Evaluating disparities in receptor status, overall survival, and time to hormone therapy among women with breast cancer.

Abstract

11096 Background: Breast cancer receptor status (ER/PR/HER2) is essential to guide treatment decisions. However, national race/ethnicity subtype studies rarely include Indigenous American Indian and Alaska Native (AI/AN) and Native Hawaiian and other Pacific Islander (NHPI) women. This study aims to compare across race/ethnicity: 1) hormone receptor (HR)/HER2 status, 2) Overall Survival (OS) for Triple Positive breast cancer, and 3) Time to Hormone Therapy (THT). Methods: A cohort study of women with breast cancer (Stage 1-4), age ≥18 years, diagnosed 2004-2017 was conducted with the National Cancer Database. Race was used as federally defined (White, Black, Asian, AI/AN, and NHPI) with Hispanic ethnicity. Primary endpoints were receptor status, OS, and THT (days from diagnosis to hormone therapy). Kaplan-Meier estimates and log-rank tests assessed OS. Multivariable logistic, Cox Proportional Hazard, and linear regression evaluated the likelihood of HR+/HER2+ (adjusted Odds Ratio [aOR]), death (adjusted Hazard Ratio [aHR]), and THT in days (adjusted β [aβ]), respectively, with 95% confidence intervals (95%CI). The majority non-Hispanic White population served as reference. All regressions were adjusted for sociodemographic and cancer characteristics. All HER2 analyses used a subset of women diagnosed post-2010, given inconsistent testing pre-2010. Results: 1,812,911 women were included who mostly had Stage 1 cancer (53%), from metropolitan areas (84%), with private insurance (51%), and a median age of 61 (IQR 51-71) years. Women were 81% White, 11% Black, 5% Hispanic, 2% Asian, 0.3% AI/AN, and 0.2% NHPI. NHPI women had the highest ER+ (84%) and PR+ (75%) cancers, while Asian women had the highest HER2+ (18%). Adjusted for covariates, only NHPI women were significantly more likely to have HR+ cancer (aOR=1.3, 95%CI=1.2-1.5) while Black women were less likely (aOR=0.6, 95%CI=0.6-0.6), compared to White women. Hispanic women were significantly more likely to have Triple Positive cancer (aOR=1.1, 95%CI=1.1-1.2) while Black women were less likely (aOR=0.9, 95%CI=0.9-0.9). Median follow-up was 63 (IQR 36-101) months. Among women with Triple Positive breast cancer, there were significant differences in OS (p< .0001) with 7-year survival ranging from 77% for NHPI women to 89% for Asian women. NHPI women had the highest risk of death (aHR=1.5, 95%CI=1.0-2.1), followed by AI/AN (aHR=1.5, 1.05-2.0), and Black (aHR=1.2, 95%CI=1.1-1.2). Adjusted for covariates, among women with HR+ breast cancer, longer THT occurred among Black (aβ=18 days, 95%CI=17-18), Hispanic (aβ=16 days, 95%CI=15-17), and NHPI women (aβ=14 days, 95%CI=9-18). Conclusions: NHPI women have higher HR+ rates while Black, Hispanic, and NHPI women with HR+ cancer experience longer times to hormone therapy. This is likely the first US analysis of breast cancer subtypes using federal race/ethnicity standards.