Gamma Knife Radiosurgery for Breast Cancer Metastases to the Brain: Outcomes and Prognostic Factors from a Large Prospectively Collected Database

Background: To examine outcomes and prognostic factors in a large prospectively collected database of patients treated with Gamma Knife (GK) radiosurgery for breast cancer metastases to the brain. Methods: All patients were treated with GK radiosurgery for brain metastases from breast cancer between 1993 and 2009. Overall survival time was calculated from the time of GK radiosurgery to the time of death from any cause. Kaplan-Meier analysis was applied to calculate overall median time to failure and clinical and radiologic features of the study population. Multivariate analysis was performed using Cox Proportional Hazards regression analysis to calculate relative risk for mortality. Results: Two hundred and ninety-two patients with were analyzed over a median follow-up of 8.53 months (reverse Kaplan-Meier follow-up of 66.81 months). The median overall survival for the entire cohort from the time of GK radiosurgery was 9.08 months (95% CI, 7.86-10.63 months). There was a significantly greater median overall survival in patients that had KPS > 70, age 65) and multiple lesions (> 3 lesions) were independent predictors of poor prognosis. The risk of mortality in patients with low KPS, multiple lesions, and older age (as defined above) was 300%, 80%, 50% greater than their counterparts, respectively. Conclusion: Patients with poor performance status and multiple brain metastases from breast cancer have worse outcomes and may be candidates for conservative management. Categories: Radiation Oncology, Neurosurgery