What is brain cancer?

Brain cancer is a disease of the brain in which cancer cells (malignant) arise in the brain tissue. Cancer cells grow to form a mass of cancer tissue (tumor) that interferes with brain functions such as muscle control, sensation, memory, and other normal body functions. Tumors composed of cancer cells are called malignant tumors, and those composed of noncancerous cells are called benign tumors. Cancer cells that develop from brain tissue are called primary brain tumors while tumors that spread from other body sites to the brain are termed metastatic brain tumors. Statistics suggest that brain cancer occurs infrequently and is likely to develop in about 22,000 new people per year in 2009, with about 13,000 deaths as estimated by the National Cancer Institute (NCI).

Not all brain tumors are alike, even if they arise from the same type of brain tissue. Tumors are assigned a grade depending on how the cells in the tumor appear microscopically. The grade also provides insight as to the cell's growth rate. NCI lists the following grades:

• Grade I: The tissue is benign. The cells look nearly like normal brain cells, and they grow slowly.



• 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 (anaplastic).



• Grade IV: The malignant tissue has cells that look most abnormal and tend to grow quickly.

The most common primary brain tumors are usually named for the brain tissue type from which they originally developed. These are gliomas, meningiomas, pituitary adenomas, vestibular schwannomas, and primitive neuroectodermal tumors (medulloblastomas). Gliomas have several subtypes which include astrocytomas, oligodendrogliomas, ependymomas, and choroid plexus papillomas. When the grades are coupled with the tumor name, it gives doctors a better understanding about the severity of the brain cancer. For example, a grade III (anaplastic) glioma is an aggressive tumor, while an acoustic neuroma is a grade I benign tumor. However, even benign tumors can cause serious problems if they grow big enough to cause increased intracranial pressure or obstruct vascular structures or cerebrospinal fluid flow.

What is metastatic brain cancer?

Cancer cells that develop in a body organ such as the lung (primary cancer tissue type) can spread via the bloodstream or lymphatic system to other body organs such as the brain. Tumors formed by such cancer cells that spread (metastasize) to other organs are called metastatic tumors. Metastatic brain cancer is a mass of cells (tumor) that originated in another body organ and has spread into the brain tissue. Metastatic tumors in the brain are more common than primary brain tumors. They are usually named after the tissue or organ where the cancer first developed (for example, metastatic lung or breast cancer tumors in the brain, which are the most common types found).

What causes brain cancer?

Primary brain tumors arise from many types of brain tissue (for example, glial cells, astrocytes, and other brain cell types). Metastatic brain cancer is caused by the spread of cancer cells from a body organ to the brain. However, the causes for the change from normal cells to cancer cells in both metastatic and primary brain tumors are not fully understood. Data gathered by research scientists show that people with certain risk factors are more likely to develop brain cancer. Individuals with risk factors such as having a job in an oil refinery, as a chemist, embalmer, or rubber-industry worker show higher rates of brain cancer. Some families have several members with brain cancer, but heredity as a cause for brain tumors has not been proven. Other risk factors such as smoking, radiation exposure, and viral infection (HIV) have been suggested but not proven to cause brain cancer. There is no good evidence that brain cancer is contagious, caused by head trauma, or caused by cell phone use. Although many lay press and Web articles claim that aspartame (artificial sweetener) causes brain cancer, as of 2009, the FDA maintains that it does not cause brain cancer and base their findings on over 100 toxicological and clinical studies regarding the sweetener's safety.

What are the symptoms and signs of brain cancer?

The most common symptoms of brain cancer are weakness, difficulty walking, seizures, and headaches. Other common symptoms are nausea, vomiting, blurry vision, or a change in a person's alertness, mental capacity, memory, speech, or personality. These symptoms can also occur in people that do not have brain cancer, and none of these symptoms alone or in combination can predict that a person has brain cancer. Cancer can occur in any part of the brain (for example, occipital, frontal, parietal, or temporal lobes, brainstem, or meningeal membranes). A few brain cancers may produce few or no symptoms (for example, some meningeal and pituitary gland tumors).

What tests are used to diagnose brain cancer?

The initial test is an interview that includes a medical history and physical examination of the person by a health-care provider. The results of this interaction will determine if other specific tests need to be done.

The most frequently used test to detect brain cancer is a CT scan (computerized tomography). This test resembles a series of X-rays and is not painful, although sometimes a dye needs to be injected into a vein for better images of some internal brain structures. Another test that is gaining popularity because of its high sensitivity for detecting anatomic changes in the brain is MRI (magnetic resonance imaging). This test also resembles a series of X-rays and shows the brain structures in detail better than CT. MRI is not as widely available as CT scanning. If the tests show evidence (tumors or abnormalities in the brain tissue) of brain cancer, then other doctors such as neurosurgeons and neurologists that specialize in treating brain ailments will be consulted to help determine what should be done to treat the patient. Occasionally, a tissue sample (biopsy) may be obtained by surgery or insertion of a needle to help determine the diagnosis. Other tests (white blood cell counts, electrolytes, or examination of cerebrospinal fluid to detect abnormal cells or increased intracranial pressure) may be ordered by the health-care practitioner to help determine the patient's state of health or to detect other health problems.

What is the treatment for brain cancer?

A treatment plan is individualized for each brain cancer patient. The treatment plan is constructed by the doctors who specialize in brain cancer, and treatments vary widely depending on the cancer type, brain location, tumor size, patient age, and patient's general health status. A major part of the plan is also determined by the patient's wishes. Patients should discuss treatment options with their health-care providers.

Surgery, radiation therapy, and chemotherapy are the major treatment categories for most brain cancers. Individual treatment plans often include a combination of these treatments. Surgical therapy attempts to remove all of the tumor cells by cutting the tumor away from normal brain tissue. This surgery is often termed invasive surgery to distinguish it from noninvasive radiosurgery or radiation therapy described below.

Radiation therapy attempts to destroy tumor cells by using high-energy radiation focused onto the tumor to destroy the tumor cells' ability to function and replicate. Radiosurgery is a nonsurgical procedure that delivers a single high dose of precisely targeted radiation using highly focused gamma-ray or X-ray beams that converge on the specific area or areas of the brain where the tumor or other abnormality is located, minimizing the amount of radiation to healthy brain tissue. 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.

Chemotherapy attempts to destroy tumor cells using chemicals (drugs) that are designed to destroy specific types of cancer cells. There are many chemical agents used; specific drug therapies are numerous, and each regimen is usually designed for the specific type of brain cancer and individualized for each patient. Chemotherapy can be administered intrathecally (by a surgically placed permanent reservoir in the brain), by lumbar puncture, by IV administration, and biodegradable chemically impregnated polymers. All treatments attempt to spare normal brain cells.

Other treatments may include hyperthermia (heat treatments), immunotherapy (immune cells directed to kill certain cancer cell types), or steroids to reduce inflammation and brain swelling. These may be added on to other treatment plans.

Clinical trials (treatment plans designed by scientists to try new chemicals or treatment methods on patients) can be another way for patients to obtain treatment specifically for their cancer cell type. Clinical trials are part of the research efforts to produce better treatments for all disease types. The best treatment for brain cancer is designed by the team of cancer specialists in conjunction with the wishes of the patient.

What are the side effects of brain cancer treatment?

Side effects of brain cancer treatment vary with the treatment plan (for example, surgery, chemotherapy, or radiation) and the overall health status of the patient. Most treatment plans try to keep all side effects to a minimum. For some patients, the side effects of brain cancer treatment can be severe. Treatment plans should include a discussion of potential side effects and the likelihood of them developing, so the patient and their caregivers (family, friends) can make appropriate treatment decisions in conjunction with their medical team. Also, if side effects develop, the patient has some knowledge of what to do about them such as when to take certain medicines or when to call their doctor to report health changes.

Surgical side effects include an increase in current symptoms, damage to normal brain tissue, brain swelling, and seizures. Other changes in brain functions such as muscle weakness, mental changes, and decreases in any brain-controlled function can occur. Combinations of these side effects may happen. The side effects are most noticeable shortly after surgery but frequently decline over time. Occasionally, the side effects do not go away.

Chemotherapy usually affects (damages or kills) rapidly growing cancer cells but also can affect normal tissue. Chemotherapy is usually given intravenously so the drugs can reach most body organs. Common side effects of chemotherapy are nausea, vomiting, hair loss, and loss of energy. The immune system is often is depressed by chemotherapy, which results in a high susceptibility to infections. Other systems, such as the kidneys and the reproductive organs, may also be damaged by chemotherapy. Most of the side effects decline over time, but some may not.

Radiation therapy has most of the same side effects as chemotherapy. Most radiation therapy is focused onto the brain cancer tissue, so some systems do not receive direct radiation (immune system, kidneys, and others). The effects on systems not receiving the direct radiation are usually not as severe as those seen with chemotherapy. However, hair and skin are usually affected, resulting in hair loss (sometimes permanently) and reddish and darkened skin that needs protection from the sun.

What is the prognosis (outcome) of treated brain cancer?

Survival of treated brain cancer varies with the cancer type, location, and overall age and general health of the patient. In general, most treatment plans seldom result in a cure. Reports of survival greater that five years (which is considered to be long-term survival), vary from less than 10% to a high of 32%, no matter what treatment plan is used.

So, why use any treatment plan? Without treatment, brain cancers are usually aggressive and result in death within a short time span. Treatment plans can prolong survival and can improve the patient's quality of life for some time. Again, the patient and caregivers should discuss the prognosis when deciding on treatment plans.

What can I do to help my family (and me) cope with my diagnosis of brain cancer?

Discuss your concerns openly with your doctors and family members. It is common for brain cancer patients to be concerned about how they can continue to lead their lives as normally as possible; it is also common for them to become anxious, depressed, and angry. Most people cope better when they discuss their concerns and feelings. Although some patients can do this with friends and relatives, others find solace in support groups (people who have brain cancer and are willing to discuss their experiences with other patients) composed of people who have experienced similar situations and feelings. The patient's treatment team of doctors should be able to connect patients with support groups. In addition, information about local support groups is available from the American Cancer Society at http://www.cancer.org/docroot/home/index.asp.

How is brain cancer prevented?

Although there is no way to prevent brain cancers, early diagnosis and treatment of tumors that tend to metastasize to the brain may reduce the risk of metastatic brain tumors. The following factors have been suggested as possible risk factors for primary brain tumors: radiation to the head, HIV infection, and environmental toxins. However, no one knows the exact causes that initiate brain cancer, especially primary brain cancer, so specific preventive measures are not known. Although Web sites and popular press articles suggest that macrobiotic diets, not using cell phones, and other methods will help prevent brain cancer, there is no reliable data to support these claims.

Where can I get more information about my type of brain cancer?

There are many types of brain cancer. For more specific information about a cancer type, questions and discussions with the patient's treatment team are the best way to obtain specific information. Also, there are many online resources available about brain cancer types. Often, these resources provide additional detailed information about pathology, statistics, treatments, and support groups for brain cancer patients. A few of the Web sites are listed below.

http://www.cancer.gov/cancerinfo/types/brain/

http://www.cancer.gov/cancertopics/wyntk/brain

http://www.cancer.gov/cancertopics/eatinghints/page3#C18

http://www.emedicinehealth.com/brain_cancer/page8_em.htm

Brain Cancer At A Glance

• Brain cancer can arise from many different types of brain cells (primary brain cancer) or occur when cancer cells from another part of the body spread (metastasize) to the brain.
• Symptoms of brain cancer vary but often include weakness, difficulty walking, seizures, and headaches. Other common symptoms are nausea, vomiting, blurry vision, or a change in a person's alertness, mental capacity, memory, speech, or personality.
• Tests for brain cancer involve a history, physical exam, and usually a CT or MRI brain scan; sometimes a brain tissue biopsy is done.
• Treatments usually are directed by a team of doctors and are designed for the individual patient; treatments may include surgery, radiotherapy, or chemotherapy, often in combination.
• Side effects of treatments range from mild to severe, and patients need to discuss plans with their treatment team members to clearly understand potential side effects and their prognosis (outcomes).
• Depending on the brain cancer type and overall health status of the patient, brain cancer frequently has only a fair to poor prognosis

References:

NIH.gov., Brain Cancer, 2009

Cancer.org., American Cancer Society; Detailed guide: Brain/CNS Tumors in Adults, 2009

NCI.NIH.gov., National Cancer Institute, Adult Brain Tumor Treatments, 2009

sourceLast Editorial Review: 8/28/2009

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