title: Polysomy for chromosomes 1 and 19 predicts earlier recurrence in anaplastic oligodendrogliomas with concurrent 1p/19q loss.
abstract: OBJECTIVE
  Loss of chromosome arms 1p and 19q is a molecular feature of oligodendroglial tumors characterized by responsiveness to chemotherapy and a favorable prognosis. The purpose of this study was to evaluate the prognostic significance of polysomy of chromosomes 1 and 19 in the setting of 1p/19q codeletion.
  
  
  METHODS
  We analyzed 64 anaplastic oligodendrogliomas with 1p/19q loss or maintenance diagnosed at Massachusetts General Hospital and Brigham and Women's Hospital from 1996 to 2005; fluorescence in situ hybridization for 1p/19q and Ki-67 immunohistochemistry was done. Polysomy was defined as more than two 1q and 19p signals in >30% of the cells with concurrent 1p/19q deletion. Tumors were divided into groups based on their 1p/19q status and compared for progression-free survival, overall survival, and 5-year survival probabilities.
  
  
  RESULTS
  Forty-six tumors (72%) in our cohort had 1p/19q loss and 18 (28%) had 1p/19q maintenance. Of those with loss, 19 (41%) had concurrent polysomy and 27 (59%) lacked polysomy. In agreement with previous studies, the group of anaplastic oligodendrogliomas with 1p/19q loss had significantly better progression-free survival and overall survival than anaplastic oligodendrogliomas with 1p/19q maintenance (P = 0.0009 and P < 0.0003, respectively). Among anaplastic oligodendrogliomas with 1p/19q loss, those with polysomy showed shorter progression-free survival than those with 1p/19q loss without polysomy (P = 0.0048). Overall survival was similar in tumors with and without polysomy. The Ki-67 labeling index was not associated with polysomy and did not have prognostic significance.
  
  
  CONCLUSIONS
  The presence of polysomy in anaplastic oligodendrogliomas with deletion of 1p/19q is a marker of earlier recurrence.
authors.affiliation: Pathology Service, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114-2698, USA.
authors.forename: Matija
authors.initials: M
authors.lastname: Snuderl
authors.forename: April F
authors.initials: AF
authors.lastname: Eichler
authors.forename: Keith L
authors.initials: KL
authors.lastname: Ligon
authors.forename: Quynh U
authors.initials: QU
authors.lastname: Vu
authors.forename: Michael
authors.initials: M
authors.lastname: Silver
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Betensky
authors.forename: Azra H
authors.initials: AH
authors.lastname: Ligon
authors.forename: Patrick Y
authors.initials: PY
authors.lastname: Wen
authors.forename: David N
authors.initials: DN
authors.lastname: Louis
authors.forename: A John
authors.initials: AJ
authors.lastname: Iafrate
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000782:Aneuploidy; D001932:Brain Neoplasms / Q000235:genetics*; D002872:Chromosome Deletion; D002878:Chromosomes, Human, Pair 1; D002888:Chromosomes, Human, Pair 19; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009837:Oligodendroglioma / Q000235:genetics* / Q000473:pathology; D011379:Prognosis