CNA burden was previously shown to be associated with overall survival and disease-specific survival in breast cancer, with chromosome 8 along with chromosomes 1 and 16 carrying the highest CNA burden, suggesting a further role of chromosome 8 in prognosis.13 Key genes in our analysis such as TTN, HSPG2, SYNE1, SYNE2 and MACF1 are frequently altered in breast and other cancers but their roles in HER2+ breast cancer tumorigenesis and trastuzumab response/resistance are as yet uncertain. This evidence concerns the gene ERBB2 and breast cancer.