Neighborhood Disadvantage and Breast Cancer among Women Living in the United States

BACKGROUND: Few large studies have investigated neighborhood socioeconomic position (nSEP) and breast cancer incidence. We evaluated the relationship between neighborhood disadvantage and incident female breast cancer in a US-based cohort. METHODS: The Sister Study (N = 50,884) is a prospective study of environmental and genetic risk factors for breast cancer. We linked geocoded residential addresses (2003-2009) to the Area Deprivation Index (ADI; 2000; census-block group), a measure of neighborhood disadvantage in which higher scores represent greater disadvantage. Cox proportional hazard models estimated hazard ratios (HR) and 95% confidence intervals (CI) for the association between ADI and breast cancer, adjusting for individual SEP, lifestyle, and hormonal factors. We evaluated breast cancer hazards overall (N = 46,993; 4,279 cases) and by estrogen receptor (ER) (ER positive and ER negative) and menopausal (pre- and postmenopausal) status. Stratified analyses explored effect modification by race/ethnicity within each cancer subtype. RESULTS: We observed no associations between ADI and overall breast cancer in the full cohort or in race/ethnicity-stratified analyses. The highest (Q4) versus lowest (Q1) ADI quartile was associated with lower ER-positive breast cancer [HR, 0.84 (95% CI, 0.72-0.99)], but the HR was above 1.0 for ER-negative breast cancer: 1.18 (95% CI, 0.84-1.65; pint = 0.024). The positive HR for ADI Q4 versus Q1 for ER-negative breast cancer was most apparent among non-Hispanic Black women [HR, 1.71 (95% CI, 0.74-3.95)], though results were not statistically significant. CONCLUSIONS: nSEP was not associated with breast cancer overall, but associations with higher disadvantage varied with ER status. IMPACT: Neighborhood-level socioeconomic context may differentially influence breast cancer risk by tumor subtype.