Repeated gamma knife radiosurgery for multiple metastatic brain tumours

Background. The effectiveness of repeated gamma knife radiosurgery (GKS) for the treatment of multiple metastatic brain tumours was evaluated. Methods. This study included 16 patients with 242 tumours, 10 men and 6 women with a mean age of 60.3 years at initial GKS, who underwent GKS four times or more for newly developed metastatic tumours. Findings. Sixteen patients underwent a total of 83 GKS procedures (range 4 to 8, mean 5.2). The mean number of metastases at each GKS procedure was 2.9 and the number of tumours tended to increase at the 5th GKS procedure compared with the 1st, but not significantly. The mean interval between each procedure was 4.8 months and was not significantly different. Median survival was 22.4 months (range 9.4-78.9 months) and the primary site was not correlated with survival time. The total number of treated tumours tended to correlate to survival time, but not significantly. Use of adjuvant whole brain radiation also had no significant effect on survival time. The Karnofsky performance status was maintained at more than 70 in most patients, but decreased significantly between initial and final GKS. Death due to progression of brain lesions occurred in only about 30% of patients regardless of the multiple newly developed brain metastases. Conclusions. Repeated radiosurgery for brain metastases is effective and relatively long survival can be expected in some patients associated with a low risk of radiation-induced injury.