Neighborhood Social Environmental Factors and Breast Cancer Subtypes among Black Women.

BACKGROUND

The disproportionate burden of more aggressive breast cancer subtypes among African American/Black women may stem from multilevel determinants. However, data are limited regarding the impacts of neighborhood social environmental characteristics among Black women.

METHODS

We evaluated the association between neighborhood-level socioeconomic status (nSES) and breast cancer subtypes in the Women's Circle of Health and Women's Circle of Health Follow-up Study, which included 1,220 Black women diagnosed from 2005 to 2017 with invasive breast cancer. nSES at diagnosis was measured using NCI's census tract-level SES index. We used multilevel multinomial logistic regression models to estimate the association of nSES with breast cancer subtypes [triple-negative breast cancer (TNBC), HER2-positive vs. luminal A], adjusting for individual-level SES, body mass index, and reproductive factors. We tested for interactions by neighborhood racial composition.

RESULTS

Compared with census tracts characterized as high nSES, the relative risk ratios (RRR) for TNBC were 1.81 [95% confidence interval (CI): 1.20-2.71] and 1.95 (95% CI: 1.27-2.99) for women residing in areas with intermediate and low nSES, respectively ( = 0.002). Neighborhood racial composition modified the association between nSES and TNBC; the highest relative risk of TNBC was among women residing in low nSES areas with low proportions of Black residents.

CONCLUSIONS

Black women residing in socioeconomically disadvantaged neighborhoods may have an increased risk of TNBC, particularly in areas with lower proportions of Black residents.

IMPACT

Places people live may influence breast tumor biology. A deeper understanding of multilevel pathways contributing to tumor biology is needed.