Glenn Lesser, MD, FACP, is the associate chief of the Section on Hematology and Oncology, a principal investigator at Wake Forest NCORP Research Base, director of Medical Neuro-Oncology, and co-leader of the Neuro-Oncology Research Program at Wake Forest Baptist Comprehensive Cancer Center in Winston-Salem, North Carolina. Dr. Lesser is also the Cancer.Net Associate Editor for Central Nervous System Tumors.
Brain tumors are either primary tumors or secondary tumors. Primary tumors start in the brain. Secondary tumors spread to the brain from a cancer that started somewhere else in the body. Secondary tumors are also called metastatic tumors.
Primary brain tumors are not common and affect about 24,000 adults in the United States each year. Most primary tumors are called glial tumors. This category of tumor includes low-grade and high-grade astrocytomas, a group that includes anaplastic astrocytoma and glioblastoma, and low-grade and high-grade oligodendrogliomas. Lymphomas can also start in the brain, but they are much rarer.
Not all brain tumors are malignant or cancerous. A cancerous tumor can grow or spread. Several types of benign, or noncancerous, brain tumors in adults may not require any treatment. In other cases, the tumors can usually be cured with surgery or radiation therapy. Meningiomas and pituitary tumors are among this type.
What causes brain cancer?
The vast majority of primary brain tumors seem to affect people at random. There are almost no risk factors or behaviors we know of that will cause these tumors in most of the people who will get them.
If a person has had radiation to their brain before, or has one of several rare diseases (such as neurofibromatosis, tuberous sclerosis complex, and certain hereditary cancer syndromes like Li-Fraumeni syndrome), then they are at greater risk of brain cancer. However, these risk factors account for a small number of brain tumors. Thus, there is nothing the average person can do to affect their chance of getting primary brain cancer.
What symptoms do people with newly diagnosed brain tumors experience?
The brain and spinal cord make up the central nervous system, which controls the functioning of our entire body, including our muscles, nerves, and internal organs. As a result, tumors of the brain can cause people to experience a wide variety of symptoms.
The main neurological symptoms are:
Weakness or numbness on one side of the body
Difficulty forming or remembering words
A tumor’s exact location in a person’s brain will dictate that person’s particular symptoms. In the same way, tumors in some locations may not cause any symptoms for a long time. These tumors are sometimes discovered by accident, when the person gets a CT or MRI scan of the brain for another medical reason.
It is important to remember that many people who experience the neurological symptoms listed above do not have a brain tumor. There is no clear cause for concern about brain cancer unless new neurological symptoms appear and last. In that situation, a person should see a doctor.
How is brain cancer treated?
Surgery alone is almost never enough to treat primary brain cancer, and so surgery is usually combined with radiation therapy and/or chemotherapy. To get the best results, it is necessary to have an experienced, multidisciplinary medical team. Each member of the team will bring different skills and expertise to the patient’s care. Here are the specializations and responsibilities of the health care professionals who may be on the medical team.
Neurosurgeon. This person is responsible for safely removing as much of the tumor as possible or performing only a biopsy if the tumor is in an area of the brain that can’t be safely operated on. The tumor sample allows a precise diagnosis to be made. It also provides tissue to analyze for several important molecular changes that might affect what type of treatment is chosen and how effective that treatment is likely to be. Removing some or all of the tumor can also improve symptoms by reducing swelling or pressure in the brain.
Radiation oncologist. This person plans and delivers a course of radiation treatments that target the visible brain tumor as well as the surrounding area where microscopic tumor cells exist. Radiation therapy is generally given in daily doses, also called fractions, for up to 6 weeks in a row. The use of a computer-generated plan limits the amount of radiation that the surrounding, normal brain tissue receives. Occasionally, radiation techniques that deliver a high dose of radiation to a very small area of the brain are used, particularly for secondary brain tumors. This method is called stereotactic radiation therapy.
Medical neuro-oncologist. This person delivers chemotherapy and other drug therapies, such as targeted therapy or immunotherapy, to people with a brain tumor. The neuro-oncologist is either a medical oncologist or a neurologist and is generally responsible for managing the side effects and problems that come from surgical, radiation, and drug treatments.
Patients may wonder about enrolling in a clinical trial as a treatment option. New approaches are needed to treat people with aggressive brain tumors, and clinical trials play an essential part in evaluating whether the approaches will work. Many clinical trials testing new therapies for brain tumors are available, and patients and their caregivers should discuss these clinical trials when meeting with their cancer care team.
What are the common side effects that people experience during and after treatment for a primary brain cancer?
Certain types of medications that are used in treating primary brain tumors can cause side effects. Steroid medications, like dexamethasone or prednisone (both available as generic drugs), are often prescribed to control brain swelling caused by “leaky” blood vessels within the tumor. Using steroids over a period of time can lead to increased appetite and weight gain, swelling of the legs, aggressive behavior, difficulty sleeping, easy bruising, and high blood sugars or diabetes. Medicines used to control seizures, called anticonvulsants, can cause tiredness, appetite changes, and clouded thinking.
Other side effects come from the tumor itself, rather than the treatment. For example, for reasons we don’t know, people who have a brain tumor also have a very high risk of developing blood clots in their legs and their lungs. Symptoms that might suggest a blood clot include swelling, pain, or redness in one leg, as well as chest pain, shortness of breath, or coughing up bloody matter.
Some people also experience increasing cognitive problems, such as poor short-term memory and difficulties with judgment, alertness, and behavior. Often these problems are caused by the tumor and may already be present when the person is diagnosed. But they may also result from surgery, radiation therapy, or, less frequently, chemotherapy, and begin months or even years after the treatments have been completed. Talk with your doctor about any problem you experience during or after treatment.