Weill Medical College of Cornell University

• Home
• The New York Brain Tumor Center
• Clinical Neuro-Oncology Program
• Brain Tumor Research Group
• Skull Base Lab
• Neuro-Oncology Active Clinical Trials List
• The Pituitary & Anterior Skull Base Surgery Program
• Program Faculty
• Conditions Treated
• Adult Pituitary Treatment
• In The News
• Pediatric Brain and Spinal Cord Tumors
• Skull Base Surgery
• Radiosurgery Program: Gamma Knife
• Stereotactic Radiosurgery
• External Beam Therapy
• Gamma Knife
• LINAC
• X-Knife
• CyberKnife

Stereotactic Radiosurgery

At NewYork-Presbyterian Hospital/Weill Cornell Medical Center, we use the most advanced methods for treating brain tumors and non-cancerous abnormalities of the brain. Stereotactic radiosurgery (SRS) and stereotactic radiotherapy are non-invasive treatments that use pencil-thin beams of radiation generated by a specially modified linear accelerator to treat brain lesions safely, effectively, and without any incisions. Radiosurgery is virtually painless and can be performed on an out patient basis without many of the usual risks and side effects associated with surgery.

Weill Cornell's expert radiation oncologists use sophisticated 3-dimensional computer-generated treatment plans that allow the radiation dose to be directed to the site of the tumor while sparing surrounding healthy brain tissue. Then, using a single high dose of ionizing radiation (for radiosurgery) or multiple treatments with smaller doses of ionizing radiation (radiotherapy), the full radiation dose is concentrated in the tumor. Very little of the surrounding tissue receives significant radiation.

Radiosurgery is not surgery in the conventional sense, as no opening is made in the skull. Radiosurgery describes the precise, tightly circumscribed delivery of radiation, usually as a high dose in a single fraction, to a defined intracranial target or other anatomic target. Originally, it was used by neurosurgeons to produce tiny, circumscribed, non-invasive lesions in the brain for movement disorders and pain. In certain cases, it may offer similar benefit and lower risk or discomfort than conventional surgery and patients can avoid both hospitalization and anesthesia.

Radiosurgery (one-session treatment) has such a dramatic effect in the target zone that the changes are considered "surgical." Through the use of three-dimensional computer-aided planning and the high degree of immobilization, the treatment can minimize the amount of radiation to healthy brain tissue. Stereotactic radiosurgery is routinely used for brain tumors and lesions. It may be the primary treatment; utilized where a tumor is inaccessible by surgical means; or as a boost or adjunct to other treatments with a recurring or malignant tumor. In some cases, it may be inappropriate.

Stereotactic radiosurgery is a way of treating brain disorders with a precise delivery of a single high dose of radiation in a one-day session. Treatment involves the use of focused radiation beams delivered to a specific area of the brain to treat abnormalities, tumors or other functional disorders. Stereotactic radiosurgery is limited to the head and neck as these areas can be immobilized with skeletal fixation devices that completely restrict the head's movement, permitting the most precise and accurate treatment. Treatment without a skeletal fixation device for a one-session treatment is not recommended because of the high potential for damage to healthy brain tissue, cranial nerves (optic, hearing, etc.) and the brain stem.

Fractionated stereotactic radiation treatments — which are received over a period of days or weeks — may be administered in the body with the assistance of removable masks and frames that achieve some degree of lesser mobilization.

A Team Approach

New-York Presbyterian/Weill Cornell is staffed by experts with highly specialized knowledge and skills in neurosurgery, neuroradiology, neurology, radiation therapy and radiation physics. Supported by 20 years of research and successful treatment of patients, the stereotactic program applies the latest technological advances in neurosurgical and radiation therapy principles to provide patients with the most advanced and skilled treatment available.

Who Can Benefit From Stereotactic Radiosurgery or Radiotherapy?

Patients with a wide range of brain tumors — both benign and malignant — as well as vascular lesions can benefit from stereotactic radiotherapy or radiosurgery. These highly effective therapies can be used alone or in combination with surgery or external beam radiation therapy to destroy tumors at the first sign of their appearance or following a recurrence.

Stereotactic radiosurgery may or may not be appropriate for a condition. It may be used as the primary treatment or in conjunction with other necessary treatments. Only a treating neurosurgeon who operates radiosurgery equipment can make the evaluation as to whether someone can be treated. A neurosurgeon must always be present during treatment and should work with a radiation oncologist when the brain is being targeted.

