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Prevention and Treatment of Cancers:
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Cancers of the brain are the consequence of abnormal growths of cells in the brain. Brain cancers can arise from primary brain cells, the cells that form other brain components (for example, membranes, blood vessels), or from the growth of cancer cells that develop in other organs and that have spread to the brain by the bloodstream (metastatic brain cancer). Although many growths in the brain are popularly called brain tumors, not all brain tumors are cancerous. Cancer is a term reserved for malignant tumors. Malignant tumors grow and spread aggressively, overpowering healthy cells by taking their space, blood, and nutrients. Like all cells of the body, tumor cells need blood and nutrients to survive. This is especially a problem in the brain, as the added growth within the closed confines of the skull can lead to an increase in intracranial pressure or the distortion of surrounding vital structures, causing their malfunction. Tumors that do not grow aggressively are called benign. Almost all tumors that begin in the brain do not spread to other parts of the body. The major difference between benign and malignant tumors is that malignant tumors can invade the brain tissues and grow rapidly. This rapid growth in the confines of the skull can quickly cause damage to nearby brain tissue. In general, a benign tumor is less serious than a malignant tumor. However, a benign tumor can still cause many problems in the brain, but usually the problems progress at a slower rate than malignant tumors. Sometimes people confuse brain aneurysms with brain tumors. Brain aneurysms are not tumors; they are areas in the brain arteries or veins that are abnormally weak and expand to form a ballooning or expansion of the vessel wall. They seldom produce any symptoms unless they begin to leak blood into the surrounding brain tissue. Aneurysms may be congenital (present at birth) or expanded or formed in brain vessels after vessel damage (for example, trauma, atherosclerosis, high blood pressure) but are not formed from cancer cells. Unfortunately, when aneurysms produce symptoms, they can resemble those produced by brain tumors. TYPES OF PRIMARY BRAIN TUMORS The brain is made up of many different types of cells and tumors that arise from a brain cell type are termed primary brain tumors. As these abnormal cells grow, they become a mass of cells, or tumor. Brain tumors that result from this transformation and abnormal growth of brain cells are called primary brain tumors because they originate in the brain. The most common primary brain tumors are gliomas, meningiomas, pituitary adenomas, vestibular schwannomas, primary CNS lymphomas, and primitive neuroectodermal tumors (medulloblastomas). The term glioma is an expansive one since it includes numerous subtypes, including astrocytomas, oligodendrogliomas, ependymomas, and choroid plexus papillomas. These primary tumors are named after the part of the brain or the type of brain cell from which they arise. GRADES Brain tumors vary in their growth rate and ability to cause symptoms. The cells in fast growing, aggressive tumors usually appear abnormal microscopically. The National Cancer Institute (NCI) uses a grading system to classify tumors. The NCI lists the following grades: Grade I: The tissue is benign. The cells look nearly like normal brain cells, and cell growth is slow. Grade II: The tissue is malignant. The cells look less like normal cells than do the cells in a grade I tumor. Grade III: The malignant tissue has cells that look very different from normal cells. The abnormal cells are actively growing. These abnormal-appearing cells are termed anaplastic. Grade IV: The malignant tissue has cells that look most abnormal and tend to grow very fast. In the United States, primary brain tumors and other nervous system cancers are estimated to develop in about 22,000 people in 2010, according to the National Cancer Institute. METASTATIC BRAIN TUMORS Metastatic brain tumors are made of cancerous cells that spread through the bloodstream from a tumor located elsewhere in the body. The most common cancers that spread to the brain are those arising from cancers that originate in the lung, breast, and kidney as well as malignant melanoma, a skin cancer. The cells spread to the brain from another tumor in a process called metastasis. The process metastasis occurs when cancer cells leave the primary cancer tissue and enter either the lymphatic system to reach the blood or the bloodstream directly. These cancer cells eventually reach the brain tissue through the bloodstream where they develop into tumors. BRAIN CANCER CAUSES As with tumors elsewhere in the body, the exact cause of most brain tumors is unknown. The following factors have been proposed as possible risk factors for primary brain tumors, but whether these factors actually increase an individual's risk of a brain tumor is not known for sure.
