Product of the gene HER2/neu (erbB2) is the transmembrane receptor with tyrosine kinase activity with a molecular weight 185 kDa that belongs to the family of the genes HER - homologs of EGFR (epidermal growth factor receptor). This gene is located on the long arm of the chromosome 17 in the region q11.2 - q12. HER2/neu gene amplifiation is found in many cancers. In mammary gland cancer this amplification is detected in 15 – 25 % of cases and strongly correlates with the overexpression of the corresponding protein.
Overexpression of the protein HER2/neu is an important prognostic and predictive factor of the invasive carcinoma of the mammary gland. It was found that this overexpression is associated with a worse prognosis. However, in patients with a proven HER2/neu gene amplification it is possible to use (albeit still with a questionable benefit) the treatment with Herceptin, a monoclonal antibody against the extracellular domain of the protein HER-2/neu.
Determination of the HER2/neu gene apmlifcation can be performed by a variety of the methodologies. Currently, the most used is fluorescent in situ hybridization (FISH). In our laboratory we use diagnostic PathVysionTM HER2/neu DNE probe kit (Vysis/Abbott).
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