Zones of defensive reaction by fish. What is a fish test for breast cancer? What does it show? predisposition to breast cancer

In all cases, without exception, the formation and growth is associated with the activity of the HER2 type gene. It is he who is responsible for how much protein will be released female body for the development of breast tissue. When the first healthy cells are reborn into malignant ones, the gene receptors receive information about what is required. additional division cellular material.

The gene starts a program to build additional tissue inside the breast, although in reality this cellular material will be used by the tumor for its growth and development. So, carcinoma, in fact, deceives the body, and forces it to feed the cancer at the expense of its own resources.

The task of fish analysis in breast cancer is precisely to identify wrong work HER2 gene, and take appropriate response measures in terms of prescribing adequate medical treatment.

If a fish test is not carried out in a timely manner for breast cancer, then even if certain drugs are used in the treatment process, this can lead to the fact that the tumor will continue to aggressively develop, covering all new breast tissues. These are the so-called consequences of incorrectly prescribed therapy due to the lack of objective data on the functioning of the HER2 gene.

In the process of passing the fish analysis, the doctor introduces into the patient's blood special substances containing coloring elements that can visualize the picture of chromosomal disorders. Thus, the doctor is able to visually see and further study the genetic abnormalities in the woman's genome that led to the development of breast cancer.

If abnormalities in the work of the HER2 gene are confirmed, then appropriate treatment is prescribed. If not, then the doctor, using other tests, establishes a different reason for the development of breast cancer.

Another important advantage of fish analysis is that in a couple of days the patient receives a comprehensive report on the genetic predisposition to the development of a particular cancer. With the help of this medical test, it is possible to simultaneously diagnose the pathology of not only the mammary gland, but also all abdominal organs.

Informative video

The FISH-staining method (fluorescent in situ hybridization) was developed at the Livermore National Laboratory (USA) in 1986. This is a fundamentally new method for studying chromosomes - a method for fluorescent DNA detection by in situ hybridization with specific molecular probes. The method is based on the ability of chromosomal DNA to bind under certain conditions to DNA fragments (DNA probes), which include nucleotide sequences complementary to chromosomal DNA. DNA probes are pre-labeled with special substances (for example, biotin or digoxigenin). Labeled DNA probes are applied to cytogenetic preparations prepared for hybridization metaphase chromosomes. After hybridization has occurred, the preparations are treated with special fluorescent dyes conjugated with substances that can selectively bind to biotin or digoxigenin. Each chromosome has a specific color. Hybridization can also be carried out with radioactively labeled probes. Cytogenetic analysis is carried out under a fluorescent microscope in ultraviolet light.

The FISH method is used to detect small deletions and translocations. Chromosomal exchanges (translocations and dicentrics) between differently colored chromosomes are easily identified as multi-colored structures.

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Learning module. Fundamentals of General and Medical Genetics
(guidelines for students) Academic discipline Biology For the direction of preparation General Medicine Co.

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Organelles with protective and digestive function
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Organelles involved in the energy supply of the cell
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Organelles involved in cell division and movement
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Granular endoplasmic reticulum
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Patterns of inheritance of traits in monohybrid crossing. Types of interaction of allelic genes
2. Learning objectives: To know: - patterns of monohybrid crossing; - I and II laws of Mendel; - types of interaction

The law of independent inheritance of traits. Types of interaction of non-allelic genes
2. Learning objectives: To know: - patterns of di- and polyhybrid crossing; - III Mendel's law; - types of interaction

Variability as a property of the living, its form. Phenotypic (modification or non-hereditary) variability. Genotypic variability
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Independent work of students under the supervision of a teacher
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Pedigree analysis
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Twin method for the study of human genetics
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Dermatoglyphic method for the study of human genetics
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Cytogenetic method in the study of human genetics
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Study of the chromosome set
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1. Viewing the demonstration preparation "Human karyotype" in the cytogenetic laboratory. With X90 magnification, leukocytes are visible in the field of view

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The FISH technique, Fluorescent in situ hybridization, was developed in the mid-1980s and is used to detect the presence or absence of specific DNA sequences on chromosomes, as well as the alpha DNA satellite located on the centromere of chromosome 6, CEP6(6p11.1-q11. one).

