Brain Cancer I

http://www.apjohncancerinstitute.org/cancer/brain.htm


What is Brain Cancer?
The brain and spinal column make up the central nervous system (CNS), where all vital functions of the body are controlled. When tumors arise in the central nervous system, they are especially problematic because a persons thought processes and movements can be affected. These tumors can also be difficult to treat because the tissues surrounding a tumor that may be affected by surgery or radiation may play a vital role in functioning.
There are two broad types of cancers occurring within this system. Primary tumors originate in the central nervous system, whereas secondary tumors migrate from cancers located elsewhere in the body, such as breast cancers. Secondary, or metastatic, brain tumors, are more common than primary brain cancers. This section focuses on primary brain cancers.What is the brain?
Together, the brain and spinal cord form the central nervous system. This complex system is part of everything we do. It controls the things we choose to do,like walk and talk,and the things our body does automatically,like breathe and digest food. The central nervous system is also involved with our senses; seeing, hearing, touching, tasting, and smelling, as well as our emotions, thoughts, and memory.The brain is a soft, spongy mass of nerve cells and supportive tissue. It has three major parts: the cerebrum, the cerebellum, and the brain stem. The parts work together, but each has special functions.
The brain is composed of:
A. The cerebrum, which is divided into two cerebral hemispheres. The cerebrum is the largest part of the brain and is divided into lobes where discrete functions occur. Higher reasoning takes place in the cerebrum.
B. The cerebellum, or little brain, located beneath the cerebrum. The cerebellum controls coordination and balance.
C. The brain stem, which is the lowest portion of the brain and connects to the spinal cord, controls involuntary functions essential for life, such as the beating of the heart and breathing.
D. The meninges, membranes that surround and protect the brain and spinal cord. There are three meninges.
The types of primary brain cancers are classified according to the type of cells from which they originate. Oncologists describe the tumor based on its characteristics. For example, a noninfiltrating tumor can be expected to grow slowly and not invade surrounding structures. A well-differentiated tumor is also slow growing, but has the potential to be invasive. Anaplastic tumors are generally more aggressive.
Gliomas - Most brain tumors are gliomas, which originate in the glial cells (the supportive cells of the nervous system). Gliomas can be described as low-grade (slow-growing); intermediate-grade (more aggressive); or high-grade (very aggressive).
There are many different types of gliomas:
E. Astrocytoma, the most common type of glioma, which usually begin in cells called astrocytes within the cerebrum, or the cerebellum. Glioblastoma multiforme is a form of very aggressive astrocytoma.
F. Oligodendroglioma, a tumor that develops from oligodendrocytes. These cells are responsible for producing the myelin that surrounds nerves.
G. Brain stem glioma, which begins in the glial cells in the brain stem.
H. Ependymoma, which begins in the ependyma, the cells that line the passageways in the brain where cerebrospinal fluid is made and stored.
I. Mixed tumors, which are composed of more than one of the glial cell types.
Nonglial tumors include:
J. Acoustic schwannoma, which occurs in the vestibular nerve.
K. Craniopharyngioma, which begins near the pituitary gland.
L. Meningiomas, which originate in the meninges surrounding the brain and spinal column. Even though these tumors are generally benign, they may cause significant symptoms as they grow and press on the brain or spinal cord.
M. Medulloblastoma, which arises from granular cells in the cerebellum.
N. Primary CNS lymphoma.
O. The pineal and pituitary glands, located near the base of the brain, can also be the source of tumors.
Since brain and spinal cord tumors behave somewhat differently than tumors arising in other parts of the body, they are often referred to as low and high grade, rather than benign and malignant. Oncologists assign the terms low, intermediate, or high grade to a patient’s tumor based on parameters that predict how quickly the tumor can grow and its potential to spread to other parts of the brain.
Treating brain and spinal cord tumors can be difficult. The blood-brain barrier, which normally serves to protect the brain and spinal cord from damaging chemicals getting into those structures, also keeps out many types of potentially beneficial chemotherapy drugs. Surgery can be difficult if the tumor is near a delicate portion of the brain or spinal cord and radiation therapy can damage healthy tissue. However, research in the past two decades has improved the survival rates of patients with brain tumors. More refined surgeries, a better understanding of what types of tumors respond to chemotherapy, and precise delivery of radiation have resulted in longer life span and better quality of life for people with brain cancers.
As we well know, there are many kinds of cancer; unfortunately they all come about because of the out-of-control growth of abnormal cells.
Healthy Cells vs. Cancer Cells
Healthy cells are like a cat. They need structure to determine the size of bones and shape of the body, tail and whiskers. The DNA in genes and chromosomes determine this. They need energy to play and prowl and sustain life. This is derived from chemicals in food. Cats need a system to deliver chemicals (food nutrients like amino acids, carbohydrates, fats, vitamins and minerals) to all parts of their body. These are the blood vessels. Growth factors take a kitten into a lazy old cat, all the while helping it to function normally.
The body and its cells are mostly made up of protein. The building blocks of proteins are substances called amino acids that in the form of enzymes and hormones literally control every chemical reaction within the cells. When these are modified, different messages are sent to a complex control system that can alter their function. There are twenty different kinds of amino acids that are essential to life. Twelve of these can be synthesized within the body however; eight must be supplied by the daily diet
What causes brain tumors?
The causes of brain tumors are not known. Researchers are trying to solve this problem. The more they can find out about the causes of brain tumors, the better the chances of finding ways to prevent them.Doctors cannot explain why one person gets a brain tumor and another doesn't, but they do know that no one can "catch" a brain tumor from another person. Brain tumors are not contagious.Although brain tumors can occur at any age, studies show that they are most common in two age groups. The first group is children 3 to 12 years old; the second is adults 40 to 70 years old.By studying large numbers of patients, researchers have found certain risk factors that increase a person's chance of developing a brain tumor. People with these risk factors have a higher-than-average risk of getting a brain tumor. For example, studies show that some types of brain tumors are more frequent among workers in certain industries, such as oil refining, rubber manufacturing, and drug manufacturing. Other studies have shown that chemists and embalmers have a higher incidence of brain tumors. Researchers also are looking at exposure to viruses as a possible cause. Because brain tumors sometimes occur in several members of the same family, researchers are studying families with a history of brain tumors to see whether heredity is a cause. At this time, scientists do not believe that head injuries cause brain tumors to develop.In most cases, patients with a brain tumor have no clear risk factors. The disease is probably the result of several factors acting together.What are primary brain tumors?
Tumors that begin in the brain tissue are known as primary brain tumors. Secondary tumors are those that develop when cancer spreads to the brain. Primary brain tumors are classified by the type of tissue in which they begin. The most common brain tumors are gliomas, which begin in the glial (supportive) tissue. There are several types of gliomas:Astrocytomas arise from small, star-shaped cells called astrocytes. They may grow anywhere in the brain or spinal cord. In adults, astrocytomas most often arise in the cerebrum. In children, they occur in the brain stem, the cerebrum, and the cerebellum. A grade III astrocytoma is sometimes called anaplastic astrocytoma. A grade IV astrocytoma is usually called glioblastoma multiforme.Brain stem gliomas occur in the lowest, stemlike part of the brain. The brain stem controls many vital functions. Tumors in this area generally cannot be removed. Most brain stem gliomas are high-grade astrocytomas.Ependymomas usually develop in the lining of the ventricles. They also may occur in the spinal cord. Although these tumors can develop at any age, they are most common in childhood and adolescence. Oligodendrogliomas arise in the cells that produce myelin, the fatty covering that protects nerves. These tumors usually arise in the cerebrum. They grow slowly and usually do not spread into surrounding brain tissue. Oligodendrogliomas are rare. They occur most often in middle- aged adults but have been found in people of all ages.There are other types of brain tumors that do not begin in glial tissue. Some of the most common are described below:
Medulloblastomas were once thought to develop from glial cells. However, recent research suggests that these tumors develop from primitive (developing) nerve cells that normally do not remain in the body after birth. For this reason, medulloblastomas are sometimes called primitive neuroectodermal tumors (PNET). Most medulloblastomas arise in the cerebellum; however, they may occur in other areas as well. These tumors occur most often in children and are more common in boys than in girls.
Meningiomas grow from the meninges. They are usually benign. Because these tumors grow very slowly, the brain may be able to adjust to their presence; meningiomas often grow quite large before they cause symptoms. They occur most often in women between 30 and 50 years of age.
Schwannomas are benign tumors that begin in Schwann cells, which produce the myelin that protects the acoustic nerve, the nerve of hearing. Acoustic neuromas are a type of schwannoma. They occur mainly in adults. These tumors affect women twice as often as men.
Craniopharyngiomas develop in the region of the pituitary gland near the hypothalamus. They are usually benign; however, they are sometimes considered malignant because they can press on or damage the hypothalamus and affect vital functions. These tumors occur most often in children and adolescents.
Germ cell tumors arise from primitive (developing) sex cells, or germ cells. The most frequent type of germ cell tumor in the brain is the germinoma.
Pineal region tumors occur in or around the pineal gland, a tiny organ near the center of the brain. The tumor can be slow growing (pineocytoma) or fast growing (pineoblastoma). The pineal region is very difficult to reach, and these tumors often cannot be removed.
What are secondary brain tumors?
