Prognostic Variables Affect How Brain Metastases Are Treated

July 1, 1997

HOUSTON--Controversy continues to shroud the issue of how single and multiple brain metastases should be treated, Moshe H. Maor, MD, said at a symposium on CNS cancer, sponsored by The University of Texas M.D. Anderson Cancer Center, where he is a radiation oncologist.

HOUSTON--Controversy continues to shroud the issue of how single andmultiple brain metastases should be treated, Moshe H. Maor, MD, said ata symposium on CNS cancer, sponsored by The University of Texas M.D. AndersonCancer Center, where he is a radiation oncologist.

"There is no question that surgical excision, whenever possible,has become the standard treatment for many patients with single brain metastases,"Dr. Maor said. "And for most patients with multiple metastases, externalwhole-brain radiotherapy remains the best treatment."

He added, however, that each case of brain metastasis presents a uniqueset of circumstances that must be considered in the treatment selectionprocess, and that may lead to controversies over treatment.

Physicians must consider the extent of the metastasis, the presenceor absence of extracranial involvement, the patient's survival prognosis,and the effects of treatment on the patient's quality of life.

In two randomized studies of selected patients with single brain metastases,patients who received radiotherapy as an adjunct to surgical excision livedlonger than patients who received radiotherapy alone, Dr. Maor said. Butthese studies did not confirm surgery plus radiotherapy as the recommendedtreatment for all patients with single metastases.

For example, surgery did not provide a survival benefit for patientswith active extracranial tumor. "Clinicians have not been able toagree as to the degree of extracranial tumor burden that renders a patientineligible for craniotomy," Dr. Maor said.

When the tumor location precludes excision, radiosurgery (high-dosefocused single-dose radiation) has been shown to be a powerful alternative.It is particularly effective in the treatment of small spherical tumorsand less effective when treating larger masses, he said.

Multiple Metastases

Surgery historically has been discouraged when two or more brain metastasesare present, Dr. Maor explained, because the risk of tumor recurrence increasesexponentially with the number of metastases. Nevertheless, he said, surgeonsat M.D. Anderson Cancer Center have had positive results with the surgicaltreatment of multiple brain metastases in some patients.

Whole-brain radiotherapy is generally the recommended treatment forpatients with two or more metastases. It provides palliation in 70% ofpatients, Dr. Maor said. Several well-designed studies using increasedradiation doses, unconventional fractionations, and radiosensitizers havefailed to improve on this percentage.

The Radiation Therapy Oncology Group (RTOG) has launched a study todetermine if radiosurgery can be used as successfully in multiple brainmetastases as in single metastases.

Consider Life Expectancy

The effect of whole-brain radiotherapy as an adjunct to surgery or radiosur-geryin patients with single brain metastases is also being considered. Thedecision in this patient group depends on the patient's prognosis basedon the status of the extracranial tumor, the radiosensitivity of the tumor,and the possibility that whole-brain radiotherapy will cause the patientfurther toxicity.

One important consideration in the decision to use this treatment isthe patient's prognosis. "Adjunctive whole-brain radiotherapy is along-term investment," Dr. Maor said. "It is not recommendedfor patients who are expected to live less than six months