Brain cancer chemotherapy consists of a variety of drugs used singly or mostly in combinations. Chemotherapy for brain cancer is generally used post surgery or to avoid harmful effects of radiation directly on the brain.
Some of the drugs used for treating brain cancer are-

Temozolomide is one of the oldest drugs used in the treatment of brain cancer. It is taken orally. It was initially used for anaplastic astrocytoma and then along with radiation for glioblastoma. Nowadays it is used after radiation therapy to treat glioblastoma. The drug works well for patients with a specific genotype. The side effects caused are constipation, nausea, fatigue and headache.

Carmustine is used to treat glioblastoma, medulloblastoma and astrocytoma. It is administered intravenously or through a wafer implant that is surgically placed into the brain cavity after the tumor is removed. The side effects include nausea and vomiting, fatigue, respiratory problems and lung scarring. Side effects of intravenous carmustine are bone marrow impairment that leads to low blood counts. In case of a wafer implant, the side effects include seizures, brain swelling and infection in the brain cavity.

PCV is an abbreviation for a combination of three drugs- procarbazine, lomustine (CCNU), and vincristine. It is used to treat oligodendroglioma and oligoastrocytoma. This combination could be used alone or with other drugs. Procarbazine and lomustine are taken orally while vincristine is given intravenously. The side effects of this combination drug include lowered blood cell counts, nausea and vomiting, constipation, fatigue, and mouth sores. Procarbazine leads to high blood pressure when taken with foods high in tyramine. Certain foods like beer, red wine, cheese, chocolate, processed meat, yogurt, etc should be avoided during this treatment.

Cisplatin and carboplatin are common drugs used to treat glioma and medulloblastoma. These drugs are administered intravenously. The side effects of this drug are nausea and vomiting, hair loss and muscle weakness.

Clinical research is going on to develop effective treatment for brain cancer. Some of the drugs under research are-

• Tamoxifen and paclitaxel that are used to treat breast cancer
• Topotecan used to treat ovarian and lung cancers
• Vorinostat used to treat cutaneous T-cell lymphoma
• Irinotecan in combination with other drugs and treatments

There are severe obstacles to enhance the effectiveness of chemotherapy in case of primary brain cancers. Blood brain barrier is a means of protecting the brain from toxic chemicals. Hence, toxins are kept out of the brain. Although this is very good under normal circumstances, it hampers the ability of many chemotherapeutic drugs to penetrate the brain cells because of blood brain barrier. Distribution of chemotherapeutic drugs within the brain is also not good.

However, there are some drugs, which are an exception to this rule and easily cross the blood brain barrier. They are BCNU, CCNU, procarbazine, thiotepa and high dose methotrexate. New approaches have been developed which destroy the blood brain barrier by using certain agents like mannitol. Some drugs bypass the blood brain barrier as they are infused directly into the cerebrospinal fluid through the carotid and vestibular arteries. Astrocytoma and high-grade glioblastoma are extensively treated with chemotherapy.

Brain cancer chemotherapy is still under clinical research for newer drugs with reduced side effects. Although, chemotherapy is not an option especially for recurred brain cancer, it is used along with other therapies in clinical trials.