Black women in the U.S. are close to 40 percent more likely to die of breast cancer than white women and twice as likely to be diagnosed with breast cancer before the age of 40.
The disparity adds to an alarming trend of women increasingly being diagnosed with breast cancer in early adulthood and middle age overall, the 2025 American Cancer Society’s annual cancer report shows.
Health and income inequalities factor into why Black women die from breast cancer at disproportionate rates. But genetics also plays a significant role. In recent years, more researchers have joined a huge push to investigate genetic mysteries behind why Black women are more likely than any other racial group to die of breast cancer, have more aggressive tumors and develop breast cancer at a younger age—despite having a slightly lower overall incidence of breast cancer than white women.
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More than 86 percent of DNA samples in genomics studies are from participants with European ancestry, and from 2016 to 2021, the proportion of samples from nonwhite populations either stayed the same or decreased. Human beings are 99.9 percent genetically identical, but their small degree of difference from one another has outsize implications for cancer and other diseases.
Certain genetic variants, or mutations, are often linked to ancestry, and some have been connected to poor health outcomes. Inherited variants in genes that keep inflammation and cell division in check can greatly influence cancer risk. For example, variants that turn off the BRCA1 and BRCA2 tumor suppressor genes are connected to a greater incidence of breast cancer in women of Ashkenazi Jewish descent.
In contrast, little is known about genetic variants that influence cancer risk for Black women because of decades of underrepresentation in genomic studies and clinical trials, says Melissa Davis, a Morehouse School of Medicine geneticist who leads one of the largest international collaborations on breast cancer disparities research.
“The groups of people who have been studied to identify genetic risk markers have largely been people of European descent,” Davis says. “That means that genetic risk that exists in other groups has gone unnoticed—undocumented—but we know it exists.”
Researchers are now including more people with African ancestry in genomic studies and have identified more variants that could impact breast cancer survivorship in Black women. And scientists are partnering internationally to share data, DNA repositories and other resources, which is leading to more discoveries that could improve cancer treatment for this population.
Why Breast Cancer Is More Deadly in Black Women
Deaths from breast cancer have been declining for all groups except Native American women since 1990—but the survival gap has widened between Black and white women.
More widespread use of mammograms, along with the implementation of targeted hormone therapies more than 40 years ago, has significantly contributed to the decline in death rates. But even though Black women are slightly more likely than white women to receive regular mammograms, targeted hormone therapies are often less effective for Black women.
“Prior to the mid-1980s, it didn’t really matter whether you were Black or white, you pretty much had the same chance of surviving breast cancer,” Davis says.
She and other scientists looked toward genetics to partly explain the difference in Black women’s response to hormone therapy and the reasons they develop cancer younger and have more aggressive tumors.
In the early 2000s scientists noted the most aggressive tumors lacked the three receptors that respond to hormone therapies and termed this cancer subtype triple-negative breast cancer (TNBC). Black women are twice as likely as white women to develop this type of cancer—a major contributor to the mortality disparity. Davis was one of the earliest researchers to work on uncovering the genetic mechanisms behind triple-negative breast cancer.
“We started asking the question, ‘What do these patients have in common that white women wouldn’t have?’” Davis says. “That pointed directly to African ancestry.”
Davis is former scientific director of the International Center for the Study of Breast Cancer Subtypes, one of the first large-scale international research cohorts to study breast cancer genetic disparities in women with African ancestry. She and the center’s founder, Lisa Newman, a researcher and chief breast surgeon at Weill Cornell Medicine, were among the first researchers to observe that most TNBC cases globally occur in sub-Saharan West Africa. Most African Americans have sub-Saharan West African ancestry.
Working with institutions in Ghana and Ethiopia, Davis and Newman created a more inclusive picture of the human genome by mapping genetic profiles of people with African ancestry who have TNBC using tissue donated by African Americans and Africans.
Research by Davis has found that African American women were far more likely than white women to have an aggressive, androgen-receptor-negative subtype of TNBC. And a 2022 study co-authored by Davis showed that having a greater amount of quantifiable African ancestry—a DNA measurement independent of self-reported race—was linked with a larger number of immune cells in the tumors of Black women with TNBC. But these cancer-fighting cells were inactivated.
The discovery could inform the development of TNBC immunotherapies that may be more effective for Black women, who currently lack therapeutics personalized to their tumor characteristics, Davis and her Morehouse School of Medicine colleague Rachel Martini write. “The advent of every new technology or treatment protocol has propagated disparities in minoritized populations,” they added.
Tracing Genetic Risks
Scientists have discovered cancer-linked gene variants unique to people of African ancestry, including one that confers protection against malaria.
