Molecularly targeted agents are now available in the treatment of brain metastases, such as the oral tyrosine kinase inhibitor (TKI) lapatinib for HER-2-expressing breast cancer patients.29 These patients have a reported high risk of brain metastases, which may be due to the poor penetration through the BBB of the otherwise effective HER-2 targeting drug trastuzumab, in addition to the possibility that HER-2 –expressing breast cancer may be more biologically aggressive.29 This evidence concerns the gene ERBB2 and breast cancer.