Ecological Study of Variability in the Relationship between Liver Cancer Mortality and Racial Residential Segregation

Abstract

Racial segregation has been identified as a predictor for the burden of cancer in several different metropolitan areas across the United States. This ecological study tested relationships between racial segregation and liver cancer mortality across several different metropolitan statistical areas in Wisconsin. Tract-level liver cancer mortality rates were calculated using cases from 2003-2012. Hotspot analysis was conducted and segregation scores in high, low, and baseline mortality tracts were compared using ANOVA. Spatial regression analysis was done, controlling for socioeconomic advantage and rurality. Black isolation scores were significantly higher in high-mortality tracts compared to baseline and low-mortality tracts, but stratification by metropolitan areas found this relationship was driven by two of the five metropolitan areas. Hispanic isolation was predictive for higher mortality in regression analysis, but this effect was not found across all metropolitan areas. This study showed associations between liver cancer mortality and racial segregation but also found that this relationship was not generalizable to all metropolitan areas in the study area.

Keywords: cancer epidemiology; liver cancer; racial segregation; structural racism.

Figure 1

Maps of Madison, WI MSA. Upper left: liver cancer SMRs. Upper right: high- and low-mortality clusters of liver cancer. Middle left: socioeconomic advantage index with white tracts indicating areas whose ACS errors were outliers. Middle right: rurality. Lower left: Black local isolation scores. Lower right: Hispanic local isolation scores. Abbreviations: WI: Wisconsin, SMR: Standardized Mortality Rate, ACS: American Community Survey.

Figure 2

Maps of Milwaukee–West Allis–Wauwatosa, WI MSA. Upper left: liver cancer SMRs. Upper right: high- and low-mortality clusters of liver cancer. Middle left: socioeconomic advantage index with white tracts indicating areas whose ACS errors were outliers. Middle right: rurality. Lower left: Black local isolation scores. Lower right: Hispanic local isolation scores. Abbreviations: WI: Wisconsin, SMR: Standardized Mortality Rate, ACS: American Community Survey.

Figure 3

Boxplots comparing segregation and other demographic variables within high-, baseline-, and low-mortality tracts. The left-most column indicates comparison pooling all five MSAs (APL: Appleton, GBY: Green Bay, MAD: Madison, MKE: Milwaukee, RAC: Racine). The columns on the right-hand side show comparisons within each individual MSA. Statistical significance was assessed using the Kruskal–Wallis test. The p-values were adjusted for multiple comparisons with Benjamini–Hochberg correction for MSA-specific testing. * indicates p < 0.05, ** indicates p < 0.01, *** indicates p < 0.001, **** indicates p < 0.0001. Abbreviation: N.S.: Not Significant.