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General Information About Adult Brain Tumors


An adult brain tumor is a disease in which abnormal cells form in the tissues of the brain.

There are many types of brain and spinal cord tumors. The tumors are formed by the abnormal growth of cells and may begin in different parts of the brain or spinal cord. Together, the brain and spinal cord make up the central nervous system (CNS).

The tumors may be benign (not cancer) or malignant (cancer). Benign brain tumors grow and press on nearby areas of the brain. They rarely spread into other tissues and may recur (come back). Malignant brain tumors are likely to grow quickly and spread into other brain tissue. When a tumor grows into or presses on an area of the brain, it may keep that part of the brain from working the way it should. Both benign and malignant brain tumors can cause symptoms and, sometimes, death.

Brain tumors can occur in both adults and children. However, treatment for children may be different than treatment for adults.

A brain tumor that starts in another part of the body and spreads to the brain is called a metastatic tumor.

Tumors that start in the brain are called primary brain tumors. Often, tumors found in the brain have started somewhere else in the body and spread to one or more parts of the brain. These are called metastatic brain tumors (or brain metastases). Metastatic brain tumors are more common than primary brain tumors.

The types of cancer that commonly spread to the brain are melanoma and cancer of the breast, colon, lung, and unknown primary site. The types of cancer that commonly spread to the spinal cord are lymphoma and cancer of the lung, breast, and prostate. About half of metastatic brain and spinal cord tumors are caused by lung cancer. Leukemia, lymphoma, breast cancer, and gastrointestinal cancer may spread to the leptomeninges (the two innermost membranes covering the brain and spinal cord).

The brain controls many important body functions.

The brain has three major parts:

  • The cerebrum is the largest part of the brain. It is at the top of the head. The cerebrum controls thinking, learning, problem solving, emotions, speech, reading, writing, and voluntary movement.
  • The cerebellum is in the lower back of the brain (near the middle of the back of the head). It controls movement, balance, and posture.
  • The brain stem connects the brain to the spinal cord. It is in the lowest part of the brain (just above the back of the neck). The brain stem controls breathing, heart rate, and the nerves and muscles used in seeing, hearing, walking, talking, and eating.

The spinal cord connects the brain to nerves in most parts of the body.

The spinal cord is a column of nerve tissue that runs from the brain stem down the center of the back. It is covered by three thin layers of tissue called membranes. These membranes are surrounded by the vertebrae (back bones). Spinal cord nerves carry messages between the brain and the rest of the body, such as a signal from the brain to cause muscles to move or from the skin to the brain about the sense of touch.

There are different types of brain and spinal cord tumors.

Brain and spinal cord tumors are named based on the type of cell they formed in and where the tumor first formed in the CNS. The grade of a tumor may be used to tell the difference between slow- and fast-growing types of the tumor. The grade of a tumor is based on how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread.

Tumor Grading System

  • Grade I (low-grade) — The tumor grows slowly, has cells that look a lot like normal cells, and rarely spreads into nearby tissues. It may be possible to remove the entire tumor by surgery.
  • Grade II — The tumor grows slowly, but may spread into nearby tissue and may recur (come back). Some tumors may become a higher-grade tumor.
  • Grade III — The tumor grows quickly, is likely to spread into nearby tissue, and the tumor cells look very different from normal cells.
  • Grade IV (high-grade) — The tumor grows and spreads very quickly and the cells do not look like normal cells. There may be areas of dead cells in the tumor. Grade IV brain tumors are harder to cure than lower-grade tumors.

Astrocytic Tumors

An astrocytic tumor begins in star-shaped brain cells called astrocytes, which help keep nerve cells healthy. An astrocyte is a type of glial cell and is sometimes called a glioma. Astrocytic tumors include the following:

  • Brain stem glioma: A brain stem glioma forms in the brain stem, which is the part of the brain connected to the spinal cord. It is often a high-grade tumor, which spreads widely through the brain stem and is hard to cure. A brain stem glioma rarely occurs in adults.
     
  • Pineal astrocytic tumor: A pineal astrocytic tumor forms in tissue around the pineal gland and may be any grade. The pineal gland is a tiny organ in the brain that makes melatonin, a hormone that helps control the sleeping and waking cycle.
     
