ERBB2 and cancer: TOP2A is among the genes reported to be co-amplified in the HER2 amplicon at 17q12-21, and alterations in TOP2A gene copy number are well studied because it is a molecular target of many anti-cancer drugs termed topo II inhibitors, including anthracyclines, epipodophyllotoxins, actinomycxin, and mitoxantrone[27,28].