Whereas it has been recognised for some time that there is a higher frequency of Her2-positive DCIS compared with Her2-positive invasive breast cancer (Park et al, 2006), there are several reports suggesting that, if a basal category of DCIS exists, it is less frequent than basal type invasive carcinoma, though others suggest a very similar frequency (Livasy et al, 2007; Meijnen et al, 2008; Tamimi et al, 2008). This evidence concerns the gene ERBB2 and invasive breast carcinoma.