ERBB2 and breast cancer: In a retrospective study including 56 patients with HER2-positive BC who developed BM, Nam and colleagues reported a median OS of 13 months in 21 patients who received trastuzumab after diagnosis of mCNS disease compared with 4 months in those (n = 35) who did not receive trastuzumab after diagnosis and 3 months in 70 BM patients with HER2-negative tumors (p = 0.0011) [26].