For African Americans, breastfeeding longer can reduce risk of aggressive breast cancer

Breast cancer is the second leading cause of cancer death among Black women, who are 36 to 41% more likely than White women to die of the disease — and more likely to develop ER-negative breast cancer, an aggressive subtype.

“Having children tends to lower the risk of developing ER-positive breast cancer, the type that’s more common in White women. But having children also increases the risk of ER-negative breast cancer, the more aggressive type more often diagnosed in Black women,“ explains Christine Ambrosone, PhD, Senior Vice President of Population Services at Roswell Park Comprehensive Cancer Center.

However, breastfeeding can lower the risk of developing ER-negative breast cancer in African American women, according to stunning findings of a novel Roswell Park study in 2014. Since then, Dr. Ambrosone and her team have worked to share this revolutionary information.

They collaborated with the Witness Project, an organization that educates medically underserved and African American women about the importance of cancer screening through stories told by survivors of breast and cervical cancer. At the same time, Ambrosone was part of a pilot study funded by the National Cancer Institute to use social media to inform expecting African American women of the findings.

Together, they reached out to women young and old so that so that older moms and grandmothers would encourage younger women to breastfeed. The message was simple: Protect yourself by breastfeeding your babies. 

“This is so important,” Dr. Ambrosone says. “If the risk of aggressive breast cancer increases a lot by having children but goes away if you breastfeed, everybody needs to know that.”

Breast cancer and the connection to estrogen

Distinct types of breast cancer are diagnosed according to how they express the estrogen receptor. Estrogen is a hormone and elevated levels of estrogen can “fuel” the growth of cancer cells that are hormone-receptor positive, such as breast, endometrial and ovarian cancers. Because receptor-positive (ER+) cancer cells use estrogen to grow, ER+ breast cancer often progresses slowly and is generally treatable with hormone therapies that block estrogen.

In contrast, estrogen receptor negative (ER-) cancer cells do not use estrogen to grow, are more aggressive and typically require other treatments like chemotherapy.

How breastfeeding helps reduce risk for cancer

Dr. Ambrosone’s research found that while Black women who have children are at increased risk for ER-negative breast cancer, that risk is greatly reduced if they breastfeed. Inflammation that occurs in breast tissue during pregnancy also can support cancer cell growth and breastfeeding helps breast tissue return to its pre-pregnancy state.

But until recently, Black women were considered less likely to breastfeed than other groups in the U.S. “That’s probably because of cultural issues. But things are changing. We started this research more than a decade ago and I think trends are changing in breastfeeding. Back with the introduction of formula, some women put their children on formula instead of breastfeeding, especially White women. Breastfeeding became something more educated, wealthy people didn’t do. You could bottle feed; you didn’t have to stay home with baby,” she says.

“I think now it’s changing because there’s more education. We have a lactation room right here in our building where women can go to pump their milk during the workday.”

Duration of breastfeeding is key to risk reduction

Cassandre Dauphin, PhD, Outreach and Engagement Manager at Roswell Park worked with Dr. Ambrosone on the 2014 Witness Project initiative. While African American women in general begin breastfeeding after giving birth, the challenge is sustaining breastfeeding long enough to reduce risk.

“Based on our previous research, we're doing navigation with patients from diagnosis through treatment, specifically for breast cancer, and we have included the importance of breastfeeding into our Breast Education curriculum," she says.  

Dauphin agrees that some of the difference between Black women and White women when it comes to breastfeeding is cultural and connects to systemic disparities that include unequal access to quality healthcare, employment and housing, among others. But she points out that the issue is not entirely whether Black women are resistant to breastfeeding, but rather the challenge of sustaining of breastfeeding. 

Recommendations set by the Centers for Disease Control are that mothers breastfeed for at least six months exclusively.

Recognizing challenges to sustaining breastfeeding

“Black women are initiating at rates comparable to other races. It’s sustaining breastfeeding that’s the challenge. For the most part, most women are initiating breastfeeding. The challenges come into play when they leave the hospital and must continue breastfeeding,” Dauphin says.

“Sometimes women go home to a family that isn’t as conducive to continuing breastfeeding. Sometimes they are in environments where their partner may not be pro-breastfeeding, or their families may not be pro-breastfeeding. There’s also sometimes stigma around breastfeeding.”

She recognizes that there is a different historical perspective of breastfeeding that comes into play when you talk about breastfeeding, especially for African American women. 

“Given the historical context of slavery and wet nursing and then the shift to how formula was introduced and promoted into society and viewed at one point as a wealthy woman’s thing to do; and then the shift now to recentering breastfeeding after the promotion of formula. This is a multilayered issue,” Dauphin concedes.

What Roswell Park learned from Ambrosone’s research is that ER-negative breast cancer is more aggressive and impacts African American women at a higher rate. Childbirth increases that risk, but breastfeeding brings that risk down.

“We don’t necessarily know why yet, and that’s why we’re continuing this research.  But we have understood that there is a relationship and it’s impacting African American women a little differently,” says Dauphin.

“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. It is one of the best tools we have to actively reduce the risk of developing ER-negative breast cancer that increases from childbirth.”