This has made a significant difference in the diagnosis. oncological diseases melanocytic genesis occurred in connection with the discovery tumor antigens. Against the background of malignancy, a mutation in three antigens is determined: CDK2NA (9p21), CDK4 (12q14) and CMM1(1p). In this regard, the possibility of an objective differential diagnosis, based on the determination of the genetic characteristics of melanocytic skin tumors, has great importance in early diagnosis melanoma and its precursors. In the nucleus with a normal set of genes under study and chromosome 6, two RREB1 genes stained red, two MYB genes stained yellow, two CCND1 genes isolated in green, and the two centromeres of chromosome 6, labeled blue color. For diagnostic purposes, fluorescent samples are used.

Evaluation of the reaction results: the number of red, yellow, green and blue signals in 30 nuclei of each sample is counted, four parameters are revealed various options genetic disorders at which the sample is genetically consistent with melanoma. For example, a sample corresponds to melanoma if the average number of CCND1 gene per nucleus is ≥2.5. The copy number of other genes is estimated according to the same principle. A drug is considered FISH-positive if at least one of the four conditions is met. Samples in which all four parameters are below the breakpoints are considered FISH-negative.

The determination of specific DNA sequences on chromosomes is carried out on sections of biopsy specimens or surgical material. In practical implementation, the FISH reaction is as follows: the test material containing DNA in the nuclei of melanocytes is processed to partially destroy its molecule in order to break the double-stranded structure and thereby facilitate access to the desired gene region. Samples are classified according to the place of attachment to the DNA molecule. The material for the FISH reaction in clinical practice is paraffin sections fabrics, smears and prints.

The FISH reaction allows you to find changes that have occurred in the DNA molecule as a result of an increase in the number of copies of a gene, loss of a gene, a change in the number of chromosomes and qualitative changes - the movement of gene loci both in the same chromosome and between two chromosomes.

To process the data obtained using the FISH reaction and study the relationship between the copy number of the genes of the three studied groups, the Spearman correlation coefficient is used.

Melanoma is characterized by an increase in copy number compared to nevus and dysplastic nevus.

A simple nevus, compared to a dysplastic nevus, has fewer copy number abnormalities (i.e., more normal copies).

To build decision rules to predict whether a sample belongs to a particular class (differential diagnosis of simple and dysplastic nevi), the mathematical apparatus of “decision trees” is used. This approach has proven itself in practice, and the results of applying this method (unlike many other methods, such as neural networks) can be clearly interpreted to build decision rules for differentiating simple, dysplastic nevi, and melanoma. The initial data in all cases were the copy numbers of four genes.

The task of constructing a decision rule for differential diagnostics is divided into several stages. At the first stage, melanoma and nevus are differentiated, without taking into account the type of nevus. At the next stage, a decision rule is built to separate simple and dysplastic nevi. Finally, at the last stage, it is possible to build a "decision tree" to determine the degree of dysplastic nevus dysplasia.

Such a division of the task of classifying nevi into subtasks makes it possible to achieve high accuracy of predictions at each of the stages. The input data for constructing the decision tree are data on the copy number of four genes for patients diagnosed with melanoma and patients diagnosed with non-melanoma (patients with different types of nevus - simple and dysplastic). For each patient, gene copy numbers are available for 30 cells.

Thus, dividing the task of predicting the diagnosis into several stages allows us to build high-precision decision rules not only for differentiating between melanoma and nevi, but also for determining the type of nevi and predicting the degree of dysplasia for a dysplastic nevus. The constructed "decision trees" are a clear way to predict a diagnosis based on gene copy numbers and can be easily used in clinical practice to differentiate benign, premalignant, and malignant melanocytic skin tumors. Proposed additional method differential diagnosis is especially important when excising giant congenital pigmented nevi and dysplastic nevi in ​​patients childhood, since when such patients are referred to medical institutions there is a high percentage of diagnostic errors. The results of using the described method are highly effective, it is advisable to use it in the diagnosis of pigmented skin tumors, especially in patients with FAMM syndrome.

