The news isn’t unexpected, but it’s still somewhat shocking: An analysis of 59 North American and European prostate cancer clinical trials found the vast majority of enrollees were white men, according to a study published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.
According to the study, the proportion of white participants in prostate cancer clinical trials has largely remained unchained for the past three decades—tracking higher than 80 percent since 1990—while the proportion of black men in these trials decreased from 11.3 percent in 1995 to 2.8 percent in 2014. This is in spite of the widespread knowledge that black men are more likely to be diagnosed with and die from prostate cancer than their white counterparts.
“In the United States, less than 60 percent of prostate cancer cases occur in non-Hispanic white men, and roughly 22 percent of cases occur in non-Hispanic black men,” said Emily Rencsok, an M.D. and Ph.D. student at the Harvard T.H. Chan School of Public Health in Boston and lead author of the study. “However, when we analyzed the diversity of enrollment in nearly 60 prostate cancer clinical trials, we found that over 96 percent of participants were white.”
Medical professional must acknowledge the extent of underrepresentation of minority men in prostate cancer clinical trials so they can find better ways to support their enrollment in future trials, Rencsok said. “Black men have a disproportionate burden of prostate cancer incidence and mortality compared with white men, and the increased enrollment of black men in prostate cancer clinical trials will help us to learn more about these racial disparities, which could ultimately lead to improved treatment options for this patient population.”
Previous analyses have shown there have been too few black men participating in clinical trials, but these studies were often focused on a specific type of prostate cancer and were limited to a small number of clinical trials. “By analyzing a larger number of prostate cancer clinical trials, we were able to conduct a comprehensive review of enrollment,” Rencsok said. “Further, we could evaluate if the diversity of enrollment in these clinical trials has changed over time.”
For this study, multi-institutional researchers analyzed 72 global phase 3 and 4 prevention, screening and treatment clinical trials for patients with prostate cancer with enrollment start dates between 1987 and 2016. Of these 72 trials, 59 had available race data, comprising approximately 844,000 participants. Roughly 20 percent of these trials were publicly funded, while the remaining 80 percent were funded by pharmaceutical or biotechnology companies. Four screening trials were conducted in Canada or Europe, and the remaining 55 trials were conducted globally with primary centers in the United States.
Of the 59 trials analyzed, 51 were treatment trials, four were prevention trials and four were screening trials. The researchers found the vast majority of participants in each of these three categories were non-Hispanic white men, comprising 83.4 percent, 84.6 percent and 97.5 percent of the participants in the treatment, prevention and screening trials, respectively. The black men category had the second highest enrollment, comprising 6.7 percent, 8.5 percent and 0.5 percent of the participants in the treatment, prevention and screening trials, respectively. Overall, more than 96 percent of the participants enrolled in these clinical trials were non-Hispanic white men.
When researchers analyzed the diversity of enrollment over time, they found the proportion of black men enrolled in prostate cancer clinical trials decreased from 11.3 percent in 1995 to 2.8 percent in 2014. Further, the researchers found the proportion of white participants in these clinical trials has largely remained higher than 80 percent since 1990.
“In recent decades, we have continued to learn about the racial disparities in prostate cancer incidence and mortality, yet our trial enrollment is mostly comprised of white men and does not reflect the populations that are most affected by this disease,” Rencsok said. “We hope this study broadly calls attention to the drastic underrepresentation of minority men in prostate cancer clinical trials, despite the increasing evidence of the racial disparities that exist in prostate cancer incidence and outcomes in these minority populations. I think that we, as both a scientific and a clinical community, need to continue to dedicate intentional and specific resources toward the recruitment of underrepresented men into trials. Further, we should focus efforts into supporting the clinical trial infrastructure in the medical centers that predominantly serve underrepresented populations, both in the United States and globally.”
Nearly 200 clinical trials were excluded from researchers’ analyses due to lack of available results, representing a limitation of this study.