title: Stereotactic radiosurgery in the treatment of metastatic disease to the brain.
abstract: OBJECTIVE
  In recent years, stereotactic radiosurgery has been growing in popularity as a treatment modality for metastatic disease to the brain. The technique has advantages of reduced cost and low morbidity compared with open surgical treatment. Furthermore, it avoids the potential cognitive side effects of fractionated whole-brain radiotherapy. We undertook this study to determine the usefulness of adjuvant radiation therapy and to determine prognostic factors in patients treated with stereotactic radiosurgery.
  
  
  METHODS
  We reviewed our series of patients with metastatic tumors treated using gamma knife stereotactic radiosurgery from August 1994 to February 1999. Nonparametric methods were used to compare treatment subgroups by demographic features including age, Karnofsky Performance Scale score, diagnosis, and systemic disease status. Univariate and multivariate analyses of survival and freedom from progression were performed using Kaplan-Meier and Cox proportional hazards regression techniques.
  
  
  RESULTS
  This study included 190 patients harboring 431 lesions who were treated in 263 treatment sessions. The median follow-up after radiosurgery was 36 weeks for all patients. The median actuarial survival from the time of radiosurgery in all patients was 34 weeks. When patients were stratified according to tumor histology, those without melanoma had a median survival of 39 weeks, and those with melanoma had a median survival of 28 weeks. The cause of death could be determined in 122 (92%) of the patients known to have died during the data capture period. For patients harboring melanoma, death was attributable to systemic disease in 31 (47%), to central nervous system-related processes in 29 (44%), and to unknown causes in 6 (9%). For non-melanoma patients, death was attributable to systemic disease in 45 (68%), to central nervous system-related processes in 17 (26%), and to unknown causes in 4 (6%). Significantly improved survival (P = 0.002) was observed in patients with controlled systemic disease. No significant difference in survival could be ascertained for patients presenting with up to four lesions, although patients with a total tumor volume greater than 9 cc had shortened survival. No survival benefit could be demonstrated for whole-brain radiotherapy administered either concomitantly or after radiosurgery.
  
  
  CONCLUSIONS
  Factors correlated with significantly improved survival included controlled systemic disease and non-melanoma histology. We found no significant survival benefit that could be discerned from adjuvant whole-brain radiotherapy in this patient group.
authors.affiliation: Department of Neurological Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, USA. josephcc@hsc.usc.edu
authors.forename: J C
authors.initials: JC
authors.lastname: Chen
authors.forename: Z
authors.initials: Z
authors.lastname: Petrovich
authors.forename: S
authors.initials: S
authors.lastname: O'Day
authors.forename: D
authors.initials: D
authors.lastname: Morton
authors.forename: R
authors.initials: R
authors.lastname: Essner
authors.forename: S L
authors.initials: SL
authors.lastname: Giannotta
authors.forename: C
authors.initials: C
authors.lastname: Yu
authors.forename: M L
authors.initials: ML
authors.lastname: Apuzzo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000401:mortality / Q000556:secondary* / Q000601:surgery*; D002423:Cause of Death; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local / Q000601:surgery; D011379:Prognosis; D016634:Radiosurgery / Q000009:adverse effects; D019233:Retreatment; D012189:Retrospective Studies; D013238:Stereotaxic Techniques; D016019:Survival Analysis