title: What factors predict the response of larger brain metastases to radiosurgery?
abstract: BACKGROUND
  Approximately 20 to 40% of patients with systemic malignancies develop brain metastases.
  
  
  OBJECTIVE
  To assess the potential role of stereotactic radiosurgery (SRS) for larger metastatic brain tumors, we reviewed our recent experience.
  
  
  METHODS
  Between 2004 and 2008, 70 patients with a metastatic brain tumor larger than 3 cm in maximum diameter underwent Gamma knife SRS. Thirty-three patients had received previous whole brain radiation therapy (WBRT) and 37 received only SRS.
  
  
  RESULTS
  The overall median follow-up was 8.1 months. At the first planned imaging follow-up at 2 months, 29 (41%) tumors had >50% volume reduction, 22 (31%) had 10 to 50% volume reduction, and 19 (28%) were stable or larger. We also evaluated brain edema using MRI T2 images. In 11 patients (16%) the peritumoral edema volume was reduced by more than 50%, in 25 (36%) it was reduced by 10 to 50%, in 21 (30%) it was stable, and in 13 (19%) it was increased. Twenty (36%) discontinued corticosteroids by the time of first imaging follow-up. Because of persistent symptoms, 7 patients (10%) required a craniotomy to remove the tumor. Tumor volume reduction (>50%) was associated with a single metastasis (P=.012), no previous WBRT (P=.002), and a tumor volume<16 cm3 (P=.002). The better peritumoral edema volume reduction (>50%) was associated with a single metastasis (P=.024), no previous WBRT (P=.05), and breast cancer histology (P=.044).
  
  
  CONCLUSIONS
  Surgical resection remains the primary approach for larger brain metastases if feasible. Tumor volume is a better indicator than maximum diameter. Tumor volume and edema responded better in patients who underwent SRS alone.
authors.affiliation: Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Huai-che
authors.initials: HC
authors.lastname: Yang
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Kano
authors.forename: L Dade
authors.initials: LD
authors.lastname: Lunsford
authors.forename: Ajay
authors.initials: A
authors.lastname: Niranjan
authors.forename: John C
authors.initials: JC
authors.lastname: Flickinger
authors.forename: Douglas
authors.initials: D
authors.lastname: Kondziolka
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016634:Radiosurgery / Q000379:methods*; D018570:Risk Assessment; D012307:Risk Factors; D016896:Treatment Outcome