Gamma knife radiosurgery of a series of only minimally selected metastatic brain tumours.

From December 1991 to October 1992, 77 lesions in 25 consecutive patients were treated with Gamma Knife radiosurgery. Thirteen patients (52%) had multiple metastases up to sixteen lesions and twelve patients had a single metastasis. The volume of the largest tumour treated was 12.5 cm3. Karnofsky performance status (KPS) of the patients was 20-90% (mean 70). Marginal tumour dose given was 18 to 35 Gy (mean 26.1 Gy) in 30 to 90% isodose line according to the tumour volume and site. All but two patients were followed by MRI or CT scan repeatedly for a minimum of 6 month or to death. All but one of the tumours were locally controlled. Seventeen patients died during follow up and in four death was due to remote CNS metastases. The median survival for this minimally selected group of patients was 8.5 months, and the median survival for the patients with a single metastasis was 10.5 months. In patients with multiple metastases the median survival reached only 2.5 months but in 11 patients out of 13 patients neurological symptoms and signs improved or stabilized shortly after radiosurgery.