From OncoLog, January 2005, Vol. 50, No. 1

New Perspectives on Brain Metastasis

by Rachel Williams

Anyone who walks past the waiting room toward the “Authorized Personnel Only” sign posted over the closed double doors of the operating rooms probably will notice family members and friends waiting for word aboutloved ones undergoing surgery for metastatic brain tumors. But no longer is it the anxiety-producing wait that it once was.

Today, brain metastasis—even multiple metastases—is not an automatic death sentence, and its treatment, while still not to be taken lightly, has become safer, minimally invasive, and more effective than it was not many years ago.

“Multiple tumors in the brain do not have as bad a prognosis as one would think,” said Jeffrey Weinberg, assistantprofessor in the Department of Neurosurgery at The University of Texas M. D. Anderson Cancer Center. “A recent study showed that a patient who has two or three lesions that can be removed actually has the same prognosis as someone who has only one brain tumor.”

In the past, the only treatment for multiple metastases was whole brain radiation, which on its own had little effect on survival. While that is still the standard treatment for four or more brain tumors, there are now a variety of effective treatment modalities for people who have fewer than four tumors.

“With a small, finite number of tumors, it may be better to treat the individual brain tumors themselves rather than the whole brain when possible,” Dr. Weinberg stated.

He explained that while whole brain radiation has benefits such as treating micrometastases (individual cells that can eventually grow into brain tumors), today it is most often used in conjunction with other treatment modalities, such as surgery and radiosurgery.

“Surgery and radiosurgery allow treatment to be directed at the tumor itself,” said Dr. Weinberg. “Because of technological advancements, both are now minimally invasive and have lower risks.” At M. D. Anderson, multidisciplinary teams that include radiation oncologists and neurosurgeons design treatment plans tailored to the patient’s individual situation.

Imaging Techniques Improve Precision

Computer-assisted surgery has made brain surgery faster, safer, and more precise. Magnetic resonance imaging allows neurosurgeons to see beneath the skull before the incision is made and locate the tumor exactly. Ultrasound provides real-time imaging of the brain as the surgery is being performed. Because of the precision, surgeons can make smaller bone openings, approach the tumor more precisely, and more completely resect it.

Advanced operative and imaging technology also allows doctors to map speech, motor, and sensory areas of the brain before surgery and thereby preserve or avoid them during surgery. Furthermore, they can perform the surgery on patients who are awake if need be in order to better identify speech control areas of the brain.

“We’ve really perfected brain surgery to be relatively safe, even for many lesions that previously were considered unresectable,” said Frederick Lang, M.D., associate professor in the Department of Neurosurgery.

While surgery now involves fewer risks and is less invasive, radiosurgery avoids the risks of a craniotomy altogether and requires only local anesthesia. This highly localized treatment is a same-day procedure.

At M. D. Anderson, radiosurgery is delivered by a team of neurosurgeons and radiation oncologists. Linear accelerators (Linac) are used in conjunction with stereotaxis that allows doctors to align exactly the correct angle and distance for directing radiation beams. The multiple low-dose beams converge from various angles, delivering to the tumor a very high dose of radiation. While radiosurgery does not actually remove the tumor, it damages the DNA so badly that the tumor is eradicated.

Weighing the Options

There is an ongoing debate about whether surgery or radiosurgery is the better option for treating brain metastasis and under what circumstances. In actuality, each has its own advantages and disadvantages.

Dr. Lang summarized the pros and cons: “The advantage of removing a tumor surgically is that it is taken out in one swoop and people tend to recover faster from swelling and neurocompromise. The disadvantage is that it requires invasive surgery.

“Radiosurgery is lot easier and avoids many of the problems of invasive surgery, but it does not eliminate the tumor immediately. It sometimes takes three or four months to shrink, causing the patient to deal with the tumor’s symptoms longer and to possibly need steroids for a longer period. The followup can be more complicated with radiosurgery than with surgery because of the risk of destroying surrounding tissue.”

Radiosurgery is optimal for very small lesions, particularly those located deep in the brain, which are hard to find, much less excise surgically. It can’t, however, be used on tumors larger than three centimeters because too large an area of brain tissue surrounding the tumor may be exposed to radiation.

Tumors that are between one and three centimeters can be treated with either approach. It’s not yet clear which approach is optimal, but M. D. Anderson is working on finding out.

“One of the most important things we’re doing in brain metastasis is a Phase III clinical trial in which people are randomized to receive either radiosurgery or surgery. We’re several years away from finishing that trial, at which time we hope to have some good data to guide these decisions.”

For people with more than one brain metastasis, M. D. Anderson physicians tend to take a more aggressive approach than many other treatment centers. Most patients with two or three tumors receive a combined surgery/radiosurgery treatment tailored to their particular situation.

“For example, we might take out one large lesion and give radiosurgery to two smaller ones,” said Dr. Lang. “Tumors that can be removed are, and those that cannot are treated with radiosurgery. The critical idea is to focally treat all of the tumors, because if you leave one or two behind untreated, the patient is not going to do as well.”

For more information on this topic or for questions about M. D. Anderson’s treatments, programs, or services, call askMDAnderson at (877) MDA-6789.

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