Abstract SPECIFIC AIMS: To assess breast cancer risk in Women Veterans. BACKGROUND/RATIONALE: Women are the fastest growing segment of patients numbering over 2 million and breast cancer incidence has more than tripled from 1995 to 2012 within the Veterans Health Administration (VHA). Preliminary data suggest that Women Veterans may be at an increased breast cancer risk based on unique service-related exposures (e.g., burn pits, depleted uranium) and Post Traumatic Stress Disorder (PTSD). Historically, breast cancer rates among African Americans (AA) are lower than those seen in the general population (8.2-13.3%). METHODS: A pilot study was conducted at Bronx, NY and Washington, DC Veterans Affairs Medical Centers. Participants were enrolled at their regular visit to Women's Health Clinics or at breast cancer education and awareness events. 5-year and lifetime risks of developing invasive breast cancer were calculated using the Gail Breast Cancer Risk Assessment Tool (BCRAT). Demographics, PTSD status, eligibility for chemoprevention and genetic counseling using the Breast Cancer Genetics Referral Screening Tool (B-RST), were also determined. ELIGIBILITY CRITERIA: Women Veterans age ≥ 35 years with no personal history of breast cancer. RESULTS: A total of 99 Women Veterans with an average age of 54 years participated between 2015 and 2018; 60% African American (AA); 13% Hispanic; 14% non-Hispanic White and 13% as other. In total, 35% (35/99) were considered high risk with a 5-year BCRAT of >1.66% and of these, 51% were AA; 14% Hispanic and 17 % were other. Prior breast biopsies were performed in only 22% (22/99) of our entire Veteran population; 57% (56/99) having a family history positive for breast cancer. Comparatively, in our high risk AA alone, 33% (6/18) had prior breast biopsies with 94% (17/18) having a positive family history. High risk patients were referred for chemoprevention; 5 (19%) accepted; and 13/35 (37%) patients were referred for genetic counseling. PTSD was present in 29% overall and in 31% of the high risk subgroup. IMPLICATIONS: The VHA, which leads the nation in mammogram compliance, is an untapped potential resource for the study of breast cancer. To our knowledge, this is the only study with 60% AA Women Veterans. High participation rates among AA in this pilot study have uncovered the potential for further inquiry into this population, which is otherwise dramatically under-represented in research. Over half (51%) of AA in this pilot study had a high risk score, likely linked to a high rate of prior breast biopsies and family history. Limitations of this study include the small sample size, exclusively urban population, geography and self-selection for screening due to a higher level of concern for breast cancer. If Women Veterans are at higher risk of breast cancer, it has been assumed that this would be related to service-related exposures, PTSD and other factors. However this pilot study, which was not designed or powered to do more than raise questions, suggests the additional possibility of an innate or genetic risk, especially in AAs. Future directions include the evaluation of genetic and molecular mutations in high risk AA Women Veterans, possibly even a role for PTSD epigenetic changes and tumorigenesis. Citation Format: Park Y-HA, Keller AT, Bidassie B, Venne VL, Heron BB, Hoffman-Hōgg L, Hawley DK, Hsu T-CM, Colonna SV, Aggarwal A. High participation of African-American women veterans in high risk breast cancer screening pilot program [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-10-06.