According to the World Health Organization, breast cancer is the most common malignancy worldwide and is a leading cause of cancer deaths. Racial disparities in breast cancer survival persist despite emphasis on early detection and availability of effective treatments. Reasons for this vary, but some possible factors include socioeconomic status, geographic residency, insurance coverage, and access to screening and care. In the United States, Black patients with breast cancer are 39% more likely to die of the disease than White patients, and this disparity is even higher in the state of Georgia, where it is estimated at 45%.
Dr Justin M. Luningham and colleagues analyzed patient records from 3 large Georgia health systems to measure the association of neighborhood deprivation with breast cancer mortality for 19,580 Black and White women. They analyzed associations among Area Deprivation Index (ADI), race, and mortality to elucidate factors contributing to disparities and inform community-level approaches to mitigate those disparities. The ADI is a percentile rank of socioeconomic disadvantage calculated from such indicators as income level, income disparity, educational attainment, employment, home values, and quality of life. Higher percentiles indicate areas with greater deprivation.
The results showed notable differences in mortality between racial groups, with deaths reported in 23.8% of Black women vs 15.9% of White women. The ADI was significantly associated with increased mortality among White women, but not among Black women. For White women, as ADI quartiles increased (ie, deprivation worsened), the rate of mortality also increased; however, for Black women, there were no significant changes in risk of mortality between ADI groups. The one exception to this was in the groups with highest deprivation, where there was no difference in mortality between Black and White women. On the basis of these findings, the authors suggested that ADI alone is insufficient to explain the observed racial disparities in breast cancer survival. Additional factors, such as built environment factors, residential segregation and lending bias, food landscape, unhealthy amenities, and access to health care, may not be fully captured by the ADI but may also be associated with increased breast cancer mortality.
Across Georgia, areas with high ADI had greater Black patient density and lower survival probability. Black women were more likely to be diagnosed with more advanced disease, while a higher proportion of White women were diagnosed with a grade 1 tumor (20.8% vs 12.5% for Black women). Lastly, the mean age at presentation was 3 years younger in Black patients across breast cancer subtypes. These findings suggest that ADI alone does not fully explain racial disparities in breast cancer survival. Therefore, further investigation is warranted to inform community-level approaches that may mitigate these disparities.
This study demonstrated that ADI was associated with breast cancer mortality among White patients but not among Black patients. The authors suggested that current screening guidelines be adapted to recommend that Black women be screened at a younger age, since mean age at diagnosis was younger among Black patients in this study. The authors hypothesized that disparities in breast cancer survival outcomes may also be impacted by chronic stress and allostatic load, triggering epigenetic modifications that persist even when the stressor is removed and across generations. Further research is needed on possible epigenetic changes brought about by past and present neighborhood deprivation, as well as to increase understanding of other factors that contribute to racial disparities in breast cancer survival, especially among those living in the least deprived areas. Determining the interplay among race, socioeconomic status, area-level deprivation, and breast cancer survival may help identify intervention strategies to one day narrow the disparity gap.
Given the findings that breast cancer survival among Black women may be associated with factors other than living in economically deprived neighborhoods, clinicians should consider other environmental factors when developing community-level approaches aimed at reducing these health disparities. The authors suggested that limited and delayed access to cancer screening and treatment in areas of greater deprivation may be another source of racial disparities in breast cancer mortality. They also suggested that implicit bias may be a factor contributing to late diagnoses and disparities in treatment for members of minority groups in the US and should be addressed.