Breast cancer survivors face an elevated risk of cardiovascular disease. This study analyzes how this elevated risk is distributed geographically and economically.
Cardiovascular disease is currently the leading cause of death among women in the United States. Among older breast cancer survivors, it exceeds breast cancer as a cause of death, and breast cancer survivors have an increased risk of cardiovascular disease in general. This can partly be explained as resulting from cardiotoxic cancer treatments, including endocrine therapy, chemotherapy, and radiotherapy.
Among breast cancer survivors, cardiovascular disease outcomes appear to affect non-White women disproportionately. However, the reason for this disparity is unclear and may have more to do with environmental exposure as well as socioeconomic status and distance from care centers. This study, published in JNCI Cancer Spectrum, provides an analysis of cardiovascular disease disparities among breast cancer survivors based on geographic factors such as rurality and county-level socioeconomic status.
Finding Relationships Between Socioeconomic Status and Cardiovascular Disease
Data for this study were gathered from 724,518 women diagnosed with localized or
regional-stage breast cancer between 2000 and 2017. Relative risks of cardiovascular disease were calculated based on Poisson regression and accounted for both race- and age-specific rates of disease in the general population according to socioeconomic status, median income, and rurality at the time of diagnosis. In order to get a better comparison of long-term outcomes for this population, a 10-year cumulative mortality risk of cardiovascular disease, which accounted for competing risks, was also calculated.
Among breast cancer survivors in the lowest category of socioeconomic status in the poorest counties, cardiovascular disease mortality was 41% higher than in those with the highest socioeconomic status in the wealthiest counties. It was also 24% higher for most rural areas relative to most urban counties. Disparities were greatest for women in the first 5 years of breast cancer diagnosis and were widest for women older than 60 years. Disparities due to rurality and socioeconomic status were found in every age group.
More Rurality Results in More Mortality
This study is notable in that it found a monotonic increase in the risk of cardiovascular disease mortality with each progressively increasing level of rurality across five rural–urban categories. This may be due to the fact that these patients, especially those with fewer economic resources, may have less screening and monitoring than their wealthier, more urban counterparts. The authors note that these findings show a need for individual factor-level analysis of various public health interventions that could help decrease these disparities, as it is unclear which specific aspect of rurality contributes to increased mortality.
Ho, K. L., Shiels, M. S., Ramin, C., Veiga, L. H. S., Chen, Y., De Gonzalez, A. B., & Vo, J. B. (2022). County-level geographic disparities in cardiovascular disease mortality among US breast cancer survivors, 2000-2018. JNCI Cancer Spectrum, 7(1). https://doi.org/10.1093/jncics/pkac083