Large Survival Disparity Within 2 Years of Diagnosis for Black vs White Women With ER-Positive Breast Cancer
- Risk for breast cancer–specific death was significantly greater during the first 2 years after diagnosis for black vs white women with ER-positive disease.
- Black women were at greater risk of death from luminal A–like and luminal B–like tumors.
In a study assessing factors in racial/ethnic survival disparities in breast cancer reported in the Journal of Clinical Oncology, Warner et al found that black women with estrogen receptor (ER)-positive breast cancer were significantly more likely to die from the disease within the first 2 years of diagnosis compared with white women. Overall, Asian and Hispanic women had better breast cancer–specific survival compared with white women.
The study involved 533 Asian, 1,122 Hispanic, 1,345 black, and 14,268 white women presenting with stage I to III breast cancer between January 2000 and December 2007 at National Comprehensive Cancer Network centers. Follow-up was through December 2009.
Hazard ratios (HRs) were based on multivariate analysis adjusting for age at diagnosis, center, year of diagnosis, socioeconomic factors (insurance type, educational attainment, employment status, menopausal status, comorbidity score, and body mass index [BMI]), tumor characteristics (stage at diagnosis, triggering event, tumor grade, ER status, progesterone receptor status, and HER2 status), and treatment (chemotherapy, hormonal therapy, and trastuzumab [Herceptin] use).
Median follow-up was 6.7 years. Overall, black women had a higher risk of breast cancer–specific death vs white women (HR = 1.21, 95% confidence interval [CI] = 1.00–1.45), with Asian women (HR = 0.56, 95% CI = 0.37–0.85) and Hispanic women (HR = 0.74, 95% CI = 0.58–0.95) having lower risk. Among women with ER-positive tumors, black women were at highest risk of death vs white women during the first 2 years after diagnosis (HR = 2.65, 95% CI = 1.34–5.24), although risk remained elevated thereafter (HR = 1.50, 95% CI = 1.12–2.00).
Black women with luminal A–like tumors (HR = 1.76, 95% CI = 1.09–2.85) and luminal B–like tumors (HR = 1.56, 95% CI = 1.14–2.15) had significantly increased risk of death vs white women, with no disparities being found between black and white women with ER-negative, HER2-positive, or triple-negative tumors.
Factors Mediating Risk
Analysis of factors mediating differences in survival indicated that 24% (P < .01) of excess mortality among black women was mediated by hormone receptor status, HER2 status, and tumor grade, with other mediators including stage at diagnosis (34%, P = .003) and BMI (19%, P = .07). BMI (15%, P = .05) was a mediator among Asian women, with lower BMI being protective. No significant mediators were identified among Hispanic women.
The investigators concluded, “Racial disparities in breast cancer survival vary by tumor subtype. Interventions are needed to reduce disparities, particularly in the first 2 years after diagnosis among black women with estrogen receptor–positive tumors.”
Erica T. Warner, ScD, MPH, of Harvard School of Public Health, is the corresponding author for the Journal of Clinical Oncology article.
The study was supported by the National Cancer Institute and National Comprehensive Cancer Network.