Research Reveals Barriers to Clinical Trial Participation

Enrollment in clinical trials is vital for the advancement of knowledge and improvement of patient outcomes, but few adults participate in cancer clinical trials. The numbers are even lower among minority adolescent and young adults (AYAs).

According to data presented at the 2020 ASCO Quality Care Symposium, racial disparities exist within AYA enrollment in clinical trials in oncology, with black men in their 20s being least likely to enroll. Furthermore, enrollment of black AYAs has not increased over time, despite increased focus on underrepresented patients.

“In a given year, only 19 black men in their 20s enrolled onto a clinical trial on average,” said Elizabeth J. Siembida, PhD, MPH, Assistant Professor, Center for Health Innovation and Outcomes Research, Northwell Health, Manhasset, NY. “We can’t say much about their cancer experience, or how they are going to respond to cancer therapy, when we are enrolling at such low numbers.”

Approximately 6 times as many AYAs are diagnosed with cancer compared with patients diagnosed as children, according to Dr Siembida. Nevertheless, 60% to 75% of pediatric patients with cancer participate in clinical trials, whereas the enrollment rate is only 2% among AYAs. Furthermore, although black patients account for approximately 11% of cancer cases diagnosed each year, only 3% of cancer clinical trial enrollees are black.

“Overall, these low numbers indicate missed opportunities for AYAs, particularly black AYAs, to access investigational therapies and participate in supportive care studies,” said Dr Siembida.

In their study, Dr Siembida and colleagues used 2000-2016 data from the Cancer Therapy Evaluation Program database to assess total enrollment of black AYAs in National Cancer Institute–sponsored clinical trials. The researchers also identified disparities in black AYA enrollment by age and sex and assessed enrollment over time.

Analysis of the proportion of enrollment by age showed that black patients diagnosed in their 20s were the least likely to enroll in cancer clinical trials. Black AYAs comprised 11.3% of all AYA enrollment, which was marginally higher than the 10.6% of black children and significantly higher than the 8% of black adults enrolled in cancer clinical trials.

In addition, analysis of black AYA enrollment by sex showed that the proportion of black men enrolled in clinical trials decreased with increasing age.

Finally, the researchers observed no significant differences in black enrollment over time, a finding Dr Siembida called “particularly striking and problematic,” given efforts to improve minority representation.

“The proportion of enrollees who are black remained stagnant across the entire study period,” said Dr Siembida. “We really do need to start to understand what the barriers are to improving enrollment in this population.”

Systemic and Clinical Barriers

According to Joseph M. Unger, PhD, MS, Associate Professor, Cancer Prevention Program, Fred Hutchinson Cancer Research Center, Seattle, WA, these barriers are probably not the result of a lack of patient interest but likely have systemic and clinical causes.

Dr Unger and colleagues analyzed 35 studies comprising nearly 10,000 patients with cancer. The results showed that 55% of patients who were offered the opportunity to participate in a clinical trial chose to enroll. The researchers also found no evidence that these rates differed significantly by race or ethnicity.

“These results dramatically underscore the willingness of cancer patients to participate in a trial if one is offered, and stand in stark contrast to the commonly cited statistic that only 5% of adult cancer patients participate in trials,” Dr Unger said. “That statistic fails to reflect the many structural and clinical hurdles that stand in the way of trial participation.”

According to Dr Unger, the similar rates of willingness to participate in clinical trials by race and ethnicity suggest that observed disparities in clinical trial participation likely manifest earlier in the treatment decision-making process and are not driven by a difference in willingness to participate. These findings also suggest that a good way to improve enrollment among minority patients may be to ensure they are invited to participate.

“The root cause of low trial participation rates in adults with cancer appears to be a clinical trial system beset with structural and clinical barriers rather than patient lack of interest,” Dr Unger concluded. “Thus, research interventions and policies to improve trial participation should focus more on these systemic, structural, and clinical barriers.”

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