Regional Variation in Disparities in Breast Cancer Specific Mortality Due to Race/Ethnicity, Socioeconomic Status, and Urbanization.

PURPOSE: Disparities in breast cancer mortality due to race/ethnicity, area socioeconomic status (SES), and urbanization have been documented. This study examined if disparities in the risk of breast cancer specific mortality due to race/ethnicity, SES, and urbanization varied within diverse regions of California.

METHODS: We identified 163,569 cases of first primary female invasive breast cancer from the California Cancer Registry diagnosed between January, 2000 and December, 2013. Cox regression was used to compute hazard ratios (HR) and 95 % confidence intervals for race/ethnicity, SES, and urbanization within eight regions of California.

RESULTS: Blacks had an increased risk of mortality in the San Francisco Bay Area (SFBA) (HR = 1.37; 1.22-1.55), Desert Sierra (HR = 1.27; 1.08-1.49), San Diego/Orange (HR = 1.43; 1.19-1.71), and Los Angeles (LA) (HR = 1.31; 1.20-1.44). Japanese (HR = 0.62; 0.47-0.81), Chinese (HR = 0.71; 0.58-0.87), and Filipino (HR = 0.81; 0.69-0.95) women had a decreased risk of mortality in LA. Southeast Asians had a decreased risk in San Diego/Orange (HR = 0.72; 0.57-0.90) and in the SFBA (HR = 0.81; 0.67-0.98). Hispanics had a decreased risk (HR = 0.73; 0.57-0.93) and American Indians had an increased risk (HR = 2.32; 1.08-4.98) in the Tri-County region. SES was a significant risk factor for mortality in all regions except the North and Tri-County. Urbanization was a statistically significant factor for mortality only in LA (HR = 1.32; 1.08-1.60).

CONCLUSIONS: Disparities in breast cancer mortality, due to race/ethnicity, SES, and urbanization vary by region which suggests that further research is warranted concerning the role of geographic regions and neighborhoods in cancer outcomes.