title: Primary glioblastoma with oligodendroglial differentiation has better clinical outcome but no difference in common biological markers compared with other types of glioblastoma.
abstract: BACKGROUND
  Glioblastoma multiforme with an oligodendroglial component (GBMO) has been recognized in the World Health Organization classification-however, the diagnostic criteria, molecular biology, and clinical outcome of primary GBMO remain unclear. Our aim was to investigate whether primary GBMO is a distinct clinicopathological subgroup of GBM and to determine the relative frequency of prognostic markers such as loss of heterozygosity (LOH) on 1p and/or 19q, O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation, and isocitrate dehydrogenase 1 (IDH1) mutation.
  
  
  METHODS
  We examined 288 cases of primary GBM and assessed the molecular markers in 57 GBMO and 50 cases of other primary GBM, correlating the data with clinical parameters and outcome.
  
  
  RESULTS
  GBMO comprised 21.5% of our GBM specimens and showed significantly longer survival compared with our other GBM (12 mo vs 5.8 mo, P = .006); there was also a strong correlation with younger age at diagnosis (56.4 y vs 60.6 y, P = .005). Singular LOH of 19q (P = .04) conferred a 1.9-fold increased hazard of shorter survival. There was no difference in the frequencies of 1p or 19q deletion, MGMT promoter methylation, or IDH1 mutation (P = .8, P = 1.0, P = 1.0, respectively).
  
  
  CONCLUSIONS
  Primary GBMO is a subgroup of GBM associated with longer survival and a younger age group but shows no difference in the frequency of LOH of 1p/19q, MGMT, and IDH1 mutation compared with other primary GBM.
authors.affiliation: Corresponding Author: Ross Laxton, PhD, Department of Clinical Neuropathology, King's College Hospital, Denmark Hill, London SE5 9RS, UK. ross.laxton@nhs.net.
authors.forename: Ross C
authors.initials: RC
authors.lastname: Laxton
authors.forename: Sergey
authors.initials: S
authors.lastname: Popov
authors.forename: Lawrence
authors.initials: L
authors.lastname: Doey
authors.forename: Alexa
authors.initials: A
authors.lastname: Jury
authors.forename: Ranj
authors.initials: R
authors.lastname: Bhangoo
authors.forename: Richard
authors.initials: R
authors.lastname: Gullan
authors.forename: Chris
authors.initials: C
authors.lastname: Chandler
authors.forename: Lucy
authors.initials: L
authors.lastname: Brazil
authors.forename: Gill
authors.initials: G
authors.lastname: Sadler
authors.forename: Ron
authors.initials: R
authors.lastname: Beaney
authors.forename: Naomi
authors.initials: N
authors.lastname: Sibtain
authors.forename: Andrew
authors.initials: A
authors.lastname: King
authors.forename: Istvan
authors.initials: I
authors.lastname: Bodi
authors.forename: Chris
authors.initials: C
authors.lastname: Jones
authors.forename: Keyoumars
authors.initials: K
authors.lastname: Ashkan
authors.forename: Safa
authors.initials: S
authors.lastname: Al-Sarraj
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000175:diagnosis / Q000235:genetics / Q000401:mortality; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics; D002888:Chromosomes, Human, Pair 19 / Q000235:genetics; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D005909:Glioblastoma / Q000175:diagnosis / Q000235:genetics* / Q000401:mortality; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000235:genetics*; D019656:Loss of Heterozygosity; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D009367:Neoplasm Staging; D009837:Oligodendroglioma / Q000175:diagnosis / Q000235:genetics* / Q000401:mortality; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics; D015996:Survival Rate; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: D025521:Tumor Suppressor Proteins; D007521:Isocitrate Dehydrogenase; C543588:IDH1 protein, human; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes
keywords: 1p/19q; IDH1; MGMT; glioblastoma with an oligodendroglial component; histopathology