To what extent do social determinants and biology contribute to racial disparities in outcomes for early stage, node negative, hormone receptor positive breast cancer? This study found that the answer may be both. The authors analyzed data from >60,000 patients in the SEER database with an Oncotype 21 gene recurrence score. Of these, 90.6% were White and 9.4% were Black. The hazard ratio for breast cancer death among Black women was 1.82. Social determinants such as insurance status and neighborhood disadvantage accounted for 19% of the disparity in survival outcomes. Aggressive tumor biology (as determined by Oncotype) was just as important accounting for 20% of this disparity. | Hoskins, JAMA Oncol 2023