Even in Clinical Trials, Breast Cancer Survival Disparities Remain for Black Women

Younger Black women with breast cancer and Black women with hormone receptor positive/HER2 negative (ERBB2) breast cancer were more likely to have worse outcomes than their white peers, even though they were all participants in the same clinical trials and received the same initial care and treatment, according to a new study published October 25 in JAMA Network Open.

These findings show that equitable initial therapy is not enough to eliminate racial or ethnic disparities in breast cancer survival, says Erica Warner, ScD, a corresponding author, an assistant investigator at Mass General Research Institute, and an assistant professor of medicine at Harvard Medical School in Boston. “There are a number of factors that may contribute — we can’t talk about racial and ethnic disparities without naming systemic racism as a fundamental cause,” she says.

“The take-home message is that even in the presence of clinical trial access, there continue to be racial and ethnic disparities in breast cancer outcomes, and this problem will require multilevel solutions,” says Arnethea Sutton, PhD, an assistant professor and a researcher at Virginia Commonwealth University in Richmond who was not involved in this study. “These differences may be attributed to factors associated with one's lived experiences and structural and individual social drivers of health,” says Dr. Sutton.

Breast Cancer Death Rates Are Highest for Black Women

For several decades, Black women have had substantially higher breast cancer mortality rates than white women, according to the American Cancer Society. Although Black women have a 4 percent lower incidence of breast cancer than white women, they have a 40 percent higher rate of death from breast cancer.

Black and White Women in the Same Breast Cancer Trials Had Different Outcomes

The aim of this study was to further examine how factors such as body mass index, age, and tumor subtype (HR+/ERBB2, ERBB2+, and HR-/ERBB2-) may contribute to higher death rates in Black women. By looking at women enrolled in clinical trials, researchers were able to factor out access or subpar initial treatment and care as a potential cause.

Researchers analyzed 9,479 participants with available survival data and race and ethnicity data from four chemotherapy trials. The study group included:

• 871 Black participants (9.2 percent)
• 7,889 non-Hispanic white participants (83.2 percent)
• 436 Hispanic participants (4.6 percent)
• 283 participants of another race or ethnicity (3 percent)

At enrollment, the median age was 52 years old, and participants were followed for a median of 9.8 years.

Investigators found that Black women in two groups had worse breast cancer outcomes than their white counterparts: Those with the hormone receptor positive/HER2 negative (ERBB2) subtype had lower rates of recurrence-free survival (meaning the cancer was more likely to come back); and younger Black women, regardless of cancer type, had lower rates of overall survival.

Although the study was not designed to find out what caused the disparities, Dr. Warner offered a few theories about why Black women who received the same early treatment as white women were still at a higher risk of death.

People Don’t Enter Trials as Blank Slates

“While Black and white participants in a clinical trial are more similar to each other than a random sample of the population — due to the inclusion and exclusion criteria for the trial — it is still likely that due to systemic racism and historical injustice, Black participants are on average more disadvantaged and have had more experiences of marginalization than white participants. Under the weathering hypothesis, this cumulative load or stress is associated with premature biological aging and greater risk of poor health outcomes,” says Warner.

The weathering hypothesis is the idea that chronic exposure to social and economic disadvantage leads to accelerated decline in physical health outcomes and could partially explain racial disparities in a wide array of health conditions.

Systemic Racism Affects All Aspects of Healthcare — and Life Outside of Healthcare

This goes back to the take-home message, which is that access to care is one part of the solution, but it is certainly not the sole solution, says Sutton. “Systemic racism is just that — it is embedded in the system, in the healthcare system, in all systems,” she says.

Multiple aspects of care must be addressed, including access, quality, and continuity, says Sutton. “Unfortunately, racism is woven into the fabric of each of those aspects — and this does not take into account racism that individuals experience outside the context of care,” she adds.

Differences in Survivor Care and Endocrine Therapy May Account for Poorer Survival for Black Women

One explanation for worse rates of recurrence-free survival for Black women with the hormone receptor positive/HER2 negative (ERBB2) subtype may be different access to long-term treatments such as endocrine therapy for HR+/ERBB2- tumors and post-trial surveillance for breast cancer recurrence, explains Warner.

In the treatment of breast cancer, endocrine therapy, also called hormone therapy, is used to block estrogen hormones from binding to cancer cells that have estrogen receptors. This slows or stops the growth of hormone-sensitive tumors, according to the National Cancer Institute.

Sutton has researched the disparity in Black women receiving and adhering to endocrine therapy. “In trying to understand it, we found that Black breast cancer survivors who receive endocrine therapy report more side effects than their white counterparts,” she says.

Worse overall survival rates may also be related to other chronic conditions. Patients who were younger when diagnosed have longer life expectancies after breast cancer treatment, and may have greater cumulative risk for the heart-toxic effects of treatment and secondary cancers, notes Warner.

Findings Could Be Leveraged to Improve Survival Rate Disparities

These findings support the need for ensuring coordinated care and follow-up for the groups with poorer outcomes, says Warner. “For example, my team, along with investigators at Boston Medical Center, has been developing and testing an intervention for Black women diagnosed with breast cancer and their healthcare providers to educate, support, and ensure receipt of timely, high-quality survivorship care,” she says.

Survivorship care guidelines address the clinical needs of breast cancer survivors, and are important for reducing deaths, says Warner. These recommendations include screenings for local recurrences (previous cancer returning) or new primary (new independent cancer arising) breast cancer.

Women should also receive education and counseling about the signs and symptoms of a recurrence, a family history assessment, and a genetic counseling referral (if appropriate), says Warner. “Women with HR+ breast cancer should be regularly asked how their endocrine therapy is going, counseled to continue taking the medication, and given support to manage side effects,” she says.

Lack of Access to Clinical Trials Contributes to Racial and Ethnic Disparities

This study's findings should propel healthcare providers and healthcare systems to lean in on evaluating the type of care individuals receive, regardless of their participation in a clinical trial, says Sutton. “Additionally, we need to continue to identify and investigate reasons behind the racial and ethnic disparities in survival that are highlighted in this study,” she says.

Resources and funding are needed to support efforts to better understand social drivers of health and social needs during care, and then work with patients to address those needs, says Sutton.

“Finally, it is important to remember that lack of access to clinical trials remains a contributor to racial and ethnic disparities. Researchers, clinicians, and other healthcare providers must remain vigilant in ensuring diversity in clinical trials. Clinical trials save lives,” she says.