Brain metastases

Metastatic brain tumors are the most common intracranial neoplasm in adults, affecting up to 10% of adults with cancer in the United States. The risk of developing brain metastases varies by primary cancer type, with lung cancer, breast cancer, and melanoma accounting for the majority. The incidence of brain metastases appears to be rising because of several factors, including an aging population, better treatment of systemic disease, and improved cranial imaging techniques. Therapeutic approaches to brain metastases include surgery, whole brain radiotherapy (WBRT), stereotactic radiosurgery (SRS), and chemotherapy. Many patients are treated with a combination of these, and treatment decisions must take into account clinical prognostic factors in order to maximize survival and neurologic function while avoiding unnecessary treatments. WBRT remains the most widely used treatment for patients with brain metastases. Although many radiation sensitizers have been studied over the years, none has emerged for widespread use. For patients with a limited number of brain metastases and favorable prognostic factors, local therapies such as surgery and SRS improve control rates and may extend survival compared with WBRT alone. SRS can also be used effectively at recurrence in patients with a limited number of lesions. Chemotherapy has traditionally played only a salvage role for brain metastases when all other treatments have failed, but research is likely to increasingly focus on systemic options such as targeted agents and angiogenesis inhibitors, as well as on novel delivery techniques and multidrug resistance pathways specific to brain in order to expand treatment options for this growing population of patients.