Brief Description of Common Brain Tumors
These tumors come from astroctyes, which are star shaped cells that are part of the supportive tissue of the brain. Low grade astrocytoms are entirely curable, and even high grade astrocytomas in children can be cured with a combination of intensive chemotherapy and radiation.
Brain Stem Tumors
The tumors located in the brain stem can come from a variety of cell types: astrocytoma, anaplastic astrocytomas, glioblastoma multiforme, or a mixed tumor. Because the brain stem is essential for basic life functioning, surgery is only possible if the tumor is well circumscribed (limited or confined). Well circumscribed low grade tumors in the brainstem can be treated effectively with surgery alone. Other tumors rely on a combination of chemotherapy and radiation. Tumors in the pons tend to be high grade, and very difficult to control.
Craniopharyngiomas are tumors that arise from the stalk of the pituitary gland at the base of the brain.The pituitary gland is the master hormone gland in the body. The histology of craniopharyngioma is low grade and generally not considered cancerous. There are serious treatment challenges if the location of the tumor is in the pituitary stalk and its growth and attachment is in the hypothalamus, which is in the center of the brain. Surgery is curative only if all the tumor is removed. Attempts to remove the tumor uniformly can disturb all hormonal function and can leave devastating neurological impairments if the hypothalamus is affected by surgery. While hormones can be replaced, the neurological impairment can be permanent. Consequently, treatment is tailored to each individual patient's tumor pattern with a combination of surgery, local chemotherapy, and radiation. Systemic chemotherapy has no effect on this tumor.
This is a type malignant brain tumor that comes from the cells that line the internal brain surface. These cells are called “ependyma" and they line the fluid spaces of the brain and spinal cord. Ependymomas grow in the fluid filled spaces of the brain and often encase the nerves (cranial nerves) and blood vessels on the surface of the brain. This makes surgery a technical challenge. However, surgery is critical for this tumor. Only by removing the vast majority, if not all of the tumor, is there a chance for a cure. After surgery, radiation is typically used for the cells left behind. Chemotherapy is reserved as a secondary role or for recurrences of the tumor. We have used chemotherapy first (neoadjuvant chemotherapy) to shrink the tumors sufficiently, in order to make a complete resection less dangerous. During surgery, we monitor all the cranial nerves with electrodes so we know that they are working, as we carefully dissect the tumor from the nerves and blood vessels.
These tumors are located anywhere on the surface in the brain. However, the most common location is in the temporal lobe of the brain. These tumors come from a cell type called a “ganglia” (a ganglion is a group of neurons). Gangligliomas are usually slow growing tumors and are mostly benign. They present mostly as seizures in children and teenagers. A complete resection can be curative.
These tumors come from a tissue that is called Primitive Neuroectodermal Tissue (“PNET”). PNET is a general term that means several different types of tumors that come from undeveloped brain cells. These tumors are malignant and are most commonly located in the cerebellum. A PNET in the cerebellum is called medulloblastoma. They are fast growing and many spread into the brain, spinal fluid or spinal cord by the time they are found. They often spread to other parts of the central nervous system via the spinal fluid. This usually occurs in younger children ages 2-6, and is more common in boys than girls. Surgery to remove the tumor, so that no more than a small grape is left behind sets the stage for effective treatment with radiation and chemotherapy. Since radiation has devastating effect in very young children, at Children's Hospital, we offer Head Start Protocols. These protocols use intensive chemotherapy to cure the tumors in young children without radiation.
Nerve cells have a covering on part of the cell called myelin. This helps the electrical signal travel faster along the cell. The cells that make the myelin are called oligodendrocytes. They are located in both halves of the brain, mostly in the frontal and temporal lobes. An oligodendroglioma is a tumor of these cells. Oligodendroglioma can be low or high grade. Complete removal is important and this may be sufficient to treat low grade oligodendrogliomas. High grade oligodendrogliomas or those that cannot be removed because of their location, require additional therapy such as radiation or chemotherapy.
Optic Nerve, Optic Pathway Glioma
Extending from the back of the eye are two large nerves going to the brain called opti nerves. The visual signals from these optic nerves then reach the back part of the brain, called the occipital lobes. This is where we “see” the visual signals by a looping track called the visual pathway. Tumors can occur along the optic nerves or optic pathway. They can cause visual impairment or blindness. These tumors can be treated effectively with a judicious combination of surgery and chemotherapy.
Pineal Gland Tumors
The pineal gland is located in the back part of the third ventricle. There are many different cell types that can cause a tumor in this area. Germiinomas are the most common, but can include teratomas, astroctyomas, pineocytomas, and pineoblastomas.