Abstract

Higher breast cancer mortality rates for African-American than non-Hispanic white women are well documented; however, it remains uncertain if this disparity occurs in disease subgroups defined by tumor molecular markers and stage at diagnosis. We examined racial differences in outcome according to subtype and stage in a diverse, population-based series of 103,498 patients.We obtained data for all invasive breast cancers diagnosed 1/1/2005-12/31/2012 and followed through 12/31/2012 among 93,760 non-Hispanic white and 9,738 African-American women in California. Molecular subtypes were categorized according to tumor expression of hormone receptor (HR, based on estrogen and progesterone receptors) and human epidermal growth factor receptor 2 (HER2). Cox proportional hazards models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI) for breast cancer-specific mortality.After adjustment for patient, tumor and treatment characteristics, outcomes were comparable by race for Stage I or IV cancer regardless of subtype, and HR+/HER2+ or HR-/HER2+ cancer regardless of stage. We found substantially higher hazards of breast cancer death among African-American women with Stage II/III HR+/HER2- (HR, 1.31, 95% CI, 1.03-1.65, and HR, 1.39, 95% CI, 1.10-1.75, respectively) and Stage III triple-negative cancers relative to whites.There are substantial racial/ethnic disparities among patients with Stages II/III HR+/HER2- and Stage III triple-negative breast cancers but not for other subtype and stage.These data provide insights to assess barriers to targeted treatment (e.g. trastuzumab or endocrine therapy) of particular subtypes of breast cancer among African-American patients.

View details for DOI 10.1158/1055-9965.EPI-15-0243

View details for PubMedID 25969506