There are three major observations from this study on NHB and NHW breast cancer mortality in the ten US cities with greater than 500,000 people and largest NHB populations. First, in the United States as a whole and in most of the cities included in this study, breast cancer mortality has declined for both NHB and NHW, although the NHW breast cancer mortality reduction has been steeper than that for NHB. Nationally, this difference has resulted in a growing NHB/NHW disparity with a greater NHB to NHW disparity in the period 2006–2013 compared to the years 1999–2005. Advances in breast cancer screening and treatment are having an impact across both races in most cities, but because NHB breast cancer mortality rate reductions have lagged in many cities, and in a few cities have actually risen, the health inequity has grown, nationally.
The second observation from these data is the presence of tremendous geographic variation in NHW and NHB breast cancer mortality and disparity. The reasons for the geographic variation are unclear though they are likely driven by structural issues rather than biological variation such as access to health care, including state variation in Medicaid coverage even prior to the Affordable Care Act, variation in healthcare quality, health insurance rates, structural racism, and dysfunction of the health care safety-net. A recent study on fifty US cities looking at Black/White breast cancer mortality disparities from 2005 to 2014 notes this variability .
In our study, the NHW breast cancer mortality rates declined for the periods 1999–2005 and 2006–2013, in every city except Detroit, where NHW breast cancer mortality rose between the two time periods. Between these two time periods, NHB breast cancer mortality declined in three cities, (New York, Philadelphia, and Chicago) and was flat or rose in the other seven major cities. These geographic variations in disparity are driven by both racial groups’ mortality rates and the relative change between them. The NHW breast cancer mortality rates across the ten cities vary by about 10 deaths per 100,000 from the lowest NHW mortality city in the period 2006–2013 (Memphis) to the highest NHW mortality city (Baltimore). The NHB breast cancer mortality rates vary by 15 deaths per 100,000 from the lowest NHB mortality city (New York City) to the highest NHB mortality city (Houston).
The third observation is that the NHB/NHW breast cancer mortality disparity in Chicago has dropped in contrast to the national trend. In the period 1999–2005, Chicago had among the highest NHB to NHW breast cancer disparity in the nation. This disparity was the result of a very high breast cancer mortality rate for NHB women, compared with a declining rate for NHW women. From 1999 to 2005, the NHB breast cancer mortality rate in Chicago was the third highest among the ten cities. In contrast, from 2006 to 2013, the NHB/NHW breast cancer disparity decreased by almost 20%, largely because of an almost 14% drop in NHB breast cancer mortality. This decline in NHB breast cancer deaths is the largest observed in the ten cities comparing the two time periods. Chicago is also the only city of the ten cities where the NHB breast cancer mortality rate dropped faster (13.9%) than the NHW (7.7%) breast cancer mortality rate. Chicago’s mortality rate decrease for NHW (7.7%) is lower than the NHW decrease in most other cities, thus also contributing to a lowering of the overall disparity in mortality outcomes in Chicago. In contrast to breast cancer disparities, analysis of NHB to NHW colorectal cancer mortality disparity showed no improvement comparing the same time periods.
Elimination of health disparities remains a major public health goal in the United States . Yet, mortality disparity for breast cancer is increasing rather than decreasing . However, Chicago’s sharp reduction in the NHB breast cancer mortality rate and NHB/NHW breast cancer mortality disparity stands in contrast with the national trend.
Observational time-trend mortality analyses do not lend themselves to causal explanations. However, one reason for the observed sharp reduction in NHB breast cancer mortality rate in Chicago could be the public health attention that racial disparity in breast cancer mortality has received in Chicago. In 2007, researchers and health activists made reducing the racial gap in breast cancer mortality a public health priority in Chicago. The Metropolitan Breast Cancer Taskforce was established as a not for profit dedicated exclusively to eliminating this disparity. Chicago-based research over this time period documented a wide array of structural and quality inequities, including poorer mammography quality, missed breast cancer for minority and lower-income women leading to later stage diagnosis [14–16], absence of American College of Radiology Breast Imaging Centers of Excellence and Academic/Comprehensive Commission on Cancer Accredited Cancer programs in minority neighborhoods where breast cancer mortality rates are highest , and breakdowns in the breast cancer diagnostic and referral process [17, 18]. The gaps led MCBCTF and others to create specific initiatives to address differential access to high quality care. A critical initiative was the creation of a metro-wide Breast Cancer Quality Consortium to engage the institutions to share quality data on breast cancer screening and treatment. Gaps in care were identified, quality improvements interventions were implemented, and improvements were made [11, 19–21].
The issue of racial disparity in breast cancer mortality was discussed widely in news outlets and community meetings [22, 23]. The Chicago Department of Public Health made the reduction of racial disparity in breast cancer mortality a cornerstone of their Healthy Chicago plan . Public policy changes through passage of breast cancer disparities reduction legislation were passed (Public Law 95-1045 and Public Law 97–0638). In addition to these efforts, MCBCTF and others implemented very specific outreach, education, and patient navigation initiatives to address identified deficits and overcome the fragmented Chicago healthcare system in particular for minority women who are more likely to enter the system through a more limited service facility rather than at a comprehensive breast center [9, 25].
Even with the notable drop in NHB breast cancer mortality and disparity in Chicago, the NHB to NHW breast cancer mortality gaps remain unacceptably large in this city and in most of the other nine cities. But public health and quality improvement approaches that focus on structural inequities in health delivery like that of the Metropolitan Chicago Breast Cancer Taskforce may be a replicable model to address breast cancer disparities in other US cities.