Comparison of the IHC, FISH, SISH and qPCR methods for the molecular diagnosis of breast cancer.

Her2 proto-oncogene amplification and protein overexpression is observed in 20-40% of patients with breast cancer and plays a crucial role in invasive breast cancer and its treatment. In the present study, we investigated samples from 131 patients with invasive breast carcinoma. In all cases, the overexpression/amplification level of Her2 was determined using manual immunohistochemistry (IHC) and/or automatic IHC, fluorescence in situ hybridization (FISH), silver in situ hybridization (SISH) and quantitative polymerase chain reaction (qPCR). Using various methods, we demonstrated candidate methods for Her2 detection and their dependability. Our results demonstrate that these methods are highly comparable for the detection of Her2 overexpression/amplification. It was also revealed that qPCR is a valuable tool for the evaluation of Her2 gene overexpression/amplification. The results from pPCR analysis positively correlated with the results from IHC and FISH analysis. Moreover, in contrast to IHC or SISH/FISH, the results obtained by qPCR were not encumbered with any subjective error on the part of the evaluator.