J Korean Neurosurg Soc 52 | October 2012 cachexia. Neurological deterioration was the cause of death in 3 patients. The mean follow-up duration was 8 months (range 3-18 months). Result of Kaplan-Meier method analysis The cumulative survival graph with Kaplan-Meier method of patients with single GKRS plus WBRT showed a stiff-declining curve compared with the curve of multiple GKRS (Fig. 1) and p-value was lesser than 0.05. Concerning the number of the lesions (above 10 and below 10) in patients with multiple GKRS, p-value is 0.7595. In terms of the average volume of the lesions (above 10 cc and below 10 cc), the p-value is 0.0243 (Fig. 2). Survival curve of patients with the average volume of lesions above 10 cc showed the stiff-de- Table 1. Patients profile Variable Multiple GKRS Sex Male 13 Female 7 Age (years) 58.2 (36-77) Mean tumor volume (cc) 1.97 (0.01-27.5) Mean total lesion volume (cc) 23.7 (0.15-79) Mean lesion numbers per patient 15.6 (3-38) Mean frequency of GKRS 3.3 (3-6) Median time to recurrence of new lesion (month) 7.1 (1.5-16) Histopathological type Adenocarcinoma 13 Large cell neuroendothelial tumor 3 Small cell lung cancer 2 Large cell undifferentiated carcinoma 1 Squamous cell carcinoma 1 GKRS : gamma knife radiosurgery, WBRT : whole brain radiation therapy 1.0 0.8 e t a r la0.6 v i v r u ev0.4 s i t a l u um0.2 C 0.0 Single GKRS+WBRT Single GKRS+WBRT-censored Multiple GKRS Multiple GKRS-censored clining curve compared with the curve of below 10 cc. In view- ing the repeated number of GKRS (more than 3 times and less than 3 times), the p-value is 0.0885. In pointing out the interval of development of new lesions (more than 7 months and less than 7 months), the p-value is 0.1769. Result of Cox proportional hazards analysis All variables are significant because the p-value of them is less than 0.05 under the 95% significant level according to the re- gression coefficient (Table 2). According to these results, au- thors realized that the proportional hazard of the total number of lesion is 1.1559. In the case of the average volume of lesions, the proportional hazard is shown 1.0005. The proportional haz- ard of the repeated number of GKRS is 0.08943. We found that the proportional hazard for the interval of development of new lesions is Single GKRS plus 0.5970. WBRT DISCUSSION Many recent study series on patients with various pathologies report survival times of 7-10.5 months for single or multiple newly-diagnosed or recurrent brain metastases9,12,15). Such patients with brain metastases from lung cancer have median survival time of 10-12 months3,8,18). Aoyama et al.1) reported pa- tients with 1-4 brain metastases under- going stereotactic radiosurgery (SRS) treatment alone had median survival times of 8 months, while patients re- ceiving SRS plus WBRT survived 7.5 months. This result confirms the effica- A (<10 cc) A-censored B (>10 cc) B-censored 6 5 61.4 (36-70) 3.2 (0.05-6.7) 25 (0.3-60) 14.3 (4-38) 1 6.8 (2-16) 1.0 0.8 e t a r la0.6 v i v r u ev0.4 s i t a l u um0.2 C 0.0 8 3 0 10 20 30 Survival time (month) 40 50 0 10 40 50 20 30 Survival time (month) Fig. 1. Cumulative Kaplan-Meier survival curves for patients with multi- ple GKRS (dashed line) and patients with single GKRS plus WBRT (solid line) after first gamma knife radiosurgery. Cumulative survival curve of patients with single GKRS plus WBRT showing stiff-declining curve com- pared with curve of multiple GKRS. GKRS : gamma knife radiosurgery, WBRT : whole brain radiation therapy. Fig. 2. Kaplan-Meier survival curves for patients with multiple GKRS ac- cording to the average volume of lesions (above 10 cc, solid line and be- low 10 cc, dashed line). Survival curve of patients with the average vol- ume of lesions above 10cc showing stiff-declining curve compared with curve of below 10 cc. GKRS : gamma knife radiosurgery. 336