Breast cancer is the most common cancer in women. Prognosis and treatment depend on many factors, including the presence of estrogen and/or progesterone receptors (ER/PR) and levels of human epidermal growth factor receptor 2 (HER2). More research is needed to understand how demographic and clinicopathological factors jointly influence patient outcomes. In this SEER-based study, data was collected for 912,059 women diagnosed with breast cancer between 2000 and 2017 with an ERPR status were recorded; 438,667 of these women had a HER2 status recorded. Kaplan-Meier analysis and Cox regression were performed to assess patient survival. Incidence rates were highest among non-Hispanic Whites and for ER+PR+ and Luminal A (HR+/HER2-) cancers.The median patient survival time was 212 months (95%CI, 211- 213). In multivariate analysis, ER-PR- patients had 47% (HR, 1.470, 95%CI: 1.457-1.484) greater risk of death than ER+PR+ patients, and non-Hispanic black patients had 28% (HR, 1.279, 95% CI: 1.250- 1.308) greater risk of death than non-Hispanic white patients. Triple-negative (HR-/HER2-) patients had double (HR, 2.043, 95%CI: 2.005- 2.083) the risk of death of Luminal A patients in univariate analysis. There is a significant need for improved treatment of breast cancers without hormone receptors or elevated HER2 protein. This study also demonstrates that Black women face a higher risk of death than White women with similar characteristics. Further investigation into this disparity is needed.
