HER2 FISH results in breast cancers with increased CEN17 signals using alternative chromosome 17 probes - reclassifying cases in the equivocal category.
Histopathology
; 71(4): 610-625, 2017 Oct.
Article
em En
| MEDLINE
| ID: mdl-28502100
ABSTRACT
AIMS:
HER2 testing of invasive breast cancer by in-situ hybridization guides therapy decisions. Probing HER2 and centromere of chromosome 17 (cen17) simultaneously is supposed to reveal both a potential HER2 gene amplification and polysomy 17. However, a considerable number of breast cancer patients with quasi polysomy 17 are considered 'equivocal', which is diagnostically meaningless. Moreover, patients with equivocal/false polysomic tumours are prevented from a potentially beneficial anti-HER2 treatment. Here we evaluated the RAI1, D17S122 and TP53 hybridization markers to indicate true polysomy reliably and to reclassify equivocal samples accurately as HER2-positive. METHODS ANDRESULTS:
Samples with (n = 82) and without (n = 52) increased cen17 copy numbers and 78 evidently HER2-amplified specimens were analysed using dual and triple marker hybridization probes. Selected putative polysomic samples were subjected to array-based comparative genomic hybridization (aCGH). We found that 37.8% samples with putative polysomy 17 did not show any gain in RAI1, D17S122 or TP53. Accordingly, aCGH revealed evidence for the presence of HER2/cen17 co-amplification rather than for true polysomy in those cases. Reflex testing using alternate 17p markers reclassified up to 56.3% equivocal cases as HER2-positive and the combined assessment of a 17p and 17q locus allows the differentiation of true versus false polysomy.CONCLUSIONS:
An increased cen17 copy number does not necessarily reflect polysomy, and reflex testing facilitates the reclassification of 'equivocals'. Nevertheless, the prognostic and predictive value of a HER2/cen17 co-amplification versus HER2 gene amplification alone must still be evaluated prospectively.Palavras-chave
Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Cromossomos Humanos Par 17
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Neoplasias da Mama
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Biomarcadores Tumorais
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Receptor ErbB-2
Limite:
Female
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Humans
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article