  • Pilocytic astrocytoma (grade I): A pilocytic astrocytoma grows slowly in the brain or spinal cord. It may be in the form of a cyst and rarely spreads into nearby tissues. This type of tumor is most common in children and young adults and in people with neurofibromatosis type 1 (NF1). A pilocytic astrocytoma rarely causes death.
     
  • Diffuse astrocytoma (grade II): A diffuse astrocytoma grows slowly, but often spreads into nearby tissues. Sometimes a diffuse astrocytoma progresses to a higher grade and becomes an anaplastic astrocytoma or a glioblastoma. A diffuse astrocytoma can form in any part of the brain but most often forms in the cerebrum. It is most common in young adults and in people with Li-Fraumeni syndrome. It is also called a low-grade diffuse astrocytoma.
     
  • Anaplastic astrocytoma (grade III): An anaplastic astrocytoma grows quickly and spreads into nearby tissues. An anaplastic astrocytoma may progress to a higher grade and become a glioblastoma. An anaplastic astrocytoma forms most often in the cerebrum and is most common in adults. An anaplastic astrocytoma is also called a malignant astrocytoma or high-grade astrocytoma.
     
  • Glioblastoma (grade IV): A glioblastoma grows and spreads very quickly. A glioblastoma forms most often in the cerebrum. This type of tumor is most common in adults. This type of tumor has a poor prognosis. It is also called glioblastoma multiforme.
     

Oligodendroglial Tumors

An oligodendroglial tumor begins in brain cells called oligodendrocytes, which help keep nerve cells healthy. Oligodendrocytes are a type of glial cell and are sometimes called a glioma. Grades of oligodendroglial tumors include the following:

  • Oligodendroglioma (grade II): An oligodendroglioma grows and spreads slowly and the tumor cells look very much like normal cells. This type of tumor most often forms in the cerebrum. An oligodendroglioma is most common in adults.
  • Anaplastic oligodendroglioma (grade III): An anaplastic oligodendroglioma grows quickly and the tumor cells look very different from normal cells. It may grow in one place or in many places throughout the brain. This type of cancer most often forms in the cerebrum.

Mixed Gliomas

A mixed glioma is a brain tumor that has two types of tumor cells in it — oligodendrocytes and astrocytes. This type of tumor most often forms in the cerebrum.

  • Oligoastrocytoma (grade II): An oligoastrocytoma is a slow-growing tumor and the tumor cells don't look very different from normal cells.
  • Anaplastic oligoastrocytoma (grade III): The tumor cells in an anaplastic oligoastrocytoma look very different from normal cells.

Ependymal Tumors

An ependymal tumor usually begins in cells that line the fluid -filled spaces in the brain and around the spinal cord. Ependymal cells are a type of glial cell and are sometimes called a glioma. Grades of ependymal tumors include the following:

  • Ependymoma (grade I or II): A grade I or II ependymoma grows slowly and has cells that look very much like normal cells. There are two types of grade I ependymoma — myxopapillary ependymoma and subependymoma. These tumors are most common in adults. A grade II ependymoma grows in the ventricle and its connecting paths or in the spinal cord. It is most common in children and young adults and in people with neurofibromatosis type 2 (NF2).
  • Anaplastic ependymoma (grade III): An anaplastic ependymoma grows very quickly and has a poor prognosis.

Embryonal Cell Tumors: Medulloblastoma (Grade IV)

A medulloblastoma is a type of embryonal tumor. The tumor forms in brain cells when the fetus is beginning to develop. This type of brain tumor often begins in the cerebellum. The tumor may spread from the brain to the spine through the cerebrospinal fluid (CSF). A medulloblastoma occurs most often in children or young adults and in people with Turcot syndrome type 2 or nevoid basal cell carcinoma syndrome.

Pineal Parenchymal Tumors

A pineal parenchymal tumor forms in parenchymal cells or pineocytes, which are the cells that make up most of the pineal gland. These tumors are different from pineal astrocytic tumors. Grades of pineal parenchymal tumors include the following:
  • Pineocytomas (grade II): A pineocytoma is a slow-growing pineal tumor that occurs most often in adults.
  • Pineoblastomas (grade IV): A pineoblastoma is a rare tumor that is very likely to spread. This type of tumor is most common in children.

