HER-2/neu evaluation by immunohistochemistry and fluorescence in situ hybridization in breast cancer: implications for daily laboratory practice.
BACKGROUND
HER-2/neu status was determined by immunohistochemistry (IHC) and fluorescence in situ hybridisation (FISH) methods in more than 300 paraffin-embedded primary breast cancer samples.


METHODS
HER-2/neu status was determined by FISH using the PathVysion kit (Vysis) and by IHC using either a monoclonal antibody CB11 or a cocktail of antibodies: the monoclonal TAB250 and the polyclonal pAb1.


RESULTS
Of the 324 cases evaluable by IHC, 65 out of 318 (20%) and 24 out of 324 (7%) were scored as positive when using the antibody cocktail and the CB11, respectively. HER-2/neu gene amplification occured in 64 out of 324 cases (20%). Concordance of FISH and IHC was found in 285 out of 318 cases (90%) and 278 out of 324 cases (86%) using the cocktail and the CB11, respectively.


CONCLUSIONS
The cost-effectiveness analysis revealed that the use of a sensitive IHC method followed by confirmation of positive results by FISH considerably decreased the FISH costs and may become standard practice for HER-2/neu evaluation.
Larsimont
Denis
D
Pathology Department, Jules Bordet Institute, Brussels, Belgium. denis.larsinomt@bordet.be
Di Leo
Angelo
A
Rouas
Ghizlane
G
Paesmans
Marianne
M
Ferreira-Filho
Fabiano
F
Bernard
Chantal
C
Cardoso
Fatima
F
Verhest
Alain
A
Piccart
Martine J
MJ
Gancberg
David
D
D000911:Antibodies, Monoclonal; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D007753:Laboratories / Q000592:standards*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis* / Q000235:genetics*; D015203:Reproducibility of Results
D000911:Antibodies, Monoclonal; D018719:Erb-b2 Receptor Tyrosine Kinases