title: Pediatric thalamic tumors in the MRI era: a Canadian perspective.
abstract: BACKGROUND
  Thalamic gliomas are rare. The natural history is unpredictable, and the optimal management of these tumors in children is poorly defined. The aim was to identify outcomes, prognostic factors, and response to various modalities of treatment in a relatively large population of pediatric thalamic tumors from many centers within a fairly homogeneous health care system.
  
  
  METHODS
  We performed a Canadian multicenter retrospective review of pediatric thalamic tumors presenting during the MRI era (1989-2012). Radiology and pathology were reviewed by central independent reviewers. Paraffin shavings for RNA extraction were taken and tested for fusion events involving KIAA1549:BRAF. Tumors were classified as unilateral or bithalamic based on their origin on imaging. Univariate and multivariate analyses on factors influencing survival were performed.
  
  
  RESULTS
  Seventy-two thalamic tumors were identified from 11 institutions. Females represented 53% of the study population, and the mean age at presentation was 8.9 years. Sixty-two tumors were unilateral and 10 bithalamic. Unilateral tumors had a greater propensity to grow inferiorly towards the brainstem. These tumors were predominantly low grade in comparison to bithalamic tumors which were high-grade astrocytomas. The 5-year overall survival was 61 ± 13% for unithalamic tumors compared to 37 ± 32% for bithalamic tumors (p = 0.097). Multivariate analysis indicated tumor grade as the only significant prognostic factor for unithalamic tumors. Six unilateral tumors, all low grade, were BRAF fusion positive.
  
  
  CONCLUSIONS
  Unilateral and bilateral thalamic tumors behave differently. Surgical resection is an appropriate treatment option in unilateral tumors, most of which are low grade, but outcome is not related to extent of resection (EOR). Bilateral thalamic tumors have a poorer prognosis, but the occasional patient does remarkably well. The efficacy of chemotherapy and radiotherapy has not been clearly demonstrated. Novel therapeutic approaches are required to improve the prognosis for malignant unilateral thalamic tumors and bilateral thalamic tumors.
authors.affiliation: Division of Pediatric Neurosurgery, Department of Surgery, University of British Columbia & British Columbia Children's Hospital, 4480 Oak St., Room K3-159, V6H 3V4, Vancouver, BC, Canada. psteinbok@cw.bc.ca.
authors.forename: Paul
authors.initials: P
authors.lastname: Steinbok
authors.affiliation: Division of Pediatric Neurosurgery, Department of Surgery, University of British Columbia & British Columbia Children's Hospital, 4480 Oak St., Room K3-159, V6H 3V4, Vancouver, BC, Canada.
authors.forename: Chittur Viswanathan
authors.initials: CV
authors.lastname: Gopalakrishnan
authors.affiliation: Division of Pediatric Neurosurgery, Department of Surgery, University of British Columbia & British Columbia Children's Hospital, 4480 Oak St., Room K3-159, V6H 3V4, Vancouver, BC, Canada.
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Hengel
authors.affiliation: Division of Neurosurgery, Royal University Hospital, Saskatoon, SK, Canada.
authors.forename: Aleksander M
authors.initials: AM
authors.lastname: Vitali
authors.affiliation: Department of Radiology, University of British Columbia & British Columbia Children's Hospital, Vancouver, BC, Canada.
authors.forename: Ken
authors.initials: K
authors.lastname: Poskitt
authors.affiliation: Division of Pathology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Hawkins
authors.affiliation: Division of Pediatric Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada.
authors.forename: James
authors.initials: J
authors.lastname: Drake
authors.affiliation: Division of Pediatric Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada.
authors.forename: Maria
authors.initials: M
authors.lastname: Lamberti-Pasculli
authors.affiliation: Division of Neurosurgery, McMaster Children's Hospital, Hamilton, ON, Canada.
authors.forename: Olufemi
authors.initials: O
authors.lastname: Ajani
authors.affiliation: Division of Neurosurgery, Alberta Children's Hospital, Calgary, AB, Canada.
authors.forename: Walter
authors.initials: W
authors.lastname: Hader
authors.affiliation: Division of Neurosurgery, Stollery Children's Hospital, Edmonton, AB, Canada.
authors.forename: Vivek
authors.initials: V
authors.lastname: Mehta
authors.affiliation: Division of Neurosurgery, IWK Health Centre, Halifax, NS, Canada.
authors.forename: P Daniel
authors.initials: PD
authors.lastname: McNeely
authors.affiliation: Section of Neurosurgery, Winnipeg's Children's Hospital, Winnipeg, MB, Canada.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: McDonald
authors.affiliation: Division of Neurosurgery, Children's Hospital, London Health Sciences Center, London, ON, Canada.
authors.forename: Adrianna
authors.initials: A
authors.lastname: Ranger
authors.affiliation: Division of Neurosurgery, University of Ottawa & Children's Hospital of Eastern Ontario, Ottawa, ON, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Vassilyadi
authors.affiliation: Division of Paediatric Neurosurgery, McGill University Health Centre, Montreal, QC, Canada.
authors.forename: Jeff
authors.initials: J
authors.lastname: Atkinson
authors.affiliation: The Arthur and Sonia Labatt Brain Tumour Research Centre, the Hospital for Sick Children, Toronto, ON, Canada.
authors.forename: Scott
authors.initials: S
authors.lastname: Ryall
authors.affiliation: Division of Hematology, Oncology and Palliative Care, Department of Pediatrics, University of Alberta & Stollery Children's Hospital, Edmonton, AB, Canada.
authors.forename: David D
authors.initials: DD
authors.lastname: Eisenstat
authors.affiliation: Division of Neurology and Oncology, Department of Pediatrics, University of British Columbia & British Columbia Children's Hospital, Vancouver, BC, Canada.
authors.forename: Juliette
authors.initials: J
authors.lastname: Hukin
mesh_terms: D000293:Adolescent; D001254:Astrocytoma / Q000175:diagnosis / Q000235:genetics / Q000628:therapy*; D001932:Brain Neoplasms / Q000175:diagnosis / Q000235:genetics / Q000628:therapy*; D002170:Canada; D017024:Chemotherapy, Adjuvant; D002648:Child; D002675:Child, Preschool; D004806:Ependymoma / Q000175:diagnosis / Q000235:genetics / Q000628:therapy*; D005260:Female; D005910:Glioma / Q000235:genetics / Q000628:therapy; D006801:Humans; D007223:Infant; D053208:Kaplan-Meier Estimate; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D015999:Multivariate Analysis; D019635:Neurosurgical Procedures; D015514:Oncogene Proteins, Fusion / Q000235:genetics; D011379:Prognosis; D016016:Proportional Hazards Models; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies; D013788:Thalamus; D016896:Treatment Outcome
chemical_list: C568616:BRAF-KIAA1549 fusion protein, human; D015514:Oncogene Proteins, Fusion
keywords: Brain tumor; Chemotherapy; Glioma; Outcome; Pediatric; Radiotherapy; Surgery; Thalamic tumor; Thalamus