Malignant Brain Tumors
Malignant tumors can arise from within the brain (primary tumors) or can go to the brain from cancers somewhere else in the body (metastatic tumors).
Primary Brain Tumors
Primary tumors arise from previously existing benign glial tumors or from stem cells (retained cells which form the brain during its development). Malignant primary brain tumors are named for the predominant cell type noted on microscopic examination of tissue obtained from the tumor by a biopsy or tumor removal procedure.
- Glioblastoma (astrocytoma grade4): These tumors grow very rapidly - frequently at a rate of 10% of their volume per week. They are incurable in spite of all the advancements in medicine and neurosurgery over the past 50 years. The average survival of patients harboring these tumors is 37 - 50 weeks following diagnosis with treatment and only 17 weeks after diagnosis without treatment. About half of the patients diagnosed with these tumors had low grade which could have been curable had they been found in time.
- Anaplastic Astrocytoma : These are also incurable tumors. Many of these arise from lower grade (more benign) and potentially curable tumors. The mean survival of lesions such as this is about 18 months with therapy.
- Malignant (or Anaplastic) Oligodendroglioma: These evolve from lower grade oligodendrogliomas and mixed gliomas. As with the abobve tumors, malignant oligodendrogliomas are also incurable in spite of treatment. The average survival of these tumors is about 3 to 5 years following diagnosis.
- Malignant ependymoma. These tumors develop from the cells lining the ventricular system (spinal fluid containing cavities of the brain). They can dump cells into the spinal fluid which then get seeded all over the brain as they travel through the spinal fluid pathways. They can also obstruct the flow of spinal fluid causing obstruction and hydrocephalus - where spinal fluid keeps getting produced but can't get out of the brain and the cavities of the brain keep enlarging as a result These tumors are also incurable. The only thing that surgery, radiation and chemotherapy can do is to prolong survival about 3 to 7 years.
- Medulloblastoma. These are found in children and young adults. They are always located in the cerebellum - the part of the brain that controls balance. Medulloblastomas are fast-growing, invasive and not infrequently spread by means of the cerebral spinal fluid to other parts of the brain. If surgically removed and treated with chemotherapy and sometimes radiation therapy there is a chance of curing them. The best chance for survival occurs when the tumor is found early when it is small and easy to remove and before it has spread to other parts of the brain.
- Other types: Malignant pineal tumors: pinealoblastoma, teratoma. primitive neuroectodermal tumor (PNET), lymphoma, germinoma, malignant meningioma, hemangiopericytoma, hemangioblastoma.
Secondary(Metastatic)Tumors
- Metastatic tumors come from cancers located in other parts of the body. They usually travel to the brain by means of the blood stream and seed within the brain substance where they continue to grow. However, some metastatic tumors grow directly into the skull from locations within the paranasal sinuses or can be trasmitted to the brain by veins. In this latter instance the tumors usually grow between the skull and the brain.
- The most common sites of the primary tumor which can spread to the brain are: lung, bowel, breast and kidney. Melanomas ( a form of skin cancer) not uncommonly travel to the brain.
- Metastatic tumors must be found early and treated as soon as possible while small. If they are small enough they may be treated non-invasively by radiosurgery which is focus radiation delivered by specialized equipment such as the Gamma Knife.
If you have a malignant tumor in your head the sooner it is found, the better your chances for survival!
