ERBB2 and breast neoplasm: It has become increasingly evident that TOP2A alterations rarely occur in HER2- breast tumors (reviewed in [9]) in line with our finding that no HER2- tumor showed focal amplification of TOP2A. In this study, TOP2A amplification or deletion was observed in 31% and 18% of HER2+ tumors, respectively, concordant with previous reports (reviewed in [9]).