Background: The concordance rate between immunohistochemical (IHC) and fluorescence in situ hybridization (FISH) results for HER2/neu according to clinical performance is controversial. The present prospective study was theerefore conducted in Indian breast cancer patients.
Methods: Fifty cases (n=50) of invasive duct cancer of breast tested for HER-2/neu by IHC and scored as 0, 1+, 2+ and 3+ by pathologists were further analyzed by FISH using a commercially available double-color probe, and the findings compared.
Results: A total concordance of 82.0% was observed with a Kappa coefficient of 0.640 (P <0.001). A high discordance was observed in 30.0% of the patients with IHC 2+, 7.1% in IHC 3+, 19.2% overall in IHC 0 and 1+.
Conclusion: IHC can be used firstly to screen the HER-2/neu status, and FISH can be used as a supplementary role to IHC and 2+ and some negative cases. And only those cases with HER-2/neu status of IHC 3+ or FISH positive should be treated with Herceptin (Trastuzumab).