ERBB2 and breast cancer: An interesting study published recently reported the activity of HER2 pathway was significantly lower in MBC samples than in IDC samples although all patients were clinically categorized as negative for HER2 amplification.24 Based on the above study, it has been reported that the activation of HER‐2/CXCR4/ Akt signaling pathway in primary breast tumors could contribute to the formation of bone metastases in breast cancer,25 and HR‐negative/HER2‐positive subtype patients had a considerably high proportion of liver metastasis,12 which might account for fewer bone and liver metastasis of MBC.