ERBB2 and metastatic neoplasm: In summary, although main molecular features from primary tumors are known to be maintained in advanced disease [9, 10], here we report higher proportion of aggressive molecular subtypes in the metastatic setting, especially in HR+/HER2‐negative disease, and unique biological features of each metastatic site, indicating a role of the tumor microenvironment and the need to biopsy metastatic disease in patients with advanced breast cancer to better select the treatment strategy for each patient.