Abstract P1-06-03: Differences in Breast Cancers among American-Indians and Whites in the United States
Authors: Gaba Anu , Cao Li , Renfrew Rebecca , Wernisch Janet , Sahmoun Abe , Goel Sanjay , Crosby Ross 
Published: March 2023

Differences in Breast Cancers among American-Indians and Whites in the United States Background - The United States has made substantial progress in improving breast cancer (BC) outcomes over the years, but unfortunately, this improvement has not impacted all races equally. BC death rates have not improved significantly for American Indian (AI) women, whereas, it significantly decreased for White women. In addition, AI women were more likely to be diagnosed at a younger age with a late-stage disease. We sought to determine the reasons for these disparities. Methods - This is a retrospective cohort study using a hospital registry database (the National Cancer Data Base) (NCDB). We identified female AIs and non-Hispanic Whites in the US diagnosed with BC between the years 2004 and 2016. We compared patient and tumor characteristics between the 2 groups and its effect on age and stage at diagnosis. We also determined hazard ratios (HRs) for overall survival using Cox regression models, both before and after adjustment for covariates. Results – Data on 6,866 AIs and 1,987,324 White women diagnosed with BC were analyzed. The mean (SD) age at diagnosis was significantly younger for AI than for White women (57.72 ± 12.23 vs. 61.87 ± 13.21). AI women traveled double the distance to their treatment facilities, lived in lower median income zip codes, reported a higher percentage of no insurance, and higher comorbidities than Whites. Furthermore, AIs were less likely to be diagnosed with Stage 0 and I BCs, had a larger tumor size, greater number of positive lymph nodes at diagnosis, and higher proportion of triple negative and HER2-positive BCs than Whites. Whites were more likely to have other cancers diagnosed prior to or after their BC diagnosis. All the above tests for comparisons were significant (p-value &lt; 0.001). Correlation between patient/tumor characteristics with age and stage at diagnosis was not significantly different between AIs and Whites. Unadjusted overall survival (OS) was significantly worse for AIs as compared to Whites (HR=1.07; 95% CI: 1.01-1.14, p-value = 0.025). After adjustment of all covariates including age, travel distance, median income of residential zip code, insurance status, cancer sequence, comorbidities, stage, tumor size, number of positive lymph nodes, grade, histology, and hormonal/HER2 status, OS was not significantly different between AIs and Whites (HR=1.04; 95% CI: 0.90-1.20, p-value = 0.601). Conclusion - Our study showed significant differences in patient and tumor characteristics among AI and White BC patients which adversely impacted BC outcomes in AIs. Survival was lower in AIs, but when adjusted for various covariates, the survival difference disappeared. Improvement in BC outcomes in AIs will involve not only improved and early access to screening to identify patients at younger ages and earlier stages at diagnosis, but also long term plans to provide affordable and the full spectrum of cancer care closer to home.

Citation Format: Anu Gaba, Li Cao, Rebecca Renfrew, Janet Wernisch, Abe Sahmoun, Sanjay Goel, Ross Crosby. Differences in Breast Cancers among American-Indians and Whites in the United States [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-06-03.