In women with ER-positive, HER2-negative disease, the crude breast cancer mortality rate tended to increase with Ki67 score, with rate ratios of 1.00, 1.29, 1.28, 1.75, 3.54, and 7.26 for Ki67 scores of 0%-5%, 6%-10%, 11%-19%, 20%-29%, 30%-39%, and 40%-100%, respectively (Ptrend < .001) (Figure 2, A, top panel and Supplementary Figures 6 and 7, available online). This evidence concerns the gene ERBB2 and breast cancer.