Breast cancer remains the most commonly diagnosed cancer in women in the U.S., and is second only to lung cancer in cancer-related deaths. In its most recent report on the status of breast cancer in the U.S., the American Cancer Society cited a 39 percent decline in breast cancer deaths since a peak in 1989. The decline in deaths is attributed to early detection, systemic treatments and targeted therapies for many breast cancers; Estrogen receptor-positive and HER2-postive breast cancer make up the majority of cases and both have effective targeted therapies.
While the decline in breast cancer deaths is seen in all races and ethnicities, the ACS report also points out that not all women benefit equally. In particular, black women are 42 percent more likely to die from their breast cancer than white woman, despite similar incidence rates between the two groups.
Breaking down disparities
Part of this disparity can be explained by tumor biology. Black women are more likely to be diagnosed before the age of 40 and with more advanced and aggressive tumors. Based on breast cancer incidence rates by subtype between 2010 and 2014, black women have twice the rate of triple negative, or basal-like breast cancers than any other racial group in the U.S.
However, tumor biology does not fully explain the disparity that exists in breast cancer-related deaths in black and white women. The incidence of obesity, diabetes and heart disease is greater in black women than white women and have a negative impact on breast cancer outcomes. Other factors including to access to care, quality of care and response to treatment also play a role.
Access to care
The ACS Facts and Figures reported an increased risk of dying from breast cancer among black women compared to white women in all 50 U.S. states, with the highest rates (more than double compared to white women) in Louisiana, Mississippi, Wisconsin, New Mexico, Missouri, Tennessee and the District of Columbia.
These results confirm previous findings from an analysis conducted by BCRF Chief Mission Officer, Dr. Marc Hulbert. The report, published last year in the journal, Cancer Epidemiology, analyzed breast cancer mortality rates by race for the 50 most populous U.S. cities between 2010 and 2014, building on prior city-level analysis from 1990-2009. Findings, reported in a previous BCRF blog, indicated an increase in the disparity in breast cancer mortality between black and white women from 17 percent in 2009 to 35 percent in 2014, with 24 cities showing a significant difference in mortality between the groups.
Results serve as call to action
With disparities in breast cancer outcomes between black and white women well established, these reports highlight an urgency in addressing the multifactorial causes underlying this gap to ensure that all women benefit from the advances being made in screening, prevention and treatment. They serve as a call to action to policymakers to remove barriers to access to care and screening in cities and states where these resources are unequally distributed in black and white communities. For scientists, the results indicate the need to identify the biology underlying the incidence of more aggressive tumors in black women. These efforts will require increasing enrollment of minority women in clinical trials to better understand differences in response to treatment and identify race-specific biomarkers that may inform personalized treatment options.
BCRF’s commitment to eradicating disparities
BCRF is addressing this growing need in disparities research by investing nearly $3 million this year to tackle the challenges in understanding the unique biology of breast cancer across racial and ethnic backgrounds. Examples of studies focused on breast cancer in African American women include work by Drs. Funmi Olopade and Dezheng Huo examining tumors from African American, indigenous African women and white women to understand the genetic factors that contribute to aggressive breast cancers in black women. Similarly, Dr. Nikhil Wagle is conducting genetic analyses of tumors from African American women with metastatic breast cancer to understand the biological underpinning of disparities in breast cancer outcomes in this population.
For more on breast cancer disparities, please see these stories.