Epidemiology and prognosis of brain metastases

A substantial, but uncertain, number of patients with cancer develop brain metastases. Risk of brain metastasis is recognized to vary with type of primary cancer. Within specific types of primary cancer, prognostic factors for development of brain metastases are being recognized. Recent data suggest that molecular biomarkers that relate to cellular function can predict risk of developing brain metastases. Such information could optimize surveillance standards and/or be used to select patients for preventive interventions. Though average survival for patients with brain metastases is typically less than 6 months, it is well-recognized that subgroups of patients have significant probability of longer survival. Multiple prognostic models have been proposed, validated, and compared without clearly demonstrating superiority of one model over another. However, some factors show consistency as predictive variables across models, and performance status is almost universally significant. Application of predictive models to specific treatments has been difficult. Tumor-specific prognostic models are evolving, and combinations of biological and clinical factors may be used to optimize models for particular primary tumor types.