Stereotactic Radiosurgery gives new hope for brain tumor sufferers.

  • Published
  • By Mike Frangipane
  • 88th Air Base Wing Public Affairs
Pamela Bishop rested comfortably in a hospital bed at Wright-Patterson Medical Center. She had arrived from home early that morning to be fitted with a frame that surrounded her head. It was not uncomfortable, but she remarked that the installation, while not painful, had nevertheless given her a headache. The headache had passed now and she was in good spirits. 

The head frame will be used to position Bishop's head for treatment of the brain tumor with which she had been diagnosed. It was a cancer that had metastasized, cancer cells that originated elsewhere in Bishop's body, as often occurs with lung, breast, liver and other cancers, had migrated to her brain to grow as a tumor. If left unchecked it would crowd out her brain functions with debilitating and often fatal result. 

Studies have shown that primary cancers metastasize to the brain at a rate of 20-40%, and brain metastases is the most common of all diagnosed brain tumors, more than all other intracranial tumors combined. 

"The brain is often a favorite site for cancer to spread," said Dr. (Lt. Col.) Ronald Hale, Chief of Radiation Oncology. While doctors can treat Bishop's primary cancer site with chemotherapy, that treatment will not impact the cancer that has metastasized to her brain. 

"The brain acts as a sanctuary from chemotherapy," said Hale. "The patient may have very good response to chemotherapy and have other sites of the disease well controlled, but the brain protects itself by keeping potential poisons out. Chemotherapy, like other drugs, is naturally kept out of the brain." 

Metastatic brain tumor is a diagnosis that just a short time ago would have meant one or both of two primary treatments. The first is whole brain radiation therapy for those cancers inaccessible to surgery. With its low survival expectancy and accompanying side effects such as nausea, vomiting, lethargy and possibly dementia, this form of treatment is not encouraging. 

The second treatment for those tumors within reach of surgery is craniotomy, open skull surgery, to remove the tumor. Besides the long recovery time of craniotomy, it too carries a list of possible side effects, such as memory loss, headaches, or balance problems. The diagnosis of a brain tumor just a short time ago meant a very difficult time lay ahead for the patient. 

But that was then. There is now a new procedure, a treatment that encourages new hope. It is called stereotactic radiosurgery. And it offers patients like Bishop the hope of a cure and the prospect of a treatment from which she will suffer fewer if any side effects and which would see her at home by early that evening, resuming her daily activities. 

Stereotactic radiosurgery is really not surgery at all. It is a technique that allows the very precise delivery of a single high dose of radiation to the tumor without the potentially destructive effects that whole brain radiation therapy might bring to the surrounding brain tissue. 

When she arrived that morning, Bishop was given Magnetic Resonance Imaging, an MRI, which would give doctors the most current detailed information about the tumor, its character, precise location and size. After being fitted with the stereotactic head frame, Bishop then had a computed tomography, or CT scan, which produced a computer model of her head. The computer model was then "fused" to the MRI and technicians marked the target, the tumor on which they wanted to focus treatment. They also marked the structures, such as the eyes and crucial parts of the brain through which they did not want radiation to pass. Then a neuro-radiologist or a neurosurgeon was consulted to confirm the correct target, the plan was developed, and the quality assurance process set in place. 

While all of this was being accomplished Bishop rested comfortably. She remained awake, was able to watch TV, to read and to engage in conversation with her sister, who was able to stay with her to help her pass the time. 

Stereotactic is a term that means the ability to use specialized procedures to localize a point in space, in this case within the space of the brain. The stereotactic radiosurgery technique involves directing fanlike arrays of successive radiation beams that will focus or converge upon the target tumor. Each beam of radiation in itself is a light dose of radiation which will do no serious damage to the tissue through which it passes. However, each successive beam as it converges in the tumor has the cumulative effect of a very large dose of radiation at the precise place it is needed, the cancer cells of which the tumor is composed. 

"In this way," said Hale, "a very high dose of radiation is delivered to the tumor while the surrounding tissue is exposed to a minimal dosage." 

Without a single incision or drop of blood, but with scalpel-like precision the tumor and its surrounding blood supply are destroyed despite the fact that it may reside in a surgically inaccessible location in the patient's brain. 

When the planning and preparation were accomplished, in this case late afternoon of the same day, Bishop was brought from her room, the head frame was secured to the table and the treatment was delivered over the course of an hour. 

"At the end of the day," said Hale, "we back out the tiny pin like screws of the head frame, the skin comes back to normal and the patient has four small spots that look like she has been stuck with four little needles." With the frame removed, Bishop departed for home, a little tired perhaps from the long day, but otherwise feeling fine. 

This new and promising treatment has been made available at Wright-Patterson Medical Center through the use of joint incentive funds which provided a $1.1 million grant for a joint project between the Department of Defense and the Veterans Administration to expand service offerings and to make them available to both DoD and VA patient populations. In recent past it has resulted in establishing high dose rate brachytherapy and prostate seed brachytherapy at the Wright-Patterson Medical Center. Stereotactic radiosurgery is another treatment made available at Wright-Patterson by the JIF grant expanding the Center's already formidable arsenal of cancer treatments.