By Maxine Bookbinder

October 8, 2019 | A new research study reveals racial and ethnic diversity is still substantially lacking in clinical trials for cancer drugs.

The study examined 230 cancer drug trials worldwide, totaling 112,293 participants between July 2008 and June 2018 and was conducted by researchers from the University of British Columbia (UBC), the University of Texas MD Anderson Cancer Center, Fred Hutchinson Cancer Center in Seattle, and Baylor University in Texas.

"There has been awareness regarding disparity; however, the magnitude of the disparity was not clear," says Dr. Jonathan Loree, the study's lead author and assistant professor at the UBC department of medicine, division of medical oncology. "The reason for this disparity is multifactorial and since we looked at global studies, there may be different reasons for the disparity in different systems."

The purpose of the study, says co-author and Baylor undergraduate student Anirudh Gothwal, is to educate the public on racial and ethnic disparities in clinical trials. "There is an unmet need to bring the issue to the surface. Not enough attention has been brought to the issue. It was a very large analysis of data that makes it obvious there is such a huge gap."

The researchers found that fewer than eight percent of cancer drug trials included information about all four of the most common racial identities in the US: white, Asian, black, and Hispanic. It is possible that patients with these backgrounds were enrolled and their races and ethnicities not recorded. And relative to their burden of cancer, says Loree, only 22% of black patients and 44% of Hispanic patients who were expected to enroll actually did enroll. According to the American Cancer Society, the cancer death rate among black American men was 19% higher in 2016 than white American men, down from 47% in 1990. Cancer death rates in black women decreased from 19% to 13% over the same time period.

Yet, black Americans still suffer the highest death rates and lowest survival rates of any racial or ethnic group for most cancers. According to the American Cancer Society, about 202,260 new cancer diagnoses and 73,000 cancer deaths are expected among black Americans in 2019.

Despite these statistics, participant diversity is minimal and record-keeping is incomplete. For example, some of the international trials mentioned only Caucasian and Asian participants; many American trials only recorded data on whites, did not specify the race of participants, or listed them as "other."

Talking with underrepresented groups and identifying problems are the first steps to increasing minority enrollment, says Loree. "The barriers to improved access to cancer care and research are complex and context dependent. I think raising awareness of this issue is an important first step that needs to be followed by engagement of physicians, their patients, and regulatory agencies within each health care system to learn how we can improve disparity."

It is difficult to specify exact reasons for this disparity. Possible causes include lower socioeconomic status, limited access to medical care, lack of trust in doctors and researchers, and the fear of unknown factors in a trial. The lack of health insurance is another barrier, says Loree. A patient without health insurance likely won't have tests, such as CT scans, that may be study requirements. Distance is another; patients without private transportation or who don't live near trial sites can't participate.

The consequences of minority underrepresentation are dire. One medicine does not work for all, particularly disorders with specific genetic factors. Some mutations that can be targeted with treatment are more common in certain groups, says Loree. "For example, in lung cancer mutations, there is a gene called EGFR that is more common in young Asian women who have never smoked. In patients with this type of lung cancer, medications that target EGFR are very effective."

NIH policy supports multi-ethnic inclusion but does not set a minimum percentage requirement. According to NIH Health Science Policy Analyst David A. Kosub, Ph.D., the NIH "requires that women and minorities be included in all clinical research unless there is a compelling rationale for exclusion. NIH peer reviewers consider the appropriateness of the inclusion of racial and ethnic minorities in the context of the scientific goals of the study. A study with an inclusion plan found to be unacceptable cannot be funded until concerns are resolved. As appropriate inclusion will vary depending on the scientific question being asked, there is not a numerical minimum threshold for inclusion."