In the archival sections from histologically normal breast tissues with high-grade and low-grade molecular abnormalities, we evaluated a large number of “morphologically normal TDLUs” and found that the level of expression of TOP2A protein in HNB tissues with high-grade molecular abnormality on microarray was intermediate between the expression levels in the HNB tissues with low-grade molecular abnormality on microarray and invasive ductal breast carcinoma tissues analyzed. Here, TOP2A is linked to invasive ductal breast carcinoma.