“Racial inequity in healthcare delivery and outcomes in the United States is well-documented, and outcomes for breast and gynecologic cancers are no exception,” explains Katherine V. Grette, MD. “In order to better address these disparities, we need to understand all of the contributing factors. Since clinical trials are set up to evaluate safety and efficacy of medications for treating these diseases, racial disparity in trial participation is a critical issue.”

For a paper published in the International Journal of Gynecological Cancer, Dr. Grette and colleagues They conducted a retrospective review to assess participation of minority women in clinical trials using immunotherapy agents for breast and gynecologic cancers. Completed trials were examined for data on race, tumor type, and start year; minority enrollment was stratified by tumor site. Based on CDC age-adjusted incidence for race, expected and observed ratios of racial participation were calculated and compared using X2 testing.

 No Trend Toward Increasing Minority Representation

“Previous research conducted by our study team demonstrated that racial minorities were underrepresented in cancer clinical research,” Dr. Grette notes. “Since immunotherapy is a fast-growing field, we wanted to determine if these disparities existed there. Furthermore, immunotherapy trials all began after the FDA had recognized the problem of minority underrepresentation in clinical trials and put certain safeguards in place to incentivize better equity and enrollment.”

A total of 53 completed immunotherapy clinical trials involving 8,820 patients were reviewed. Breast cancer trials were most common (n = 24) and involved the most patients (n = 6,248, 71%). Racial breakdown was provided in 41 studies (77%) for a total of 7,201 patients. Race reporting was lowest in uterine (67%) and cervical cancer trials (67%), and highest in ovarian cancer trials (86%). White patients comprised 70% (n = 5,022) of all the patients across the studies. Only 5% of patients involved were Black (n = 339), among whom 83% (n = 282) were enrolled in breast cancer trials. While all trials reported race between 2013 and 2015, no consistent trend was seen toward increasing race reporting or in enrollment of Black patients over time, the study authors note.

Minority Patients Grossly Underrepresented in Trials

“Minority patients are grossly underrepresented in clinical and immunotherapy trials for breast and gynecologic cancers,” Dr. Grette says. “This disparity is especially striking among Black patients. For example, pembrolizumab is one of the oldest and most well-studied immunologic agents, but only seven Black patients contributed to our understanding of its function and approval for use in gynecologic malignancies. That begs an important question: Can we really draw any conclusions about the effectiveness of a medication in minority patients when so few non-White women were enrolled?”

In all cancer sites, enrollment of Black patients was far lower than expected given the incidence of these cancers among Black women, Dr. Grette notes. Compared with what was expected, observed enrollment of Black women was 32-fold lower for ovarian, 19-fold lower for cervical, 15-fold lower for uterine, and 11-fold lower for breast cancer (Table).

“As the applications of immunotherapy in gynecologic and breast cancers continue to expand, we need to pay special attention to more equitable enrollment in clinical trials,” Dr. Grette concludes. “When new trials are being proposed, principal investigators should be required to demonstrate how they will ensure minority enrollment. For oncologists who are not directly involved in research but have patients who qualify for clinical trials, it is important to understand this disparity and seek to understand why a patient may be hesitant to participate.”

Dr. Grette and colleagues concur that the focus of future research in this area should be on solving the race disparity. “In an ongoing study involving 1,021 patients with endometrial cancer, our institution found that the use of lay navigators whose demographics matched our patient population eliminated the racial disparity in enrollment and also narrowed the disparity in progression-free survival between Black and White women enrolled in clinical trials,” she says. “Adoption of these kinds of evidence-based strategies will help solve inequity in clinical trial enrollment and health outcomes.”

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