11.SEER*Explorer: An interactive website for SEER cancer statistics [Internet]. Surveillance Research Program, National Cancer Institute, Data source(s): SEER Incidence Data, November 2023 Submission (1975–2021), SEER 22 registries. [2025 Feb 25]. Available from: https://seer.cancer.gov/statistics-network/explorer/
- 12.National Cancer Institute . SEER*Explorer: An interactive website for SEER cancer statistics. Surveillance Research Program, National Cancer Institute. [2025 Feb 25]. Available from: https://seer.cancer.gov/explorer/
- 13.Overview of the SEER Program. [2025 Feb 25]. Available from https://seer.cancer.gov/about/overview.html#:∼:text=About%20SEER,-SEER%20Registries%20Toggle&text=SEER%20coverage%20includes%2042.0%20percent,percent%20of%20Hawaiian/Pacific%20Islanders
- 14.Chen MS, Jr., Lara PN, Dang JH, et al. Twenty years post-NIH Revitalization Act: enhancing minority participation in clinical trials (EMPaCT): laying the groundwork for improving minority clinical trial accrual: renewing the case for enhancing minority participation in cancer clinical trials. Cancer. 2014;120(Suppl 7):1091–1096. doi: 10.1002/cncr.28575 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Clinical Trials Registration and Results Information Submission. 2016. 42 CFR §11 [2025 Feb 25]. Available from: https://clinicaltrials.gov/policy/fdaaa-801-final-rule [PubMed]
- 16.Ellard-Gray A, Jeffrey NK, Choubak M, et al. Finding the hidden participant: Solutions for recruiting hidden, hard-to-reach, and vulnerable populations. Int J Qual Methods. 2015;14(5):1609406915621420. doi: 10.1177/1609406915621420 [DOI] [Google Scholar]
- 17.National Academies of Sciences E, Medicine . Improving representation in clinical trials and research: building research equity for women and underrepresented groups. 2022. [PubMed] [Google Scholar]
- 18.Wang T, Villanueva DJ, Banerjee A, et al. Reporting and representation of participant race and ethnicity in phase III clinical trials for solid tumors. Future Sci OA. 2025;11(1):2458415. doi: 10.1080/20565623.2025.2458415 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.** Hantel A, Kohlschmidt J, Eisfeld AK, et al. Inequities in alliance acute leukemia clinical trial and biobank participation: defining targets for intervention. J Clin Oncol. 2022;40(32):3709–3718. doi: 10.1200/jco.22.00307 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.** Gopishetty S, Kota V, Guddati AK.. Age and race distribution in patients in phase III oncology clinical trials. Am J Transl Res. 2020;12(9):5977–5983. [PMC free article] [PubMed] [Google Scholar]
- 21.** Pittell H, Calip GS, Pierre A, et al. Racial and ethnic inequities in US oncology clinical trial participation from 2017 to 2022. JAMA Netw Open. 2023;6(7):e2322515. doi: 10.1001/jamanetworkopen.2023.22515 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.** Kanapuru B, Fernandes LL, Fashoyin-Aje LA, et al. Analysis of racial and ethnic disparities in multiple myeloma US FDA drug approval trials. Blood Adv. 2022;6(6):1684–1691. doi: 10.1182/bloodadvances.2021005482 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Berger JS, Melloni C, Wang TY, et al. Reporting and representation of race/ethnicity in published randomized trials. Am Heart J. 2009;158(5):742–747. doi: 10.1016/j.ahj.2009.08.018 [DOI] [PubMed] [Google Scholar]
- 24.Park IU, Taylor AL.. Race and ethnicity in trials of antihypertensive therapy to prevent cardiovascular outcomes: a systematic review. Ann Fam Med. 2007;5(5):444–452. doi: 10.1370/afm.708 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Unson CG, Dunbar N, Curry L, et al. The effects of knowledge, attitudes, and significant others on decisions to enroll in a clinical trial on osteoporosis: implications for recruitment of older African-American women. J Natl Med Assoc. 2001;93(10):392–401. discussion 402–4. [PMC free article] [PubMed] [Google Scholar]
- 26.Robinson SB, Ashley M, Haynes MA.. Attitude of African-Americans regarding prostate cancer clinical trials. J Community Health. 1996;21(2):77–87. doi: 10.1007/bf01682300 [DOI] [PubMed] [Google Scholar]
- 27.Corbie-Smith G, Thomas SB, Williams MV, et al. Attitudes and beliefs of African Americans toward participation in medical research. J Gen Intern Med. 1999;14(9):537–546. doi: 10.1046/j.1525-1497.1999.07048.x [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Swanson GM, Ward AJ.. Recruiting minorities into clinical trials: toward a participant-friendly system. J Natl Cancer Inst. 1995;87(23):1747–1759. doi: 10.1093/jnci/87.23.1747 [DOI] [PubMed] [Google Scholar]
- 29.Harris Y, Gorelick PB, Samuels P, et al. Why African Americans may not be participating in clinical trials. J Natl Med Assoc. 1996;88(10):630–634. [PMC free article] [PubMed] [Google Scholar]
