Investigators have found that Black women may have a higher risk of dying from all subtypes of breast cancer compared with White women, according to a recent study published by Torres et al in the Journal of Clinical Oncology. The findings demonstrated that higher mortality rates among Black women with breast cancer may be partially attributable to factors that are independent of tumor biology—including socioeconomic inequalities, delays in diagnosis, and inadequate access to timely quality cancer treatment resulting from systemic racism.
Background
Breast cancer is the most diagnosed cancer type among U.S. women and the second leading cause of cancer-related mortality. Black women who develop breast cancer are about 40% more likely to die of the disease compared with White women; however, it has previously been unclear whether this disparity exists across all types of breast cancer.
Though it is often discussed as a single disease, breast cancer has multiple subtypes that differ in risk factors, treatment, and prognosis. These subtypes are defined based on whether the cancer cells carry hormone receptors for estrogen or progesterone—which can be targeted for treatment—and HER2, a protein associated with cancer aggressiveness that can act as another potential treatment target.
“There had been an anecdotal sense in the research community that differences in survival between Black and White women were greater for the most treatable [types] of the disease—tumors that carry hormone receptors—and smaller for the historically less-treatable, hormone [receptor]–negative tumors,” explained senior study author Erica Warner, ScD, MPH, a cancer epidemiologist at Massachusetts General Hospital.
Study Methods and Results
In a meta-analysis, investigators combined data from 18 studies involving 228,885 breast cancer cases that were published between 2009 and 2022. They noted that 34,262 of the patients were Black women.
The investigators discovered that survival was worse among Black women for all breast cancer subtypes. Disparity sizes ranged from 17% to 50%, depending on the type of breast cancer. For instance, there was a larger racial disparity for hormone receptor–positive tumors. Compared with the mortality rate for hormone receptor–negative tumors among Black women, hormone receptor–positive tumors were associated with a higher risk of mortality among these patients (34% to 50% vs 17% to 20%, respectively).
Because hormone receptor–negative tumors are less common, racial disparities in breast cancer survival for these subtypes were likely not observed in prior research because individual studies lacked statistical power because of the small number of cases.
“There may also be differences in the biological characteristics of some tumor subtypes between racial groups that our therapies are not attuned to, potentially because of underrepresentation of Black women in clinical trials,” detailed Dr. Warner.
Nonetheless, these racial disparities were not inevitable. The investigators highlighted several existing multilevel intervention programs that have successfully reduced disparities in cancer survival. These programs are designed to leverage multiple strategies, including helping patients navigate the health-care system, proactively identifying social needs, connecting patients with resources to address those needs, and implementing systems that alert health-care workers of missed appointments or unmet care milestones. At the national level, interventions such as ACCURE and Equal Hope aim to close gaps in mortality and survival between Black and White women.
Conclusions
“Our findings demonstrate that multiple, interacting factors contribute to disparities in breast cancer survival between Black and White women,” emphasized Dr. Warner. “To achieve equity, intervention is necessary at multiple levels—from community to health-care systems and individual health-care providers, to patients themselves learning about their disease and what their expectations should be for their care,” she suggested.
“These findings underscore a stark reality in our health-care system: Black women are facing higher risks of death from breast cancer compared to their White counterparts, across all types of the disease. This disparity isn't just about biology,” underscored co–study author Paulette Chandler, MD, MPH, an associate epidemiologist in the Division of Preventive Medicine at Brigham and Women’s Hospital. “It's a call to action for health-care providers, policymakers, and communities alike to confront these inequities head-on and strive for meaningful change in breast cancer outcomes,” she concluded.
DISCLOSURE: The research in this study was funded by the National Cancer Institute. For full disclosures of the study authors, visit ascopubs.org.
