Knoll MA, et al. - Researchers assessed the survival of patients with 1 to 4 vs ≥5 brain metastases treated with radiosurgery by evaluating a retrospective multi-institutional database. A multivariable model of overall survival (OS) was constructed using Cox hazard regression. A high correlation was seen between the number of intracranial metastases and overall disease burden and clinical status, although previously the number of brain metastases was accepted as an independent prognostic indicator. Data showed that the number of intracranial metastases alone was not an independent predictive factor, but rather served as a surrogate for other clinical factors, after proper matching and controlling for these other determinants of survival.