African Americans Underrepresented in Clinical Trials of Cancer Treatments

By Linda Carroll

June 24, 2020

(Reuters Health) - The number of black patients in U.S. clinical trials testing new oncologic drugs falls far short of what would be expected based on prevalence of the specific cancers those medications were designed to treat, a new study suggests.

Across a range of cancers, the percentage of African American trial participants in 2014-2018 and the percentage of African Americans among people with that form of cancer showed a 1-to-3 ratio, Texas researchers report in Annals of Internal Medicine.

"The most important thing in this study is that in the United States, African American persons have the highest death rates and the lowest survival rates of any ethnic group for cancers," said the study's lead author, Dr. Samer Al Hadidi, a postdoctoral researcher at the Baylor College of Medicine in Houston.

"And despite that, the medications we use nowadays are approved based on studies with more non-African Americans even though the cancers are more common in African Americans," Al Hadidi said. "African Americans are just not enrolled at the same rate as whites."

Without an adequate number of African Americans in the clinical trials, it will be difficult to tease out any biological differences in cancer behavior between blacks and whites, Al Hadidi said. "Differences in tumor biology in African Americans may either cause them to respond better or worse to the medications we have," he added.

To take a closer look at African American participation in clinical trials testing cancer drugs, Al Hadidi and his colleagues examined public data from the U.S. Food and Drug Administration for 75 new oncologic drug approvals between 2014 and 2018.

The researchers calculated a "participation-to-prevalence ratio" (PPR) for black participation in the trials by dividing the percentage of trial participants who were African American by the percentage of African Americans among those with the disease. Thus, a PPR of 1.0 would indicate identical representation of African Americans in the trial and disease populations, the authors explain.

During the period studied, a total of 61,763 patients were enrolled in clinical trials that resulted in subsequent FDA approval for cancer medications. The proportion of African Americans enrolled in these trials was 7.44%, and the overall PPR was 0.31.

The researchers found that African Americans were underrepresented across all major cancer types.

Breast cancer trials had a PPR of 0.29, for example, while the ratio was 0.18 for prostate cancer, 0.15 for lung cancer, and 0.12 for hematologic cancer.

Al Hadidi thinks that one way to improve participation rates would be to offer additional funding to sites that enrolled more African Americans in clinical trials.

Experts interviewed by Reuters Health suggested that a race-based focus would not provide the most helpful information.

"There's actually a lot of data to show that disparities in outcome are not due to biological differences," said Dr. Otis Brawley, a professor of oncology and epidemiology at the Johns Hopkins School of Medicine and the Johns Hopkins Bloomberg School of Public Health in Baltimore.

For example, Dr. Brawley said, African American women with early stage breast cancer do not get surgery at the same rate as white women.

When it comes to biological differences, the important question is not race, so much as where people come from, Dr. Brawley said, pointing to the example of sickle cell anemia. Genes for the disease can be found in black people from sub-Saharan Africa and also in whites from Southern Europe, but black people whose ancestors came from southern Africa do not generally have the gene, Dr. Brawley said. So superficial racial category is not what determines the risk for that disease.

"I don't want to say you shouldn't look at differences amongst populations, but using race is not appropriate," Brawley said. "Dividing people into the five racial categories the OMB gives us is like slicing soup."

Similarly, Robert Fullilove supports diversity in clinical research, but believes that the important factor is environment rather than race. People from rough neighborhoods, such as Harlem, are going to have a different risk when it comes to cancer than those who grow up in wealthy areas, like Beverly Hills, said Fullilove, a professor of sociomedical sciences at the Columbia Irving Medical Center and associate dean of community and minority affairs at Columbia Mailman School of Public Health in New York City.

Even so, it is often difficult to get people from disadvantaged neighborhoods, like Harlem, to participate in clinical trials, Fullilove said. The best way to do that is to partner up with members of the community before a trial is started to get help recruiting participants, he added.

SOURCE: Annals of Internal Medicine, online June 23, 2020.