Polysomy for chromosomes 1 and 19 predicts earlier recurrence in anaplastic oligodendrogliomas with concurrent 1p/19q loss.
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.
Snuderl
Matija
M
Pathology Service, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114-2698, USA.
Eichler
April F
AF
Ligon
Keith L
KL
Vu
Quynh U
QU
Silver
Michael
M
Betensky
Rebecca A
RA
Ligon
Azra H
AH
Wen
Patrick Y
PY
Louis
David N
DN
Iafrate
A John
AJ
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