Environmental toxins (for example, chemicals used in oil refineries, embalming chemicals, rubber industry chemicals) BRAIN CANCER SYMPTOMS AND SIGNS Not all brain tumors cause symptoms, and some (such as tumors of the pituitary gland that cause no symptoms) are found mainly after death, with the death not caused by the brain tumor. The symptoms of brain tumors are numerous and not specific to brain tumors, meaning they can be caused by many other illnesses as well. The only way to know for sure what is causing the symptoms is to undergo diagnostic testing. Early symptoms may not occur; if they do, they occur for the following reasons and are listed below: Some symptoms are caused by swelling in the brain primarily caused by the tumor or its surrounding inflammation. The following symptoms are most common:
Other nonspecific symptoms and signs include the following:
In many people, the onset of these symptoms is very gradual and may be overlooked by both the person with the brain tumor and the person's family members, even for long time periods. Occasionally, however, these symptoms appear more rapidly. In some instances, the person acts as if he or she is having a stroke. In some patients, the symptoms may be more pronounced if the cancer is located mainly in a specific brain lobe that is usually responsible for certain body functions. For example, behavioral changes may predominate in frontal-lobe cancers while difficulty with speech or movements may predominate in cancers within the parietal lobe. When to Seek Medical Care Seek care from a health-care provider right away, probably emergently, if a person develops any of the following symptoms:
Although headaches are thought to be a common symptom of brain cancer, they may not occur until late in the progression of the disease. If any significant change in a person's headache pattern occurs rapidly, health-care providers may suggest that you go the emergency department. If a person has a known brain tumor, any new symptoms or relatively sudden or rapid worsening of symptoms also warrants a trip to the nearest hospital emergency department. Be on the lookout for the following new symptoms:
Exams and Tests If findings of a medical interview and physical examination suggest to the health-care provider that a person may have a problem in the brain or brain stem, additional tests may be done. Many people will have a CT scanof the brain, especially if the person is seen emergently. This test is like an X-ray but shows more detail in three dimensions. Usually, a harmless dye is injected into the bloodstream to highlight abnormalities on the scan. If the person has mental-status change as the main symptom, blood or urine tests may be done to rule out drug use. This is because MRI has a higher sensitivity for detecting the presence and characteristics of a tumor. Specifically, the relationship of the tumor to the surrounding brain, the brain coverings, cerebrospinal fluid spaces, and vascular structures is assessed to come up with a provisional diagnosis of the nature of the tumor. Currently, however, many institutions that do have MRI scanners still use the CT scan as a screening test for tumors. A word of caution to readers; while radiologic examinations of the brain usually are excellent tests, they are not without any risks. People that "doctor shop" or frequent emergency centers with the main complaint of "headache" often obtain multiple brain scans in close succession. This may put the individuals at increased risk of radiation damage to cells. Patients are urged to have a primary medical caregiver to help coordinate all tests to avoid overexposure to radiation from diagnostic testing. The next step in diagnosis is confirmation that the person has cancer in the brain. A small sample of the tumor (a biopsy) is taken to identify the type of tumor and the grade of the tumor. The most widely used technique for obtaining a biopsy is a surgical procedure called a craniotomy. The skull is opened, usually with the intention of removing the whole tumor if possible. A biopsy is then taken from the tumor. If the surgeon is unable to remove the entire tumor, a small piece of the tumor is removed. In some cases, it is possible to collect a biopsy without opening the skull. The exact location of the tumor in the brain is determined stereotactically, that is, by using CT or MRI scans while the head is held still in a frame. A small hole is then made in the skull and a needle guided through the hole to the tumor. The needle collects the biopsy and is removed. This technique is called stereotaxis, or stereotactic biopsy. This process does not treat the tumor and is generally reserved for situations in which the tumor is either inaccessible or is thought to be sensitive to radiation therapy (such as CNS lymphoma or pineal germ cell tumor). The biopsy is examined under a microscope by a pathologist (a physician who specializes in diagnosing diseases by looking at cells and tissues) and usually assigned a NCI grade. BRAIN CANCER TREATMENT Treatment for brain cancer should be individualized for each patient. Treatment regimens are based on the patient's age and general health status as well as the size, location, type, and grade of the tumor. In most cases of brain cancer, surgery, radiation, and chemotherapy are the main types of treatment. Often, more than one treatment type is used. The treatment types are further described below. The patient, family, and friends will have many questions about the tumor, the treatment, how treatment will affect the person, and the person's long-term outlook (prognosis). Members of the person's health-care team are the best source of this information. Don't hesitate to ask them any questions. SELF-CARE AT HOME The person's health-care provider and the physician team in charge of their case should discuss details about home care with both the patient and family members. Home care usually includes supportive measures needed according to the