Some choices – such as whether you exercise, smoke, or drink – can affect your health. But there aren’t many known risk factors for triple-negative breast cancer (TNBC) you can control. 

This aggressive cancer type often arises in people who are younger than the average person with breast cancer. Black and Latina women also get TNBC more often than other groups. The reasons why aren’t entirely clear, and they’re surely complicated. But emerging evidence suggests some answers may be found in a long history of racially discriminatory practices and policies – and the many ways they continue to shape our communities.

“We believe all these separate risks work together to increase incidence [of TNBC in some groups compared to others],” says Scott Siegel, PhD, a psychologist and director of population health at ChristianaCare. “They may add up or maybe multiply together in terms of impact on [TNBC] risk.”

How Do Bias and Structural Racism Affect Triple-Negative Breast Cancer Rates?

Siegel recently published a study on racial disparities in TNBC. He got interested in this aggressive form of breast cancer based on earlier findings that white and Black people get breast cancer at a similar rate. But Black people are 40% more likely to die from it. 

About half the reason for that, he says, is that the rate of TNBC is higher in Black women. About 10%-15% of all breast cancers are TNBC. TNBC more often spreads before a doctor finds it. It’s also harder to beat. The 5-year survival rate for TNBC that’s spread is 12%. That’s compared to 29% for other forms of metastatic breast cancer. (The survival rate is the percentage of people with the same type and stage of cancer still alive a certain amount of time – usually 5 years – after diagnosis.)

To understand racial disparities in incidence and outcomes, “the traditional approach looks at individual risk factors,” Siegel says. “But the research in general is showing that where people live has a lot to do with their health. Everything from neighborhood income to access to healthy food to air quality.”

He wanted to know what puts some people at more risk for TNBC than others. Racially segregated neighborhoods mean that differences between neighborhoods add to racial disparities. Structural racism – or all the ways in which discrimination is enforced in housing, education, employment, income, health care, and more – shapes those distinctions.

“You see vast differences in neighborhoods,” Siegel says. “Neighborhoods are exposed to lots of different risks. It’s difficult to look at one exposure at a time. We’re trying to take a wholistic view.”

Linking Structural Racism to Breast Cancer Outcomes

Siegel focused on more than 3,300 women with breast cancer in a particular county in Delaware from 2012 to 2020. It’s an area that’s known for having more TNBC cases than other places. While other studies had looked at economic differences, Siegel was more interested in segregation.

He says the data showed that predominantly Black neighborhoods had more risk for TNBC than predominantly white neighborhoods. And the differences couldn’t be explained by race. Even when they accounted for the differences in race, they still saw an effect of neighborhoods.

The findings suggest that the environment in predominantly Black neighborhoods differs in ways that add up to greater TNBC risk. They imply that historical policies and practices that led to communities that are segregated by race have led to lasting health disparities. 

These may stem from a range of factors, including easier access to health care in some neighborhoods and easier access to fast food and liquor stores in others. Siegel did find more stores selling alcohol and unhealthy foods in predominantly Black neighborhoods with more TNBC cases. They also had more obesity and alcohol use disorders.

While segregation is no longer the law, Siegel says, “a whole bunch of other processes more or less have maintained communities the way they are. Segregated minority communities haven’t had access to investment over years. They have less access to resources that promote health, like grocery stores and stable housing, but more exposure to air pollution and liquor stores. We believe the most upstream factor is structural racism.”

Lasting Effects of History and Racial Disparities in TNBC 

In another study, Jesse Plascak, PhD, an epidemiologist at Ohio State University, studied the effects of discriminatory mortgage lending practices, or redlining, from the 1930s and how it’s related to breast cancer outcomes by race today. The idea was that these lending practices, which have been illegal for decades, might still affect communities in ways that produce health disparities.

“The idea is not that these individuals diagnosed with breast cancer were directly affected by these practices,” he says. “Most of them weren’t born yet. But these are places that have had differential investment of resources and other characteristics that may be present today as a result of these structural racist practices in the 1930s and ’40s.”

The study included nearly 15,000 women with breast cancer, including thousands identifying as Latina, non-Latina Black, and non-Latina white. They found that women living in areas that hadn’t been redlined or discriminated against in the past had better breast cancer outcomes. But that only was true when the women identified as white. Among other differences, women with breast cancer who lived in areas without redlining in the past less often had TNBC.

“These effects can be lasting,” Plascak says. “They shape places; they shape people. People may move or stay, but they shape the places themselves in terms of resources being invested or not invested.”

What Does This Mean for Me?

Plascak says he wants to learn more about how these practices lead to differences in cancer types and outcomes more specifically. “There’s not much we can do about something that happened 100 years ago,” he says. “But if we can figure out it’s causing something today that we can modify, then we should focus on that.”

Siegel also is interested in exploring how to “translate the findings into action” with the goal to shrink disparities. To start, he aims to share the findings with policymakers and the public. 

“There are absolutely steps we can take right now to make neighborhoods healthier,” he says. “We do not have to accept these disparities. That’s the most important thing. When you can point to structural factors, we now have intervention targets, and we can address those.”