Barriers to enrolling a diverse population of patients in clinical trials are complex and multilevel, concluded a recent study.1

“The problem of severe under-enrollment of racial and ethnic minorities into clinical trials persists,” says lead author Lauren M. Hamel, PhD, an assistant professor in the department of oncology at Wayne State University School of Medicine and the Karmanos Cancer Institute in Detroit. This is true despite a National Institutes of Health requirement that members of minority populations be represented in clinical research.

“Our research team has extensive experience studying racial healthcare disparities, especially in cancer treatment and cancer clinical trials,” notes Hamel. “So we were in a great position to take this on.” To increase enrollment of racial and ethnic minorities in clinical trials, future interventions should address barriers at multiple levels, the researchers concluded.

“My colleagues and I have studied what prevents and facilitates enrollment into clinical trials for many years,” says Hamel. Thus, it came as no surprise that barriers to diverse enrollment exist on multiple levels.

“What this paper provides is a summary of the barriers at each level, how they influence one another, and also some ideas for solutions to the problem,” Hamel says. Ideally, interventions should address as many levels as possible — system, individual, and interpersonal.

“This increases the likelihood of an intervention achieving substantial and sustained change and to produce additive, and possibly multiplicative, effects,” says Hamel. Scarce resources are an obstacle. “A multilevel intervention is not always possible,” acknowledges Hamel. “However, it’s important to recognize that discussions about clinical trials do not exist in a vacuum.” Some key findings include the following:

  • Barriers at the system level can create barriers at the individual level.

For instance, physicians might not mention a clinical trial to a patient if they don’t believe it’s adequately supported by the hospital.

  • Individual attitudes are a factor.

Negative attitudes toward minority patients could lead physicians to believe these patients will be poor candidates for clinical trials, for example.

Sarah L. Goff, MD, associate professor of medicine at University of Massachusetts Medical School–Baystate Medical Center in Springfield, notes that studies often are designed without input from patients. Thus, patients don’t have any say as to the pertinence of the study question, the design of the study, and how results will be communicated to participants.

Goff views this as one underlying cause of lack of diverse enrollment. “The movement toward funders encouraging various levels of patient and stakeholder engagement in research holds promise for addressing ethical issues related to enrollment of racial and ethnic minorities in clinical trials,” says Goff.


  1. Hamel LM, Penner LA, Albrecht TL, et al. Barriers to clinical trial enrollment in racial and ethnic minority patients with cancer. Cancer Control 2016; 23(4):327-337.


  • Sarah L. Goff, MD, Assistant Professor of Medicine, University of Massachusetts Medical School–Baystate Medical Center, Springfield. Email:
  • Lauren M. Hamel, PhD, Assistant Professor, Department of Oncology, Wayne State University School of Medicine/Karmanos Cancer Institute, Detroit. Phone: (313) 576-9672. Fax: (313) 576-8270. Email: