title: Outcomes and patterns of failure for grade 2 meningioma treated with reduced-margin intensity modulated radiation therapy.
abstract: OBJECTIVE
  The purpose of this study was to evaluate intracranial control and patterns of local recurrence (LR) for grade 2 meningiomas treated with intensity modulated radiation therapy (IMRT) with limited total margin expansions of ≤1 cm.
  
  
  METHODS
  We reviewed records of patients with a neuropathological diagnosis of grade 2 meningioma who underwent IMRT at our institution between 2002 and 2012. Actuarial rates were determined by the Kaplan-Meier method from the end of RT. LR was defined as in-field if ≥90% of the recurrence was within the prescription isodose, out-of-field (marginal) if ≥90% was outside of the prescription isodose, and both if neither criterion was met.
  
  
  RESULTS
  Between 2002 and 2012, a total of 54 consecutive patients underwent IMRT for grade 2 meningioma. Eight of these patients had total initial margins >1 cm and were excluded, leaving 46 patients for analysis. The median imaging follow-up period was 26.2 months (range, 7-107 months). The median dose for fractionated IMRT was 59.4 Gy (range, 49.2-61.2 Gy). Median clinical target volume (CTV), planning target volume (PTV), and total margin expansion were 0.5 cm, 0.3 cm, and 0.8 cm, respectively. LR occurred in 8 patients (17%), with 2-year and 3-year actuarial local control (LC) of 92% and 74%, respectively. Six of 8 patients (85%) had a known pattern of failure. Five patients (83%) had in-field LR; no patients had marginal LR; and 1 patient (17%) had both.
  
  
  CONCLUSIONS
  The use of IMRT to treat grade 2 meningiomas with total initial margins (CTV + PTV) ≤1 cm did not appear to compromise outcomes or increase marginal failures compared with other modern retrospective series. Of the 46 patients who had margins ≤1 cm, none experienced marginal failure only. These results demonstrate efficacy and low risk of marginal failure after IMRT treatment of grade 2 meningiomas with reduced margins, warranting study within a prospective clinical trial.
authors.affiliation: Department of Radiation Oncology, Emory University, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Press
authors.affiliation: Department of Radiation Oncology, Emory University, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia. Electronic address: roshansprabhu@gmail.com.
authors.forename: Roshan S
authors.initials: RS
authors.lastname: Prabhu
authors.affiliation: Department of Pathology, Emory University, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Christina L
authors.initials: CL
authors.lastname: Appin
authors.affiliation: Department of Pathology, Emory University, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Brat
authors.affiliation: Department of Radiation Oncology, Emory University, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Hui-Kuo G
authors.initials: HK
authors.lastname: Shu
authors.affiliation: Department of Neurosurgery, Emory University, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Constantinos
authors.initials: C
authors.lastname: Hadjipanayis
authors.affiliation: Department of Neurosurgery, Emory University, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Olson
authors.affiliation: Department of Neurosurgery, Emory University, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Nelson M
authors.initials: NM
authors.lastname: Oyesiku
authors.affiliation: Department of Radiation Oncology, Emory University, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Curran
authors.affiliation: Department of Radiation Oncology, Emory University, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Ian
authors.initials: I
authors.lastname: Crocker
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology; D001932:Brain Neoplasms / Q000532:radiotherapy*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008579:Meningioma / Q000532:radiotherapy*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011379:Prognosis; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult