Evaluation of Prognostic Factors for Early Mortality after Stereotactic Radiosurgery for Brain Metastases: A Single Institutional Retrospective Review

BACKGROUND: Stereotactic radiosurgery (SRS) is used commonly for patients with brain metastases (BM) to improve intracranial disease control. However, survival of these patients is often dictated by their systemic disease course. The value of SRS becomes less clear in patients with anticipated short survival. OBJECTIVE: To evaluate prognostic factors, which may predict early death (within 90 d) after SRS. METHODS: A total of 1427 patients with BM were treated with SRS at our institution (2000-2012). There were 1385 cases included in this study; 1057 patients underwent upfront SRS and 328 underwent salvage SRS. The primary endpoint of the study was all-cause mortality within 90 d after first SRS. Multivariate analyses were performed to develop prognostic indices. RESULTS: Two hundred sixty-six patients (19%, 95% confidence interval 17%-21%) died within 90 d after SRS. Multivariate analysis of upfront SRS patients showed that Karnofsky Performance Status, primary tumor type, extracranial metastases, age at SRS, boost treatment, total tumor volume, prior surgery, and interval from primary to BM were independent prognostic factors for 90-d mortality. The first 4 factors were also independent predictors in patients treated with salvage SRS. Based on these factors, an index was defined for each group that categorized patients into 3 and 2 prognostic groups, respectively. Ninety-day mortality was 5% to 7% in the most favorable cohort and 36% to 39% in the least favorable. CONCLUSION: Indices based on readily available patient, clinical, and treatment factors that are highly predictive of early death in patients treated with upfront or salvage SRS can be calculated and used to define well-separated prognostic groups.