Davis and other researchers have found that a variant in a gene called DARC—which controls inflammation, a key driver of cancer—causes the gene to be expressed at lower levels in people with sub-Saharan West African ancestry. DARC is expressed in red blood cells and tumors. In red blood cells, DARC produces a protein that malarial parasites can invade.
Low DARC expression in people with sub-Saharan West African ancestry evolved selectively because malaria is endemic in the region. But there is a disadvantage—lower levels of DARC in tumors are tied to reduced cancer survivorship.Davis filed a patent for a test to measure DARC expression, which, if developed, could help determine cancer treatment plans for Black women.
In addition to DARC, researchers are also exploring how variants in the BRCA1 and BRCA2 tumor suppressor genes—which have been more widely studied in other groups—impact Black women. Multiple variants in the BRCA1 and BRCA2 tumor suppressor genes were found to be prevalent in Black women with breast cancer in Florida, according to a 2015 study conducted by researchers at the University of Florida study. The study’s authors suggested that it may be beneficial for Black women who develop breast cancer at age 50 or younger to undergo BRCA screening.
And researchers at the African Ancestry Breast Cancer Genetic Consortium, led by Vanderbilt University Medical Center, published findings last May from what they say is possibly the largest genome-wide association study of women with African ancestry for breast cancer. The study, which included data from more than 40,000 women from several African countries, Barbados and the U.S., identified 12 variants associated with breast cancer in women with African ancestry. Three were tied to TNBC.
Progressive research practices—such as establishing larger research cohorts and sharing more data, as has been required by the National Institutes of Health—have been increasing the pace of genetic research on breast cancer disparities, says Brittany Jenkins-Lord, a molecular biologist at the Johns Hopkins Bloomberg School of Public Health.
“All of the [NIH-funded] studies are supposed to be FAIR [findable, accessible, interoperable and reusable],” Jenkins-Lord says. “In the past, you had to contact investigators yourself and ask them for the data,” she adds. “They could decide whether or not they wanted to give it to you, and if you’re a competitor, they might not.”
Discovering more genetic variants also helps Black women assess their individual cancer risk, says Altovise Ewing-Crawford, a health equity geneticist at Genentech. Physicians are less likely to recommend Black patients for genetic testing because of a perceived lack of information about variants unique to African ancestry. Ewing-Crawford advises Black women to undergo genetic testing because of known variants—and because scientists are continually finding more.
“As genomic research becomes more inclusive and prioritizes the discovery of genetic variants in … diverse populations, we may see the benefits of genetic testing extend more equitably,” Ewing-Crawford says.
Other Cancer Risk Factors
Researchers are starting to understand how genetics interact with nonmedical health factors, such as institutional racism and environmental risks, to contribute to breast cancer death risk. “Making connections between environmental exposures and cancer has been done for probably a century now,” Jenkins-Lord told the author of this article in an interview for a piece in Hopkins Bloomberg Public Health magazine. “You have your risk, you have your outcome, but in the middle, you have everything biological that’s happening.”
Jenkins-Lord and other researchers are studying the epigenetics of inner-city populations—ideal subjects because of their diversity of income and race—for additional insights. In Baltimore, where Jenkins-Lord works, the city’s mostly white and affluent Cheswolde and Crosscountry neighborhoods have a 16-year-longer life expectancy than parts of the mostly Black neighborhoods Upton and Druid Heights, a divide related in part to cancer outcomes.
In Black women who lived in disadvantaged neighborhoods in Baltimore, Jenkins-Lord found that a key tumor suppressor gene was expressed at lower levels, but the gene was not affected in white women living in those same neighborhoods.“We’re looking at the contribution of genetics to the expression of this tumor suppressor, [and] we know the environment is contributing in some way,” Jenkins-Lord says.
In the Atlanta metropolitan area, Jasmine Miller-Kleinhenz, a University of Mississippi Medical Center cancer biologist, found that women with breast cancer living in areas experiencing contemporary redlining, or the systematic denial of mortgage loans based on a location’s racial demographics, experienced accelerated biological aging. “That’s important because cancer is primarily a disease of aging cells,” Miller-Kleinhenz says. Almost 90 percent of Black women in the study lived in redlined areas compared with about 30 percent of white women.
The latest research on breast cancer disparities connects data on socioeconomic characteristics, genetic ancestry and gene expression with health outcomes, Jenkins-Lord says. “It’s a gene-versus-environment question, and I think that’s where this research is going to continue to go,” she says. “Your genetics … are going to have an impact, but where you live and your exposures over your lifetime are also going to impact the expression of these cancer-related genes.”
