Today, many methods for diagnosing cancer have been developed. One of the most reliable methods for identifying cancer pathologies is the IHC study. What it is? Immunohistochemistry (abbreviated IHC) allows you to accurately detect malignant cells in the material obtained by biopsy. How is such a test conducted? And how to decipher its results? We will consider these issues in the article.
Description of procedure
Scientists have established that cancer cells produce specific proteins - antigens. The immune system perceives these substances as foreign agents and begins to produce antibodies against them. Thus, the human body is trying to fight the tumor.
The IHC study is based on the reaction of antigens and antibodies. What it is? During immunohistochemistry, a piece of tissue is taken for analysis. It is treated with antibodies to various types of malignant cells. The material is then examined under a microscope and the reaction is monitored.
If cancer cells are contained in a piece of tissue, then their antigens interact with antibodies. At the same time, luminescence (fluorescence) is noted in the biomaterial. This is a sign of malignant cells. This method allows you to identify cancer with an accuracy of 100%.
Analysis technique
The patient undergoes a biopsy before an IHC test. What it is? Under local anesthesia, a piece of tissue is plucked out of the tumor (biopsy). This material is examined under a microscope. In some cases, tissue removed during a surgical or endoscopic operation is taken for analysis.
Then the biopsy sample is degreased and treated with paraffin. This is necessary for the safety of the material. The result is paraffin blocks, which are then cut into extremely thin layers.
The obtained sections are treated with preparations with antibodies to different types of malignant cells. The following analysis kits may be used:
- Small panel. This kit contains up to 5 antibodies.
- The big panel. May contain from 6 to several tens of types of antibodies.
The choice of antibodies for the study depends on the intended diagnosis. In the direction of the analysis, the attending physician indicates which types of antigens must be identified in the patient. Depending on this, reagents for the test are selected.
You can get the results of the analysis on your hands after 1 - 2 weeks after the study.
What analysis shows
Often, patients are prescribed both a histogram and an IHC study. What is it and how are these two types of analyzes different? With a histogram, the biomaterial is examined under a microscope and the presence of cancer cells is determined. In an immunohistochemical study, malignant neoplasms are detected using the antigen-antibody reaction. This method of research is considered more informative.
IHC shows not only the presence of atypical cells. Using this study, you can identify:
- a variety of neoplasm;
- the spread of the oncological process;
- location of the primary metastatic tumor;
- stage of cancer;
- tumor growth rates.
In addition, using immunohistochemistry, it is possible to determine the sensitivity of cancer cells to chemotherapy and radiation. This allows you to choose the most effective treatment.
Indicators
In decoding, IHC studies indicate the concentration of antigens of malignant neoplasms. Normally, such proteins should be completely absent. Their presence in the biomaterial indicates the development of the tumor. The higher the concentration of antigens, the more actively the growth of the neoplasm occurs.
In addition, the type of atypical cells and their number are indicated in the analysis results. Only an oncologist can interpret the test data accurately.
Breast Cancer Detection
This test is prescribed if breast cancer is suspected. An IHC study in this case helps to identify not only the presence of malignant cells, but also the sensitivity of the tumor receptors to hormones. Indeed, often the growth of a breast tumor depends on the level of estrogen and progesterone. Using this study, you can also assess the need for hormone medication.
A special set of markers is used to diagnose breast cancer. In decoding the analysis, it is necessary to pay attention to the concentration of Ki-67 antigen. By this indicator, one can judge the prognosis of the disease, because it indicates the tumor growth rate.
The concentration of antigen is determined as a percentage. Depending on the level of Ki-67, a treatment method is selected:
- Less than 15%. The prognosis of the disease is considered favorable. Possible cure with hormonal therapy.
- From 16 to 30%. Moderate neoplasm growth. The spread of the tumor can be stopped with the help of hormones.
- Over 30 %. This concentration of antigen indicates the rapid growth of a cancerous tumor. Chemotherapy is required.
If the antigen index is less than 10%, then in the vast majority of cases, tumor growth can be stopped using hormones. A concentration of Ki-67 over 90% is considered extremely dangerous. This indicates an advanced stage of cancer. In such cases, the disease most often leads to death.
Application in gynecology
Often, doctors prescribe patients an IHC study for cervical dysplasia. This pathology is accompanied by the degeneration of healthy cells into atypical ones. Doctors assess this condition as precancerous. Grade 3 dysplasia almost always leads to the formation of a malignant tumor on the cervix.
IHC helps to assess the risk of cancer in patients with dysplasia. For research using antibodies to proteins p16INK4a and Ki-67.
The analysis determines not only the concentration of antigens, but also the ratio between the levels of the above proteins. The reference values of the indicators of the study are individual and depend on the proposed diagnosis. Only the attending physician can decrypt the test results accurately. High antigen concentrations and the ratio between p16INK4a and Ki-67 indicate a high risk of cervical cancer.
Where can I turn in
Where is the IHC study done? Such a test can be done in many commercial medical centers and laboratories (for example, in "Invitro" or "Hemotest"), as well as in large oncological medical institutions. The analysis does not require the patient to stay in the hospital, except when the study is carried out after surgery.
Immunohistochemistry is not included in the list of services that are provided under the compulsory medical insurance policy. Therefore, such an analysis can be passed only for a fee. Its price varies from 4,000 to 20,000 rubles. The cost of the test depends on the number of antigens to be detected in the biopsy. The greater the number of markers indicated in the direction of analysis, the higher the cost of the study.