Metastasis is the spread of cancer. Cancer that begins in other parts of the body may spread to the brain and cause secondary tumors. These tumors are not the same as primary brain tumors. Cancer that spreads to the brain is the same disease and has the same name as the original (primary) cancer. For example, if lung cancer spreads to the brain, the disease is called metastatic lung cancer because the cells in the secondary tumor resemble abnormal lung cells, not abnormal brain cells.Treatment for secondary brain tumors depends on where the cancer started and the extent of the spread, as well as other factors, including the patient's age, general health, and response to previous treatment.What are adult brain tumors? Adult brain tumors are diseases in which cancer (malignant) cells begin to grow in the tissues of the brain. The brain controls memory and learning, senses (hearing, sight, smell, taste, and touch), and emotion. It also controls other parts of the body, including muscles, organs, and blood vessels. Tumors that start in the brain are called primary brain tumors. What are metastatic brain tumors? Often, tumors found in the brain have started somewhere else in the body and spread (metastasized) to the brain. These are called metastatic brain tumors.What are the symptoms of an adult brain tumor? A doctor should be seen if the following symptoms appear:
Frequent headaches.
Vomiting.
Loss of appetite.
Changes in mood and personality.
Changes in ability to think and learn.
Seizures.What is the treatment for brain tumors?
Treatment for a brain tumor depends on a number of factors. Among these are the type, location, and size of the tumor, as well as the patient's age and general health. Treatment methods and schedules often vary for children and adults. A treatment plan is developed to fit each patient's needs.The patient's doctor may want to discuss the case with other doctors who treat brain tumors. Also, the patient may want to talk with the doctor about taking part in a research study of new treatment methods. Such studies are called clinical trials.Many patients want to learn all they can about their disease and their treatment choices so they can take an active part in decisions about their medical care. A person with a brain tumor will have many questions, and the doctor is the best person to answer them. Most patients want to know what kind of tumor they have, how it can be treated, how effective the treatment is likely to be, and how much it is likely to cost.Many people find it helpful to make a list of their questions before they see the doctor. Taking notes can make it easier to remember what the doctor says. Some patients also find that it helps to have a family member or friend with them when they talk with the doctor,either to take part in the discussion or just to listen.Patients and their families have a lot to learn about brain tumors and their treatment. They should not feel that they need to understand everything the first time they hear it. They will have other chances to ask the doctor to explain things that are not clear. What tests are used to find and diagnose adult brain tumors? Tests that examine the brain and spinal cord are used to detect (find) adult brain tumor. The following tests and procedures may be used:
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): 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 the patient through 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).Adult brain tumor is diagnosed and removed in surgery. If a brain tumor is suspected, a biopsy is done by removing part of the skull and using a needle to remove a sample of the brain tissue. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are found, the doctor will remove as much tumor as safely possible during the same surgery. An MRI may then be done to determine if any cancer cells remain after surgery. Tests are also done to find out the grade of the tumor.What is the grade of a tumor?
The grade of a tumor refers to how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread. The pathologist determines the grade of the tumor using tissue removed for biopsy. The following grading system may be used for adult brain tumors: Grade IThe tumor grows slowly, has cells that look similar to normal cells, and rarely spreads into nearby tissues. It may be possible to remove the entire tumor by surgery.Grade IIThe tumor grows slowly, but may spread into nearby tissue and may become a higher-grade tumor.Grade IIIThe tumor grows quickly, is likely to spread into nearby tissue, and the tumor cells look very different from normal cells.Grade IVThe tumor grows very aggressively, has cells that look very different from normal cells, and is difficult to treat successfully. The chance of recovery (prognosis) and choice of treatment depend on the type, grade, and location of the tumor and whether cancer cells remain after surgery and/or have spread to other parts of the brain. How are adult brain tumors treated? Different types of treatment are available for patients with adult brain tumor. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. Before starting treatment, patients may want to think about taking part in a clinical trial. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment.
Three types of standard treatment are used. 1. Surgery Surgery is used, when possible, to treat adult brain tumor2. Radiation therapy Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. The way the radiation therapy is given depends on the type and stage of the cancer being treated.3. Chemotherapy Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping the cells from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the spinal column, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). A dissolving wafer may be used to deliver an anticancer drug directly into the brain tumor site after the tumor has been removed by surgery. The way the chemotherapy is given depends on the type and stage of the cancer being treated.
How metastatic brain tumors are treated? Tumors that have spread to the brain from somewhere else in the body are usually treated with radiation therapy and/or surgery. Chemotherapy may be used if the primary tumor is the kind that responds well to chemotherapy. Clinical trials are under way to study new treatments. Brain Stem Gliomas Treatment of brain stem gliomas may include the following:
Hyperfractionated radiation therapy.
A clinical trial of new anticancer drugs and/or biologic therapy.Pineal Astrocytic Tumors Treatment of pineal astrocytic tumors may include the following:]
Surgery and radiation therapy, with or without chemotherapy.
