1p/19q testing has no significance in the workup of glioblastomas. Issue 6 (9th September 2013)

• Record Type: Journal Article
• Authors: Clark, K. H.; Villano, J. L.; Nikiforova, M. N.; Hamilton, R. L.; Horbinski, C.
• Is Part Of: Neuropathology & applied neurobiology. Volume 39:Issue 6(2013)
• Page Start: 706
• Page End: 717
• Publication Date: 2013-09-09
• Subjects: Nervous system -- Diseases -- Pathology -- Periodicals; Nervous system -- Diseases -- Periodicals; 616.8
• DOI: 10.1111/nan.12031
• Languages: English
• ISSNs: 0305-1846

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="nan12031-sec-0001" sec-type="section"> <title>Aims</title> <p>To determine whether testing for isolated 1p or 19q losses, or as a codeletion, has any significance in the workup of glioblastomas (GBMs).</p> </sec> <sec id="nan12031-sec-0002" sec-type="section"> <title>Methods</title> <p>Upfront 1p/19q testing by fluorescence <italic>in situ</italic> hybridization (FISH) and/or polymerase chain reaction (PCR)‐based loss of heterozygosity (LOH) was done in 491 gliomas that were histologically diagnosed as GBMs. Outcomes were determined and measured against 1p/19q results.</p> </sec> <sec id="nan12031-sec-0003" sec-type="section"> <title>Results</title> <p>Twenty‐eight showed apparent 1p/19q codeletion by either FISH and/or PCR‐based LOH, but only 1/26 showed codeletion by both tests. Over 90% of tumours with apparent codeletion by either FISH or LOH also had 10q LOH and/or <italic>EGFR</italic> amplification, features inversely related to true whole‐arm 1p/19q codeletion. Furthermore, only 1/28 tumours demonstrated an R132H IDH1 mutation. Neither 1p/19q codeletion by FISH nor LOH had an impact on GBM survival. Isolated losses of 1p or 19q also had no impact on survival.</p> </sec> <sec id="nan12031-sec-0004" sec-type="section"> <title>Conclusions</title> <p>These data suggest that (i) 1p/19q testing is not useful on gliomas that are histologically GBMs; (ii) codeletion testing should be reserved only for cases with compatible morphology; and (iii) <italic>EGFR</italic>, 10q, and IDH1 testing can help act as safeguards against a false‐positive 1p/19q result.</p> </sec> </abstract>