Physicians at Memorial Sloan Kettering have extensive experience in caring for patients whose cancer has spread to the brain. They tend to treat these metastatic brain tumors aggressively, and in doing so, they can often extend patients’ lives and improve their quality of life.
An important part of this success has been advances in the delivery of radiation therapy, many pioneered by Memorial Sloan Kettering experts, including a sophisticated type of external radiation therapy known as stereotactic radiosurgery.
Stereotactic radiosurgery, or SRS, uses advanced imaging technologies combined with sophisticated computer guidance to deliver a highly targeted and intense dose of radiation that conforms to the three-dimensional shape and size of a tumor, with fewer side effects than conventional radiation techniques.
For some patients, this single-day, high-dose treatment can replace the daily delivery of lower doses of radiation over a course of therapy that can last up to six weeks.
“The vast majority of the time, SRS can either eliminate metastatic brain tumors or stabilize and shrink them so that they remain inactive after treatment,” explains radiation oncologist Kathryn Beal. “Most patients tolerate the treatment very well, and because it’s typically done in one day, it causes very little or no interruption in the delivery of other treatments [such as] chemotherapy.”
In addition, many patients can resume their normal activities the day after treatment.
How Stereotactic Radiosurgery Works
To deliver stereotactic radiosurgery, Memorial Sloan Kettering radiation oncologists use what is called a micro-multileaf collimator system, in which the radiation beam is covered by many layers of computer-controlled metal leaves.
These leaves shape the beam to match a three-dimensional outline of the tumor generated by an MRI scan. This allows the radiation to be delivered with great precision to the cancerous tissue, sparing the surrounding healthy brain tissue from any significant dose. The system also controls the intensity of the beam so that no area gets too large a dose.
Stereotactic radiosurgery has become an increasingly common approach for patients who have three or fewer brain tumors that are three centimeters or less in diameter. Candidates for stereotactic radiosurgery include those patients whose disease is not surgically accessible or is too advanced for neurosurgery, as well as those who cannot tolerate anesthesia.
Other brain tumors such as acoustic neuromas also can be treated with this technique.
Unique Access to New Treatment Combinations
At Memorial Sloan Kettering, patients with brain metastases are cared for by a multidisciplinary team of experts — which includes radiation oncologists, medical physicists, neurosurgeons, neurologists, neuro-radiologists, and expert nursing staff — that is among the most experienced in the world, treating hundreds of people with stereotactic radiosurgery annually.
“We’ve been using stereotactic radiosurgery more often over the past several years because we’re getting better at diagnosing brain metastases early, when they’re relatively small and ideal for this therapy,” says Dr. Beal. “Treating appropriate patients with SRS versus other therapies limits side effects and thus improves their quality of life.”
Research conducted at Memorial Sloan Kettering demonstrating the clinical advantages of stereotactic radiosurgery among patients with brain metastasis supports this clinical experience. A 2009 study led by Dr. Beal concluded that SRS given after surgery to remove brain metastases can reduce the postoperative rate of recurrence from about 40 percent to approximately 10 percent.
A subsequent study she led in 2012 showed that combining the delivery of stereotactic radiosurgery with ipilimumab — a vaccine that has improved survival in patients with metastatic melanoma — may yield improved survival and tumor control in patients with brain metastases. A larger prospective clinical trial is needed to confirm this finding.
“What makes Memorial Sloan Kettering unique is that many of our patients can benefit from the opportunity to receive SRS in combination with other treatments such as neurosurgery and newly developed cancer drugs — both of which can reduce the risk of cancer recurrence and improve survival and tumor control,” notes Dr. Beal, who is leading research to determine the effectiveness of such treatment combinations.