Brain cancer can arise either through cancerous cells originating in the brain or through cancerous cells originating in other organs and metastasizing to the brain. When cancerous cells originate in the brain, it is often called gliomas or glioblastoma multiform (GBM). These cancers can be highly lethal and are often treated with surgery, radiation, and a chemotherapy, temozolomide (Temodar). Temodar is one of the few cancer drugs which can penetrate the blood-brain barrier. In the US, gliomas, and GBMs make up ~30,000 cases a year.
When a cancer originates in a non-brain organ and eventually metastasizes to the brain, it most commonly comes from lung, breast, melanoma (skin), and kidney cancers. This collection of brain metastasis makes up ~250,000 cases a year and is growing rapidly. In fact, as we develop better therapies in these indications, we are seeing a rapid rise in brain metastasis. For example, the rate of brain metastasis in advanced breast cancer has increased from ~12% in 2000 to an estimated 30% rate. Treatment of brain metastasis may include radiation therapy and surgery or other ablative techniques. Systemic agents utilized to treat these cancers have less benefit once the cancer metastasizes to the brain as they are unable to cross the blood-brain barrier and have therapeutic effect in the region.
For more information on brain cancers, please see the National Brain Tumor Society.