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Brain Tumors
IntroductionTumors of the brain are diverse and present great challenges to neurosurgeons, oncologists and their patients. Radiation therapy benefits most patients with brain tumors, so all such patients should ask their neurosurgeon, neurologist or primary care physician about seeing a radiation oncologist prior to selecting a course of therapy. Extensive surgery on the brain can sometimes be avoided. Therapy of brain tumors is complex and evolving. The physicians of Valley Radiotherapy Associates (VRA) will first carefully evaluate the computed tomography (CT) or magnetic resonance imaging (MRI) studies, review the tumor type (when a biopsy is available) and perform a complete neurologic and general physical examination to catalog the signs and symptoms affecting the life of the individual patient. If additional studies are needed, VRA can assist in obtaining them. More than one treatment option often merits consideration. A VRA radiation oncologist will review those options involving radiation and provide a recommendation. If a patient has not already consulted with a neurosurgeon or medical oncologist, VRA will assist in arranging a consultation as appropriate. We also are glad to provide information about specialized radiation techniques, such as stereotactic radiosurgery (XKnife and Gamma-Knife), stereotactic radiotherapy, conformal radiotherapy, intensity modulated radiotherapy (IMRT), interstitial implantation and proton beam therapy. At VRA, our radiation oncologists not only have specialty expertise in brain tumors within our group, we also provide referrals to regional academic centers of excellence in brain tumor research, if a patient requires specialized radiation not available through VRA. We also will assist in coordinating care with a regional center, so that any patient can conveniently obtain as much of their treatment in their local community as possible. Below are information sections about the more common brain tumors, and the VRA approach to treating these tumors. Some brain tumors are quite rare. If you do not find the information you are seeking, please feel free to contact one of our offices and we would be glad to assist you in obtaining additional information. 1Levin, VA, Sheline, GE and Gutin, PH. "Neoplasms of the Central Nervous System" in Devita, VT, Hellman, S and Rosenberg, SA, eds. Principles and Practice of Oncology, 3rd edition, pp. 1557-1611;JB Lippincott, Philadelphia, 1989 Brain MetastasesMetastasis, or spread of cancer from other parts of the body to the brain affects approximately 10-15% of cancer patients. Metastatic spread accounts for the vast majority of tumors affecting the brain, and over 100,000 people in the United States develop brain metastases each year. The most common metastatic tumors affecting brain are lung, breast and melanoma, but any type of cancer can spread to the brain. Two to four weeks of radiation therapy to the whole brain clearly improves survival and reduces symptoms for patients with brain metastases. Patients with a small number of metastases confined to the brain may benefit from more intensive local treatment, either with surgery or stereotactic radiosurgery(SRS). Radiation therapy to the whole brain usually must be added after surgical resection, but selected patients may be able to be treated with stereotactic radiosurgery alone. Stereotactic radiosurgery is also effective for patients whose tumors have recurred in a small volume after whole brain radiation or surgery. 2Borgelt, et. al. "The palliation of brain metastases: final results of the first two studies by the Radiation Therapy Oncology Group" IJROBP,6: 1-8; 1980 Malignant Gliomas [Anaplastic Astrocytomas (AA) and Glioblastoma Multiforme (GBM)]Approximately 20,000 cancers each year in the United States arise only within the brain itself, and almost half of these are malignant gliomas. Malignant gliomas are usually divided into anaplastic astrocytomas (AA) and glioblastoma multiforme (GBM), depending on how these tumors appear under the microscope. Unfortunately, malignant gliomas grow rapidly, behave aggressively and show resistance to many conventional treatment approaches. Because malignant gliomas extensively infiltrate surrounding normal brain, complete surgical removal is often not possible. Six to seven weeks of radiation therapy after surgery clearly improves survival, but many tumors still progress. When indicated, VRA physicians will utilize three-dimensional, CT based treatment planning and conformal radiotherapy to avoid treating unaffected normal brain. Side effects of therapy are consequently lower. Chemotherapy, especially for anaplastic astrocytomas, confers an additional survival benefit for some. Patients with smaller tumors (generally less than 5 centimeters) should be considered for insertion of temporary radioactive sources directly into the tumor (known as interstitial implantation) or a fractionated stereotactic radiotherapy boost. VRA participates in regional and national investigational clinical trials of promising new therapies for this aggressive group of tumors, and may recommend this approach when appropriate. We frequently work with regional institutions to allow patients to receive as much of their radiation therapy in their local communities as conveniently possible. 