Meningeal Tumors

A meningeal tumor, also called a meningioma, forms in the meninges (thin layers of tissue that cover the brain and spinal cord). It can form from different types of brain or spinal cord cells. A meningioma is most common in adults. Types of meningeal tumors include the following:

  • Meningioma (grade I): A grade I meningioma is the most common type of meningeal tumor. A grade I meningioma is a slow-growing, benign tumor that forms most often in the dura mater (the layer of tissue that covers the brain and is closest to the skull). It is most common in women.
  • Meningioma (grade II and III): This is a rare, malignant meningeal tumor. It grows quickly and is likely to spread within the brain and spinal cord. A grade III meningioma is most common in men.

A hemangiopericytoma is not a meningeal tumor but is treated like a grade II or III meningioma. A hemangiopericytoma usually forms in the dura mater. It often recurs (comes back) after treatment and usually spreads to other parts of the body.

Germ Cell Tumors

A germ cell tumor forms in germ cells, which are the cells that develop into sperm in men or ova (eggs) in women. Germ cell tumors usually form in the center of the brain, near the pineal gland. Germ cell tumors can spread to other parts of the brain and spinal cord. There are different types of germ cell tumors. These include germinomas, teratomas, embryonal yolk sac carcinomas, and choriocarcinomas. Germ cell tumors can be either benign or malignant.

Most germ cell tumors occur in children and in people with Klinefelter syndrome.

Tumors of the Sellar Region: Craniopharyngioma (Grade I) and Pituitary Tumor

A tumor of the sellar region begins in the center of the brain, just above the back of the nose. It can form from different types of brain or spinal cord cells.

  • Craniopharyngioma (grade I): A craniopharyngioma is a rare tumor that usually forms just above the pituitary gland (a pea-sized organ at the bottom of the brain that controls other glands). The tumor may grow into nearby tissues, including the pituitary gland and optic nerves. This can affect many functions, including hormone-making and vision. These tumors occur in adults and children.
  • Pituitary tumor.
  • Other Adult Brain Tumors

    There are many other types of adult brain tumors that are rare and are not discussed in this summary.

    Recurrent Brain Tumors

    A recurrent brain tumor is a tumor that has recurred (come back) after it has been treated. Brain tumors often recur, sometimes many years after the first tumor. The tumor may recur at the same place in the brain or in other parts of the central nervous system.

    The symptoms of adult brain and spinal cord tumors are not the same in every person.

    The symptoms caused by a brain tumor depend on where the tumor formed in the brain, the functions controlled by that part of the brain, and the size of the tumor. Headaches and other symptoms may be caused by adult brain tumors. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:

    Brain Tumors

    • Morning headache or headache that goes away after vomiting.
    • Frequent nausea and vomiting.
    • Vision, hearing, and speech problems.
    • Loss of balance and trouble walking.
    • Weakness on one side of the body.
    • Unusual sleepiness or change in activity level.
    • Unusual changes in personality or behavior.
    • Seizures.

    Spinal Cord Tumors

    • Back pain or pain that spreads from the back towards the arms or legs.
    • A change in bowel habits or trouble urinating.
    • Weakness in the legs.
    • Trouble walking.

    Tests that examine the brain and spinal cord are used to detect (find) adult brain tumors.

    The following tests and procedures may be used:

    • Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
       
    • Neurological exam: A series of questions and tests to check the brain, spinal cord, and nerve function. The exam checks a person’s mental status, coordination, and ability to walk normally, and how well the muscles, senses, and reflexes work. This may also be called a neuro exam or a neurologic exam.
       
    • Visual field exam: An exam to check a person’s field of vision (the total area in which objects can be seen). This test measures both central vision (how much a person can see when looking straight ahead) and peripheral vision (how much a person can see in all other directions while staring straight ahead). Any loss of vision may be a sign of a tumor that has damaged or pressed on the parts of the brain that affect eyesight.
       
