Mapping Cumulative Risk in Delaware: Approach and Implications for Health Equity.

BACKGROUND: Addressing health equity requires attention to upstream determinants of health, including environmental and social factors that act in tandem to increase communities' exposure to and vulnerability to toxicants. Cumulative risk assessment, which evaluates combined risks from environmental and social factors, is a useful approach for estimating potential drivers of health disparities. We developed a cumulative risk score of multiple indices of environmental and social conditions and assessed block group-level differences in New Castle County, Delaware. METHODS: This cross-sectional study used choropleth maps to visualize the distribution of environmental, social, and cumulative risks and Moran's I statistics to assess spatial clustering of cumulative risk across the county and among individual block groups. RESULTS: Findings indicate that environmental risk rarely occurs without social risk and that environmental and social risks co-occur in distinct areas, resulting in large-scale clustering of cumulative risk. Areas of higher cumulative risk had more Black residents and people of lower socioeconomic status. CONCLUSIONS: Replicable measures of cumulative risk can show how environmental and social risks are inequitably distributed by race and socioeconomic status, as seen here in New Castle County. Such measures can support upstream approaches to reduce health disparities resulting from histories of environmental racism.

Neighborhood factors and triple negative breast cancer: The role of cumulative exposure to area-level risk factors.

BACKGROUND: Despite similar incidence rates among Black and White women, breast cancer mortality rates are 40% higher among Black women. More than half of the racial difference in breast cancer mortality can be attributed to triple negative breast cancer (TNBC), an aggressive subtype of invasive breast cancer that disproportionately affects Black women. Recent research has implicated neighborhood conditions in the etiology of TNBC. This study investigated the relationship between cumulative neighborhood-level exposures and TNBC risk. METHODS: This single-institution retrospective study was conducted on a cohort of 3316 breast cancer cases from New Castle County, Delaware (from 2012 to 2020), an area of the country with elevated TNBC rates. Cases were stratified into TNBC and "Non-TNBC" diagnosis and geocoded by residential address. Neighborhood exposures included census tract-level measures of unhealthy alcohol use, metabolic dysfunction, breastfeeding, and environmental hazards. An overall cumulative risk score was calculated based on tract-level exposures. RESULTS: Univariate analyses showed each tract-level exposure was associated with greater TNBC odds. In multivariate analyses that controlled for patient-level race and age, tract-level exposures were not associated with TNBC odds. However, in a second multivariate model that included patient-level variables and considered tract-level risk factors as a cumulative exposure risk score, each one unit increase in cumulative exposure was significantly associated with a 10% increase in TNBC odds. Higher cumulative exposure risk scores were found in census tracts with relatively high proportions of Black residents. CONCLUSIONS: Cumulative exposure to neighborhood-level risk factors that disproportionately affect Black communities was associated with greater TNBC risk.

Policy Recommendations for Reducing Tobacco Exposure for Youth and Adults in Wilmington, Delaware.

Objective: To highlight and recommend policies that can be projected to reduce disproportionate tobacco exposure for youth and adults in Wilmington, Delaware's densest and most disadvantaged neighborhoods. Four policy options were drawn from the literature: pharmacy tobacco bans, zoning-based tobacco retailer reductions, residential density caps, and buffers around K-12 schools. Method: Changes in tobacco retailer density and resident-to-retailer distance in Wilmington's medium- and high- density residentially zoned neighborhoods were projected using GIS analysis of current conditions and projections for each of the four policies. Results: Banning tobacco sales in pharmacies was found to be least effective, while 500-meter buffers around K-12 schools was projected to have the greatest impact on both retailer density and resident-to-retailer distance. Policy Implications: As a result of these findings, the authors recommend a ban of tobacco sales with a 500-meter radius of all K-12 schools in the City of Wilmington.

Aggregated spatial intensity as a method for estimating point-level exposures within area-level units: The case of tobacco retailer exposure in census tracts.

BACKGROUND: Aggregating point-level events to area-level units can produce misleading interpretations when displayed via choropleth maps. We developed the aggregated intensity method to share point-level location information across unit boundaries prior to aggregation. This method was applied to tobacco retailers among census tracts in New Castle County, DE. METHODS: Aggregated intensity uses kernel density estimation to generate spatially continuous expected counts of events per unit area, then aggregates these results to area-level units. We calculated a relative difference measure to compare aggregated intensity to observed counts. RESULTS: Aggregated intensity produces estimates of event exposure unconstrained by boundaries. The relative difference between aggregated intensity and counts is greater for units with many events proximal to their borders. The appropriateness of aggregated intensity depends on events' spatial influence and proximity to unit boundaries, as well as computational inputs. CONCLUSIONS: Aggregated intensity may facilitate more spatially realistic estimates of exposure to point-level events.

