Racial disparities in breast cancer diagnosis and treatment by hormone receptor and HER2 status.

BACKGROUND: African American and Hispanic women are more likely to be diagnosed with aggressive forms of breast cancer. Disparities within each subtype of breast cancer have not been well documented.
METHODS: Using data from 18 SEER cancer registries, we identified 102,064 women aged 20 years or older, diagnosed with invasive breast cancer in 2010-2011, and with known stage, hormone receptor (HR), and HER2 status. Associations between race/ethnicity and cancer stage and receipt of guideline-concordant treatment were evaluated according to HR/HER2 status.
RESULTS: Overall, African American and Hispanic women were 30% to 60% more likely to be diagnosed with stage II-IV breast cancer compared with non-Hispanic whites. African American women had 40% to 70% higher risks of stage IV breast cancer across all four subtypes. American Indian/Alaska Native women had a 3.9-fold higher risk of stage IV triple-negative breast cancer. African American and Hispanic whites were 30% to 40% more likely to receive non-guideline-concordant treatment for breast cancer overall and across subtypes.
CONCLUSIONS: Women in several racial/ethnic groups are more likely to be diagnosed with more advanced stage breast cancer. African American and American Indian/Alaska Native women in particular had the highest risk of being diagnosed with stage IV triple-negative breast cancer. African American and Hispanic women were also consistently at higher risk of not receiving guideline-concordant treatment across subtypes. IMPACT: These findings provide important characterization of which subtypes of breast cancer racial/ethnic disparities in stage and treatment persist. ©2015 American Association for Cancer Research.