title: Positive correlation between occlusion rate and nidus size of proton beam treated brain arteriovenous malformations (AVMs).
abstract: BACKGROUND
  Proton beam radiotherapy of arteriovenous malformations (AVM) in the brain has been performed in Uppsala since 1991. An earlier study based on the first 26 patients concluded that proton beam can be used for treating large and medium sized AVMs that were considered difficult to treat with photons due to the risk of side effects. In the present study we analyzed the result from treating the subsequent 65 patients.
  
  
  METHODS
  A retrospective review of the patients' medical records, treatment protocols and radiological results was done. Information about gender, age, presenting symptoms, clinical course, the size of AVM nidus and rate of occlusion was collected. Outcome parameters were the occlusion of the AVM, clinical outcome and side effects.
  
  
  RESULTS
  The rate of total occlusion was overall 68%. For target volume 0-2 cm(3) it was 77%, for 3-10 cm(3) 80%, for 11-15 cm(3) 50% and for 16-51 cm(3) 20%. Those with total regress of the AVM had significantly smaller target volumes (p < 0.009) higher fraction dose (p < 0.001) as well as total dose (p < 0.004) compared to the rest. The target volume was an independent predictor of total occlusion (p = 0.03). There was no difference between those with and without total occlusion regarding mean age, gender distribution or symptoms at diagnosis. Forty-one patients developed a mild radiation-induced brain edema and this was more common in those that had total occlusion of the AVM. Two patients had brain hemorrhages after treatment. One of these had no effect and the other only partial occlusion from proton beams. Two thirds of those presenting with seizures reported an improved seizure situation after treatment.
  
  
  CONCLUSIONS
  Our observations agree with earlier results and show that proton beam irradiation is a treatment alternative for brain AVMs since it has a high occlusion rate even in larger AVMs.
authors.affiliation: a Department of Radiology , Oncology and Radiation Sciences, Uppsala University Uppsala Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Blomquist
authors.affiliation: b Department of Neuroscience , section of Neurosurgery, Uppsala University , Uppsala , Sweden.
authors.forename: Elisabeth Ronne
authors.initials: ER
authors.lastname: Engström
authors.affiliation: a Department of Radiology , Oncology and Radiation Sciences, Uppsala University Uppsala Sweden.
authors.forename: Ljubisa
authors.initials: L
authors.lastname: Borota
authors.affiliation: c Department of Radiology Odense University Hospital , Odense Denmark.
authors.forename: Gyula
authors.initials: G
authors.lastname: Gál
authors.affiliation: a Department of Radiology , Oncology and Radiation Sciences, Uppsala University Uppsala Sweden.
authors.forename: Kristina
authors.initials: K
authors.lastname: Nilsson
authors.affiliation: b Department of Neuroscience , section of Neurosurgery, Uppsala University , Uppsala , Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Lewén
authors.affiliation: a Department of Radiology , Oncology and Radiation Sciences, Uppsala University Uppsala Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Montelius
authors.affiliation: a Department of Radiology , Oncology and Radiation Sciences, Uppsala University Uppsala Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Grusell
authors.affiliation: a Department of Radiology , Oncology and Radiation Sciences, Uppsala University Uppsala Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Isacsson
authors.affiliation: b Department of Neuroscience , section of Neurosurgery, Uppsala University , Uppsala , Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Enblad
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D016896:Treatment Outcome