We then examined a second independent patient cohort of 118 patients with non‐high‐grade (low‐ and intermediate‐grade) DCIS, with or without associated early invasive cancer (stage 0 and stage I), for increased power in evaluation of TBX3 association with invasiveness of low‐grade breast cancers. The gene discussed is TBX3; the disease is ductal breast carcinoma in situ.