patient's symptoms. For example, walkers may be given for those patients who have gait or minor balance problems. If a person has mental-status changes, a care plan should be directed to the patient's individual needs. For example, a caregiver may be assigned to administer the patient's daily medications. If the patient's prognosis is poor, it is appropriate to discuss options of hospice care, advance directives to doctors, and provisions for a living will. Home hospice care is a way of providing pain and symptom relief, as well as emotional and spiritual support for the patient and the family, at home rather than in the hospital. It involves a multidisciplinary approach that may include a physician or other care provider, nurses, a pharmacist, aides, a social worker, a spiritual caregiver, and counselors. Advance directives and living wills are legal documents that spell out specifically which treatments are to be given and which are to be withheld. For example, a person with advanced brain cancer may not want to be put on a ventilator (breathing machine) if he or she stops breathing. Patients have the right to make these decisions for themselves as long as they remain mentally competent. Directives should be available to health-care personnel, especially when any emergent change in the person's condition occurs, otherwise a person's care directives may not be done. TYPES OF TREATMENTS FOR BRAIN CANCER Treatment of brain cancer is usually complex. Most treatment plans involve several consulting doctors. The treatment protocols vary widely according to the location of the tumor, its size, grade, and type, the patient's age, and any additional medical problems that the person may have. The most widely used treatments are surgery, radiation therapy, and chemotherapy. In some cases, more than one of these treatment types is used. Most people with a brain tumor undergo surgery. The purposes of surgery are to confirm that the abnormality seen on the brain scan is indeed a tumor, to assign a grade to the tumor, and to remove the tumor. If the tumor cannot be removed, the surgeon will take a sample of the tumor to identify its type and grade. Patients may undergo several treatments and procedures before surgery. Overview of surgery for resection of brain tumor The intent of surgery for tumors is to remove as much of the tumor as is safely possible with the minimal possible loss in brain function. The large majority of patients undergo this procedure under general anesthesia. Some surgeries are done awake or under light sedation for the purpose of mapping language function. For surgery done under general anesthesia, an endotracheal tube is placed, while for those done awake, a laryngeal mask airway (or no airway) is placed and the patient is deeply sedated. The head is appropriately positioned using a clamp system that holds the skull motionless. An image-guided navigation system is often used to help determine the precise location of the incision. The scalp is prepped, after the hair is clipped, the planned incision line is infiltrated with local anesthesia, and the scalp is then incised and pushed aside to expose the skull bone. A portion of the skull is temporarily cut away and the lining tissues of the brain are opened. If it is necessary to determine whether brain function is compromised, the patient is awakened from sedation in order to respond as mapping procedures are carried out. In either case, tumor resection is then carried out. A portion of the tumor is usually sent to a pathologist for analysis. The surgeon may also decide to place biodegradable polymer wafers that deliver chemotherapy drugs (Gliadel wafers) into the tumor cavity. Once the tumor resection is complete, the membranes surrounding the brain are closed and the skull is closed, often with the use of titanium plates and screws that help hold it rigidly in its desired position. The scalp is closed; some surgeons use drains placed under the scalp for a day or two after surgery to minimize the accumulation of blood or fluid. Stereotactic radiosurgery is a newer "knifeless" technique that destroys a brain tumor without opening the skull. CT or MRI scan is used to pinpoint the exact location of the tumor in the brain. High-energy radiation beams are trained on the tumor from different angles. The radiation destroys the tumor. Equipment used to do radiosurgery varies in its radiation source; a gamma knife uses focused gamma rays, and a linear accelerator uses photons, while heavy-charged particle radiosurgery uses a proton beam. Radiation therapy (also called radiotherapy) is the use of high-energy rays to kill tumor cells and stop them from growing and multiplying. Radiation therapy is sometimes used for people who cannot undergo surgery. In other cases, it is used after surgery to kill any tumor cells that may remain. Radiation therapy is a local therapy. This means that it affects only cells in its path. It does not harm cells elsewhere in the body or even elsewhere in the brain. Radiation can be administered in either of two ways. External radiation uses a high-energy beam of radiation targeted at the tumor. The beam travels through the skin, the skull, healthy brain tissue, and other tissues to get at the tumor. The treatments are usually given five days a week for about four to six weeks. Each treatment takes only a few minutes. The gamma knife and cyber knife are two terms that describe methods that use external radiation to kill cancer cells in the brain. Internal or implant radiation uses a tiny radioactive capsule that is placed inside the tumor itself. The radiation emitted from the capsule destroys the tumor. The radioactivity of the capsule decreases a little bit each day; the amount of radioactivity of the capsule is carefully calculated to run out when the optimal dose has been given. You need to stay in the hospital for several days while receiving this treatment. Chemotherapy is the use of powerful drugs to kill tumor cells. A