Higher prevalence of triple negative breast cancer (TNBC) in black women with associated poor outcomes due to various disparities is well documented within a single state. We examine multiple states to better understand the state effect on such differences in incidence and prevalence of TNBC in black women.
Female patients of ages 19 years old and above with breast cancer from the Surveillance, Epidemiology and End Results (SEER) Program across 13 states (608 counties) from 2015 (n = 66,444) and 2016 (n = 66,122) were examined. The relationships between the proportion of black and white women and the rate of patients with different tumor subtypes (luminal A, luminal B, HR-HER2+, and triple negative) were examined at the county level using ordinary least-square regression models. In parallel, due to consideration of various state-specific healthcare policies, socio-cultural norms, and socio-economic disparities, multi-level regression models were applied to examine the nested, random effect of each state on TNBC prevalence in each county. Bonferroni correction was applied to reduce the Type I error caused by repeated use of the same variables in multiple tests.
The baseline breast cancer rates between black and white women were similar in the population (0.171% for black and 0.168% for white). Consistent to previous studies, we demonstrate a significant positive correlation (p < 0.001) in TNBC in black females in both years. Surprisingly, when accounted for the random effects on states, 38.2% (2015) and 34.3% (2016) increase in incidence of TNBC in black females were seen, suggestive of state-specific disparity affecting race-specific health. In 2015, other subtypes of breast cancer in both black and white females did not result in significant relationship. Interestingly, in 2016, there was a significant relationship seen between the TNBC rate in white females and the white female population rate only after adjusting for the state effect (p = 0.026). This indicates the impact of non-biological factors such as state-wide health policies. Additionally, HR-HER2+ black females had a significant relationship against respective population rate only after adjusting for the state effect as well (p = 0.0394). For luminal A white females, a 15% decrease in incidence was seen after adjusting for state effect (p = 0.0424).
This is the first known across-state examination of breast cancer subtypes by race with random effects on state. This study shows the role of state-specific factors affecting incidence in black and white females and potentially indicates the importance of state-level management for breast cancer on health disparities in addition to race-driven effects. Further studies are needed to elucidate comparable differences between states affecting the rates of various subtypes of breast cancer and thus health outcomes.
Jeon, H., Lee, M., & Jaloudi, M. (2021). Geographical disparities of incidence and prevalence of triple-negative breast cancers: Multistate study data analysis. To Appear in American Society of Clinical Oncology Annual Meeting Proceedings (ASCO '21). June 4-8.