BM-08 * PROGNOSTIC FACTORS FOR SRS-TREATED PATIENTS WITH CEREBRAL METASTASIS: IMPLICATIONS ON RANDOMIZED CONTROL TRIAL DESIGN AND INTER-INSTITUTIONAL COLLABORATIVE EFFORTS

Abstract

INTRODUCTION: Defining key prognostic factors for patients with cerebral metastases who underwent stereotactic radiosurgery (SRS) treatment will greatly facilitate future clinical trial designs. However, these is little agreement in terms of these prognostic factors in the existing literature. METHODS: We adopted a two-phase study design where results from one cohort were validated in a second independent cohort. The exploratory analysis reviewed the survival outcomes of 1017 consecutive patients (with 3610 metastases) who underwent Gamma radiosurgery at the University of California, San Diego (UCSD)/San Diego Gamma Knife Center (SDGKC). Multivariate analysis was performed to identify prognostic factors. Results were validated using data derived from 2253 consecutive patients (with 17,539 metastases) treated with SRS at the Tokyo Women's Medical University (TWMU). RESULTS: For the SDGKC cohort, the median overall survival of patients following SRS was 7 months. Two year follow-up data was available for 85 % of the patients. Multivariable analysis found that patient age, Karnofsky performance score, systemic cancer status, tumor histology, number of metastasis, and cumulative tumor volume independently associated with overall survival (p < 0.001). All statistical associations were validated in multivariate analysis of data derived from the TWMU cohort. CONCLUSIONS: This is the first large scale study that defined prognostic factors for SRS treated patients with cerebral metastasis using an inter-institutional validation study design. The work establishes a model for collaborative interactions between large volume centers and provides prognostic variables that should be incorporated into future clinical trial design.