Chemotherapy for the treatment of metastatic brain tumors.

Metastatic brain tumors are the most common complication of systemic cancer and affect 20-40% of all adult cancer patients. Whole-brain radiotherapy and surgical resection of accessible, solitary lesions have been the mainstay of treatment. Recently, chemotherapy has become a more viable treatment option for metastatic brain tumors. Many different drugs and administrative approaches have been shown to be clinically active. Traditional chemotherapy given before or during irradiation can be effective with agents such as cyclophosphamide, cisplatin and etoposide. Nontraditional approaches, such as tempozolomide and intra-arterial administration of carboplatin, have demonstrated activity against recurrent metastatic disease. In early clinical trials of interstitial chemotherapy, biodegradable polymers have shown some clinical efficacy and have been well-tolerated. Molecular approaches are also under investigation in response to new information regarding the metastatic phenotype. Potential targets include growth factor receptors and other protein tyrosine kinases, internal signal transduction pathways, ras activation and matrix metalloprotease activity. New clinical trials will be needed to investigate these new molecular-based therapeutics, alone and in combination with currently available treatment options, to determine the optimal application of chemotherapy to metastatic brain tumors.