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.