Stereotactic radiosurgery can effectively treat such cranial lesions as:

• Arteriovenous malformations
• All benign brain tumors including:
• Acoustic Neuromas
• Meningiomas
• Pineal and Pituitary
• All malignant brain tumors including:
• Glial and astrocytomas
• Low-grade tumors
• Recurrent Glioblastoma multiforme
• Vestibular schwannomas
• Metastatic brain tumors
• Functional disorders including:
• Trigeminal Neuralgia
• Essential Tremor
• Parkinson's Tremor/Rigidity

Because all forms of radiation treatments work over time, they may be inappropriate if symptoms are severe or life-threatening. Relief of acute symptoms may drive the first treatment choice to open skull surgery or medication. For instance, if current symptoms when diagnosed are so severe that quality of life is affected the appropriate choice for the first treatment may be surgery to relieve those symptoms. The secondary treatment could then be radiosurgery.

In other cases where cells are extremely fast growing (with or without severe symptoms), such as in brain metastases, radiosurgery can quickly control the brain tumors to allow time to treat the primary cancer site. Medication can be given for the side effects of edema and radiation therapy may be used over a period of time to help eliminate the stray cancer cells from the brain.

Previous Radiation

Stereotactic radiosurgery can be used in patients who have failed standard radiation techniques or in patients who have already received the maximum radiation dose permissible or whole brain radiation. At this time, there are no known cases of radiation-induced new tumors from stereotactic radiosurgery in 30 years of treatments. This may be attributed to the preciseness of the treatment and the sparing of healthy nerves and tissues. A patient who has had stereotactic radiosurgery for a brain tumor or condition may later have open skull surgery without problems. In many cases, if necessary, additional treatments of stereotactic radiosurgery can be performed.

What to Expect

Prior to treatment, the radiosurgery team members meet to develop a treatment plan and discuss optimal imaging techniques. On the day of the procedure, a neurosurgeon places a special stereotactic frame to aid in localizing the brain lesion and hold the patient's head motionless during treatment. After a treatment planning CT scan is performed with the frame in place, the lesion's location and dimensions are precisely defined. A state-of-the-art computer-generated treatment plan is then used to direct the prescribed radiation dose to the lesion with pinpoint accuracy. The treatment's goal is to shrink the lesion over time. In many cases, the treated lesions completely disappear.

How it Works

Stereotactic radiosurgery works the same as all other forms of radiation treatment. It does not remove the tumor or lesion, but it distorts the DNA of the tumor cells. The cells then lose their ability to reproduce and retain fluids. The tumor reduction occurs at the rate of the normal growth rate of the specific tumor cell. In lesions such as AVMs (a tangle of blood vessels in the brain), radiosurgery causes the blood vessels to thicken and close off. The shrinking of a tumor or closing off of a vessel occurs over a period of time. For benign tumors and vessels, this will usually be 18 months to two years. For malignant tumors and metastatic tumors, results may be seen as soon as a couple of months as these cells are very fast-growing.

Side Effects

• Swelling: As with all radiation treatments, the cells of the irradiated tumors lose their ability to regulate fluids and edema or swelling may occur. This does not happen in all treatments. If swelling does occur, and it causes symptoms that are unpleasant, then a mild course of steroid medication may be given to reduce the fluid within the tumor cavity.
• Necrosis: The tumor tissue that remains after the radiation treatment will typically shrink. On rare occasions this necrotic or dead tissue can cause further problems and may require removal. This occurs in a very small percentage of cases.
• Other Effects: Other side effects may occur dependent upon the site of targeting and the dosage of radiation received. This should be discussed throughly with your treating physician.

Types

There are three basic forms of stereotactic radiosurgery represented by three different technological instruments. Each instrument operates differently, has a different source of radiation and may be more effective under different circumstances. The three are:

• Particle beam (photon)
• Cobalt60 based (proton): Gamma Knife
• Linear accelerator based: X-Knife, CyberKnife, Clinac

The particle beam or cyclotron is in limited use in the United States. In addition to brain tumors, it also treats body cancers in a fractionated manner. There is not much material available on the technology and outcomes at this time. The particle beam is extremely large and funded by public research.