ERBB2 and breast cancer: Perez et al. investigated the efficacy of trastuzumab plus adjuvant chemotherapies, in a large randomized phase III clinical trial, showing that in patients with HER2 IHC−/FISH+ BC no advance in DFS has been obtained adding trastuzumab, while patients with HER2 IHC3+/FISH− BC exhibited DFS similar to those with HER2 IHC3+/FISH+ tumors, suggesting a key role of HER2 protein overexpression15.