Racial minority groups underrepresented in radiation therapy clinical trials
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The racial diversity of radiation therapy clinical trials did not appear to match that of the 2018 U.S. Census population, according to study results presented at the virtual ASTRO Annual Meeting.
“Black patient trial participation was below that expected from the 2018 U.S. Census population in every subgroup analyzed, with the exception of U.S. female-specific cancer trials and male-specific cancer trials. However, our comparison fails to consider differences in incidence between racial populations,” Emily H. Bero, medical student at Medical College of Wisconsin, said during a press conference. “Examining the etiology of inequitable access to clinical trial participation was beyond the scope of our study. Nonetheless, we acknowledge racism as a public health emergency, and we hope this study is informative and offers the opportunity to engage in conversations about race and advancing equitable policies. Structural racism, systemic bias and related barriers consistently limit inclusion of patients from excluded minority groups in clinical trials.”
Bero and colleagues pooled data from 121 clinical trials of radiation therapy included on clinicaltrials.gov between 1996 and 2019.
Researchers categorized trials by various subgroups, including U.S.-based (51.6%), radiation therapy toxicity mitigation/prevention (27.9%), female cancer (17.2%) and proton therapy (7.4%). They used chi-square tests to compare the percentages of different racial groups with 2018 U.S. Census population estimates.
Results showed a statistically significant difference between the racial composition of the radiation therapy trials and census estimates (P < .001). The trials combined had a higher percentage of white participants (84.8% vs. 72.2%) and lower percentages of Black participants (11.8% vs. 12.7%) Asian participants (2.9% vs. 5.6%) and participants of other races such as Native Hawaiian, Pacific Islander, American Indian, Alaskan native or more than one race (0.5% vs. 9.5%) compared with census data. Researchers did not examine inclusion of Hispanic patients in trials because ethnicity is a separate census category.
U.S. clinical trials, radiation therapy toxicity mitigation/prevention clinical trials and female cancer clinical trials all had significantly different racial composition compared with census data (P < .001 for all).
The investigators found the most diverse racial composition in female cancer trials (83.3% white, 13.1% Black, 3.4% Asian, 0.3% other) and male cancer trials (80.2% white, 18.4% Black, 1.4% Asian, 0% other), whereas proton therapy trials had the least racial diversity (93.2% white, 6% Black, 0.9% Asian, 0% other).
“When considering all trials, Asian and other excluded populations had the largest magnitudes of difference from the 2018 U.S. Census population data. All differences were statistically significant, and were most pronounced in trials evaluating proton therapy,” Bero said. “This highlights that not only is there inequitable participation on clinical trials, but specific trials using modalities, such as proton therapy, appear to be differentially susceptible to these inequitable distributions. Our findings point to a need for oncologists designing clinical trials and institutions implementing trials to increase inclusion of excluded groups. Efforts to overcome enrollment disparities in radiation trials are important and worthy of continued investigation.”
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Fumiko Chino, MD
Clinical trials are an essential component of the development and testing of the next generation of anticancer therapies that will translate to more birthdays for our patients. They are a means to ensure that new therapies are both safe and effective, and they allow patients access to cutting-edge therapies that are otherwise unavailable. When access to clinical trials is inequitable, it widens health care disparities and contributes to poorer cancer outcomes for vulnerable populations.
As health care inequities have never been more apparent than during a global pandemic, this ASTRO abstract is an essential look back at patient equity and inclusion in our field. By highlighting the groups which are underrepresented in radiation clinical trials, Bero and colleagues sound the alarm on the work that we need to do to move forward to a more equitable future where all patients have equal access to the best treatments.
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Vishal Gupta, MD
This is an interesting study that confirms that there are disparities among patients enrolled in radiation oncology trials. We have known that minorities are underrepresented in clinical trials, but the findings from this study raise questions as to why there is a racial disparity in trial enrollment. Reducing and eventually eliminating these disparities will make studies more applicable to the entire U.S population.
It was noteworthy that Black patients comprised 12% of the population in the trials and 12.7% of the U.S. population, which shows that Black patients may not be underrepresented in radiation oncology trials in general. However, Asians and other minorities were underrepresented. Another noteworthy finding is the differences in proton therapy trial recruitment. Proton therapy is an expensive treatment modality and only about 30 centers are functional in the U.S. today. It would be interesting to analyze this more in-depth. Perhaps proton facilities are not located near Black communities. Or, are the cancer types eligible for proton trials less common among Black patients?
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Bero EH, et al. Abstract 204. Presented at: American Society for Radiation Oncology Annual Meeting (virtual); Oct. 25-28, 2020.
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