Heart Failure Among Younger Versus Older Breast Cancer Survivors: A Longitudinal Cohort Analysis

Abstract

Background Breast cancer is the leading cancer-related cause of death for women worldwide (American Cancer Society, Cancer Facts & Figures, 2020). In the United States, about 1 in 8 women (approximately 18%) will develop invasive breast cancer over the course of her lifetime (American Cancer Society, Cancer Facts & Figures, 2020). Recent studies have shown that patients treated for breast cancer are more than three times more likely to develop congestive heart failure when compared to patients without cancer (Mayo Clinic & Klein, 2018). In this cohort analysis, we assessed the risk of heart failure stratified by age. When stratified by age, we predict that the risk of heart failure for breast cancer survivors will be higher among older versus younger patients.Methods A population-based, retrospective cohort study of 22,299 female breast cancer survivors were selected. SAS version 9.4 was used for survival analysis on breast cancer survivors with heart failure as the outcome, then stratified by two age groups (18-64, 65+). Kaplan Meier curves were analyzed as well as the Cox Proportional Hazards model. ArcMap version 10.1 was used to geocode a further subsection of this cohort, 7,193 breast cancer survivors living in Chicago with a match rate of 68%. Geographic Information Systems (GIS) maps were created to display the spatial distribution of breast cancer survivors per community area, breast cancer cases stratified by age, heart failure cases per community areas, heart failure cases stratified by age, a hotspot analysis of breast cancer cases stratified by age, and a hotspot analysis of heart failure cases stratified by age.Results The age group of 65+ breast cancer survivors had a 1.291 times higher risk of heart failure in comparison to younger breast cancers survivors (18-64). Metastasized cancer, hypertension medication at baseline, hypertension medication most recent, diabetes medication most recent, diabetes medication at baseline, smoking status, race, ethnicity, hypertension, myocardial infarction, diabetes mellitus, coronary artery disease, atrial fibrillation, SBP baseline, and BMI baseline were adjusted for in this analysis. In ArcMap, geocoded patient data showed breast cancer survivors and heart failure cases clustered in the North side of Chicago (Lincoln Park, Lakeview, Edgewater) as well as downtown Chicago (Near North Side). The highest rates of heart failure among breast cancer survivors were between 19-33% in Fuller Park, Roseland, and South Lawndale communities. Hot spot analysis showed the highest rate of heart failure among breast cancer survivors.Discussion Age was found to increase the risk of heart failure in older versus younger breast cancer survivors. Sample size limited this analysis of the influence of only two age categories on heart failure in breast cancer survivors. This study was limited to cancer patients within the Northwestern Medicine network, which biases the population to a higher concentration of cases nearer to Northwestern Medicine. To combat this, future studies could partner with other hospital networks like the Advocate Health Care system with more locations on the South and West sides of Chicago.

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