Racial disparities in health insurance, triple-negative breast cancer diagnosis, tumor stage, treatment and survival in a large nationwide SEER cohort in the United States

It remains unclear whether there are racial disparities in mortality between women of different races who have the same subtype of breast cancer when tumor stage and size and treatment are controlled for. The present study aimed to investigate whether racial disparities in mortality existed between women of different races who had the same subtype of breast cancer when health insurance, tumor stage and size and treatment were controlled for in a large cohort of women with breast cancer in the United States. This study identified 399,564 women who were diagnosed with incident breast cancer at age ≥20 years between 2010 and 2016 in 17 Surveillance, Epidemiology and End Results (SEER) registries, including 277,319 non-Hispanic white (white), 44,149 non-Hispanic black (black), 34,141 non-Hispanic Asian or Pacific Islander (Asian) and 43,955 Hispanic women. White and Asian women exhibited a lower proportion of triple-negative breast cancer (9.8 and 9.1% respectively) than black (20.8%) and Hispanic women (12.6%). Black women had a significantly higher risk of all-cause mortality compared with white women in only those with triple-negative breast cancer (hazard ratio: 1.39, 95% CI: 1.29-1.51) and those with hormone receptor-negative/human epidermal growth factor receptor 2 (HER2)-positive breast cancer (1.53, 1.48-1.58) after adjusting for confounders. In those with hormone receptor-positive breast cancer, regardless of HER2 receptor status, the risk of all-cause mortality was not statistically different between black and white women, while the risk of breast cancer-specific mortality was significantly higher in all subtypes of breast cancer among black women. There were racial disparities in the presentation of triple-negative breast cancer and in all-cause and breast cancer specific mortality following stratification by triple-negative status and adjusting for tumor stage, size, grade and treatment.