title: Factors that determine local control with gamma knife radiosurgery: The role of primary histology.
abstract: BACKGROUND
  Stereotactic radiosurgery for the treatment of brain metastases is commonly delivered without regard to primary cancer histology. This study sought to determine if the primary site of origin for brain metastases affected the propensity for local failure.
  
  
  METHODS
  A total of 83 patients with 200 brain metastases were examined retrospectively for predictors of infield failure. Tumor, patient, and treatment characteristics were analyzed including primary tumor histology, radiosurgical dose and age. Cox proportional hazards models, univariate and multivariate analyses were used to identify predictors of local failure.
  
  
  RESULTS
  Freedom from local failure for the entire population was 83% and 65% at 6 and 12 months, respectively. Multivariate analysis revealed that breast cancer brain metastases have a significantly lower risk of local failure than melanoma (HR = 0.31, p< 0.001). Additionally, multivariate analysis revealed that increasing dose lowered risk for local failure (HR = 0.87, p<0.001).
  
  
  CONCLUSIONS
  Melanoma histology leads to a higher rate of local failure. Higher prescription dose results in higher incidence of local control.
authors.affiliation: Department of Radiation Oncology, Wake Forest University, Winston-Salem, NC, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Black
authors.affiliation: Department of Radiation Oncology, Wake Forest University, Winston-Salem, NC, USA.
authors.forename: Brandi R
authors.initials: BR
authors.lastname: Page
authors.affiliation: Department of Radiation Oncology, Wake Forest University, Winston-Salem, NC, USA.
authors.forename: John T
authors.initials: JT
authors.lastname: Lucas
authors.affiliation: School of Medicine, Wake Forest University, Winston-Salem, NC, USA.
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Hughes
authors.affiliation: Department of Neurosurgery, Wake Forest University, Winston-Salem, NC, USA.
authors.forename: Adrian W
authors.initials: AW
authors.lastname: Laxton
authors.affiliation: Department of Neurosurgery, Wake Forest University, Winston-Salem, NC, USA.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Tatter
authors.affiliation: Department of Radiation Oncology, Wake Forest University, Winston-Salem, NC, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Munley
authors.affiliation: Department of Radiation Oncology, Wake Forest University, Winston-Salem, NC, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Chan
keywords: brain metastasis; brain neoplasms; breast neoplasms; gamma knife; histology; melanoma; multivariate analysis; predictive outcomes; proportional hazards models; radiosensitivity; retrospective studies; stereotactic radiosurgery