Distant metastases after diagnosis: Racial disparities in breast cancer outcomes.

Abstract

1084 Background: Black women diagnosed with breast cancer are more likely to have a poor prognosis, regardless of breast cancer subtype. Despite having a lower incidence rate of breast cancer when compared to white women, black women have the highest breast cancer death rate of all racial and ethnic groups, a characteristic often attributed to late stage at diagnosis. Distant metastases are considered the leading cause of death from breast cancer. We performed a follow up study of women with breast cancer in the Mount Sinai Health System (MSHS) to determine differences in distant metastases rates among black versus white women. Methods: Women were initially recruited as part of an NIH funded cross-sectional study from 2013-2020 to examine the link between insulin resistance (IR) and breast cancer prognosis. Women self-identified as black or white race. Data was collected via retrospective analysis of electronic medical records (EMR) between September 2020-January 2021. Distant metastases at diagnosis was defined as evidence of metastases in a secondary organ (not lymph node). Stage at diagnosis was recorded for all patients. Distant metastases after diagnosis was defined as evidence of metastases at any time after initiation of treatment. Univariate analysis was performed using Fisher’s exact test, multivariate analysis was performed by binary logistic regression, and results expressed as odds ratio (OR) and 95% confidence interval (CI). A p value <0.05 was considered statistically significant. Results: We identified 441 women enrolled in the IR study within the MSHS (340 white women, 101 black women). Median follow up time for all women was 2.95 years (median = 3.12 years for white and 2.51 years for black women (p=0.017)). Among these patients, 11 developed distant metastases after diagnosis: 4 (1.2%) white and 7 (6.9%) black (p=0.004). Multivariate analysis adjusting for age, race and stage at diagnosis revealed that black women were more likely to have distant metastasis (OR 5.8, CI 1.3-25.2), as were younger women (OR for age (years) 0.9, CI 0.9-1.0), and those with more advanced stage at diagnosis. Conclusions: Black women demonstrated a far higher percentage of distant metastases after diagnosis even when accounting for age and stage. These findings suggest that racial disparities still exist in the development of distant metastases, independent from a late-stage diagnosis. The source of existing disparities needs to be further understood and may be found in surveillance, treatment differences, or follow up.