ESR1 and ductal breast carcinoma in situ: Tamimi et al (2008) also report significant differences between molecular phenotypes in DCIS and invasive breast cancer. In a large study comparing the immunoprofile of invasive breast cancer (n=2249) and their associated DCIS (n=272), they showed that the basal subtype (defined as ER/PR/Her2 negative, positive for EGFR and for CK5/6) was less frequent in DCIS compared with invasive cancers (7.7 of 10.9%), and more so when restricted to invasive ductal carcinoma.