    • Tumor marker test: A procedure in which a blood, urine, or tissue sample is examined to measure the amounts of certain substances released into the blood by organs, tissues, or tumor cells in the body. Certain substances are linked to specific types of cancer when found in increased levels in the body. These are called tumor markers.
       
    • Gene testing: A laboratory test in which a sample of blood or tissue is tested for changes in a chromosome that has been linked with a certain type of brain tumor.
       
    • Lumbar puncture: A procedure used to collect cerebrospinal fluid from the spinal column. This is done by placing a needle into the spinal column. The cerebrospinal fluid is viewed under a microscope by a pathologist to check for signs of cancer. This procedure is also called an LP or spinal tap.
       
    • CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
       
    • MRI (magnetic resonance imaging) with gadolinium: A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of the brain and spinal cord. A substance called gadolinium is injected into a vein. The gadolinium collects around the cancer cells so they show up brighter in the picture. This procedure is also called nuclear magnetic resonance imaging (NMRI). Sometimes a procedure called magnetic resonance spectroscopy (MRS) is done during the MRI scan. An MRS is used to diagnose tumors, based on their chemical make-up.
       
    • SPECT scan (single photon emission computed tomography scan): A procedure that uses a special camera linked to a computer to make a 3-dimensional (3-D) picture of the brain. A small amount of a radioactive substance is injected into a vein or inhaled through the nose. As the substance travels through the blood, the camera rotates around the head and takes pictures of the brain. There will be increased blood flow and more chemical reactions (metabolism) in areas where cancer cells are growing. These areas will show up brighter in the picture. This procedure may be done just before or after a CT scan.
       
    • PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the brain. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
       
    • Angiogram: A procedure to look at blood vessels and the flow of blood in the brain. A contrast dye is injected into the blood vessel. As the contrast dye moves through the blood vessel, x-rays are taken to see if there are any blockages.
       

    Most adult brain tumors are diagnosed and removed in surgery.

    If doctors think there may be a brain tumor, a biopsy may be done to remove a sample of tissue. For tumors in the brain, the biopsy is done by removing part of the skull and using a needle to remove the tissue sample. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are found, the doctor may remove as much tumor as safely possible during the same surgery. After the surgery, a pathologist checks the cancer cells to find out the type and grade of brain tumor. The grade of the tumor is based on how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread. A CT scan or MRI may be used to find out if any cancer cells remain after surgery.

    The following tests may be done on the tumor tissue that is removed:

    • Immunohistochemistry study: A laboratory test in which a substance such as an antibody, dye, or radioisotope is added to a sample of cancer tissue to test for certain antigens. This type of study is used to tell the difference between different types of cancer.
    • Light and electron microscopy: A laboratory test in which cells in a sample of tissue are viewed under regular and high-powered microscopes to look for certain changes in the cells.
    • Cytogenetic analysis: A laboratory test in which cells in a sample of tissue are viewed under a microscope to look for certain changes in the chromosomes.

    Sometimes a biopsy or surgery cannot be done safely because of where the tumor formed in the brain or spinal cord. These tumors are diagnosed based on the results of imaging tests and other procedures.

    Certain factors affect prognosis (chance of recovery) and treatment options.

    The prognosis (chance of recovery) and treatment options for primary brain tumors depend on the following:

    • The type and grade of the tumor.
    • Where the tumor is in the brain.
    • Whether the tumor can be removed by surgery.
    • Whether cancer cells remain after surgery.
    • Whether there are certain changes in the chromosomes.
    • Whether the cancer has just been diagnosed or has recurred (come back).
    • The patient's general health.

    The prognosis and treatment options for metastatic brain tumors depend on the following:

    • Whether the patient is younger than 60 years.
    • Whether there are more than two tumors in the brain or spinal cord.
    • Where in the brain or spinal cord the tumors are.
    • How well the tumor responds to treatment.
    • Whether the primary tumor continues to grow or spread.

    The prognosis is better for brain metastases from breast cancer than from other types of primary cancer. The prognosis is worse for brain metastases from colon cancer.

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    Source: National Cancer Institute, www.cancer.gov