Abstract BackgroundAlthough advances in screening, detection, diagnosis, and treatment have reduced overall breast cancer mortality, well-documented socioeconomic and racial/ethnic disparities persist. The objective of this study was to utilize the area deprivation index (ADI), a compositive measure of neighborhood disadvantage, on breast cancer survival in South Florida, predominantly consisting of Miami-Dade County residents. The ADI is based on a measure created by the Health Resources & Services Administration (HRSA) over three decades ago, and has since been refined, adapted, and validated to the Census Block Group neighborhood level. The ADI score (1-10) includes factors from the domains of income/employment (e.g., median family income), education (e.g., % population >25 with <9 years of education), housing (e.g., % occupied housing without complete plumbing), and household characteristics (e.g., % single-parent households with children <18). MethodsPatients treated at our medical campus, comprised of both a safety-net hospital and an adjacent academic cancer center, with stage I-IV breast cancer from 2005-2017 were identified from our local tumor registry. Our main outcome of interest was breast cancer-specific survival (BCSS). The ADI was calculated for each patient at the census block group level using the University of Wisconsin Neighborhood Atlas (https://www.neighborhoodatlas.medicine.wisc.edu/mapping) and categorized into tertiles. Random effects frailty models were conducted, controlling for patient and tumor characteristics [grade, stage, receptor status (ER+/HER-, ER+/HER2+, ER-HER2+, ER-/HER2-)], and NCCN-guideline appropriate treatment. ResultsThe study population was 5,377 breast cancer patients with 55.5% being Hispanic, 27.0% being non-Hispanic White (NHW), and 17.5% being non-Hispanic Black (NHB). The distribution of NHB was highest in the most disadvantaged neighborhoods compared to NHW and Hispanics (p<0.001). In addition, more uninsured patients lived in the most disadvantaged neighborhoods compared to those with any type of insurance. After controlling for multiple covariates including comorbidities, race/ethnicity, insurance status, and tumor subtype, we found that those individuals living in the most disadvantaged neighborhoods (highest ADI tertile) had a significantly increased hazard of breast cancer specific death compared to those living in the most advantaged neighborhoods (T2: HR: 1.27 95% CI: 1.00, 1.63, p<0.05 and T3: HR: 1.5 95% CI 1.17, 1.91, p<0.05). ConclusionThis study is the first to evaluate BCSS through the lens of the ADI, a composite measure of neighborhood advantage and disadvantage using census block group data reflective of social determinants of health domains spanning income, education, employment, and housing quality. Our study suggests that breast cancer survival disparities are partly influenced by neighborhood disadvantage. Even when accounting for sociodemographics, tumor characteristics, and NCCN-guideline appropriate treatment, survival disparities remained, suggesting potential social and environmental factors impacting survival. To address these disparities, effective interventions are. needed that account for the social and environmental contexts in which cancer patients live and are treated. Table: ADI (Tertiles) and Breast Cancer-Specific SurvivalHR (95% CI)Area Deprivation Index (vs. most advantaged)ADI Tertile 21.27 (1.00, 1.63)ADI Tertile 3 (more disadvantaged)1.50 (1.17, 1.91)Race (vs. NHW)Hispanic0.94 (0.72, 1.22)NHB1.71 (1.27, 2.31)Age1.02 (1.01, 1.02)Insurance (vs. Private)Government1.49 (1.19, 1.86)Insurance, NOS0.97 (0.62, 1.51)Uninsured1.15 (0.87, 1.52)Unknown1.19 (0.78, 1.82)Receptor Status (vs. ER+/HER2-)ER+/HER2+1.40 (1.06, 1.86)ER-/HER2-2.11 (1.70, 2.60)ER-/HER2+1.20 (0.85, 1.69)Unknown0.88 (0.51, 1.51)Body Mass Index (vs. Normal Weight (18.5 – 24.9)Underweight (Less than 18.5)1.40 (0.72, 2.72)Overweight (25.0 – 29.9)0.70 (0.56, 0.88)Obese (> 29.9)0.79 (0.63, 0.98)Hypertension0.84 (0.67, 1.03)Diabetes Mellitus1.02 (0.74, 1.40)NCCN-guideline concordant Treatment0.84 (0.75, 0.94) Citation Format: Neha Goel, Seraphina Choi, Sina Yadegarynia, Kristin Rojas, Susan Kesmodel, Erin Kobetz, Ashly Westrick. Neighborhood disadvantage predicts worse breast cancer-specific survival [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-12-08.