Abstract 5913: Socioeconomic position, race/ethnicity and breast cancer mortality among young women in California
Authors: Zhang Zhenzhen , Velie Ellen , Ye Shangyuan , Zou Joe , Marcus Lydia , Luoh Shiuh-Wen , Jiang Duo , Yu Mandi 
Published: June 2022

Background: Research has demonstrated that women with lower individual-level socioeconomic position (SEP) are at higher risk for breast cancer (BC) mortality. Census tract-level household educational attainment has been considered both as a proxy for individual-level SEP and an indicator of neighborhood social environment. Few studies have evaluated the association of census tract-level SEP on BC mortality by race/ethnicity, particularly within stage at diagnosis in young women.

Objective: To determine associations between residential SEP, measured by household educational attainment, and BC mortality by race/ethnicity within stage at diagnosis among young women in California, 2006-2015.

Methods: Data are from a pilot data product, the California Cancer Registry Data with Synthetic Census Tracts, which is available to external researchers coordinated with confidential data available to qualified internal users. The present study includes 41,886 young (25-49 years of age) California women who were diagnosed with primary invasive BC during 2006-2015. SEP was defined based on % of households completing a bachelor’s degree or higher (categorized as ≤30%, 30-60%, and ≥60% of households). Multivariate analyses were conducted to examine the association between SEP and BC mortality by race/ethnicity within stage at diagnosis by calculating hazard ratios (HR) and 95% confidence interval (CI), adjusting for age at diagnosis, marital status, tumor histology and diagnosis year.

Results: For Stage I BC, compared to census tracts with ≤30% bachelor’s degree, the adjusted HR (95% CI) was 0.57 (0.44, 0.74) for tracts with 30-60% and 0.48 (0.32, 0.72) for tracts with ≥60% of households attaining a bachelor’s degree. For Stage II, the corresponding HRs (95% CIs) are 0.75 (0.66-0.84) and 0.54 (0.44-0.67); for Stage III, 0.80 (0.72-0.89) and 0.63 (0.51-0.76); and for Stage IV 0.73 (0.65-0.84) and 0.53 (0.41-0.69). When examined by race/ethnicity and stage at diagnosis, a significantly reduced mortality was associated with residing in census tracts with ≥60% of households having attained a bachelor’s degree compared to ≤30% for Stage I only among Asian (HR=0.30; 95% CI=0.11-0.77); for Stage II for White (HR=0.53; 95% CI=0.41-0.70) and Asian (HR=0.56; 95% CI=0.34-0.91); for Stage III White (HR=0.72; 95% CI=0.55-0.94) and Hispanic (HR=0.49; 95% CI=0.24-0.99); and for Stage IV White (HR=0.58; 95% CI=0.41-0.82) and Asian (HR=0.48; 95% CI=0.26-0.90) populations. Sample size was limited among Black and Asian Pacific Islander subgroups.

Conclusion: Higher census tract-level SEP, defined as ≥60% of the population having a bachelor’s degree, is associated with a significantly decreased risk for BC-mortality at all stages of diagnosis. This effect isn't consistent across all stages of diagnosis among Hispanic populations, but is consistent among Non-Hispanic White and Asian populations in California, 2006-2015.

Citation Format: Zhenzhen Zhang, Ellen Velie, Shangyuan Ye, Joe Zou, Lydia Marcus, Shiuh-Wen Luoh, Duo Jiang, Mandi Yu. Socioeconomic position, race/ethnicity and breast cancer mortality among young women in California [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5913.