[Cerebral metastases treated with stereotaxic gamma radiation. 6-year experience with the "gamma knife" at the Haukeland hospital].
During the last 6 years we have treated 32 patients with 45 metastases to the brain in the Gamma Knife unit. 21 of these were treated exclusively with the Gamma Knife. The remaining 11 patients received radiosurgery for recurrent disease after surgery and whole-brain irradiation (six patients), new metastases after whole-brain irradiation alone (three patients) or for local regrowth after surgery (two patients). The range of tumour volume was 0.1-43.3 cm3 (median 2.4 cm3). Marginal tumour dose was 5-30 Gy (median and mean: 25 Gy) to the 30-70% isodose-volume line according to tumour volume and localization. 19 patients died during the period of follow-up. Only three patients died from their intracranial metastases. Thus, local growth control was achieved in 29 patients. 16 patients died from extracranial manifestations. The average survival time for the patients who died during the observation period was 11 (1-37 months), and the survival time for patients still alive was 10-75 (median 14, average 29) months. Mean observation period for all patients was 17 (1-75) months. Brain metastases are physically and biologically ideal lesions to treat with radiosurgery. Stereotactic radiosurgery applied to radiographically small and distinct metastases is safe, non-invasive and highly effective. The treatment requires only a short stay in hospital, and is much less inconvenient to the patient than open surgery or whole-brain irradiation. Radiosurgery can be used on lesions inaccessible to open neurosurgery or resistant to classical fractionated radiotherapy. Gamma Knife treatment has become our first choice for patients with less than four intracranial metastases with diameters less than 3-3.5 cm.