The reference values (norm) of HER-2 / neu concentration in serum are less than 15 ng / ml.
The HER-2 / neu marker is a receptor of human epidermal growth factor, a protein found on normal cells of epidermal origin with a molecular weight of 185,000. It consists of 3 functional parts: internal (cytosolic), short transmembrane and extracellular. The cytoplasmic region of the HER-2 / neu receptor molecule has tyrosine kinase activity and is responsible for signal transmission. The hydrophobic transmembrane portion connects the intracellular kinase and extracellular ends of the receptor. As a result of proteolytic processes, the extracellular part of the HER-2 / neu receptor enters the blood, where it can be identified. It is a glycoprotein with a molecular mass of 97,000-115,000.
Until recently, the presence of HER-2 / neu receptors in breast cancer patients was determined histochemically after the puncture of the tumor. These receptors are found only in 20-30% of women with breast cancer. The main goal of the histochemical study is to determine the indications for trastuzumab (antibodies to HER-2 / neu receptors), which is indicated when more than 10% positive cells (2+ or 3+) are detected. Later it was found out that a significant number of patients with breast cancer respond positively to trastuzumab treatment with a negative histochemical result.
At present, test systems have been obtained for the quantitative determination of HER-2 / neu in serum, which correlates well with histochemical data. An increase in serum HER-2 / neu concentration is observed in women with breast cancer, especially in the presence of metastases. The value of 15 ng / ml is used as the separation point. Values above this level indicate HER-2 / neu-positive breast cancer. Elevated levels of HER-2 / neu strongly correlate with poor prognosis, low survival and aggressive course of the disease (such tumors have high proliferative and metastatic activity). Effective specific (trastuzumab), hormonal and chemotherapy are accompanied by a decrease in the level of HER-2 / neu in the serum.
Determination of HER-2 / neu content in serum is used:
- for monitoring metastatic breast cancer;
- to select patients for specific therapy (trastuzumab);
- for the diagnosis of recurrences of breast cancer;
- to determine the prognosis and course of breast cancer;
- for monitoring specific therapy, as well as treatment with hormonal and chemotherapeutic drugs.
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