The disparities in breast cancer incidence and mortality rates between Black and White women in the United States have been well documented. Studies over the past decade consistently show that although Black women have a 4% lower breast cancer incidence rate than White women, they are still between 40% and 42% more likely to die of the disease.1,2 In addition, Black women younger than age 50 have a mortality rate twice as high as White women that age.1
Although differences in breast cancer tumor biology are partially responsible for these outcome discrepancies between Black and White women, a meta-analysis by Erica T. Warner, ScD, MPH, Investigator in the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital’s Mongan Institute, and Associate Professor of Medicine at Harvard Medical School, and her colleagues, has found that socioeconomic inequality, delays in diagnosis, and inadequate access to timely quality treatment also play a significant role. The meta-analysis examined 18 studies published from January 1, 2000, to December 31, 2022, which included 34,262 Black and 182,466 White patients diagnosed with breast cancer. The studies compared survival rates between these patients within breast cancer subtypes defined by hormone receptor and HER2/neu (HER2; now also known as ERBB2) status.
“We have figured out as a society how to improve breast cancer outcomes overall. Now, we have to focus on how to apply what we’ve learned to improve survival for Black women.”— Erica T. Warner, ScD, MPH
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The researchers found that Black women experienced worse survival outcomes across all breast cancer subtypes, although the percentages varied. The summary risk of breast cancer mortality was 50% higher among hormone receptor–positive HER2-negative tumors; 34% higher for hormone receptor–positive/HER2-positive tumors; 20% higher for hormone receptor–negative/HER2-positive tumors; and 17% higher among individuals with hormone receptor–negative/HER2-negative tumors. Black women also had poorer overall survival than White women across all breast cancer subtypes.
In a wide-ranging interview with The ASCO Post, Dr. Warner discussed how the contributing factors of breast cancer subtypes and socioeconomic inequality, delays in diagnosis, and inadequate access to timely quality cancer treatment impact survival outcomes as well as offered solutions to reducing unconscious bias in clinical care.
Understanding the Mechanisms Contributing to Disparities
Please talk about why there is such disparity in the risk of dying among the various breast cancer tumor subtypes diagnosed in Black women compared with White women.
Our findings suggest that there are both subtype-specific and subtype-independent mechanisms contributing to poorer survival among Black women with breast cancer. One hypothesis is the amenability idea that the more clinical interventions we have for a specific tumor type across the care continuum from prevention and early detection to more treatment options, the greater the opportunity for disparities compared with tumor types that are less amenable to these interventions. And that hypothesis applies here with the hormone receptor–positive, HER2-negative tumors vs the triple-negative tumors. Until recently, there were no targeted therapies for triple-negative breast cancer, and survival depended mostly on early detection and chemotherapy, surgery, and radiation therapy.
In contrast, there’s a lot we can do for hormone receptor–positive HER2-negative tumors, because they are slower growing than triple-negative tumors and more likely to be detected early by routine mammography. And we have effective therapies for even later stages of those breast cancers.
They are some of the biological differences in terms of faster- vs slower-growing tumors and the fact that the faster-growing triple-negative tumors are more common in Black women than in White women. A lot of work is underway to understand why these tumors differ by race and ethnicity. However, if you look at breast cancer mortality overall and don’t separate it by subtypes, the higher prevalence of those triple-negative tumors among Black women does contribute to the overall survival disparity between Black and White women.
Overcoming Systemic Racism
In addition to disparities in mortality rates due to differences in the biological characteristics of tumor types between Black and White women, your study found that higher mortality rates among Black women were also at least partially attributable to socioeconomic inequality, delays in diagnosis, and inadequate access to timely quality cancer treatment resulting from systemic racism. Please talk about the role systemic racism plays in worse cancer survival in Black women.
We know that despite effective early-detection approaches and innovative therapy, Black women with breast cancer have worse survival outcomes than White women. Systemic racism plays into that fact by allowing socioeconomic inequality, delays in diagnosis, and inadequate access to timely quality cancer treatment.
For example, redlining, the historic discriminatory practice of denying credit, insurance, and health care or prohibitively raising the rates in neighborhoods that have significant numbers of racial and ethnic minorities, still exists today, and academic cancer centers are not located in these neighborhoods. As a result, patients living in these areas have limited care options. Reductions in Medicaid expansion, especially in southern states, have further exacerbated access to and receipt of care and also contribute to increasing cancer risk factors in this population.
We have consistent data showing that mammography rates are similar for Black and White women or Black women’s screening rates are modestly higher. This suggests that disparities in care are predominantly happening in the postmammography setting.
There may be a subset of Black women who are not getting mammography screenings, which may contribute to their worse survival outcome. But many Black women are being screened, and it is not translating into early diagnosis, high-quality treatment, treatment completion, and better outcomes.
Improving Survival Outcomes
How can greater equity in breast cancer mortality be achieved? Would increasing representation of minority women in clinical trials help to improve survival outcomes?
This is an area that presents enormous opportunity for us. Breast cancer mortality has been declining dramatically for the past 40 years, so we have figured out as a society how to improve breast cancer outcomes overall. Now, we have to focus on how to apply what we’ve learned to improve survival for Black women.
Clinical trials are important because this is where we investigate the newest therapies. Making sure that these therapies are equally effective in Black women and other minority populations is crucial. We don’t have a lot of evidence to suggest that the efficacy of specific medications varies by race, but sometimes we are also testing how those drugs are delivered, and that’s often where we find greater challenges.
For example, drugs that require intensive on-site care make it more difficult for patients who face socioeconomic and social determinants of health barriers and have greater social needs to receive timely and complete treatment. So, to the extent that representation in clinical trials can be expanded to include more minority patients, that will help us design delivery approaches for cutting-edge therapeutics that may close the gaps in the receipt and completion of care between Black and White women with breast cancer.
Addressing Unconscious Bias
Your meta-analysis also included data showing that 63% of Black patients with cancer reported having at least one negative care experience with their oncologist or cancer care team, and 31% said they received poorer quality of care because of their race. However, although most oncologists surveyed in previous studies you cite acknowledged worse outcomes and poorer quality care among minority patients, most did not view themselves as a contributor. In fact, many (56%) reported it was not possible that they had unintentional racial or ethnic bias in the care they delivered. What do you think is the disconnect between what patients say they experience because of their race and oncologists’ response that there is not intentional racial or ethnic bias in the care they provide?
It’s challenging for a physicians to acknowledge they may inadvertently or unwillingly have caused or created an experience that made a minority patient uncomfortable. We are doing a lot of cultural diversity training in our health-care systems to reduce unconscious bias in cancer care, but we haven’t seen the fruit of that effort yet. Ultimately, the goal is to make experiences of discrimination as never events in oncology care.
We need to address discrimination in any form the same way we address other patient safety issues in our health-care systems—by promoting staff education and training, effective communication between providers and patients, engaging patients in their care, and monitoring and reporting incidents to learn and improve practices.
DISCLOSURE: Dr. Warner reported no conflicts of interest.
REFERENCES
1. McDowell S: Breast cancer death rates are highest for Black women—Again. American Cancer Society. October 3, 2022. Available at www.cancer.org/research/acs-research-news/breast-cancer-death-rates-are-highest-for-black-women-again.html. Accessed March 13, 2025.
2. Yedjou CG, et al: Adv Exp Med Biol 1152:31-49, 2019.
