Actress Mary Tyler Moore has reportedly underwent surgery to have a meningioma, a type of tumor that develops from the membrane that surrounds the brain and spinal cord, removed. AAN.com Editor-in-Chief Orly Avitzur, MD, MBA, FAAN, interviewed Myrna Rosenfeld, MD, PhD, FAAN, Adjunct Professor of Neurology with the Department of Neurology at the University of Pennsylvania in Philadelphia.
What is a meningioma?
Meningiomas are tumors that arise from the meninges, which are the membranes that cover the brain and spinal cord. Therefore, meningiomas are not truly tumors of the brain but rather grow from the meninges and push into the brain or spinal cord.
What are the typical symptoms?
Symptoms will vary based on the location of the meningioma. Seizures are relatively common and due to the irritation caused by the pressure on the brain. This pressure can also produce headaches. Meningiomas that occur over the middle and top of the brain can cause change in behavior or memory or weakness in the legs. Meningiomas can affect vision or facial feeling by pressing on the nerves that control these functions. When they press on the spinal cord they often cause pain in the back or limbs.
Who is at risk? Are there any other medical conditions or factors are associated with a higher incidence of meningioma?
Meningiomas most commonly occur in adults, usually between the ages of 40 and 70 years. They are extremely rare in children. Meningiomas are also more common in women at a ratio of 3 to 1 for brain meningiomas and up to 6 to 1 for spinal cord meningiomas. The increased occurrence of meningiomas in women has led some experts to suggest there is a link between the development of meningiomas and female hormones such as contraceptives or hormone replacement; however this has not been proven. Radiation appears to be a risk factor for the development of meningiomas, although with newer radiation techniques this link is becoming less clear. In general, however, I think most neuro-oncologists would currently agree that radiation increases the risk of developing a meningioma.
Incidentally, there is currently little evidence that there is an association between the use of cell phones and an increased risk for the development of a brain tumor of any type. That said, the few studies that suggested a link included a few patients with meningiomas. However, the studies were predominantly focused on gliomas and acoustic neuromas (due to their prevalence near the acoustic nerves). Therefore, one can only say that there is currently no strong data suggesting an association.
How are meningiomas classified?
Meningiomas are classified according to several criteria that include the appearance of the cells of the tumor (cell type), the rate at which the tumor cells are growing (called cell proliferation rate or mitotic index) and whether the meningioma simply presses into the brain or actually grows and invades into the brain tissue. Using these criteria, the World Health Organization (WHO) developed a schema for classifying (also called grading) meningioma. WHO is the organization that develops the criteria used by most oncologists and pathologists for grading tumors in general. Using the WHO classification schema, a benign meningioma is WHO grade I. Atypical meningiomas are called WHO grade II, and malignant meningiomas, WHO grade III. Benign tumors are slow growing and if treated (see below), usually do not come back. The higher grade tumors grow faster and have an increased risk of regrowing after treatment and of invading into brain and thus being more destructive. In oncology parlance, the atypical and malignant meningiomas are considered “more aggressive”. Malignant meningiomas can also metastasize, or spread, to other locations within the nervous system.
What percentage are benign and what percentage are malignant?
The majority of meningiomas (approximately 90%) are benign (WHO grade I). These tumors are slow growing and often cause no symptoms. In many cases they are found incidentally when a person gets a brain scan for an unrelated reason. Many of these tumors never need treatment. When they cause symptoms, it is due to pressure on the brain or spinal cord. Atypical meningiomas (WHO grade II) account for about 7 to 8% of all meningiomas. Atypical meningiomas grow faster than benign tumors, and cause more pressure on the brain Malignant meningiomas are the least common, accounting for about 3% of all meningiomas.
What are the various treatment options?
The decision to treat a meningioma is based on the size and location of the tumor, whether or not it is causing symptoms, and the overall health of the patient. As noted above, the vast majority of meningiomas are benign, slow growing and do not cause symptoms. These are often just watched over time with occasional brain imaging studies (MRI or CT scans). Many of these patients will never need any treatment nor suffer any ill effects of having the meningioma. When treatment is recommended, surgery to remove the meningioma is the most common and successful option. If surgery cannot be done –perhaps due to the location of the tumor or the condition of the patient such as an unrelated medical problem— focal radiation to the tumor can be given. Radiation may also be given after surgery if not all the tumor was removed in order to reduce the risk that the tumor will regrow. Radiation can be given over several weeks, or in some cases, in one dose.
The use of chemotherapy or other systemic treatments such as immunotherapy or hormonal therapies have not been shown to be effective although there are individuals that appear to have some responses. In general these treatments are only used when all other options (radiation and surgery) are been tried and the tumor continues to grow or keeps coming back.
Are there indicators for good or poor outcome?
As noted above, many benign meningiomas never need treatment and never cause problems. In most cases when they are treated with surgical removal they do not recur and outcomes are excellent. If the surgeon is unable to remove the entire tumor, there is a risk it will regrow. Patients with atypical and malignant meningiomas have increased risk for having symptoms from their tumors and increased risk that the tumors will return after treatment.
Are there any ongoing clinical trials?
Most clinical trials in meningiomas focus on patients with recurrent meningiomas (those tumor that come back after surgery and/or radiation) or patients with atypical or malignant meningiomas. As these meningiomas are very rare, it is difficult to carry out these trials because the number of patients is so few. The best place to look for a trial is the National Institutes of Health Clinical Trial website, http://www.clinicaltrials.gov.
Any promising areas of research?
A major focus of research is aimed at understanding the genetic changes that occur in meningiomas. This could lead to treatments that prevent meningioma development in susceptible patients and specific treatments to slow or stop meningioma growth after they develop. Studies to determine if in fact hormones play a role in meningioma development and growth are in process, as well as the use of immunotherapies and anti-angiogenic agents to treat meningiomas.