Astrocytoma

Astrocytomas account for about 4% of brain tumors. They develop from cells called astrocytes that help repair damaged neurons in the brain. Astrocytomas can be slow-growing or aggressive, depending on the grade of the tumor. Tumor grade is a description of how the cancer cells look under a microscope compared to normal cells. Grade I astrocytomas, also known as pilocytic astrocytomas, frequently occur in children and do not often progress to higher grade tumors. These grade I tumors can (at times) be cured with surgery alone. Grade II astrocytomas frequently are “inoperable” because they are invasive and do not form a discrete mass. High-grade astrocytomas such as anaplastic astrocytomas (grade III) and glioblastomas (grade IV) look very different from healthy cells under a microscope and grow very aggressively. These tumors have many cells in the process of dividing (how tumors grow) and abnormal blood vessels which are created to bring nutrients to these actively dividing tumor cells. These tumors can invade healthy tissue throughout the brain. New alterations in the DNA such as MGMT, P53, and IDH-1(abbreviations for specific genes) have been discovered and can be used to help your doctor with prognosis as well as to guide your treatment. As new genetic information is learned, therapies are being created to target the genetic alterations.

Ependymoma

Ependymomas account for about 22% of all brain tumors. These tumors form in the ependymal cells that line the ventricles in the brain and can also occur in the spinal cord. Ependymomas are usually low-grade and rarely invade healthy tissue, but they can also be very aggressive. They occur frequently in children and can spread through the spinal fluid to other parts of the brain and spinal cord.

Oligodendroglioma

These tumors make up 4-15% of gliomas and arise from the oligodendrocytes, which make up the myelin sheaths (insulation) that surround and protect the nerve fibers in your brain. These can be slow-growing, but can often be aggressive and invade healthy tissue throughout your brain. Genetic deletions in the chromosomes 1p and 19q have been associated with a better prognosis and response to chemotherapy.

Meningioma

Meningiomas account for over 41% of brain tumors. These tumors form in the meninges, the layers of tissue surrounding the brain. Most meningiomas are benign and can be observed or removed by surgery. About 20% of meningiomas are malignant but relatively slow-growing. These tumors can very rarely invade healthy brain tissue but are not very aggressive, so these tumors can usually be removed with surgery. The ability to be removed depends on the tumor size and location. Rarely, meningiomas in certain areas along the brain cannot be removed safely or completely due to the risks of neurologic injury.

Schwannoma

These tumors form in the Schwann cells that surround or insulate your cranial nerves and other nerves throughout your body. Schwannomas are benign tumors, but can still press on vital parts of your brain, spinal cord, nerves, and muscles, and cause many neurologic symptoms. Doctors usually treat aggressive or malignant schwannomas with a combination of surgery and radiation therapy. Multiple schwannomas may be an indication of Neurofibromatosis, a genetic condition that makes a person prone to develop these types of tumors.

Medulloblastoma

These tumors form in the neuroectodermal cells (very young nervous system cells) in the cerebellum. Medulloblastomas are malignant and usually very aggressive and can spread throughout the brain and spinal fluid, and can also (rarely) metastasize outside of the central nervous system. Doctors commonly treat these tumors with a combination of surgery, chemotherapy, and radiation.

Craniopharyngioma

Craniopharyngiomas arise from embryonic (very early development) cells along the pituitary gland. These tumors, therefore, are typically found in between the brain and the pituitary gland and can press on vital structures such as the pituitary gland, hypothalamus, and optic nerve. These tumors can cause hormone and vision problems, and are difficult to remove without further damaging these structures. Both surgery and radiation play a role in treatment.

Central Nervous System Lymphoma

Lymphomas of the central nervous system are relatively rare and form in the lymph tissues of the brain and spinal cord. Elderly people or people with immune disorders such as autoimmune deficiency syndrome (AIDS) are much more likely to develop lymphomas of the brain. Doctors usually treat these tumors with chemotherapy, and less often with a combination of radiation and chemotherapy.