Racial disparities in triple negative breast cancer: toward a causal architecture approach.

BACKGROUND: Triple negative breast cancer (TNBC) is an aggressive subtype of invasive breast cancer that disproportionately affects Black women and contributes to racial disparities in breast cancer mortality. Prior research has suggested that neighborhood effects may contribute to this disparity beyond individual risk factors. METHODS: The sample included a cohort of 3316 breast cancer cases diagnosed between 2012 and 2020 in New Castle County, Delaware, a geographic region of the US with elevated rates of TNBC. Multilevel methods and geospatial mapping evaluated whether the race, income, and race/income versions of the neighborhood Index of Concentration at the Extremes (ICE) metric could efficiently identify census tracts (CT) with higher odds of TNBC relative to other forms of invasive breast cancer. Odds ratios (OR) and 95% confidence intervals (CI) were reported; p-values < 0.05 were significant. Additional analyses examined area-level differences in exposure to metabolic risk factors, including unhealthy alcohol use and obesity. RESULTS: The ICE-Race, -Income-, and Race/Income metrics were each associated with greater census tract odds of TNBC on a bivariate basis. However, only ICE-Race was significantly associated with higher odds of TNBC after adjustment for patient-level age and race (most disadvantaged CT: OR = 2.09; 95% CI 1.40-3.13), providing support for neighborhood effects. Higher counts of alcohol and fast-food retailers, and correspondingly higher rates of unhealthy alcohol use and obesity, were observed in CTs that were classified into the most disadvantaged ICE-Race quintile and had the highest odds of TNBC. CONCLUSION: The use of ICE can facilitate the monitoring of cancer inequities and advance the study of racial disparities in breast cancer.

A Population Health Assessment in a Community Cancer Center Catchment Area: Triple-Negative Breast Cancer, Alcohol Use, and Obesity in New Castle County, Delaware.

BACKGROUND: The NCI requires designated cancer centers to conduct catchment area assessments to guide cancer control and prevention efforts designed to reduce the local cancer burden. We extended and adapted this approach to a community cancer center catchment area with elevated rates of triple-negative breast cancer (TNBC). METHODS: Cancer registry data for 462 TNBC and 2,987 "Not-TNBC" cases diagnosed between 2012 and 2020 at the Helen F. Graham Cancer Center & Research Institute (HFGCCRI), located in New Castle County, Delaware, were geocoded to detect areas of elevated risk (hot spots) and decreased risk (cold spots). Next, electronic health record (EHR) data on obesity and alcohol use disorder (AUD) and catchment area measures of fast-food and alcohol retailers were used to assess for spatial relationships between TNBC hot spots and potentially modifiable risk factors. RESULTS: Two hot and two cold spots were identified for TNBC within the catchment area. The hot spots accounted for 11% of the catchment area but nearly a third of all TNBC cases. Higher rates of unhealthy alcohol use and obesity were observed within the hot spots. CONCLUSIONS: The use of spatial methods to analyze cancer registry and other secondary data sources can inform cancer control and prevention efforts within community cancer center catchment areas, where limited resources can preclude the collection of new primary data. IMPACT: Targeting community outreach and engagement activities to TNBC hot spots offers the potential to reduce the population-level burden of cancer efficiently and equitably.

Characterizing the spatial relationship between smoking status and tobacco retail exposure: Implications for policy development and evaluation.

Tobacco retail density and smoking prevalence remain elevated in marginalized communities, underscoring the need for strategies to address these place-based disparities. The spatial variation of smokers and tobacco retailers is often measured by aggregating them to area-level units (e.g., census tracts), but spatial statistical methods that use point-level data, such as spatial intensity and K-functions, can better describe their geographic patterns. We applied these methods to a case study in New Castle County, DE to characterize the cross-sectional spatial relationship between tobacco retailers and smokers, finding that current smokers experience greater tobacco retail exposure and clustering relative to former smokers. We discuss how analysis at different geographic scales can provide complementary insights for tobacco control policy.