ERBB2 and ductal breast carcinoma in situ: HER-2/neu and TP53 gene expression in normal breast tissue is different from what is found in invasive breast carcinoma, and this variation can be assessed by immunohistochemistry.4,5 Many studies have already analyzed c-erbB-2 and p53 protein expression in ductal carcinoma in situ and invasive ductal carcinoma, but most of these studies were carried out in tissue from different women, thereby restricting the usefulness of these data for studying tumor progression.4,5