Furthermore, the Her2+ subtype was significantly more frequent in DCIS compared with invasive disease (13.6 of 5.5%), as previously reported, as was the luminal B subtype (defined as ER+/Her2+), reported as 13.2% frequency in DCIS compared with 5.2% in invasive cancers. Here, ESR1 is linked to ductal breast carcinoma in situ.