title: A comparison of clinical and radiologic outcomes between frame-based and frameless stereotactic radiosurgery for brain metastases.
abstract: OBJECTIVE
  Modern experiences in stereotactic radiosurgery (SRS) report noninvasive frameless techniques as an effective alternative to frame-based SRS. Frameless techniques potentially increase positional uncertainty and planning target volume margins are frequently used. Here, we compare rates of local control and radiation necrosis in frameless versus frame-based SRS.
  
  
  METHODS
  Ninety-eight patients (170 lesions) with radiologic and clinical follow-up were analyzed. Group 1 contained 34 patients (61 lesions) immobilized with an invasive stereotactic frame. Group 2 had 64 patients (109 lesions) immobilized with a frameless SRS mask. Patient, tumor, and treatment characteristics were recorded, as were intervals to local recurrence and radiation necrosis (asymptomatic and symptomatic).
  
  
  RESULTS
  Median patient age was 59 years (range, 25-89), and Karnofsky performance scale was 80 (range, 50-100). Median radiologic and clinical follow-up was 6.5 months (range, 0.7-44.3) and 7 months (range, 0.7-45.7). A median of 2 tumors were treated per course (range, 1-5) with a median dose of 18 Gy (range, 13-24 Gy). The median time to local failure was not reached, and Kaplan-Meier estimates of local failure were not statistically significant between groups (P = .303). Actuarial 6-month local failure rates were 7.2% in group 1 and 12.6% in group 2 (P = .295), with 12-month local failure rates of 14.5% and 26.8% (P = .185), respectively. There was no statistically significant difference in symptomatic (P = .391) or asymptomatic (P = .149) radiation necrosis. Six-month radiation necrosis was 0% in group 1 and 1.6% in group 2 (P = .311) with 12-month rates of 20.2% and 3.8%, respectively (P = .059). Median time to necrosis was not reached in group 1, but was 44 months in group 2.
  
  
  CONCLUSIONS
  Frameless SRS demonstrates clinical outcomes comparable to frame-based techniques with respect to local failure and radiation necrosis.
authors: Department of Radiation Oncology, Nebraska Medicine, University of Nebraska Medical Center Campus, Omaha, Nebraska. Electronic address: nathan.bennion@unmc.edu.
authors: Nathan R
authors: NR
authors: Bennion
authors: Department of Radiation Oncology, Nebraska Medicine, University of Nebraska Medical Center Campus, Omaha, Nebraska.
authors: Timothy
authors: T
authors: Malouff
authors: Department of Radiation Oncology, Nebraska Medicine, University of Nebraska Medical Center Campus, Omaha, Nebraska.
authors: Vivek
authors: V
authors: Verma
authors: Department of Radiation Oncology, Nebraska Medicine, University of Nebraska Medical Center Campus, Omaha, Nebraska.
authors: Kyle
authors: K
authors: Denniston
authors: Department of Radiation Oncology, Nebraska Medicine, University of Nebraska Medical Center Campus, Omaha, Nebraska.
authors: Abhijeet
authors: A
authors: Bhirud
authors: Department of Radiation Oncology, Nebraska Medicine, University of Nebraska Medical Center Campus, Omaha, Nebraska.
authors: Weining
authors: W
authors: Zhen
authors: Department of Radiation Oncology, Nebraska Medicine, University of Nebraska Medical Center Campus, Omaha, Nebraska.
authors: Andrew
authors: A
authors: Wahl
authors: Department of Radiation Oncology, Nebraska Medicine, University of Nebraska Medical Center Campus, Omaha, Nebraska.
authors: Chi
authors: C
authors: Lin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology; D001932:Brain Neoplasms / Q000532:radiotherapy* / Q000556:secondary; D005260:Female; D006801:Humans; D007103:Immobilization / Q000295:instrumentation* / Q000379:methods; D008297:Male; D008397:Masks; D008875:Middle Aged; D009336:Necrosis / Q000209:etiology; D056888:Patient Positioning / Q000295:instrumentation* / Q000379:methods; D011832:Radiation Injuries / Q000453:epidemiology*; D016634:Radiosurgery / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D016896:Treatment Outcome