Brain Tumors

Brain tumors represent a diverse group of diseases, many of which are often treated with radiation therapy. Various radiation techniques can be used, including 3D conformal radiation, intensity modulated radiation therapy (IMRT), and sterotactic radiation. When using radiation, accuracy in targeting these tumors is vital, both to successfully treat the tumor, and to minimize side effects from treatment to adjacent critical structures. This accuracy is a product of many careful steps in the planning and delivery of the radiation:

In preparation for treatment, a plastic mask is custom made to conform to the contour of the patient’s head and face. This mask is used daily to help reproduce the patient’s head position for treatment. Sometimes for very high dose single treatments, a metal frame is used instead. The imaging studies used to delineate the tumor (such as CAT scans and MRI’s) are imported into a computer equipped with sophisticated software programs. These programs recreate the patient’s anatomy in three-dimensions, allowing the radiation therapy team to look at the relationship of the tumor to the surrounding normal tissues and determine the best angles to deliver the radiation.

Other computer programs allow the team to optimize the strength of each beam to give the best distribution of radiation to the tumor. The final treatment plan is electronically transferred to the computer controlling the machine that will deliver the radiation. When the patient returns to clinic to start radiation therapy, all the set up parameters are confirmed to match those in the plan before radiation therapy starts. In addition, x-rays are taken to insure the patient is appropriately positioned for treatment.

To insure their performance, all of our treatment machines undergo extensive and continuous quality assurance testing under the supervision of an experienced medical physicist.

• Malignant Gliomas (Glioblastoma, Anaplastic Glioma)
• Low Grade Gliomas
• Meningiomas
• Vestibular Schwannomas (also called “Acoustic neuromas”)
• Pituitary Tumors
• Brain Metastasis (tumors which start elsewhere and spread to the brain)

The most common malignant tumors that arise in the brain are malignant gliomas, which include glioblastomas and anaplastic gliomas. These tumors tend to be very aggressive and grow quickly. The first line of treatment is surgery, but many times they cannot be completely removed because they infiltrate critical portions of the brain. Usually, radiation is given after surgery, with the radiation fields covering both the tumor bed as well as the surrounding area to cover any microscopic spread the tumor. A typical course of treatment is six to seven weeks, Monday-Friday. While radiation rarely cures these cancers, it has been shown to improve survival times compared with patients who do not receive radiation.

These tumors are less aggressive types of gliomas than malignant gliomas, and grow more slowly. They infiltrate into normal brain tissue and have indistinct borders, making surgical removal difficult. Since they are slow growing, recommendations for treatment take into consideration the location of the tumor, the symptoms it is causing, the age of the patient, and possible side effects of treatment. Radiation is used to delay progression of low grade gliomas, but the timing of its use is controversial. Radiation tends to be recommended if the tumor is not operable and is causing symptoms.

A tumor arising from the lining of the brain (the “meninges”) is a meningioma. These are usually benign, slow growing tumors although with time they can become quite large and cause symptoms due to compression of the adjacent brain. Radiation is often used to treat meningiomas which are in areas difficult to access with surgery, such as those at the base of the skull. Unlike gliomas, benign meningiomas do not invade adjacent tissues, so radiation fields only need to encompass the tumor itself. Therefore, precise targeting of the meningioma is of paramount importance to avoid damage to adjacent normal tissues. While radiation usually does not eradicate a meningioma, it is very effective in preventing further growth.

Schwannomas (or “neuromas”) arise from the lining of a nerve (analogous to meningiomas arising from the lining of the brain). Like meningiomas, they are usually benign. Radiation is often recommended for treatment of vestibular schwannomas (also termed “acoustic neuromas”). These tumors may cause tinnitus, or ringing, in the affected ear, hearing loss and balance difficulties. While the radiation itself may cause further hearing loss, the risk of hearing loss may be reduced by giving multiple small daily doses rather than one large dose. Since these tumors are located next to the brainstem, stereotactic radiation is used to precisely target tumor.

Most tumors of the pituitary gland are “pituitary adenomas” which are benign and slow growing. Sometimes, they secrete hormones that can cause various symptoms, such as abnormally excessive growth, excessive thyroid hormone production, or infertility. Most, however, do not produce hormones and come to medical attention by causing vision changes from compression of the optic nerves that sit above the pituitary. In general, surgery is used first to try to resect these tumors and provide tissue to confirm the diagnosis. However, radiation can be effective in treating tumors that cannot be completely resected. As with vestibular schwannomas (above), pituitary tumors are usually approached with stereotactic radiation. Sometimes a single, large treatment of radiation is used. However, if the optic nerves are very close to the tumor, multiple smaller daily doses of radiation are employed to reduce the risk of damage to the optic nerves.

A tumor that spreads to the brain from another part of the body is called a brain metastasis. Common types of cancer that can metastasize to the brain are lung, breast, colon, kidney, and melanoma. Different radiation therapy approaches are used depending upon the type of cancer, the number of brain metastasis, and the extent of cancer elsewhere in the body. Patients with multiple brain metastases are usually treated with radiation fields that encompass the whole brain. Those with one or only a few metastatses may be treated with stereotactic radiation, delivering high doses or radiation the tumor(s) that are present. Sometimes, whole brain radiation is given followed by a boost with stereotactic radiation. Deciding which of these approaches to use can be challenging and should only be made after a full discussion with your radiation oncologist.