Cancer
Disparities by Race, Ethnicity, and Socioeconomic Status in Survival among a Community-based Sample of Young Women with Metastatic Breast Cancer in the United States Jennifer Wang* Jennifer Wang Andrea Betts Caitlin Murphy
Background: Breast cancer is the most commonly diagnosed cancer in young women. We examined differences in survival by race/ethnicity and socioeconomic status (SES) among young women diagnosed with metastatic breast cancer (mBC) in community-based settings.
Methods: Young women (age 18-49 years) diagnosed with de novo or recurrent mBC between 2013 and 2021 were identified from the Flatiron Health electronic health record database, comprising 280 community-based cancer clinics in the U.S. Survival was compared by race/ethnicity and census-tract level SES, overall and by clinical subtype (HR+/HER2-, HER2+, triple negative [TN]). Cox proportional hazards models were used to examine associations with all-cause mortality, adjusting for age and year at diagnosis, clinical subtype, and practice type (community, academic).
Results: We identified 3,204 young women diagnosed with mBC (57.3% non-Hispanic White [NHW], 15.9% non-Hispanic Black [NHB], 13.0% Hispanic, 3.6% non-Hispanic Asian or Pacific Islander, 10.1% non-Hispanic Other). Most women had HR+/HER2- mBC, and a higher proportion of NHB and Hispanic vs. NHW women had TN mBC. Median survival was 47 months (95% CI: 44, 50) and differed by race/ethnicity and SES. For example, NHB women (34 months, 95% CI: 30, 38) had worse survival compared to NHW women (47 months, 95% CI: 42, 52), and women in the highest (59 months, 95% CI: 52, 72) vs. lowest quintile (40 months, 95% CI: 34, 49) of SES had better survival. In adjusted analysis, race/ethnicity was associated with mortality but not SES. For example, NHB women had 1.11 (95% CI: 0.96, 1.30) times increased risk compared to NHW women. This pattern persisted for women with HR+/HER2- but not HER2+ or TN mBC.
Discussion: There were no differences by race/ethnicity and SES in survival of young women with TN mBC, suggesting this subtype is not inherently more aggressive in young Black and Hispanic women. By contrast, disparities persisted for young women with HR+/HER2- mBC.