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.
"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, external whole-brain radiotherapy remains the best treatment."
He added, however, that each case of brain metastasis presents a unique set of circumstances that must be considered in the treatment selection process, and that may lead to controversies over treatment.
Physicians must consider the extent of the metastasis, the presence or 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 lived longer than patients who received radiotherapy alone, Dr. Maor said. But these studies did not confirm surgery plus radiotherapy as the recommended treatment for all patients with single metastases.
For example, surgery did not provide a survival benefit for patients with active extracranial tumor. "Clinicians have not been able to agree as to the degree of extracranial tumor burden that renders a patient ineligible for craniotomy," Dr. Maor said.
When the tumor location precludes excision, radiosurgery (high-dose focused single-dose radiation) has been shown to be a powerful alternative. It is particularly effective in the treatment of small spherical tumors and less effective when treating larger masses, he said.
Surgery historically has been discouraged when two or more brain metastases are present, Dr. Maor explained, because the risk of tumor recurrence increases exponentially with the number of metastases. Nevertheless, he said, surgeons at M.D. Anderson Cancer Center have had positive results with the surgical treatment of multiple brain metastases in some patients.
Whole-brain radiotherapy is generally the recommended treatment for patients with two or more metastases. It provides palliation in 70% of patients, Dr. Maor said. Several well-designed studies using increased radiation doses, unconventional fractionations, and radiosensitizers have failed to improve on this percentage.
The Radiation Therapy Oncology Group (RTOG) has launched a study to determine if radiosurgery can be used as successfully in multiple brain metastases as in single metastases.
Consider Life Expectancy
The effect of whole-brain radiotherapy as an adjunct to surgery or radiosur-gery in patients with single brain metastases is also being considered. The decision in this patient group depends on the patient's prognosis based on the status of the extracranial tumor, the radiosensitivity of the tumor, and the possibility that whole-brain radiotherapy will cause the patient further toxicity.
One important consideration in the decision to use this treatment is the patient's prognosis. "Adjunctive whole-brain radiotherapy is a long-term investment," Dr. Maor said. "It is not recommended for patients who are expected to live less than six months