- 30.Mouton CP, Harris S, Rovi S, et al. Barriers to black women’s participation in cancer clinical trials. J Natl Med Assoc. 1997;89(11):721–727. [PMC free article] [PubMed] [Google Scholar]
- 31.Shavers VL, Lynch CF, Burmeister LF.. Racial differences in factors that influence the willingness to participate in medical research studies. Ann Epidemiol. 2002;12(4):248–256. doi: 10.1016/s1047-2797(01)00265-4 [DOI] [PubMed] [Google Scholar]
- 32.Shavers-Hornaday VL, Lynch CF, Burmeister LF, et al. Why are African Americans under-represented in medical research studies? Impediments to participation. Ethn Health. 1997;2(1-2):31–45. doi: 10.1080/13557858.1997.9961813 [DOI] [PubMed] [Google Scholar]
- 33.Brown DR, Fouad MN, Basen-Engquist K, et al. Recruitment and retention of minority women in cancer screening, prevention, and treatment trials. Ann Epidemiol. 2000;10(8 Suppl):S13–S21. doi: 10.1016/s1047-2797(00)00197-6 [DOI] [PubMed] [Google Scholar]
- 34.Williams MV, Parker RM, Baker DW, et al. Inadequate functional health literacy among patients at two public hospitals. JAMA. 1995;274(21):1677–1682. doi: 10.1001/jama.1995.03530210031026 [DOI] [PubMed] [Google Scholar]
- 35.Paskett ED, DeGraffinreid C, Tatum CM, et al. The recruitment of African-Americans to cancer prevention and control studies. Prev Med. 1996;25(5):547–553. doi: 10.1006/pmed.1996.0088 [DOI] [PubMed] [Google Scholar]
- 36.Diehl KM, Green EM, Weinberg A, et al. Features associated with successful recruitment of diverse patients onto cancer clinical trials: report from the American College of Surgeons Oncology Group. Ann Surg Oncol. 2011;18(13):3544–3550. doi: 10.1245/s10434-011-1818-9 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 37.Ford JG, Howerton MW, Lai GY, et al. Barriers to recruiting underrepresented populations to cancer clinical trials: a systematic review. Cancer. 2008;112(2):228–242. doi: 10.1002/cncr.23157 [DOI] [PubMed] [Google Scholar]
- 38.Langford AT, Resnicow K, Dimond EP, et al. Racial/ethnic differences in clinical trial enrollment, refusal rates, ineligibility, and reasons for decline among patients at sites in the National Cancer Institute’s Community Cancer Centers Program. Cancer. 2014;120(6):877–884. doi: 10.1002/cncr.28483 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 39.Pariera KL, Murphy ST, Meng J, et al. Exploring willingness to participate in clinical trials by ethnicity. J Racial Ethn Health Disparities. 2017;4(4):763–769. doi: 10.1007/s40615-016-0280-6 [DOI] [PubMed] [Google Scholar]
- 40.Mohd Noor A, Sarker D, Vizor S, et al. Effect of patient socioeconomic status on access to early-phase cancer trials. J Clin Oncol. 2013;31(2):224–230. doi: 10.1200/jco.2012.45.0999 [DOI] [PubMed] [Google Scholar]
- 41.Arana-Chicas E, Prisco LMH, Sharma S, et al. Barriers to participation in clinical trials of rural older adult cancer survivors: a qualitative study. J Rural Health. 2025;41(1):e12852. doi: 10.1111/jrh.12852 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 42.Unger JM, McAneny BL, Osarogiagbon RU.. Cancer in rural America: improving access to clinical trials and quality of oncologic care. CA Cancer J Clin. 2025;75(4):341–361. doi: 10.3322/caac.70006 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 43.Tanner A, Kim SH, Friedman DB, et al. Promoting clinical research to medically underserved communities: current practices and perceptions about clinical trial recruiting strategies. Contemp Clin Trials. 2015;41:39–44. doi: 10.1016/j.cct.2014.12.010 [DOI] [PubMed] [Google Scholar]
- 44.Tanner A, Kim SH, Friedman DB, et al. Barriers to medical research participation as perceived by clinical trial investigators: communicating with rural and African American communities. J Health Commun. 2015;20(1):88–96. doi: 10.1080/10810730.2014.908985 [DOI] [PubMed] [Google Scholar]
- 45.Ghebre RG, Jones LA, Wenzel JA, et al. State-of-the-science of patient navigation as a strategy for enhancing minority clinical trial accrual. Cancer. 2014;120(Suppl 7):1122–1130. doi: 10.1002/cncr.28570 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 46.Anwuri VV, Hall LE, Mathews K, et al. An institutional strategy to increase minority recruitment to therapeutic trials. Cancer Causes Control. 2013;24(10):1797–1809. doi: 10.1007/s10552-013-0258-1 [DOI] [PMC free article] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The data sources utilized by this study are publicly available at https://clinicaltrials.gov/ and https://seer.cancer.gov/. The data that support the findings of this study are available from the corresponding author upon reasonable request.