www.jkns.or.kr http://dx.doi.org/10.3340/jkns.2012.52.4.334 J Korean Neurosurg Soc 52 : 334-338, 2012 Print ISSN 2005-3711 On-line ISSN 1598-7876 Copyright © 2012 The Korean Neurosurgical Society Clinical Article Multiple Gamma Knife Radiosurgery for Multiple Metachronous Brain Metastases Associated with Lung Cancer : Survival Time Hyung-Seok Kim, M.D., Eun-Jeong Koh, M.D., Ph.D., Ha-Young Choi, M.D., Ph.D. Department of Neurosurgery, Research Institute of Clinical Medicine, Chonbuk National University Hospital-Chonbuk National University School of Medicine, Jeonju, Korea Objective : We compared the survival time between patients with multiple gamma knife radiosurgery (GKRS) and patients with a single GKRS plus whole brain radiation therapy (WBRT), in patients with multiple metachronous brain metastases from lung cancer. Methods : From May 2006 to July 2010, we analyzed 31 patients out of 112 patients who showed multiple metachronous brain metastases. 20 out of 31 patients underwent multiple GKRS (group A) and 11 patients underwent a single GKRS plus WBRT (group B). We compared the survival time between group A and B. Kaplan-Meier method and Cox proportional hazards were used to analyze relationship between survival and 1) the number of lesions in each patient, 2) the average volume of lesions in each patient, 3) the number of repeated GKRS, and 4) the interval of develop- ment of new lesions, respectively. Results : Median survival time was 18 months (range 6-50 months) in group A and 6 months (range 3-18 months) in group B. Only the average volume of individual lesion (over 10 cc) was negatively related with survival time according to Kaplan-Meier method. Cox-proportional hazard ratio of each variable was 1.1559 for the number of lesions, 1.0005 for the average volume of lesions, 0.0894 for the numbers of repeated GKRS, and 0.5970 for the interval of development of new lesions. Conclusion : This study showed extended survival time in group A compared with group B. Our result supports that multiple GKRS is of value in ex- tending the survival time in patients with multiple metachronous brain metastases, and that the number of the lesions and the frequency of devel- opment of new lesions are not an obstacle in treating patients with GKRS. Key Words : Survival time · Gamma knife radiosurgery · Whole brain radiation therapy · Metastases · Lung cancer. INTRODUCTION Brain metastases presenting as multiple lesions (more than three in number) correlate with a poor median survival time of 3-6 months4). Wong et al.20) reported a median survival time of 5.8 months in patients with solitary brain metastases and 3.5 months of median survival time in those with multiple metas- tases. However, Karlsson et al.13) found patients with controlled primary diseases who underwent gamma knife radiosurgery (GKRS) had median survival times of 12.1 months for single le- sions and 8.6 months for multiple lesions. Bhatnagar et al.5) showed all patients with four or more intracranial metastases had a median overall survival time of 8 months after radiosur- gery. Chang et al.6) reported that their patients showed the me- dian survival time of 10 months after GKRS (range 8.7-11.4 months), and they concluded that GKRS may be a good treat- ment option for the local control of metastatic lesions and for improved survival time in patients with multiple metastatic brain lesions, even in those patients harboring more than 15 metastatic brain lesions. In this study, we analyzed the usefulness of multiple GKRS by studying on the survival time between patients with multiple GKRS (group A) and patients with a single GKRS plus whole brain radiation therapy (WBRT) (group B). And we also inves- tigated four factors in patients with multiple GKRS to find the factors associated with survival time in group A : 1) the number • Received : April 4, 2012 • Revised : August 28, 2012 • Accepted : October 4, 2012 • Address for reprints : Eun-Jeong Koh, M.D., Ph.D. Department of Neurosurgery, Chonbuk National University Medical School/Hospital, 20 Geonji-ro, Deokjin-gu, Jeongju 561-712, Korea Tel : +82-63-250-1870, Fax : +82-63-277-3273, E-mail : kohejns@jbnu.ac.kr • This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 334