title: Radiosurgery for recurrent brain metastases after whole-brain radiotherapy : factors affecting radiation-induced neurological dysfunction.
abstract: OBJECTIVE
  We retrospectively analyzed survival, local control rate, and incidence of radiation toxicities after radiosurgery for recurrent metastatic brain lesions whose initial metastases were treated with whole-brain radiotherapy. Various radiotherapeutical indices were examined to suggest predictors of radiation-related neurological dysfunction.
  
  
  METHODS
  In 46 patients, total 100 of recurrent metastases (mean 2.2, ranged 1-10) were treated by CyberKnife radiosurgery at average dose of 23.1 Gy in 1 to 3 fractions. The median prior radiation dose was 32.7 Gy, the median time since radiation was 5.0 months, and the mean tumor volume was 12.4 cm(3). Side effects were expressed in terms of radiation therapy oncology group (RTOG) neurotoxicity criteria.
  
  
  RESULTS
  Mass reduction was observed in 30 patients (65%) on MRI. After the salvage treatment, one-year progression-free survival rate was 57% and median survival was 10 months. Age (<60 years) and tumor volume affected survival rate (p=0.03, each). Acute (</=1 month) toxicity was observed in 22% of patients, subacute and chronic (>6 months) toxicity occurred in 21%, respectively. Less acute toxicity was observed with small tumors (<10 cm(3), p=0.03), and less chronic toxicity occurred at lower cumulative doses (<100 Gy, p=0.004). "Radiation toxicity factor" (cumulative dose times tumor volume of <1,000 Gyxcm(3)) was a significant predictor of both acute and chronic CNS toxicities.
  
  
  CONCLUSIONS
  Salvage CyberKnife radiosurgery is effective for recurrent brain metastases in previously irradiated patients, but careful evaluation is advised in patients with large tumors and high cumulative radiation doses to avoid toxicity.
authors.affiliation: Neuro-Oncology Clinic, National Cancer Center, Goyang, Korea.
authors.forename: Ho-Shin
authors.initials: HS
authors.lastname: Gwak
authors.forename: Hyung Jun
authors.initials: HJ
authors.lastname: Yoo
authors.forename: Sang-Min
authors.initials: SM
authors.lastname: Youn
authors.forename: Dong Han
authors.initials: DH
authors.lastname: Lee
authors.forename: Mi Sook
authors.initials: MS
authors.lastname: Kim
authors.forename: Chang Hun
authors.initials: CH
authors.lastname: Rhee