Quantification of Her-2/Neu Gene in Breast Cancer Patientsusing Real Time-Polymerase Chain Reaction (Q-PCR) andCorrelation with Immunohistochemistry Findings

Background: HER-2/neu is a proto-oncogene that encodes a transmembrane tyrosine kinase growth factorwhich is crucial for stimulating growth and cellular motility. Overexpression of HER-2/neu is observed in 10-35%of human breast cancers and is associated with pathogenesis, prognosis as well as response to therapy. Giventhe imperative role of HER-2/neu overexpression in breast cancer, it is important to determine the magnitudeof amplification which may facilitate a better prognosis as well as personalized therapy in affected patients. Inthis study, we determined HER-2/neu protein expression by immunohistochemistry (IHC) concurrently withHER-2/neu DNA amplification by quantitative real time-polymerase chain reaction (Q-PCR). Materials and
Methods: A total of 53 paired tissue samples from breast cancer patients were frozen-sectioned to characterizethe tumour and normal tissues. Only tissues with 80% tumour cells were used in this study. For confirmation,Q-PCR was used to determine the HER-2/neu DNA amplification.
Results: We found 20/53 (37.7%) of thetumour tissues to be positive for HER-2/neu protein overexpression using IHC. Out of these twenty, only 9/53(17%) cases were in agreement with the Q-PCR results. The concordance rate between IHC and Q-PCR was79.3%. Approximately 20.7% of positive IHC cases showed no HER-2/neu gene amplification using Q-PCR.
Conclusion: In conclusion, IHC can be used as an initial screening method for detection of the HER-2/neu proteinoverexpression. Techniques such as Q-PCR should be employed to verify the IHC results for uncertain cases aswell as determination of HER-2/neu gene amplification