Compared to other ER‐positive tumors, ultralow risk tumors were significantly (Fisher's test, P < .05) more likely to be of smaller tumor size, lower grade, progesterone receptor (PR)‐positive, human epidermal growth factor 2 (HER2)‐negative and have low Ki‐67 levels (proliferation‐marker). The gene discussed is MKI67; the disease is neoplasm.