title: Clinical implications of medulloblastoma subgroups: incidence of CSF diversion surgery.
abstract: OBJECTIVE
  While medulloblastoma was initially thought to comprise a single homogeneous entity, it is now accepted that it in fact comprises 4 discrete subgroups, each with its own distinct demographics, clinical presentation, transcriptomics, genetics, and outcome. Hydrocephalus is a common complication of medulloblastoma and not infrequently requires CSF diversion. The authors report the incidence of CSF diversion surgery in each of the subgroups of medulloblastoma (Wnt, Shh, Group 3, and Group 4).
  
  
  METHODS
  The medical and imaging records for patients who underwent surgery for medulloblastoma at The Hospital for Sick Children were retrospectively reviewed. The primary outcome was the requirement for CSF diversion surgery either before or within 60 days of tumor resection. The modified Canadian Preoperative Prediction Rule for Hydrocephalus (mCPPRH) was compared among subgroups.
  
  
  RESULTS
  Of 143 medulloblastoma patients, treated from 1991 to 2013, sufficient data were available for 130 patients (15 with Wnt, 30 with Shh, 30 with Group 3, and 55 with Group 4 medulloblastomas). Of these, 28 patients (22%) ultimately underwent CSF diversion surgery: 0% with Wnt, 29% with Shh, 29% with Group 3, and 43% with Group 4 tumors. Patients in the Wnt subgroup had a lower incidence of CSF diversion than all other patients combined (p = 0.04). Wnt patients had a lower mCPPRH score (lower risk of CSF diversion, p = 0.045), were older, had smaller ventricles at diagnosis, and had no leptomeningeal metastases.
  
  
  CONCLUSIONS
  The overall rate of CSF diversion surgery for Shh, Group 3, and Group 4 medulloblastomas is around 30%, but no patients in the present series with a Wnt medulloblastoma required shunting. The low incidence of hydrocephalus in patients with Wnt medulloblastoma likely reflects both host factors (age) and disease factors (lack of metastases). The absence of hydrocephalus in patients with Wnt medulloblastomas likely contributes to their excellent rate of survival and may also contribute to a higher quality of life than for patients in other subgroups.
authors.affiliation: Developmental and Stem Cell Biology, Division of Neurosurgery, Neurooncology and Neuropathology, Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Christian
authors.initials: C
authors.lastname: Schneider
authors.forename: Vijay
authors.initials: V
authors.lastname: Ramaswamy
authors.forename: Abhaya V
authors.initials: AV
authors.lastname: Kulkarni
authors.forename: James T
authors.initials: JT
authors.lastname: Rutka
authors.forename: Marc
authors.initials: M
authors.lastname: Remke
authors.forename: Uri
authors.initials: U
authors.lastname: Tabori
authors.forename: Cynthia
authors.initials: C
authors.lastname: Hawkins
authors.forename: Eric
authors.initials: E
authors.lastname: Bouffet
authors.forename: Michael D
authors.initials: MD
authors.lastname: Taylor
mesh_terms: D000293:Adolescent; D014408:Biomarkers, Tumor / Q000032:analysis*; D002170:Canada; D002528:Cerebellar Neoplasms / Q000737:chemistry / Q000150:complications* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D005260:Female; D053823:Hedgehog Proteins / Q000032:analysis*; D006801:Humans; D006849:Hydrocephalus / Q000175:diagnosis / Q000209:etiology / Q000601:surgery*; D015994:Incidence; D007223:Infant; D008297:Male; D008527:Medulloblastoma / Q000737:chemistry / Q000150:complications* / Q000473:pathology; D011237:Predictive Value of Tests; D011788:Quality of Life; D012189:Retrospective Studies; D012720:Severity of Illness Index; D020542:Third Ventricle; D014696:Ventriculostomy / Q000379:methods / Q000706:statistics & numerical data*; D051153:Wnt Proteins / Q000032:analysis*
chemical_list: D014408:Biomarkers, Tumor; D053823:Hedgehog Proteins; C509239:SHH protein, human; D051153:Wnt Proteins
keywords: ETV = endoscopic third ventriculostomy; FOR = frontal and occipital horn ratio; endoscopic third ventriculostomy; hydrocephalus; mCPPRH; mCPPRH = modified Canadian Preoperative Prediction Rule for Hydrocephalus; medulloblastoma; molecular subgroups; oncology; pediatric; posterior fossa; shunt