title: Codeletions at 1p and 19q predict a lower risk of pseudoprogression in oligodendrogliomas and mixed oligoastrocytomas.
abstract: BACKGROUND
  Pseudoprogression (PsP) occurs at a higher rate in glioblastoma multiforme with a methylated MGMT promoter-a subset with increased sensitivity to chemoradiotherapy and better overall prognosis. In oligodendroglioma (OG) and oligoastrocytoma (OA), presence of 1p/19q codeletions is highly predictive of response to treatment and is often associated with the methylated MGMT promoter; hence, this study queries whether the presence of 1p/19q codeletions in OG/OA correlates with a higher rate of PsP following therapy.
  
  
  METHODS
  A retrospective analysis was performed on all OG/OA in a database of patients with brain tumors who underwent resection of their tumor since 1998. Eighty-eight cases (37 with and 51 without 1p/19q codeletions) met inclusion criteria, and their patient data were analyzed to determine whether the presence of 1p/19q codeletions was associated with PsP and survival.
  
  
  RESULTS
  OG/OA (World Health Organization grades II and III) with 1p/19q codeletions had a significantly improved survival (P = .041). Multivariate analysis found that PsP occurred less frequently in OG/OA with 1p/19q codeletions compared with tumors without codeletions (odds ratio, 0.047; 95% confidence interval, 0.005-0.426; P = .0066). The rate of PsP was 19% for the entire cohort, 31% for tumors without codeletions, and 3% for tumors with codeletions. When early posttreatment contrast enhancement developed in tumors with 1p/19q codeletions, it occurred exclusively in tumors that were histologically OA and not OG.
  
  
  CONCLUSIONS
  Codeletions of 1p/19q are a marker of good prognosis but are unexpectedly associated with a lower likelihood of PsP. PsP does not correlate with sensitivity to treatment and improved survival in OG/OA.
authors.affiliation: Corresponding author: David D. Tran, MD, PhD, Department of Medicine, Division of Medical Oncology, Neuro-Oncology Program, Washington University School of Medicine, Campus Box 8069, 660 South Euclid Avenue, Saint Louis, MO 63110. dtran@dom.wustl.edu.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Lin
authors.forename: Jingxia
authors.initials: J
authors.lastname: Liu
authors.forename: John
authors.initials: J
authors.lastname: Evans
authors.forename: Eric C
authors.initials: EC
authors.lastname: Leuthardt
authors.forename: Keith M
authors.initials: KM
authors.lastname: Rich
authors.forename: Ralph G
authors.initials: RG
authors.lastname: Dacey
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Dowling
authors.forename: Albert H
authors.initials: AH
authors.lastname: Kim
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Zipfel
authors.forename: Robert L
authors.initials: RL
authors.lastname: Grubb
authors.forename: Jiayi
authors.initials: J
authors.lastname: Huang
authors.forename: Clifford G
authors.initials: CG
authors.lastname: Robinson
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Simpson
authors.forename: Gerald P
authors.initials: GP
authors.lastname: Linette
authors.forename: Michael R
authors.initials: MR
authors.lastname: Chicoine
authors.forename: David D
authors.initials: DD
authors.lastname: Tran
mesh_terms: D000328:Adult; D001254:Astrocytoma / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D001932:Brain Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D002872:Chromosome Deletion; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics*; D002888:Chromosomes, Human, Pair 19 / Q000235:genetics*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009837:Oligodendroglioma / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D055815:Young Adult
keywords: 1p/19q codeletions; oligoastrocytoma; oligodendroglioma; p53.; pseudoprogression