The goal of this study was to determine whether the greater relative risk of breast cancer mortality observed among women with hormone receptor-negative tumors was similar for those with different demographic characteristics, such as race/ethnicity, age of cancer diagnosis, and year of cancer diagnosis, and for those with different tumor characteristics, such as stage, grade, tumor size, and histology, using data from Surveillance, Epidemiology, and End Results (SEER), the population-based tumor registry program of the National Cancer Institute (NCI). This evidence concerns the gene NR4A1 and neoplasm.