Outcomes and cost-effectiveness of gamma knife radiosurgery and whole brain radiotherapy for multiple metastatic brain tumors.

We aimed to analyze the outcomes and cost-effectiveness of gamma knife radiosurgery (GKRS) and whole brain radiotherapy (WBRT) for multiple metastatic brain tumors. Over a period of 5 years, 156 patients with multiple metastatic brain tumors were enrolled and freely assigned by the referring doctors to either gamma knife radiosurgery (GKRS, Group A, n=56), or to whole brain radiotherapy (WBRT, Group B, n=100). The follow-up time was set at 1200 days (3.3 years) post-treatment. The number of tumors, patient age, extent of systemic disease and Karnofsky performance scale (KPS) score, were recorded and recursive partitioning analysis used. The outcomes analyzed were: mortality, survival time, neurological complications, post-treatment KPS score, quality-adjusted life years (QALY), and cost-effectiveness. A paired t-test was used for statistical analysis. Mortality rates for patients receiving GKRS and WBRT were 81.1% and 93.0%, respectively (p=0.05). The mortality rate was lower for GKRS (74.4%) than for WBRT (97.1%) in patients with initial KPS70 (p=0.02). The mortality rate was also significantly lower for GKRS (78.9%) than WBRT (95.5%) in patients with 2-5 tumors (p<0.05). Post-treatment KPS score (mean+/-standard deviation [s.d.] was higher for patients receiving GKRS (73.8+/-13.2) than for those receiving WBRT (45.5+/-26.0), p<0.01. The median survival time for GKRS and WBRT was 9.5 months and 8.3 months, respectively, p=0.72. The mean (+/- s.d.) QALY was 0.76+/-0.23 for GKRS and 0.59+/-0.18 for WBRT, respectively (p<0.05). The cost-effectiveness per unit of QALY was better for the GKRS treatment (US$10,381/QALY) than in the WBRT treatment (US$17,622/QALY), p<0.05. The cost-effectiveness per KPS score was also higher for the GKRS treatment (US$139/KPS score) than for WBRT (US$229/KPS score), p<0.01. Thus, the mortality rate for multiple metastatic brain tumors treated by GKRS is significantly better with a good initial KPS score and when the tumor number is 2-5. GKRS results in a better post-treatment KPS score, QALY, and higher cost-effectiveness than WBRT for treating multiple metastatic brain tumors.