title: Tumor volume as a predictor of survival and local control in patients with brain metastases treated with Gamma Knife surgery.
abstract: OBJECTIVE
  The aim of this study was to examine tumor volume as a prognostic factor for patients with brain metastases treated with Gamma Knife surgery (GKS).
  
  
  METHODS
  Two hundred fifty patients with 1-14 brain metastases who had initially undergone GKS alone at a single institution were retrospectively reviewed. Patients who received upfront whole brain radiation therapy were excluded. Survival times were estimated using the Kaplan-Meier method. Univariate and multivariate analyses using Cox proportional hazard regression models were used to determine if various prognostic factors could predict overall survival, distant brain failure, and local control.
  
  
  RESULTS
  Median overall survival was 7.1 months and the 1-year local control rate was 91.5%. Median time to distant brain failure was 8.0 months. On univariate analysis an increasing total tumor volume was significantly associated with worse survival (p = 0.031) whereas the number of brain metastases, analyzed as a continuous variable, was not (p = 0.082). After adjusting for age, Karnofsky Performance Scale score, and extracranial disease on multivariate analysis, total tumor volume was found to be a better predictor of overall survival (p = 0.046) than number of brain metastases analyzed as a continuous variable (p = 0.098). A total tumor volume cutoff value of ≥ 2 cm(3) (p = 0.008) was a stronger predictor of overall survival than the number of brain metastases (p = 0.098). Larger tumor volume and extracranial disease, but not the number of brain metastases, were predictive of distant brain failure on multivariate analysis. Local tumor control at 1 year was 97% for lesions < 2 cm(3) compared with 75% for lesions ≥ 2 cm(3) (p < 0.001).
  
  
  CONCLUSIONS
  After adjusting for other factors, a total brain metastasis volume was a strong and independent predictor for overall survival, distant brain failure, and local control, even when considering the number of metastases.
authors: Departments of Radiation Oncology and Neurosurgery, William Beaumont Hospital, Royal Oak, MI, USA, 48073.
authors: Andrew M
authors: AM
authors: Baschnagel
authors: Kurt D
authors: KD
authors: Meyer
authors: Peter Y
authors: PY
authors: Chen
authors: Daniel J
authors: DJ
authors: Krauss
authors: Rick E
authors: RE
authors: Olson
authors: Daniel R
authors: DR
authors: Pieper
authors: Ann H
authors: AH
authors: Maitz
authors: Hong
authors: H
authors: Ye
authors: Inga Siiner
authors: IS
authors: Grills
mesh_terms: D000368:Aged; D001932:Brain Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis / Q000473:pathology* / Q000628:therapy; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D011379:Prognosis; D016634:Radiosurgery / Q000379:methods; D016896:Treatment Outcome; D047368:Tumor Burden / Q000502:physiology*