Study Reveals 30-Year Trends in Cancer Clinical Trial Diversity
A 30-year study using artificial intelligence (AI) examined racial and ethnic representation in cancer clinical trials published between 1995 and 2025. The goal was to see if participant diversity in cancer research has meaningfully improved over the past three decades.
Why does diversity in clinical trial enrollment matter?
Understanding who participates in clinical trials is crucial because treatments need to be proven safe and effective for people of all backgrounds. In recent years, there have been many initiatives to improve outreach to communities who have been underrepresented in clinical trials.
Researchers analyzed 1,385 cancer clinical trials published in two major medical journals, The Lancet and The New England Journal of Medicine.
To process thirty years of data efficiently, the study team used an AI tool to extract information from texts, tables, and charts across all the published papers. The research team divided the studies into three distinct decades to track changes over time:
1995 to 2005: 334 studies
2006 to 2015: 448 studies
2016 to 2025: 603 studies
How clinical trials are reaching more patients and where they still fall short
The study revealed two very different trends in how clinical trials are run and who gets to participate in them.
Clinical trials expanded significantly across international borders:
Trials involving sites on multiple continents grew from 27% in the first decade to 58% in the most recent decade.
Participation in Asian countries increased significantly, rising from 14% to 45% of trials.
Journal reporting on race and ethnicity also improved, rising from 16% of published papers to 47%.
Enrollment gaps remain for specific groups
While overall non-White participation appeared to increase, researchers found that this rise was almost entirely due to trials expanding into Asian countries.
When researchers looked at trial enrollment without including participants in Asia, representation for other minority groups actually declined or stayed stagnant over 30 years:
Black participants: The average enrollment of Black participants per study dropped from 6.8% in the first decade down to 1.5% in the most recent decade.
Hispanic participants: Representation remained consistently low across all three decades, hovering between 4.0% and 5.4%.
Actionable steps for patients and caregivers
Social determinants of health, such as geographic location, financial resources, access to academic medical centers, language barriers, and healthcare systemic factors, continue to impact who enters cancer research. While these findings highlight some improvements, there is still more work to be done.
When clinical trials lack diverse representation, it becomes harder to know if new treatments work equally well for every population group. However, there are many things that one as a patient or a caregiver could do to reduce this gap and feel more empowered.
If you or a family member are considering a cancer clinical trial, systemic barriers should not stand in the way of accessing care options. There are financial and community resources you can review.
Seek language and communication resources
Language should never be a barrier to understanding your medical options, like requesting formal medical interpreters rather than relying on family members to translate complex study documents. Or asking for trial consent forms and educational materials in your preferred language.
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Jimena Vicencio