single drug or a combination may be used. The drugs are given by mouth or through an IV line. Two drugs, temozolomide (Temodar) and bevacizumab (Avastin), have recently been approved for the treatment of malignant gliomas. They are more effective and have fewer adverse effects when compared with older drugs. Temozolomide has another advantage in that it is administered orally, eliminating the need for intravenous lines and hospital stays for chemotherapy. Chemotherapy is usually given in cycles. A cycle consists of a short period of intensive treatment followed by a period of rest and recovery. Each cycle lasts a few weeks. The side effects of chemotherapy are well known and are very difficult to tolerate for some people. They include nausea and vomiting, mouth sores, loss of appetite, loss of hair, and many others. Some of these side effects can be relieved or improved by medication. Clinical trials are available for virtually every kind of cancer. The disadvantage is that the therapy has not been proven to work or does not work in everyone. Many people with cancer are eligible for participation in clinical trials. To find out more, ask your health-care provider. A list of clinical trials is available at the web site of the National Cancer Institute. Side Effects of Brain Cancer Treatments Treatment plans try to limit or reduce side effects associated with brain cancer treatment. However, most patients will experience some side effects; some side effects can be severe. People who undergo brain cancer treatment should ask about the potential side effects and help decide if the proposed treatment(s) will be worth the benefits and what to do if side effects appear. Side effects of chemotherapy may include nausea, vomiting, hair loss, and weakness. The immune system is usually suppressed, which makes the person more susceptible to infections. Other organ systems such as the kidneys or reproductive organs may be damaged. Although these side effects usually decline as treatment ends, some may not, especially if other organ systems are damaged. Patients and brain cancer team members should carefully consider side effects; often some of them can be reduced by medical treatment and may not be permanent. Brain cancer patients who are candidates for treatment should understand that without surgery, chemotherapy, or radiation therapy (or combinations of them) the prognosis or outlook for most patients is poor. FOLLOW-UP Once a brain tumor is diagnosed, the patient needs to be very careful to keep all appointments with consultants and the primary health-care provider. In general, people with brain cancer are at increased risk for additional medical problems and, potentially, reoccurrence or worsening of their symptoms. After treatment, patients will be returning for follow-up visits with their cancer team members. A schedule of follow-up checkups and tests will be recommended. The purpose of this follow-up is to ensure that any recurrence of cancer or any long-term effect of the treatment is identified promptly so that it can be treated right away. BRAIN CANCER PREVENTION In general, there is no known way to prevent brain cancers. However, early diagnosis and treatment of tumors that tend to metastasize to the brain may reduce the risk of metastatic brain tumors. Avoiding or reducing contact with radiation (especially to the head) and avoiding toxic chemicals associated with the oil and rubber industry, embalming chemicals, and other environmental toxins may help prevent brain cancers. Avoiding HIV infection is also suggested. The popular press and some web sites suggest that avoiding cell phone use and using a macrobiotic diet will help avoid brain cancer. Currently, there is no good evidence for these claims. In December 2010, a large study of about 59,000 cell phone users, with use times ranging over five to 10 years, claims that no substantial change in brain cancer incidence could be found in these individuals. Investigators suggest that "high usage" of cell phones over long time periods is yet to be investigated. However, for those who want to minimize any radiation dose from cell phones, the reader can consult the web for a list of phones that produce the highest and lowest radiation levels. BRAIN CANCER PROGNOSIS The major factor(s) that influence brain cancer survival is related to the following: the type of cancer, its location, whether it can be surgically removed or reduced, and the age and overall health status of the patient. The long-term survival rate (greater than five years) for people with primary brain cancer varies from less than 10% to about 32%, despite aggressive surgery, radiation, and chemotherapy treatments. Treatments do prolong survival over the short term and, perhaps more importantly, improve quality of life for some time, although this time period can vary greatly. Most people with metastatic brain cancer die from their primary cancer rather than from the brain lesions. People who have seizures generally do poorly over the following six months. Support Groups and Counseling Living with cancer presents many new challenges for the patient and their family and friends. Many people feel anxious and depressed. Some people feel angry and resentful; others feel helpless and defeated. Friends and family members can be very supportive. They may be hesitant to offer support until they see how the person is coping with the disease. If patients want to talk about their concerns, the patient should be encouraged to do so with their friends and family. Many people with cancer are helped profoundly by talking to other people who have cancer. Sharing concerns with others who have been through the same thing can be remarkably reassuring. Support groups of people with cancer may be available through the medical center where you are receiving your treatment. The American Cancer Society also has information about support groups all over the United States. Back to Prevention and Treatment of Cancer |