Abstract Background: Despite advances in medical knowledge and treatment, disparities in breast cancer outcomes persist along demographic and socioeconomic lines. To quantify these disparities, the Area Deprivation Index (ADI) emerges as a powerful metric. It offers insights into the interplay between neighborhood socioeconomic status and breast cancer outcomes by encompassing factors pertaining to income, education, employment, and housing quality. There have been limited studies to examine the role of race and neighborhood disadvantage on specific breast cancer outcomes. Kentucky also faces a unique burden as it has the third highest breast cancer mortality rate in the United States. This study aims to examine the association between neighborhood socioeconomic disadvantage, and breast cancer outcomes including receipt of surgical treatment, radiation therapy, chemotherapy, and breast cancer-specific survival. While also examining how any associations are modified by race and ethnicity among Kentucky breast cancer patients. Methods: We conducted a retrospective cohort analysis using data from the Kentucky Cancer Registry (KCR) among breast cancer patients diagnosed between 2010 and 2017 with follow-up data through December 31, 2022. The KCR dataset was then linked with census tract data to examine ADI. We conducted consecutive multilevel logistic regression for binary outcomes and Cox Proportional hazard models using SAS (version 9.4, SAS Institute, Inc., Cary, North Carolina, USA) for time-to-event of breast cancer survival. Results: Women in the most disadvantaged quartile (4th quartile) were more likely to be Non-Hispanic Black (NH-Black), Appalachian residents, current tobacco users, divorced and using government insurance. Compared to women in the least disadvantaged neighborhoods (1st quartile) women living in the most disadvantaged neighborhoods (4th quartile) were 50% more likely to die from breast cancer (HR: 1.50, 95 CI: 1.28-1.76). Women in the most disadvantaged neighborhoods (4th quartile) were also more likely to be diagnosed at later stages (aOR:1.26, 95 CI:1.13-1.42). These associations were all observed after adjusting for age, race, tobacco use, marital status, insurance status, family history, and residence in Appalachia. Conclusions: Women living in areas of greater disadvantage had significantly increased odds of late-stage diagnosis and risk of breast cancer death regardless of race suggesting that neighborhood-level factors contribute to breast cancer disparities. Our findings underscore the need for neighborhood-level interventions to improve cancer outcomes. Citation Format: Breyanna E. Walker, Elinita Pollard, Justin Moore, Sydney Howard, Pamela Hull, Kathleen O'Connor, Samantha Jones, Lovoria Williams, Adebola Adegboyega, Veronica Jones, Eric Durban, Xiaoqin Wang, Wendi Owen. Investigating the role of race/ethnicity on the association between neighborhood deprivation and breast cancer outcomes among Kentucky breast cancer patients years 2010-2022 [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr A058.