Breastfeeding may play a critical role in reducing the risk of one of the most aggressive forms of breast cancer among Black women, according to ongoing research and community outreach led by scientists at Roswell Park Comprehensive Cancer Center.
Breast cancer remains the second leading cause of cancer death among Black women in the United States. Studies show they are 36% to 41% more likely than White women to die from the disease and are disproportionately affected by estrogen receptor–negative (ER-negative) breast cancer, a subtype known for its aggressive behavior and limited treatment options.
Childbirth’s Complex Role in Breast Cancer Risk
Researchers have found that childbirth can influence breast cancer risk differently depending on the cancer subtype.
“Having children tends to lower the risk of developing ER-positive breast cancer, the type that’s more common in White women,” said Christine Ambrosone, PhD, Senior Vice President of Population Services at Roswell Park. “But having children also increases the risk of ER-negative breast cancer, the more aggressive type more often diagnosed in Black women.”
However, Ambrosone’s team identified a significant protective factor: breastfeeding.
A landmark Roswell Park study published in 2014 found that breastfeeding substantially reduced the elevated risk of ER-negative breast cancer among African American women who had given birth. Since then, researchers have focused on spreading awareness of the finding through education and community partnerships.
Outreach Efforts Aim to Close the Knowledge Gap
To share the research with medically underserved communities, Roswell Park collaborated with the Witness Project, a program that educates African American women about cancer prevention and screening through survivor-led storytelling.
The team also participated in a National Cancer Institute–funded pilot program using social media to reach expectant mothers with information about breastfeeding’s protective benefits.
Their outreach strategy included engaging not only new mothers but also older family members, encouraging them to support breastfeeding across generations.
“The message was simple: Protect yourself by breastfeeding your babies,” Ambrosone said. “If the risk of aggressive breast cancer increases by having children but goes away if you breastfeed, everybody needs to know that.”
Understanding ER-Positive vs. ER-Negative Breast Cancer
Breast cancers are often classified by whether they express estrogen receptors.
ER-positive cancers use estrogen to grow and typically progress more slowly. They can often be treated with hormone therapies designed to block estrogen’s effects.
ER-negative cancers, by contrast, do not rely on estrogen for growth. These tumors are generally more aggressive and less responsive to hormone therapy, often requiring treatments such as chemotherapy.
How Breastfeeding May Reduce Cancer Risk
Researchers believe breastfeeding helps the body reverse some of the biological changes that occur during pregnancy.
Inflammation in breast tissue during pregnancy can create an environment that supports cancer cell growth. Breastfeeding appears to help breast tissue return more quickly to its pre-pregnancy state, reducing that risk.
While the exact mechanisms are still being studied, the association between breastfeeding and reduced ER-negative breast cancer risk has remained consistent in follow-up research.
The Challenge Is Duration, Not Initiation
Experts say the key barrier is not whether Black women begin breastfeeding, but whether they are able to continue long enough to gain health benefits.
“Black women are initiating at rates comparable to other races,” said Cassandre Dauphin, PhD, Outreach and Engagement Manager at Roswell Park. “It’s sustaining breastfeeding that’s the challenge.”
The Centers for Disease Control and Prevention recommends exclusive breastfeeding for at least six months, a duration associated with stronger protective effects.
However, many women face obstacles after leaving the hospital, including limited workplace accommodations, lack of family support, social stigma, and broader systemic inequities such as unequal access to healthcare, employment, and housing.
Cultural and Historical Factors Also Play a Role
Researchers note that breastfeeding patterns among African American women are shaped by a complex historical context, including the legacy of slavery-era wet nursing, shifts in infant-feeding practices, and decades of formula marketing that reshaped cultural norms.
“This is a multilayered issue,” Dauphin said, adding that modern education campaigns are helping reframe breastfeeding as both a maternal and public health priority.
Roswell Park has incorporated breastfeeding education into its breast cancer outreach and patient navigation programs, emphasizing its benefits for both mothers and infants.
A Preventive Tool With Dual Benefits
Although scientists continue to investigate why breastfeeding offers this protection, the evidence suggests it may be one of the most actionable ways to counter an increased cancer risk associated with childbirth in Black women.
“The most important thing for African American women to know is that breastfeeding isn’t always easy, but there are many benefits for both mom and baby,” Dauphin said. “It is one of the best tools we have to actively reduce the risk of developing ER-negative breast cancer that increases from childbirth.”
Public health advocates hope that expanding awareness, workplace support, and culturally informed education will help more women sustain breastfeeding — and, in doing so, potentially reduce disparities in one of the deadliest forms of breast cancer.
