In the United States, age-adjusted breast-cancer mortality is about 40% higher among Black women than among non-Hispanic White women (27.7 vs. 20.0 deaths per 100,000 women from 2014 through 2018), despite a lower incidence among Black women (125.8 vs. 139.2 cases per 100,000 women) (see table). It may therefore come as a surprise to many clinicians that before 1980, breast-cancer mortality was slightly lower among Black women than among White ...