Among the 551 patients for whom global genetic ancestry data were available, having a higher percentage of West African genetic ancestry was associated with shorter breast cancer DFS among 246 patients in the HR-positive/ERBB2-negative subgroup compared with all patients with global ancestry data (hazard ratio, 1.45 [95% CI, 1.04-2.04]; P = .03 vs 1.23 [95% CI, 0.98-1.53]; P = .07) (Table 2). This evidence concerns the gene ERBB2 and breast cancer.