title: Hypofractionated stereotactic radiotherapy of acoustic neuroma: volume changes and hearing results after 89-month median follow-up.
abstract: OBJECTIVE
  The goal of this work was to evaluate toxicity and local control following hypofractionated stereotactic radiation treatment with special focus on changes in tumor volume and hearing capacity.
  
  
  METHODS
  In all, 29 patients with unilateral acoustic neuroma were treated between 2001 and 2007 within a prospective radiation protocol (7 × 4 Gy ICRU dose). Median tumor volume was 0.9 ml. Follow-up started at 6 months and was repeated annually with MRI volumetry and audiometry. Hearing preservation was defined as preservation of Class A/B hearing according to the guidelines of the American Academy of Otolaryngology (1995).
  
  
  RESULTS
  No patient had any intervention after a median imaging follow-up of 89.5 months, one patient showed radiological progression. Transient increase of tumor volume developed in 17/29 patients, whereas 22/29 patients (75.9%) presented with a volume reduction at last follow-up. A total of 21 patients were eligible for hearing evaluation. Mean pure tone average (PTA) deteriorated from 39.3 to 65.9 dB and mean speech discrimination score (SDS) dropped from 74.3 to 38.1%. The 5-year actuarial Class A/B hearing preservation rate was 50.0 ± 14.4%.
  
  
  CONCLUSIONS
  Radiation increases only minimally, if at all, the hearing deterioration which emerges by observation alone. Presbyacusis is not responsible for this deterioration. Transient tumor enlargement is common. Today radiation of small- and medium-sized acoustic neuroma can be performed with different highly conformal techniques as fractionated treatment or single low-dose radiosurgery with equal results regarding tumor control, hearing preservation, and side effects. Hypofractionation is more comfortable for the patient than conventional regimens and represents a serious alternative to frameless radiosurgery.
authors.affiliation: University Clinic of Radiotherapy and Radio-Oncology, Salzburg County Hospital, Paracelsus Medical University Clinics (PMU), Müllner Hauptstraße 48, 5020, Salzburg, Austria, m.kranzinger@salk.at.
authors.forename: Manfred
authors.initials: M
authors.lastname: Kranzinger
authors.forename: Franz
authors.initials: F
authors.lastname: Zehentmayr
authors.forename: Gerd
authors.initials: G
authors.lastname: Fastner
authors.forename: Gerhard
authors.initials: G
authors.lastname: Oberascher
authors.forename: Florian
authors.initials: F
authors.lastname: Merz
authors.forename: Olaf
authors.initials: O
authors.lastname: Nairz
authors.forename: Hassan
authors.initials: H
authors.lastname: Rahim
authors.forename: Felix
authors.initials: F
authors.lastname: Sedlmayer
mesh_terms: D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D005260:Female; D005500:Follow-Up Studies; D034381:Hearing Loss / Q000175:diagnosis* / Q000209:etiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000601:surgery*; D011183:Postoperative Complications / Q000175:diagnosis* / Q000209:etiology*; D016634:Radiosurgery / Q000379:methods*; D012086:Reoperation; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden