No one knows what causes brain tumors; there are only a few known risk factors that have been established by research. Children who receive radiation to the head have a higher risk of developing a brain tumor as adults, as do people who have certain rare genetic conditions such as neurofibromatosis or Li-Fraumeni syndrome. But those cases represent a fraction of the approximately 35,000 new primary brain tumors diagnosed each year. Age is also a risk factor -- people over the age of 65 are diagnosed with brain cancer at a rate four times higher than younger people.
A primary brain tumor is one that originates in the brain, and not all primary brain tumors are cancerous; benign tumors are not aggressive and normally do not spread to surrounding tissues, although they can be serious and even life threatening.
The National Cancer Institute estimates there will be about 23,380 new cases of brain cancer diagnosed in 2014.
What Is a Tumor?
A tumor is a mass of tissue that's formed by an accumulation of abnormal cells. Normally, the cells in your body age, die, and are replaced by new cells. With cancer and other tumors, something disrupts this cycle. Tumor cells grow, even though the body does not need them, and unlike normal old cells, they don't die. As this process goes on, the tumor continues to grow as more and more cells are added to the mass.
Primary brain tumors emerge from the various cells that make up the brain and central nervous system and are named for the kind of cell in which they first form. The most common types of adult brain tumors are gliomas and astrocytic tumors. These tumors form from astrocytes and other types of glial cells, which are cells that help keep nerves healthy.
The second most common type of adult brain tumors are meningeal tumors. These form in the meninges, the thin layer of tissue that covers the brain and spinal cord.
What's the Difference Between Benign and Malignant Brain Tumors?
Benign brain tumors are noncancerous. Malignant primary brain tumors are cancers that originate in the brain, typically grow faster than benign tumors, and aggressively invade surrounding tissue. Although brain cancer rarely spreads to other organs, it will spread to other parts of the brain and central nervous system.
Benign brain tumors usually have clearly defined borders and usually are not deeply rooted in brain tissue. This makes them easier to surgically remove, assuming they are in an area of the brain that can be safely operated on. But even after they've been removed, they can still come back, although benign tumors are less likely to recur than malignant ones.
Although benign tumors in other parts of the body can cause problems, they are not generally considered to be a major health problem or to be life-threatening. But even a benign brain tumor can be a serious health problem. Brain tumors damage the cells around them by causing inflammation and putting increased pressure on the tissue under and around it as well as inside the skull.
What Are the Symptoms of a Brain Tumor in Adults?
Symptoms of brain tumors vary according to the type of tumor and the location. Because different areas of the brain control different functions of the body, where the tumor lies affects the way symptoms are manifested.
Some tumors have no symptoms until they are quite large and then cause a serious, rapid decline in health. Other tumors may have symptoms that develop slowly.
Other symptoms include:
- Changes in speech or hearing
- Changes in vision
- Balance problems
- Problems with walking
- Numbness or tingling in the arms or legs
- Problems with memory
- Personality changes
- Inability to concentrate
- Weakness in one part of the body
It's important to keep in mind that these symptoms can be caused by a number of different conditions. Don't assume you have a brain tumor just because you experience some of them. Check with your doctor.
How Are Brain Tumors Diagnosed?
To diagnose a brain tumor, the doctor starts by asking questions about your symptoms and taking a personal and family health history. Then he or she performs a physical exam, including a neurological exam. If there's reason to suspect a brain tumor, the doctor may request one or more of the following tests:
- Imaging studies such as a CT(CAT) scan or MRI to see detailed images of the brain
- Angiogram or MRA, which involve the use of dye and X-rays of blood vessels in the brain to look for signs of a tumor or abnormal blood vessels
The doctor may also ask for a biopsy to determine whether or not the tumor is cancer. A tissue sample is removed from the brain either during surgery to remove the tumor or with a needle inserted through a small hole drilled into the skull before treatment is started. The sample is then sent to a lab for testing.
How Are Brain Tumors Treated?
Surgery to remove the tumor is typically the first option once a brain tumor has been diagnosed. However, some tumors can't be surgically removed because of their location in the brain. In those cases, chemotherapy and radiation therapy are both options for killing and shrinking the tumor. Sometimes, chemotherapy or radiation is also used after surgery to kill any remaining cancer cells. Tumors that are deep in the brain or in areas that are difficult reach may be treated with Gamma Knife therapy, which is a form of highly focused radiation therapy.
Because treatment for cancer also can damage healthy tissue, it's important to discuss possible side and long-term effects of whatever treatment is being used with your doctor. The doctor can explain the risk and the possibility of losing certain faculties. The doctor can also explain the importance of planning for rehabilitation following treatment. Rehabilitation could involve working with several different therapists, such as:
- Physical therapist to regain strength and balance
- Speech therapist to address problems with speaking, expressing thoughts, or swallowing
- Occupational therapist to help manage daily activities such as using the bathroom, bathing, and dressing