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2022 ASCO Quality Care Symposium

Black Americans Underrepresented in Oncology Trials, With Variability Across Disease Areas and Trial Sites

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Mr. Ted Bebi
Mr. Ted Bebi

Key Points:

  • In an analysis of more than 433,000 patients participating in interventional clinical trials in the United States between 2010 and 2021, Black individuals accounted for 15% of participants overall but only 8.5% of oncology trial participants.
  • Participation rates among Black Americans were higher for breast cancer (11.4%) than for lung cancer (8.1%).
  • Enrollment by Black patients into breast and lung cancer trials was concentrated geographically, with 70% of individuals enrolling at 10% of study sites.

New data indicate that Black Americans continue to be underrepresented in oncology clinical trials, accounting for only 8.5% of participants enrolled in interventional trials from 2010 to 2021, even though 14.6% of Americans are Black. These data, presented at the 2022 ASCO Quality Care Symposium (Abstract 88), suggest there is further work to be done in oncology trials in order to meet the U.S. Food and Drug Administration (FDA) industry guidance stating that enrollment in clinical trials should reflect the population who will ultimately use a treatment.1 Clinical trial participation by Black Americans was lower for oncology than for cardiovascular and central nervous system (CNS) trials, and participation rates varied across disease types and clinical trial sites.

Historically, U.S. clinical trials have included a disproportionately high percentage of White patients while underrecruiting minority groups.2 Questions regarding the generalizability of results for clinical decision-making are raised when trials lack sufficient diversity, and racial disparities in cancer outcomes are continued.3 Increasing clinical trial diversity has been an important initiative in improving health equity and the quality of cancer care, which is reflected in the recent FDA guidance regarding clinical trial diversity.1

Questions regarding the generalizability of results for clinical decision-making are raised when trials lack sufficient diversity, and racial disparities in cancer outcomes are continued.

To better understand progress made toward this benchmark, researchers at Medidata, a private technology company, analyzed the diversity of clinical trials in a large, historical database analysis including more than 433,000 patients enrolled in nearly 3,000 clinical trials (phases 1 to 3) from 2010 to 2021 across therapeutic areas. Participation by Black patients was assessed at different levels of granularity “in order to elucidate existing disparities while also producing insights that can hopefully catalyze change in the industry,” explained presenting author Ted Bebi, a Medidata employee.

Overall, 78.3% of U.S. participants across clinical trials from 2010 to 2021 were White. Black patients accounted for about 15% of participants, which is representative of the population of Black individuals, according to the 2020 U.S. census. Asian patients accounted for 3.1% of participants, 1.1% reported “other,” and race was unknown or not reported for 1.7% of patients. Participation rates by Black patients varied by therapeutic area and were lower in oncology (8.5%) than in cardiovascular disease (15.3%) or CNS disease (19.9%; Table).

Table. Participation by Black Patients in U.S. Clinical Trials in Selected Indications, 2010-2021 Participation by Black Patients in U.S. Clinical Trials in Selected Indications, 2010-2021
Abbreviations: CNS, central nervous system.View larger

Clinical trial representation of Black patients was lower within oncology trials for lung cancer (8.1%) than for breast cancer (11.4%; Table). This variability was also observed in CNS trials, with Black patients accounting for 17.3% of participants in migraine trials but only 5.0% of those for Alzheimer's disease. Variability in diversity was also found across clinical trial study sites. Black participants enrolled at only 30% of lung cancer trial sites and 50% of breast cancer trial sites. Moreover, 70% of Black participants enrolled at only 10% of sites for lung and breast cancer trials.

Study author Elizabeth Lamont, MS, MD, MMSc, of Medidata, concluded that their analysis provides new insights regarding variability in the enrollment of Black patients in clinical trials by disease area and geography. “The finding that Black clinical trial patients are enrolled at a smaller number of clinical trial sites merits study to ensure appropriate trial coverage in neighborhoods with large amounts of Black patients,” she added.

Looking ahead, the researchers hope to further explore reasons behind the observed variability in the participation of Black patients across disease areas and trial sites and the mechanisms of this variability. By understanding these disparities in greater detail, they hope to identify possible solutions to improve the diversity of clinical trials.

— Mindy Tanzola, PhD


  1. U.S. Food & Drug Administration. FDA takes important steps to increase racial and ethnic diversity in clinical trials. Accessed September 20, 2022.
  2. Duma N, Vera Aguilera J, Paludo J, et al. Representation of minorities and women in oncology clinical trials: review of the past 14 years. J Oncol Pract. 2018;14(1):e1-e10.
  3. Oyer RA, Hurley P, Boehmer L, et al. Increasing racial and ethnic diversity in cancer clinical trials: an American Society of Clinical Oncology and Association of Community Cancer Centers joint research statement. J Clin Oncol. 2022;40(19):2163-2171.

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