Analysis of aneusomy level and HER-2 gene copy number and their effect on amplification rate in breast cancer specimens read as 2+ in immunohistochemical analysis

R. Merola, M. Mottolese, G. Orlandi, E. Vico, F. Cognetti, I. Sperduti, A. Fabi, G. Vitelli, A. M. Cianciulli

Research output: Contribution to journalArticlepeer-review

Abstract

Our aim was to determine the aneusomy level and the HER-2 gene copy numbers, by fluorescence in situ hybridization (FISH) and to analyze their impact on the amplification rate in breast carcinomas considered HER-2 weakly positive cases by immunohistochemistry. We evaluated 343 breast carcinomas using double colour FISH (LSI Her-2/neu gene and CEP 17). Monosomy and polysomy were demonstrated in 24.2% and 46.1% respectively and 101/343 (29.6%) of the specimens were amplified by FISH. A statistically significant difference was observed, when we compared the amplification percentage in polysomic and monosomic specimens (P <0.0001) and, among polysomic specimens, when tumours were compared with HER-2 gene signals number per cell between 3 and 10 and >10 respectively (P <0.0001). Logistic regression analysis showed that HER-2 signals >10 and polysomy absence were independently associated with amplification. Our results confirm that the majority of 2+ IHC cases express the HER-2 protein without gene amplification and highlight the effect of chromosome 17 aneusomy and the HER-2 gene copy number on amplification.

Original languageEnglish
Pages (from-to)1501-1506
Number of pages6
JournalEuropean Journal of Cancer
Volume42
Issue number10
DOIs
Publication statusPublished - Jul 2006

Keywords

  • Breast cancer
  • Chromosome 17 aneusomy
  • FISH
  • HER-2 gene
  • HER-2 gene signal number
  • IHC 2+
  • Trastuzumab

ASJC Scopus subject areas

  • Cancer Research
  • Hematology
  • Oncology

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