Brain tumors have more than 120 different types, according to the National Brain Tumor Society. Some brain tumors, such as a glioblastoma multiforme, are malignant and may be fast-growing. Other types of brain tumors, such as a meningioma, may be slow-growing and benign.
Primary brain tumors form in brain cells and are categorized by the type of cell or where in the brain they first develop. For instance, astrocytomas form in star-shaped cells called astrocytes. Pituitary tumors are found in the pituitary gland at the bottom of the brain. The most common primary brain tumors are called gliomas, which originate in the glial (supportive) tissue. About one-third of all primary brain tumors and other nervous system tumors form from glial cells.
Aside from tumors in the brain, cancer may begin in, or spread to, other areas of the central nervous system (CNS), such as the spinal cord or column, or the peripheral nerves. Cancer that develops in the spinal cord or its surrounding structures is called spinal cancer. Most tumors of the spine are metastatic tumors, which have spread to the spine from another location in the body.
Many brain tumors are cancerous. For example, more than half of all gliomas diagnosed in adults are glioblastomas, a very aggressive form of brain cancer. Ependymomas and oligodendrogliomas also are types of brain tumors that may be malignant. But not all brain tumors are cancerous. Many meningiomas, craniopharyngiomas and pituitary tumors are benign. That’s why it’s important to get a thorough and accurate diagnosis of a brain tumor. It’s also important to understand that even benign tumors can damage brain tissue and cause side effects, such as headaches, fatigue and double or blurred vision. So even if a brain tumor is not cancerous, receiving timely and appropriate treatment may be critical to your overall health.Types of brain cancer
Astrocytomas, which are the most common CNS tumor, arise anywhere in the brain or spinal cord, and develop from small, star-shaped cells called astrocytes. In adults, astrocytomas most often occur in the cerebrum, the largest part of the brain. The cerebrum uses sensory information to tell us what’s going on around us and how the body should respond. The cerebrum also controls speech, movement and emotions, as well as reading, thinking and learning.
Brain stem gliomas are a type of astrocytoma that forms in the brain stem, which controls many vital functions, such as body temperature, blood pressure, breathing, hunger and thirst. The brain stem also transmits all the signals to the body from the brain. The brain stem is in the lowest part of the brain and connects the brain and spinal cord. Tumors in this area can be difficult to treat. Most brain stem gliomas are high-grade astrocytomas.
Glioblastoma multiforme, also known as glioblastoma, GBM or grade IV astrocytoma, is a fast-growing, aggressive type of CNS tumor that forms on the supportive tissue of the brain. Glioblastoma is the most common grade IV brain cancer. Glioblastomas may appear in any lobe of the brain, but they develop more commonly in the frontal and temporal lobes. Glioblastomas usually affect adults.
Meningioma develop in the cells of the membrane that surround the brain and spinal cord. Meningiomas (also called meningeal tumors) account for approximately 15 percent of all intracranial tumors. Most of these tumors are benign (non-cancerous and slow-growing). Meningiomas are typically removed with surgery. Some meningiomas may not need immediate treatment and may remain undetected for years. Most meningiomas are diagnosed in women between 30 and 50 years old.
Aside from astrocytomas, there are a number of different primary brain tumors and other nervous system tumors that form from glial cells. They include:
Pituitary tumors are lumps that form in the pituitary, a small gland about the size of a pea that sits inside the skull, just below the brain and above the nasal passages. The pituitary gland produces hormones that control the levels of other hormones secreted by endocrine glands throughout the body, giving it an important role in controlling key body functions and the hormonal system.
The pituitary gland is made up of four parts: the anterior (front) lobe and posterior (back) lobe, which function independently of each other, as well as the intermediate area between the two lobes and the stalk that connects the pituitary to the interbrain (which includes the thalamus, hypothalamus and epithalamus). Most pituitary tumors form in the anterior lobe. They very rarely develop in the posterior lobe. Pituitary tumors represent 9 to 12 percent of all primary brain tumors.
The vast majority of pituitary tumors are pituitary adenomas, benign growths that do not spread beyond the skull. Even though these tumors are not cancerous, they often cause other medical issues because they are located near the brain and may cause the pituitary to produce excess hormones.
Pituitary cancers, called pituitary carcinomas, are very rare—only a few hundred have been documented in the United States, according to the American Cancer Society. Because pituitary cancers and benign adenomas look very similar under a microscope, the carcinomas are often diagnosed only when they spread to other parts of the body.
There are a number of different brain tumors that do not begin in glial tissue.
Craniopharyngiomas develop in the area of the brain near the pituitary gland (the main endocrine gland that produces hormones that control other glands and many body functions, especially growth) near the hypothalamus. These brain tumors are usually benign. However, they may sometimes be considered malignant because they may create pressure on, or damage, the hypothalamus and affect vital functions (such as body temperature, hunger and thirst). These tumors occur most often in children and adolescents, or adults over age 50.
Germ cell tumors arise from developing sex (egg or sperm) cells, also known as germ cells. The most common type of germ cell tumor in the brain is the germinoma. Aside from the brain, germinomas can form in the ovaries, testicles, chest and abdomen. Most germ cell tumors occur in children.
Pineal region tumors occur in or around the pineal gland, a small organ located in the center of the brain. The pineal gland produces melatonin, a hormone that plays an important role in the sleep-wake cycle. These brain cancer tumors can be slow growing (pineocytoma) or fast growing (pineoblastoma). Since the pineal region is very difficult to reach, it requires a high level of surgical expertise to remove these tumors.
Medulloblastomas are fast-growing brain tumors that develop from the neurons of the cerebellum. The cerebellum is the lower back of the brain and controls movement, balance and posture. These tumors are usually found in children or young adults.
Primary CNS lymphomas develop in lymph tissue of the brain or spinal cord. This type of brain tumor is usually found in people whose immune systems are compromised.
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