ABSTRACT
Introduction Central nervous system (CNS) tumors are the most feared cancers. Although cancers not involving the CNS (‘systemic’ cancers, e.g. breast, lung, colon) can cause pain, substantial disability and even death, they attack the body whereas CNS tumors cause seizures, dementia, paralysis and aphasia, symptoms that attack the self. CNS tumors are also feared because many are intractable to therapies that are effective when applied to systemic tumors. There are several reasons why many CNS tumors resist treatment. For example, surgical techniques that allow complete removal of a breast or colon cancer along with a margin of surrounding normal tissue are not feasible in the brain. Radiation therapy that controls tumors elsewhere in the body often fails to do so in the CNS unless it destroys vital normal CNS tissue along with the tumor. Most CNS tumors are either intrinsically resistant to chemotherapeutic agents or develop resistance through genetic instability during treatment.
