Study sheds light on diversity of study participants at CCR

An illustrated crowd of diverse people

Diversity in clinical trials is critical for understanding how well a treatment may work in different populations. A new study done by CCR researchers describes representation based on sex, age and ethnicity in clinical trials done at CCR. Image credit: iStock

A recent study analyzing the demographics of clinical trial participants at CCR describes the representation of various population groups in cancer research. The results, published February 19 in the Journal of the National Cancer Institute, suggest that older adults, women, Asians, Hawaiians, Pacific Islanders, American Indians, Alaska Natives, and Hispanics are underrepresented in clinical trials done by CCR, while Blacks or African Americans have higher representation.

People can respond differently to treatments depending on their biology, including ancestry and biological sex. For these reasons, it is important for clinical trials investigating new therapies to include diverse populations.

“By including every population in a clinical trial, you can have higher confidence to say who will benefit from a certain therapy,” explains Charalampos “Harris” Floudas, M.D., DMSc, M.S., Assistant Research Physician in the Center for Immuno-Oncology.

Floudas and his team sought to better understand the diversity of clinical trials conducted by CCR. They analyzed demographic data capturing the sex, age, race and ethnicity of 38,531 people who enrolled in clinical trials for cancer treatment at CCR between 2005 and 2020, in comparison to similar demographic data of the general population that goes on to develop a given type of cancer (called the incidence rate).

In the past, Black and African American populations have often been under-represented in research. However, the results of this study show that Black and African American populations are currently represented well in CCR trials, likely because this population is very prevalent in the Maryland and Washington D.C. area, where the National Cancer Institute is located.

Older adults, women, Asians, Hawaiians or Pacific Islanders, American Indians or Alaska Natives, and Hispanics or Latinos are underrepresented in these clinical trials, to varying degrees. For example, women develop 49.5% of all cancers included in this study, but they represent 41.7% of participants in CCR clinical trials. Whereas Hispanic cancer patients make up 13% of the overall cancer cases included in this study, they represent only 7.1% of participants in CCR clinical trials.

The researchers speculate that some of these under-represented groups, such as older adults with mobility issues and Native Americans living in rural and remote areas, may experience difficulties in traveling to the CCR clinics to receive treatment, underscoring the importance of programs that provide funding and support for treatment-related travel.

Of note, the researchers found that the overall proportion of older adults, African Americans, Asian/Pacific Islanders, and Hispanic participants in these trials increased over the 15 years of this study, indicating positive participation trends for these groups. However, an increase in representation of women did not occur over this same time period, indicating that more targeted strategies to support their participation in studies are especially needed.

Floudas notes that this study is only a first look at CCR’s trial participation, however, and it is a positive initial step toward new strategies for increasing diversity in trials. His team plans to conduct a follow-up study for older adults across race and ethnicity, which will inform future recruitment strategies for clinical trials.


This research was made possible with the collaboration amongst CCR researchers Harris Floudas, M.D., DMSc, M.S., James Gulley, M.D., Ph.D., Fatima Karzai, M.D., and Nirmal Choradia, M.D. In the Q&A that follows, they each elaborate on the background of this study and possible future directions.

What was the inspiration behind the need to conduct the study?

JG: We have all realized that access to clinical trials is not equitable and I believe we can increase diversity in clinical trials and gain insights about the applicability of findings to diverse patient populations. However, to do this, we have to first measure where we are with our current cancer patient populations.

FK: This study is a foundation for determining what we are doing well but also what we can do better in the recruitment and retention of under-represented minorities in clinical trials. The CCR community needs to tackle under-representation in clinical trial accrual as a collective, and this type of study helps to start defining that path.

What is the importance of studying and understanding the demographics in past clinical trials?

HF: Detailed analysis of the demographics is necessary to establish if there is a problem (underrepresentation) with a specific clinical trial, and if so, to understand potential reasons for this problem. Data are required to validate our hypotheses and allow us to consider ways to improve.

What are the future directions for this research? How do you hope these findings will be used?

FK: We will use this study as a starting point and go on to determine ways in which to improve diversity in clinical trials at CCR. First, data capture for sex, race, and ethnicity needs to be improved for all clinical trials (including self-reporting). Next, understanding our catchment areas and how to expand upon them is important and stems from this research. We can identify what barriers we can address to increase opportunities for clinical trial exposure. This is multi-factorial, involving reaching out to the communities affected, as well as expanding the ways in which patients are exposed to learning about clinical research.

NC: We would ideally like to identify places that have good relationships with specific oncology groups at CCR and provide this information to them to increase outreach. I also think spreading knowledge about what the NCI has to offer and the research we conduct would help build a more diverse patient population. It would be valuable to have more discussions with patients and advocacy groups as to areas of outreach to broaden our reach.

What do you think are the most effective methods for increasing diversity in clinical trials?

HF: Consistent, targeted outreach to the recognized underrepresented populations will be necessary, proportional to the magnitude of underrepresentation. Studying the factors limiting accessibility for patients and ways to simplify the referral process will be key to facilitating potential participants and their providers.

FK: This requires collaboration, determination, and multifaceted efforts. Our recommendations include collecting data about patient experiences to identify strengths and opportunities for improvement, strengthening the delivery of culturally sensitive communications and patient-centered care, implementing metrics to assess accrual and diversity in accrual to clinical trials, and institutional partnerships to increase awareness of CCR clinical trials. It is imperative to make a meaningful difference for our patients by being firmly committed to increasing diversity, equity and inclusion in our clinical trials. This should be at the forefront of our scientific endeavors as it will improve scientific rigor and the quality of healthcare we deliver.


The new Office of Healthcare Delivery and Equity Research at CCR also leads institutional efforts in multiple ways. Associate Director Brenda Adjei, Ed.D., M.P.H., provides a glimpse of other CCR-wide efforts to increase diversity in clinical trial enrollment.

The analyses conducted by Choradia et al., 2024, provide an important first step toward identifying opportunities to enhance equitable representation in NCI’s clinical research. This is not only important in terms of enriching cancer research – it is a critical aspect of fulfilling the NCI mission to reduce the cancer burden for all. Our new office builds on strong leadership support and commitment to this goal, and the foundational efforts of CCR’s Clinical Trials Diversity and Inclusion Committee, which outlined recommendations to strengthen healthcare delivery and equity in CCR.

To overcome barriers to clinical trial participation among populations underrepresented in clinical research, our new office has prioritized improving data collection, building and enhancing clinical and community engagement efforts, and implementing multilevel and evidence-based initiatives in collaboration with our CCR clinical teams. The demographic data reported in this paper highlight the need to understand who our patients are and how we can best address their cancer care needs. This approach (called “catchment area analysis”) will help us to strengthen our metrics and data systems, understand what outreach has been effective, and what innovative models and engagement strategies on which we should focus. This data will also inform targeted and tailored efforts to increase awareness of CCR’s clinical research among clinical and community partners, reduce barriers to clinical trial participation among diverse population groups, and enhance efforts to provide culturally and linguistically appropriate patient-centered care at CCR.

Similar to the national cancer care community, CCR leadership has prioritized the implementation of initiatives to improve access, outreach, engagement, and diversity in CCR clinical trials. We have a lot to do and are excited about our planned efforts to engage with our local and national clinical and community partners in providing access to NCI’s clinical trials.

The team would also like to thank the NIH Biomedical Translational Research Information System (BTRIS) team for providing the data that made this study possible.

Posted on Thu, 04/25/2024