A clinical trial of external radiation therapy plus hyperthermia therapy or new methods of delivering radiation therapy.
A clinical trial of new anticancer drugs and biologic therapy following radiation therapy.] Pilocytic Astrocytomas Treatment of pilocytic astrocytoma is usually surgery with or without radiation therapy.Diffuse Astrocytomas Treatment of diffuse astrocytoma may include the following:
Surgery, usually with radiation therapy.
A clinical trial of surgery and radiation therapy with or without chemotherapy for tumors that cannot be completely removed by surgery.
A clinical trial of radiation therapy delayed until the tumor progresses.
A clinical trial comparing high-dose and low-dose radiation therapy.Anaplastic Astrocytomas Treatment of anaplastic astrocytoma may include the following:
Surgery plus radiation therapy, with or without chemotherapy.
A clinical trial of external radiation therapy plus hyperthermia therapy or new methods of delivering radiation therapy.
A clinical trial of new anticancer drugs and biologic therapy following radiation therapy.
A clinical trial of chemotherapy combined with different methods of delivering radiation therapy.Glioblastoma Treatment of glioblastoma may include the following:
Surgery plus radiation therapy, with or without chemotherapy.
A clinical trial of chemotherapy placed into the brain during surgery.
A clinical trial of radiation and concurrent chemotherapy.
A clinical trial of external radiation therapy plus hyperthermia therapy or new methods of delivering radiation therapy.
A clinical trial of new anticancer drugs and biologic therapy following radiation therapy.
A clinical trial of chemotherapy and new methods of delivering radiation therapy.
Clinical trials of new treatments. Oligodendroglial Tumors Treatment of oligodendrogliomas may include the following:
Surgery, usually with radiation therapy.
A clinical trial of surgery and radiation therapy with or without chemotherapy for tumors that cannot be completely removed by surgery.Treatment of anaplastic oligodendroglioma may include the following:
Surgery plus radiation therapy with or without chemotherapy.
A clinical trial of external radiation therapy plus hyperthermia therapy or new methods of delivering radiation therapy.
A clinical trial of new anticancer drugs and biologic therapy following radiation therapy.Mixed Gliomas Treatment of mixed gliomas may include the following:
Surgery plus radiation therapy with or without chemotherapy.
A clinical trial of external radiation therapy plus hyperthermia therapy or new methods of delivering radiation therapy.
A clinical trial of new anticancer drugs or biologic therapy following radiation therapy.Ependymal Tumors Treatment of grade I and grade II ependymomas is usually surgery with or without radiation therapy.Treatment of anaplastic ependymoma may include the following:
Surgery plus radiation therapy.
A clinical trial of surgery followed by chemotherapy before, during, and after radiation therapy.
A clinical trial of chemotherapy and/or biologic therapy. Medulloblastoma Treatment of medulloblastomas may include the following:
Surgery plus radiation therapy to the brain and spine.
A clinical trial of surgery and radiation therapy to the brain and spine for tumors that are more difficult to treat successfully.
A clinical trial of chemotherapy.Pineal Parenchymal Tumors Treatment of pineal parenchymal tumors may include the following:
Surgery plus radiation therapy with or without chemotherapy.
A clinical trial of external radiation therapy plus hyperthermia therapy or new methods of delivering radiation therapy.
A clinical trial of new anticancer drugs and biologic therapy following radiation therapy.Meningeal Tumors Treatment of meningiomas may include the following:
Surgery with or without radiation therapy.
Radiation therapy for tumors that cannot be removed by surgery. Treatment of malignant meningioma may include the following:
Surgery plus radiation therapy.
A clinical trial of external radiation therapy plus hyperthermia therapy or new methods of delivering radiation therapy.
A clinical trial of new anticancer drugs and/or biologic therapy following radiation therapy.Germ Cell Tumors Treatment of central nervous system germ cell tumors depends on the type of cancer cells, the location of the tumor, whether the cancer can be removed in an operation, and other factors. Craniopharyngioma Treatment of craniopharyngiomas may include the following:
Surgery to remove the entire tumor.
Surgery to remove as much of the tumor as possible, followed by radiation therapy.Recurrent Adult Brain Tumor Treatment of recurrent adult brain tumors may include the following:
Surgery with or without chemotherapy.
Radiation therapy, if not used during previous treatment, with or without chemotherapy.
Internal radiation therapy.
Chemotherapy.
A clinical trial of new anticancer drugs.
A clinical trial of chemotherapy placed into the brain during surgery.
A clinical trial of biologic therapy. Metastatic Brain Tumors Treatment of a single metastatic brain tumor is usually surgery followed by radiation therapy to the brain.Treatment of more than one metastatic brain tumor may include the following:
Radiation therapy to the brain.
Surgery, for large tumors that are pressing on areas of the brain and causing symptoms.