ERBB2 and breast cancer: Median time to brain metastases from initial diagnosis of primary BC was 19.9 months in TNBC, 32.1 months in HER2-positive without trastuzumab, 35.4 months in HER2-positive with trastuzumab, and 59.8 months in HR-positive/HER2-negative patients, respectively (p<0.001, Figure 2A).