Differences in Breast Cancers Among American Indian/Alaska Native and non-Hispanic Whites in the USA.

Importance: Breast cancer (BC) death rates have not improved for American Indian/Alaska Native (AI/AN) women, whereas, it has significantly decreased for non-Hispanic White (White) women.

Objective: Delineate the differences in patient and tumor characteristics among AI/AN and Whites with BC, and its impact on age and stage at diagnosis as well as overall survival (OS).

Methods: Hospital-based, cohort study using the National Cancer Database to identify female AI/AN and Whites diagnosed with BC between the years 2004 and 2016.

Results: BC in 6866 AI/AN (0.3%) and 1,987,324 Whites (99.7%) were studied. The median age at diagnosis was 58 for AI/AN and 62 for Whites. AI BC patients traveled double the distance for treatment, lived in lower median income zip codes, had a higher percentage of uninsured, higher comorbidities, lower percentage of Stage 0/I, larger tumor size, greater number of positive lymph nodes, higher proportion of triple negative and HER2-positive BC than Whites. All the above comparisons were significant, p<0.001. Association between patient/tumor characteristics with age and stage at diagnosis was not significantly different between AI/AN and Whites. Unadjusted OS was worse for AI/AN as compared to Whites (HR=1.07, 95% CI=1.01-1.14, p=0.023). After adjustment of all covariates, OS was not different (HR=1.038, 95%CI=0.902-1.195, p=0.601).

Conclusion: There were significant differences in patient/tumor characteristics among AI/AN and White BC which adversely impacted OS in AI/AN. However, when adjusted for various covariates, the survival was similar, suggesting that the worse survival in AI/AN is mostly the impact of known biological, socio-economic, and environmental determinants of health.