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ACT FOR CHANGE

IBCERCC Report

Secretary Sebelius, we need a national breast cancer prevention plan

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Tracking Our Environmental Health

We're championing legislation to create a national system that tracks environmental pollution and diseases like breast cancer.

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STRONG VOICES

Janet Gray, Ph.D.
Janet Gray, Ph.D.

As author of our 2008 and 2010 State of the Evidence reports, Dr. Gray drives the science behind all our work.

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Race, Ethnicity and Class

Breast cancer rates vary among different ethnic and socioeconomic groups. While more research is needed to understand these variations, it is clear that poverty is linked to greater chemical exposure and thus greater risk.

Varying rates of breast cancer can be observed among different groups of women, although much more research is needed to more fully understand the factors at play. Most data report incidence and mortality rates based upon five broad ethnic/racial groupings, but these groupings often collapse vastly diverse geographic, cultural and socioeconomic groups into a single category. When these groups are examined separately, incidence may vary within the large group. For instance, U.S.-born Filipina women in California have higher rates of breast cancer than non-Hispanic whites, while U.S.-born Japanese women have low rates than non-Hispanic whites, although both non-white groups are categorized as “Asian/Pacific Islander” in most studies (Gomez et al., 2010). Furthermore, current evidence suggests that socioeconomic status may play a more significant role in breast cancer risk than race or ethnicity.

Risk of breast cancer varies among different ethnic and socioeconomic groups. However, because racial categories are historical, social and political rather than biological, scholars are questioning the assumption that well-documented disparities associated with race and ethnicity in various disease outcomes, including cancer, are determined by racial and ethnic identity (Kreiger, 2005, Roberts, 2012). It is therefore essential to consider factors such as geographic location (home, work, school, recreation), environmental safety and exposures, social and socioeconomic status, personal and community stress and security, and lifestyle factors including diet, exercise, and alcohol and pharmaceutical use. 

We know that the levels of chemicals related to breast cancer in people’s bodies can vary by race, ethnicity and socioeconomic status. As a group, African Americans have higher levels than whites or Mexican Americans of many chemicals, including PCBs, mercury, lead, PAHs, dioxins and phthalates (CDC, 2009; CDC, 2012). Mexican Americans as a group have higher levels of the pesticides DDT/DDE and 2,3,5,TCP (Smigal, 2006). People with lower socioeconomic status have higher levels of BPA (Nelson, 2012), while triclosan levels (used in antibacterial soaps and other consumer products) are higher among those with higher socioeconomic status.

Data from the broad groups indicate that white women have the highest overall breast cancer rates, and the majority of women diagnosed with breast cancer are over 45. Yet a greater proportion of African American women are diagnosed with breast cancer before age 45 (Smigal, 2006), and African American women are more likely to die from the disease than women from any other group.

One constituent of the higher mortality rates among African American women is the fact that they are more likely to develop an aggressive “triple-negative” type of breast cancer (Bowen, 2006; Jones, 2004), which is more difficult to treat. While Latinas have lower rates of breast cancer than both white and African American women, they, too, are more likely to have aggressive “triple-negative” tumors (Bauer, 2007). The risk factors for cancer may also vary by racial and ethnic group. For example, for young black women, giving birth at a young age and having four or more children before age 45 increases the risk of breast cancer. In contrast, for white women early childbearing reduces the risk of breast cancer (Palmer, 2003).

Socioeconomic status also plays a role in determining a group’s exposures to chemicals associated with increased breast cancer risk. A study found that African Americans, people with less formal education, and people with lower socioeconomic status were more likely to live within a mile of a polluting facility identified by the EPA (Mohai, 2009). This study reaffirms findings from a number of other studies conducted in the past 20 years (Brulle, 2006). Another recent study found that pregnant African American, Latina and Asian/Pacific Islander women were more likely to live in counties with higher air pollution (Woodruff, 2003).

Given the complex interrelationships between race and ethnicity and social, community, economic and environmental factors, teasing apart factors involved in disease development can be complicated. If racial and ethnic minorities often are exposed to disproportionately high levels and varieties of environmental pollutants in the U.S. (Brulle, 2006), the same is true of people in poverty (Rauh, 2008). Additionally, the way individuals are affected by chemicals is influenced by factors associated both directly and indirectly with race/ethnicity. Many studies have reported that at all ages black non-Hispanic women were diagnosed at later stages than were white non-Hispanic women, and Hispanic women fell in between. Yet when the analyses focused on poverty level, rather than on age or race/ethnicity, a very different picture emerged: Regardless of age or race/ethnicity (no interaction effects), poorer women were diagnosed with more advanced stages of the disease (Campbell, 2009). Certainly, many factors are involved in the link between stage of disease at diagnosis and poverty level, just as in the link between racial/ethnic categories and disease stage. Yet the sorts of assumptions made, questions asked and variables pursued might well be very different.