HER-2 expression was significantly greater in OR- or PR-negative than OR- or PR-positive DCIS (HER-2 positive tumours, 48% OR positive and 58% PR positive; HER-2 negative tumours, 87% OR positive and 93% PR positive (P<0.001, Mann–Whitney U-test). This evidence concerns the gene ERBB2 and ductal breast carcinoma in situ.