A new report from The American Cancer Society shows that in every US state, breast cancer incidence rates are higher in non-Hispanic white (NHW) women than in non-Hispanic black (NHB) women. Rates of death from the disease, however, are higher in NHB women than in NHW women in every state, indicating that social and structural factors, along with biologic factors, may contribute to discrepancies in outcomes.
Using the National Cancer Institute’s (NCI) Surveillance, Epidemiology, and End Results (SEER) program and the Centers for Disease Control and Prevention’s National Program of Cancer Registries, the researchers predicted that there will be approximately 252,710 new cases of breast cancer and 40,610 breast cancer deaths in 2017. According to the research, overall breast cancer incidence from 2005-2014 increased among Asian/Pacific Islander (API) (1.7% per year), non-Hispanic black (0.4% per year), and Hispanic (0.3% per year) women. Non-Hispanic white and American Indian/Alaska native women saw breast cancer incidence rates remain stable.
The authors note that racial and ethnic difference in breast cancer subtypes may reflect variation in the prevalence of risk factors for the disease. Hormone receptor (HR)-positive/HER2-negative breast cancer is the most common subtype in each racial/ethnic group, with incidence rates ranging from 53 cases per 100,000 in Hispanics to 82 cases per 100,000 in NHW. The authors note that lower overall rates of breast cancer in AI/AN, Hispanic, and API women are a result of lower rates of the HR-positive/HER2-negative subtype. However, incidence of triple-negative breast cancer, which is typically of the basal subtype, is twice as high in NHB women (24 per 100000) as in NHW women (12 per 100000).
From 1989 to 2015, breast cancer mortality rates decreased by 39% (322,600 deaths averted) in the United States. From 2006 to 2015, all racial/ethnic groups experienced decreased breast cancer death rates. When looking closer at the data, though, it is evident that not all women benefited equally from this decline. In 2015, breast cancer death rates were 39% higher in black women than in white women. Excess death rates in black women ranged from 20% in Nevada to 66% in Louisiana. From 2011 through 2015, breast cancer mortality rates were 42% higher among NHB women (29.5 per 100,000) than NHW women (20.8 per 100000). However, breast cancer incidence rates were slightly lower among NHB women (125.5 per 100000) than among NHW women (128.5 per 100000).
The mortality gap between white and black patients with breast cancer, which, according to the authors, emerged in the early 1980s and continued to widen, may have stabilized. The authors attribute this stabilization to improvements in treatment and earlier detection by mammography. However, the authors suggest that improving access to care for all populations could help to eliminate the racial disparity in breast cancer mortality rates.