ERBB2 and breast cancer: In the past decade, next-generation sequencing and comprehensive genomic profiling have been developed to facilitate detailed classification of cancers, and efficient and unbiased detection of clinically actionable mutations.[1–3] Genetic alterations underlying the cancer pathology reflect cancer biology and might predict response to therapy better than histology.[4,5] It is well established that human epidermal growth factor receptor 2 (HER2) is an oncogene, associated with higher risk of recurrence and a poor prognosis in breast cancer.