Survival and intracranial control of patients with 5 or more brain metastases treated with gamma knife stereotactic radiosurgery.

PURPOSE: Limited data are available to help inform decisions about stereotactic radiosurgery for patients with ≥5 brain metastases. We therefore performed a retrospective analysis of patients treated for >5 brain metastases. MATERIALS/
METHODS: Patients who underwent treatment for ≥5 brain metastases from October 2000 to September 2010 were identified. Overall survival (OS) for each patient was calculated from the date of first treatment of ≥5 metastases. Intracranial recurrence-free survival was defined when posttreatment magnetic resonance imaginag showed evidence for disease progression. Cox proportional hazards regression was performed for OS and intracranial recurrence free survival. Variables included sex, age, Karnofsky Performance Status (KPS), histology, prior whole-brain radiation treatment or Gamma Knife treatment, and number of metastases treated.
RESULTS: A total of 103 patients were identified. Median OS was 8.3 months. Median OS was 7.6 months and 8.3 months, for patients with 5 to 9 and ≥10 metastases, respectively. KPS was the only significant variable affecting OS (P <0.01). Forty-six patients had post-Gamma Knife surveillance imaging recorded. There was a trend towards a higher hazard for intracranial failure for patients with 10+ versus 5 to 9 metastases, however, the association did not reach statistical significance (univariate P=0.09, multivariate P=0.21).
CONCLUSIONS: OS for carefully selected patients with 5 or more brain metastases treated with stereotactic radiosurgery alone is reasonable and compares well with historical controls. KPS is the most important factor predicting OS.