Solid lesions had the highest fraction of proliferating epithelial cells (median 11.5% vs 2.8% p < 0.02—Mann–Whitney, Supplementary Fig. 5a), and interestingly 3/10 HG-DCIS cribriform lesions (two Her2-like, one Luminal B) had markedly higher proliferation. Here, ERBB2 is linked to ductal breast carcinoma in situ.