title: Visual outcome and tumor control after conformal radiotherapy for patients with optic nerve sheath meningioma.
abstract: OBJECTIVE
  Optic nerve sheath meningioma (ONSM) is a rare tumor that almost uniformly leads to visual dysfunction and even blindness without intervention. Because surgical extirpation carries a high risk of postoperative blindness, vision-sparing treatment strategies are desirable.
  
  
  METHODS
  We retrospectively reviewed the outcomes of 25 patients (25 optic nerves) with ONSM, treated at a single institution with conformal fractionated radiotherapy by either stereotactic photon or proton radiation. Primary endpoints were local control and visual acuity.
  
  
  RESULTS
  The patients presented with symptoms of visual loss (21) or orbital pain (3) or were incidentally diagnosed by imaging (3). The mean age was 44 years, and 64% were female patients. The indication for treatment was the development or progression of symptoms. Of the patients, 13 were treated with photons, 9 were treated with protons, and 3 received a combination of photons and protons. The median dose delivered was 50.4 gray equivalents (range, 45-59.4 gray equivalents). Median follow-up after radiotherapy was 30 months (range, 3-168 months), with 3 patients lost to follow-up. At most recent follow-up, 21 of 22 patients (95%) had improved (14) or stable (7) visual acuity. One patient had worsened visual acuity after initial postirradiation improvement. Of the 22 patients, 20 (95%) had no radiographic progression. Three patients had evidence of asymptomatic, limited retinopathy on ophthalmologic examination, and one had recurrent ONSM 11 years after treatment.
  
  
  CONCLUSIONS
  Highly conformal, fractionated radiation therapy for symptomatic primary ONSM provides tumor control and improvement in visual function in most cases, with minimal treatment-induced morbidity. Longer follow-up is needed to assess the durability of tumor control and treatment-related late effects.
authors.affiliation: Harvard Radiation Oncology Program, Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. narvold@partners.org
authors.forename: Nils D
authors.initials: ND
authors.lastname: Arvold
authors.forename: Simmons
authors.initials: S
authors.lastname: Lessell
authors.forename: Marc
authors.initials: M
authors.lastname: Bussiere
authors.forename: Kevin
authors.initials: K
authors.lastname: Beaudette
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Rizzo
authors.forename: Jay S
authors.initials: JS
authors.lastname: Loeffler
authors.forename: Helen A
authors.initials: HA
authors.lastname: Shih
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000150:complications / Q000532:radiotherapy*; D008579:Meningioma / Q000150:complications / Q000532:radiotherapy*; D008875:Middle Aged; D019574:Optic Nerve Neoplasms / Q000150:complications / Q000532:radiotherapy*; D009918:Orbital Neoplasms / Q000532:radiotherapy; D017785:Photons / Q000627:therapeutic use; D061766:Proton Therapy; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods*; D012189:Retrospective Studies; D014786:Vision Disorders / Q000209:etiology / Q000532:radiotherapy; D014792:Visual Acuity; D055815:Young Adult; D011522:Protons
chemical_list: D011522:Protons