Patients with multiple brain metastases are often treated primarily with fractionated whole-brain radiation therapy (WBRT). In previous reports the authors have shown that patients with four or fewer brain metastases can benefit from stereotactic radiosurgery in addition to fractionated WBRT. In this paper the authors review their experience using linear accelerator stereotactic radiosurgery to treat patients with multiple brain metastases.Fifty-three patients with 149 brain metastases underwent stereotactic radiosurgery. The mean age of patients was 53.1 years (range 20-78 years). There were 23 men and 30 women. The primary tumor location was lung (27 patients), melanoma (10), breast (six), ovary (six), and other (four). All patients harbored at least two metastatic tumors treated with radiosurgery; 27 patients (51%) harbored two lesions, 17 (32%) three lesions, eight (15%) four lesions, and one patient (2%) harbored five lesions. The mean radiation dose administered was 19.6 Gy (range 14-30 Gy), and the mean secondary collimator size was 15.7 mm (range 7.5-40 mm). One hundred thirty-two (89%) of the 149 treated tumors were available for review on magnetic resonance (MR) imaging at 3 months posttreatment. Fifty-two percent were smaller in size, 31% were stable, 9% had increased in size, and 8% had disappeared. New metastatic tumors appeared in 12 (23%) of the 53 patients on MR imaging within 6 months posttreatment. Radiation-induced necrosis occurred at the site of eight (5.4%) of the 149 tumors at 6 months. Seven tumors (4.7%) subsequently required surgical resection for either tumor progression (four cases) or worsening edema from radiation-induced necrosis (three cases). Median actuarial survival was 9.6 months.Stereotactic radiosurgery can be used to treat patients with up to four brain metastases with a 91% rate of either decrease or stabilization in tumor size and a low rate of radiation-induced necrosis. In the authors' study only a small number of patients subsequently required surgical resection of a treated lesion.
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