Abstract: Objective To explore overexpression of HER-2/neu gene by fluorescence in situ hybridization(FISH) in breast cancer and explore the clinical implications. Methods HER-2/neu gene in 33 cases with kainogeneous female breast cancer was detected by FISH from January 2008 up to now, and the relationship between HER-2/neu gene overexpression with clinical and pathological characters investigated. Results HER-2/neu gene expression rate was 39.4%. The overexpression was not correlated with tumor size, menostasis and clinical tumor stage(P>0.05). It was positively correlated with axillary lymph node status(P<0.05) and P53 gene(P<0.05); and negatively correlated with ER(P<0.01), but not correlated with PR(P>0.05). The overexpression cases with HER-2/neu gene showed 11 strongly and 5 moderately positive expression of HER-2 protein by immunohistochemistry. Conclusion FISH technique could detect the overexpression of HER-2/neu gene in breast cancer. It has favourable concordance with strongly positive expression of HER-2 protein(3+), but in the of moderately positive cases, FISH must be applied.

Key words: breast cancer, HER-2/neu gene, fluorescent in situ hybridization