Mammary cancer - dangerous disease, which according to statistics takes the first place among cancerous ailments in women. The risk of developing this disease increases in all women over 40 years of age and may be due to several other factors. Among the most probable causes causes of breast cancer include obesity, genetic or hereditary predisposition, early onset of menstruation and late completion, hormonal or radiation therapy.

In addition, the risk of morbidity is increased in nulliparous women and women who have had cancer. Men can also develop breast cancer.

Types and methods of diagnosis

The first step in diagnosing breast cancer is a routine examination by a mammologist. Women over 40 should have these checkups at least once every two years. The doctor performs a visual examination, palpation and mammography of the mammary glands. Visual signs of the development of the disease can be:

general information

X-ray of the breast (mammography) allows you to determine the presence, size and location of the tumor. To improve the accuracy of the results obtained, the technology of introducing a contrast agent is used. If the tumor has already been detected, then the method of pneumocystography is used - the removal of the tumor fluid and the introduction of air into the cavity. If the presence of a tumor is not specified, then ductography is used - the introduction of a contrast agent into the milk ducts.

These methods allow you to visualize the presence of formations in the tissues of the mammary gland.

If the presence of a tumor also becomes apparent on mammography, the patient is given a referral to a set of diagnostic measures:

On ultrasound, the doctor can distinguish a tumor from a cyst and clarify the localization of the formation. After that, a tissue sample is taken from it for a biopsy. A biopsy allows you to find out the type of formation: benign or malignant, and also to determine whether the tumor is hormone-dependent. This information allows the doctor to decide on a treatment strategy, but does not always make it possible to determine the stage. Often, even with all the necessary diagnostic measures it can be determined only after the operation.

The mechanism of histological studies

A tissue biopsy is performed both before and after the operation. The procedure is carried out after clarification of the localization of education.

A biopsy is the process of removing a piece of tissue, and its study is called "histological examination" or simply "histology".

A medical worker, using a special needle, takes a small amount of tissue from the neoplasm, or the tumor already removed from the patient's body is sent for histological examination. Then the tissue fragment is stained and processed in a special way to increase the contrast and make it easier to study. The slice is examined with a microscope by a specialist and gives a conclusion about the quality of the tumor formation. Much in this study depends on the attentiveness and qualifications of the laboratory assistant giving the conclusion.

A related study is immunohistochemistry. In general, it can also be called "histology", because. the method is based on the study of tissues, but immunohistochemistry is a more advanced method of analysis. The tissue in this study is also stained with special reagents, which not only enhance visual contrast, but also combine (“label”) with antibodies in a special way, which makes it possible to clarify large quantity characteristics of the neoplasm. The reaction in this case occurs much faster, which allows you to quickly get the results of the analysis.

Immunohistochemistry allows not only to clarify the type of neoplasm, but also to plan a patient treatment strategy based on the detection of tumor tissue sensitivity to various types therapeutic impact. In addition, the conduct of this study is automated as much as possible, which makes it possible to minimize the likelihood of diagnostic error due to the human factor.

There are also modern diagnostic measures that allow to detect the presence of a tumor in the body: this is a spectral analysis of blood, an immunological (biochemical) analysis, a FISH test of tumor tissue. A genetic blood test allows any woman to verify the presence or absence of prerequisites for the occurrence of breast cancer. CT and MRI allow you to accurately determine the localization of the tumor and trace the dynamics of its development, evaluate the structure of the neoplasm.

How to detect cancer by blood test?

