Brain Tumors: Primary - Chemotherapy

Chemotherapy

Chemotherapy involves the use of drugs to kill cancer cells. They may be given by mouth, injected into an IV, or injected directly into the central nervous system. Chemotherapy is not an effective initial treatment for low-grade brain tumors, mostly because standard drugs cannot pass through the blood-brain barrier. In general, chemotherapy for brain tumors is usually administered following surgery or radiation therapy. It is often given as salvage therapy for recurrent or slowly progressing cancers in patients who have previously been treated.

The role of chemotherapy with brain cancers is constantly under investigation, and there are some promising studies. For instance, researchers have identified certain genetic arrangements in specific brain tumors that make them sensitive to the effects of chemotherapy.

Drugs Used in Chemotherapy

Carmustine (also called BCNU). Carmustine is known as a nitrosourea. The response of gliomas to these drugs appears to depend upon certain genetic factors. About 70% of gliomas have an enzyme (MGMT) that protects against their actions. The other 30% are sensitive to it. At this time, it is commonly used for glioblastoma multiforme and, to date, no drug has proved to be superior for these tumors. Unfortunately, most patients quickly develop resistance to the drug, so there have been few improvements in survival rates with its use.

PCV and its Drugs. The drug regimen called PCV (procarbazine, CCNU, and vincristine) is an effective treatment for many common brain tumors. (CCNU is also referred to as lomustine and, like carmustine above, is a nitrosourea.) PCV has significant benefits for about two-thirds of patients with oligodendrogliomas. It has produced improvements in patients with anaplastic astrocytoma and glioblastoma multiforme, but does not appear to be any more effective than carmustine for these tumors. This regimen has significant toxicity, including suppression of red blood cell production and causing nausea, vomiting, and weight loss. Patients must adhere to certain dietary restrictions. Each of these drugs is also used separately and in other combinations.