Chromogenic in situ hybridization for Her-2/neu-oncogene in breast cancer: comparison of a new dual-colour chromogenic in situ hybridization with immunohistochemistry and fluorescence in situ hybridization.
OBJECTIVE
Her-2/neu testing is used as a marker for Herceptin therapy. The aim was to investigate new dual-colour chromogenic in situ hybridization (CISH), in a large number of breast carcinomas (n = 205) with DNA-specific dual-colour probes (ZytoVision, Bremerhaven, Germany) and to compare the results with immunohistochemistry (n = 205) and fluorescence in situ hybridization (FISH) (n = 129).


RESULTS
Paraffin-embedded tissue of 205 patients was used. After immunohistochemistry with a focus on immunohistochemically uncertain cases, Her-2/neu amplification using dual-colour CISH (ZytoVision) was analysed. Validation by FISH was performed. The results were: immunohistochemistry, 27.8% with strong expression, 53.7% with uncertain overexpression and 18.5% with no expression; FISH, 25.6% amplified and 74.4% negative; CISH, 35.6% amplified, 62.9% negative and 1.5% not evaluable. Comparison of immunohistochemistry with CISH: CISH negative in 100% with immunohistochemistry 0/1+, amplified in 82.5% with immunohistochemistry 3+; 5.9% contradictory results: 4.4% immunohistochemistry 3+ and negative by CISH, 1.5% negative in immunohistochemistry but amplified by CISH; FISH (129 cases), 8.5% contradictory results to immunohistochemistry, 6.2% immunohistochemistry 3+ and negative by FISH, 2.3% negative by immunohistochemistry and amplified by FISH; comparison of CISH and FISH, 94.6% same results, 3.9% different ones, 1.6% CISH not analysable.


CONCLUSIONS
CISH, using dual-colour probes (ZytoVision) is as good as FISH for Her-2/neu analysis. The few discrepant results are likely to be caused by polysomy or tumour heterogeneity.
Mayr
Doris
D
Pathologisches Institut, Ludwig Maximilians Universitaet, München, Germany. doris.mayr@med.uni-muenchen.de
Heim
Sibylle
S
Weyrauch
Kerstin
K
Zeindl-Eberhart
Evelyn
E
Kunz
Anne
A
Engel
Jutta
J
Kirchner
Thomas
T
D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism*; D016009:Chi-Square Distribution; D002863:Chromogenic Compounds; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D017403:In Situ Hybridization / Q000379:methods*; D009367:Neoplasm Staging; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*
D002863:Chromogenic Compounds; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human