ERBB2 and breast carcinoma: Table 2 summarized the metastatic sites of different breast subtypes. The HR-/HER2+ had the most frequent brain metastasis (0.1%) compared with 0.01% in HR+/HER2- breast cancer, 0.02% in HR+/HER2+ and 0.07% in TNBC (P < 0.0001). The HR-/HER2+ subtype also had the most frequent metastasis to the liver (0.9%) and the lung (0.55%) and the most frequent multiple metastasis (0.79%) compared with other subtypes including TNBC (P < 0.0001, Table 2).