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Racial, Ethnic Minorities Underrepresented in Cancer Research

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Black, Hispanic, American Indian, and Alaskan Native people are vastly underrepresented in research studies on breast, prostate, lung, and colorectal cancer, according to an analysis.

The research was published online on Nov. 8, 2021, by the journal JAMA Network Open. Read “Racial and Ethnic Disparities Among Participants in Precision Oncology Clinical Studies.”

About racial diversity in clinical trials
About the study
What this means for you

About racial diversity in clinical trials

Clinical trials are carefully designed research studies that depend on volunteers to improve medical care over time.

Clinical trials looking at new treatments are usually conducted in a series of four steps, or phases, from phase I to phase IV. Each phase builds on the one before it:

  • Phase I trials look at the best way to give a new treatment, as well as the safest dose.
  • Phase II trials look at how effective the new treatment is.
  • Phase III trials compare the safety and effectiveness of the new treatment with the current standard of care.
  • Phase IV trials look at whether the new treatment has benefits or long-term side effects that were not seen in the phase II and phase III trials.

Clinical trials are the main way scientists develop new and improved cancer treatments. Yet studies show that less than 5% of adults diagnosed with cancer participate in clinical trials, and most of those participants are white.

Black Americans make up more than 13% of the U.S. population. But in the clinical trials that led to FDA approval of four new breast cancer treatments in 2020, only 2% to 9% of participants were Black. Similarly, Hispanic or Latin Americans make up 18.5% of the U.S. population, but accounted for 0% to 9% of participants in those same trials.

Researchers have found a number of barriers that stop people of color from participating in clinical trials, including:

  • travel and transportation time and expense
  • out-of-pocket costs
  • lack of trust in the healthcare system
  • lack of awareness of clinical trial opportunities, possibly because doctors don’t discuss clinical trials with patients of color

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About the study

This study looked at racial and ethnic representation in precision oncology studies on breast, prostate, lung, and colorectal cancers.

Precision oncology means doctors test a cancer tumor to identify specific changes at the molecular level that can then be targeted with medicines.

For example, HER2-positive breast cancers have too many copies of the HER2 gene, which then make too much of the HER2 protein. The HER2 protein sits on the surface of a cancer cell and receives signals that tell the cancer to grow and spread. Anti-HER2 targeted therapies, such as Herceptin (chemical name: trastuzumab) and Perjeta (chemical name: pertuzumab), attach to the HER2 proteins on the surface of a cancer cell and block them from receiving growth signals. Because anti-HER2 medicines target the HER2 protein, they’re considered precision oncology medicines.

In this study, the scientists searched ClinicalTrials.gov for U.S.-based precision oncology studies on breast, prostate, lung, and colorectal cancer that were completed.

The researchers excluded studies from their analysis if they took place in sites outside the United States and if they didn’t look at precision oncology medicines.

Of the 197 studies that met the researchers’ search criteria:

  • 93 studies reported the participants’ race or ethnicity
  • 104 studies had no information about the participants’ race or ethnicity

The 93 studies included 5,867 people:

  • 82.2% were non-Hispanic white
  • 10% were Black
  • 4.1% were Asian
  • 3.4% were Hispanic
  • 0.3% were American Indian or Alaskan Native

The researchers also looked to see which studies had the highest and lowest proportion of participants by race or ethnicity.

Studies on lung cancer had the highest proportion of white and Asian participants and the lowest proportion of Black, Hispanic, and either American Indian or Alaskan Native participants.

Studies on colorectal cancer had the highest proportion of Hispanic participants.

Studies on prostate cancer had the highest proportion of Black and either American Indian or Alaskan Native participants and the lowest proportion of Asian participants.

The researchers then compared the proportion of each racial or ethnic group in the studies with the proportion of each group in the U.S. population diagnosed with that particular type of cancer.

Overall, the results showed that white and Asian participants were overrepresented and the other racial and ethnic groups were substantially underrepresented:

  • white participants were overrepresented by about 35%
  • Asian participants were overrepresented by about 46%
  • Black participants were underrepresented by about 51%
  • Hispanic participants were underrepresented by about 76%
  • American Indian and Alaskan Native participants were collectively underrepresented by about 57%

Looking specifically at precision oncology studies on breast cancer:

  • white participants were overrepresented by about 32%
  • Asian participants were overrepresented by about 95%
  • Black participants were underrepresented by about 38%
  • Hispanic participants were underrepresented by about 36%

The researchers were unable to analyze information on American Indian and Alaskan Native participants in breast cancer studies because the number of participants was too small.

“We demonstrate that precision oncology studies for breast, lung, prostate, and colorectal cancers underrepresent racial and ethnic minority populations relative to their cancer incidence in the U.S. population,” the researchers wrote. “Increased emphasis on equitable recruitment and enrollment for precision oncology studies is essential, as resulting discoveries are used to personalize treatments, and it is unclear whether current precision medicine breakthroughs can be broadly applicable to, or safe for, our diverse cancer population.”

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What this means for you

While this study confirms what other research has found, the results are very troubling.

Not participating in clinical trials may be one of the reasons that Black, Hispanic, American Indian, and Alaskan Native people have worse breast cancer outcomes than white and Asian people.

Lack of diversity among clinical trial participants means that new cancer treatments are being tested in groups of people that are not representative of the broader population that will receive these treatments if they are approved.

“We need everyone appropriately represented because we want to make sure a therapy works the same way and the side effects are the same in different populations,” said Karen Winkfield, M.D., Ph.D., a radiation oncologist and executive director of the Meharry-Vanderbilt Alliance in Nashville, Tennessee. “We also want to make sure we are providing precision medicine. Sometimes a medicine might work better in one population than another. We need to learn these things up front so we can give each patient the right medicine at the right time.”

Being part of a clinical trial means you’re helping find better treatments. Your participation could help save lives. Still, it’s a very personal decision.

If you’re interested in finding a clinical trial that might be right for you and your unique situation, ask your medical team. If your doctors aren’t knowledgeable about clinical trials, ask if they can refer you to a doctor who is. You also can search ClinicalTrials.gov to see which trials you might be eligible for.

Read our Special Report: Increasing Racial Diversity in Breast Cancer Clinical Trials for more information.

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Written by: Jamie DePolo, senior editor

Reviewed by: Brian Wojciechowski, M.D., medical adviser


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