5Walker, MD et.al. "Evaluation of BCNU and/or radiotherapy in the treatment of anaplastic gliomas: a cooperative clinical trial" J Neurosurg, 49: 333; 1978 Low-Grade GliomasAs their name suggests, low grade gliomas are related to malignant gliomas [see above], but behave less aggressively and are only about half as common. Most patients with low grade gliomas have had a seizure, and a significant number of patients remain stable for years on anti-seizure medication alone. Unfortunately, most low grade gliomas gradually enlarge over time and many acquire the more aggressive behavior characteristic of malignant gliomas. Available evidence suggests that patients who undergo complete surgical removal or receive radiation therapy survive longer than untreated patients. An otherwise healthy patient should strongly consider accepting complete surgical removal, only if this can be achieved without permanent neurological impairment. Patients who cannot undergo complete surgical removal should have a biopsy for diagnosis and receive five to six weeks of highly conformal radiation directed at the tumor only. Small tumors (<3 cm) preferably should receive stereotactically directed fractionated radiotherapy. 7Shaw, EG et. al. "Management of supratentorial low-grade gliomas" Oncology 7: 97-108; 1993 MeningiomasMeningiomas are the most common benign, or non-spreading, brain tumor. They form from the brain's specialized covering, called the meninges, and represent about 15% of all tumors arising in the brain. Most meningiomas are slow-growing and probably have been present for years before causing symptoms. Complete surgical removal almost always results in cure. A few meningiomas arise in very sensitive parts of the brain and cannot safely be completely removed. Five to six weeks of radiation therapy delivered with conformal fields to the part of the tumor remaining after surgery frequently prevents recurrence. Stereotactic radiosurgery also effectively treats small residual meningiomas located at least 5 mm (about 1/4") from important nerves and brain. Acoustic NeuromasAcoustic neuromas arise from the nerve which controls hearing and balance. Like meningiomas [see above], acoustic neuromas are benign, or non-spreading, tumors, but are only about half as common. Acoustic neuromas cause varying amounts of hearing loss. They are common in neurofibromatosis, a genetic condition causing characteristic tumors of skin and nerves. Complete removal with surgery is almost always curative, but often results in complete loss of hearing in the affected ear. Recurrence is frequent after incomplete surgical removal, and can be prevented with five to six weeks of conformal radiation therapy directed at the residual tumor. Stereotactic radiosurgery (SRS) is an effective alternative, and useful hearing can be preserved in some patients. Tumors larger than 2 centimeters are more difficult to treat with SRS, because numbness or weakness of the face for several months after treatment occurs frequently. VRA recommends that patients with larger tumors who wish to avoid surgery be offered stereotactic fractionated radiotherapy over five to six weeks. Until more information is available, however, patients must understand and accept that fractionated stereotactic treatment may not produce cure in as many patients as SRS or surgery. 8Flickinger, JC et.al. "Outcome analysis of acoustic neuroma management: a comparison of microsurgery and stereotactic radiosurgery" Neurosurgery 36: 215-24; 1995 Pituitary AdenomasPituitary tumors make up about 5% of tumors arising in the brain. Although pituitary tumors are almost always benign, or non-spreading, they can produce profound overproduction of some hormones. The three most commonly affected hormones are prolactin (which causes milk secretion), cortisol (which causes weight gain and a characteristic round face), and growth hormone (which causes slowly progressive enlargement of face and hands). Although some pituitary tumors produce no substances at all, uncontrolled growth of any pituitary tumor can cause both hormone deficiencies and visual loss. Surgery produces the most rapid and effective control of hormone overproduction. It may also save vision by removing tumor pressing on the optic nerve. However, some larger tumors and many incompletely removed tumors grow back following surgery. Radiation therapy not only prevents many of these recurrences, it also gradually reduces associated hormone overproduction. Many hormone levels continue to decline several years following completion of a five week course of radiation. Evidence suggests that stereotactic radiosurgery (SRS) also reduces hormone production rapidly and effectively, and may be an alternative to surgical resection for small tumors completely confined to the pituitary gland. At VRA, incompletely removed or recurrent tumors adjacent to the optic nerves are treated for approximately five weeks with conformal post-operative fractionated radiation therapy. SRS may be considered in special circumstances when the tumor recurs following carefully fractionated radiation, although the risk of a complication may be significant. Further Information and Resources: |
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