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.