Brain tumors make 1% of all cancers. The most common types of tumors are gliomas(50% of all CNS tumors), meningiomas(20% of all CNS tumors) and primary CNS lymphomas(1% of all CNS tumors). Other common types are oligodendrogliomas, ependymal and choroid plexus tumors, medulloblastomas, neurilemmomas, hemangioblastomas, neurosarcomas and sarcomas. The incidence of high-grade astrocytomas in the elderly seems to be rising. Frequent use of imaging modalities like CT scan and MRI of brain has resulted in increased recognition of CNS tumors in elderly population with neurological problems.
These CNS tumors present with headeche, nausea, vomiting, seizures, altered mental status and focal neurologic symptoms.
The diagnosis is usually confirmed with CT scan or MRI. Surgery is the initial and primary treatment for CNS tumors. It can be curative for benign tumors. Radiation Therapy can cure some tumors (like medulloblastomas) and prolong suffering in others. Radiation is also the primary tratment for metastatic brain tumors, epidural cord compression and leptomeningeal malignancies.
Chemotherapy has only small role to play in the treatment of CNS tumors. Some of the tumors that are treated with chemotherapy include high grade astocytomas (BCNU), anaplastic oligodendrogliomas and primary CNS lymphoma (CHOP).
Corticosteroids are important in relieving cerebral edema. Anticonvulsants are used prophylactically to prevent and treat seizure. In the event of deep venous thrombosis anticoagulation with heparin and coumarin is achieved.
Low grade Astocytomas have favorable outcome. The most powerful prediction of survival is age. The mean age at presentation is 37 years. Children survive for more than 10 years. For patients older than 40 years survival is only 5 years. These tumors can be "observed" for many years and Surgery or Radiation therapy can be considered for diseased progression. High grade astocytomas are aggressive, with survival measured in months. Surgery is the main modality of treatment. Radiation therapy and sometimes chemotherapy can be used. Oligodendrogliomas make 4% of all tumors. The median survival for low grade oligodendrogliomas is about 10 years and for patient with anaplastic oligodendrogliomas is 3 to 5 years. Surgery is the main modality of treatment. Chemotherapy (PCV) and radiation therapy also have a role.
Primary CNS lymphomas are rapidly increasing in incidence. One of the main reasons for this is the epidemic of AIDS. Primary CNS lymphoma is also seen following renal and cardiac transplantation and in congenitel immunodeficiency syndrome. They are primarily treated with chemotherapy (CHOP). Radiation therapy also has a role to play. In transplant settings withdrawal of immunosuppression might be sufficient.
Brain metastases are the most common CNS tumors. Cancers of lung, breast, melanomas and unknown primary frequently metastasize to brain. Single brain metastases can be treated with surgery and radiation therapy. Multiple brain metastases are treated with whole brain radiation. Chemotherapy is rarely used.
Sometimes metastases can involve leptomeninges. This results in involvement of brain, spinal cord and cranial nerves. Lumbar puncture is important in diagnosis. Treatments include Radiation therapy to the entire neuroaxis. Intrathecal chemotherapy has an important role to play.