Abstract PO-197: Neighborhood- and individual-level psychosocial stress and risk of breast cancer among Black women
Authors: Barber Lauren E. , Zirpoli Gary R. , Cozier Yvette C. , Bertrand Kimberly A. , Adams-Campbell Lucile L. , Palmer Julie R. 
Published: December 2020

Abstract
Background Psychosocial stress has been linked to adverse health outcomes, including cancer. However, prior studies have not consistently demonstrated an association between psychosocial stress and risk of breast cancer. Further investigation is needed to help elucidate the relation, especially among Black women, who experience some unique stressors. Methods Within the Black Women’s Health Study, an ongoing prospective cohort of 59,000 African American women, we analyzed the association between neighborhood- and individual-level psychosocial stress factors and risk of breast cancer by estrogen receptor (ER) status. Participants reported individual-level factors on baseline and follow-up questionnaires.
Neighborhood-level factors were determined by linking participant addresses to year 2000 and 2010 United States Census data, including median household income, percentage of adults aged ≥25 years who have completed college, percentage unemployed, and percentage of individuals below the poverty line. We used Cox proportional hazards regression to estimate hazard ratios (HR) and 95% confidence intervals (CI) adjusted for established breast cancer risk factors. Results During follow-up from 1995 to 2017, 2,167 incident breast cancer cases (1,259 ER+; 687 ER-) were identified. In multivariable models, women living in the most disadvantaged neighborhoods had a 26% (HR=1.26, 95% CI 1.00-1.58 for highest vs. lowest quartile) higher risk of ER- breast cancer compared to those living in the least disadvantaged neighborhoods. The comparable HR for lowest versus highest quartile of neighborhood socioeconomic status (SES) was 1.24 (95% CI 0.98-1.57). Conversely, living in the lowest quartile of neighborhood SES was associated with a reduced risk of ER+ breast cancer (HR=0.83, 95% CI 0.70-0.98). With respect to individual-level factors, marital status (married/living together vs. single: HR=1.29, 95% CI 1.08-1.53), education (≥16 vs. ≤12 years of education: HR=1.18, 95% CI 1.00-1.41), and childhood sexual abuse (sexual assault ≥4 times vs. no abuse: HR=1.35, 95% CI 1.01- 1.79) were associated with higher risk of ER+, but not ER- breast cancer. Women who experienced racism more frequently in their daily lives had a modestly elevated risk of ER+ (highest vs. lowest quartile of racism score: HR=1.14, 95% CI 0.94-1.38), but not ER- breast cancer. Conclusion In this cohort of African American women, neighborhood disadvantage and lower neighborhood SES were associated with an increased risk of ER- breast cancer, whereas individual stressors were associated with an increased risk of ER+ breast cancer. Neighborhood-level factors are proxies for social and environmental exposures that could influence breast cancer risk through direct (e.g., chronic stress, inflammation) and indirect (e.g., barriers to healthy behaviors) pathways. Because residence in low SES neighborhoods is common among Black women, these exposures could contribute to observed racial disparities in incidence of ER- breast cancer.
Citation Format: Lauren E. Barber, Gary R. Zirpoli, Yvette C. Cozier, Kimberly A. Bertrand, Lucile L. Adams-Campbell, Julie R. Palmer. Neighborhood- and individual-level psychosocial stress and risk of breast cancer among Black women [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-197.