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. This evidence concerns the gene ERBB2 and breast carcinoma.