Abstract C061: Disparities in second breast cancers among women with ductal carcinoma in situ

Abstract Introduction: Breast cancer is the leading cause of cancer-related death among women in the United States and Oklahoma. Outcomes from DCIS are generally favorable, however, up to 50% of patients will develop an SBC after DCIS, with approximately 30% diagnosed as invasive SBC. Our research objective was to use a combination of data sources (registry, demographic, clinical, and socioeconomic data) to explore the presence of disparities and treatment outcomes, among women of different racial, ethnic, and socioeconomic groups in Oklahoma. Methods: We conducted a retrospective cohort study comparing the overall incidence of DCIS, invasive breast cancer (IBC), and the development of SBCs in women residing in Oklahoma at the time of diagnosis. We obtained data from the Oklahoma Central Cancer Registry (OCCR) and included women diagnosed with breast cancer from 1997-2021 in our analyses. We restricted analyses to women with DCIS as their first primary cancer. SBC was defined as a second primary cancer diagnosed at least six months after the first DCIS diagnosis. We evaluated demographic and cancer-related characteristics of women diagnosed with DCIS as their first cancer by development of a SBC. Results: In initial analyses, we identified 7,903 women with DCIS as their initial cancer diagnosis. Of the women with DCIS, 80% were over 50 years of age at diagnosis and the majority were non-Hispanic (NH) White (85%). For cancer-related characteristics, 33% of tumors were well or moderately differentiated (44% unknown) and 51% of tumors originated in the left breast. Of these women, 513 were subsequently diagnosed with a SBC, which included both in situ (26%) and invasive breast cancers (74%). Among women with a SBC, a higher percentage of women were <50 years of age at the initial DCIS diagnosis (27% vs. 19%) and NH Black (9.4% vs. 6.7%) compared to those without a SBC. Discussion: As a next step, we will further evaluate the risk of SBC among women in the OCCR and National Cancer Data Base to evaluate disparities at the national level. We are planning to evaluate the risk of an SBC after diagnosis of a DCIS by demographic and cancer-related characteristics using multivariable models. We will also evaluate survival among women with DCIS who develop a subsequent SBC. Citation Format: Amanda Janitz, Bethany Hannafon, Mary L Williams, Elizabeth Wellberg, Chao Xu, William Dooley. Disparities in second breast cancers among women with ductal carcinoma in situ [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 C061.