Role of chemotherapy on brain metastasis.

Cytotoxic chemotherapy has been considered ineffective for brain metastasis, traditionally because of poor penetration across the blood-brain barrier. However, cytotoxic chemotherapy could be effective in some specific situation, e.g. macroscopic brain metastasis of chemosensitive disease, such as small cell lung cancer, germ cell tumor and breast cancer. Recently, tyrosine kinase inhibitors targeting epidermal growth factor receptor (EGFR) (gefitinib and erlotinib) or human epidermal growth factor receptor 2 (HER2) (lapatinib) have a promising activity to brain metastasis of lung cancer with activating EGFR mutations or breast cancer with HER2 over expression. More molecular targeting agents will also be used against brain metastasis with the advance of understanding of molecular mechanism of cancer.