ERBB2 and breast cancer: However, the younger age distribution for breast cancer, studies documenting higher mortality risk after adjusting for socioeconomic status, and the two-fold higher population-based incidence rates of the biologically aggressive triple-negative breast cancer (TNBC; tumors that are negative for estrogen receptor, progesterone receptor, and HER2/neu) phenotype within the African American community have fueled speculation that African ancestry itself might be associated with hereditary susceptibility for specific patterns of breast cancer.12-14