A blood test is mainly prescribed by a doctor after an ultrasound examination. There are situations when a patient, on his own initiative, donates blood for window markers or genetic analysis in order to determine whether he has a predisposition to breast cancer. In some cases general analysis blood can serve as a reason for contacting an oncology dispensary (together with palpation of a seal or visual signs of cancer).

Biochemical analysis

Blood as a material for research allows the following diagnostic measures:

At the same time, only the first two analyzes can be called specialized methods for determining cancer, the second of which is more of a preventive measure than an operational one. Two other blood tests are carried out mainly before the operation to determine the state of the body and the extent of the process. However, as already mentioned, if a seal is felt in the chest and at the same time a general blood test shows more than two negative diagnostic coefficients, this is a reason to contact a specialist. Negative coefficients are indicators outside the norm in certain parameters of the blood composition.

A biochemical blood test reveals the presence of antibodies to tumor cells. Such bodies are called tumor markers. The number and type of tumor markers depends on the specifics (localization) cancerous tumor and stages of its development. Tumor markers include:

In the case of breast cancer, the attending physician will be primarily interested in the presence of the CA-15-3 tumor marker, since its presence in the blood unambiguously indicates a breast cancer disease. Deciphering the result takes an average of one day. Biochemical analysis is carried out several times during the course of the disease. Blood for him is taken from a vein in the morning on an empty stomach. Two weeks before the test, the patient stops taking all medicines(to be specified by the attending physician). Two days before donating blood, you can not take alcohol, fatty and fried foods.

One hour before the procedure, you can not smoke and it is desirable to reduce emotional stress. Blood on biochemical analysis usually do not give up immediately after radiation and physiotherapy.

Definition of genetic factors

Before talking about a genetic blood test, the difference between the concepts of "genetic" and "hereditary" should be emphasized. The genetic factor in the occurrence of cancer is a broader concept that implies not only the presence of relatives with breast cancer, but also a specific gene mutation, due to which the risk of this disease increases.

The hereditary factor implies a potential risk of breast cancer based on a family history. At the same time, not only women, but also men can get a mutant gene, but its carrier will not necessarily get sick.

Any woman can undergo a genetic analysis. This is especially recommended for those whose direct relatives have had breast cancer. Before the procedure for donating blood for analysis, a specialist in the field of genetics should talk to the patient, who will explain the nuances of deciphering the results. No special preparation is required from the patient before donating blood.

In case of receipt positive result BRCA gene mutations, but in the absence of other alarming symptoms, you should not panic. Women with a mutation in these genes can be recommended as a preventive measure regular self-examinations and medical examinations. After 40 years, it makes sense to think about removing the ovaries and breasts, women younger age who do not plan to have children in the future, sometimes recommend taking contraceptives. The decision on these measures lies entirely on the shoulders of the woman herself and requires a thoughtful approach and consultation with doctors.

The latest diagnostic methods

A spectral analysis of blood reveals the presence of neoplasms in the body with a probability of up to 93%. It's relative cheap way diagnostics, which is based on the irradiation of blood serum with an infrared spectrum and the analysis of its molecular composition.

The conclusion on the spectral analysis of blood is given on the principle of "presence-absence" and is aimed at identifying most types of malignant tumors. Also, this study is able to determine the stage of development of breast cancer. The interpretation of the results takes place in the laboratory and does not require an additional doctor's opinion.

In order to donate blood for spectral analysis, it is necessary to complete the medication intake 2 months before the procedure. From the moment of X-ray or other exposure, as well as chemotherapy, at least 3 months must pass. In addition, the woman must not be pregnant or menstruating at the time of blood sampling. Blood sampling takes place on an empty stomach in the morning. Spectral analysis of blood takes an average of 12 working days.

One of latest methods diagnosis of cancers is the so-called "fish test" (FISH, fluorescent hybridization). Its effectiveness is still under discussion, the main question of its feasibility is the costly research procedure. The essence of the method consists in labeling cell fragments with a fluorescent composition and further microscopic examination cells. According to which parts of the genetic material the labeled fragments have contacted, it is possible to understand whether the patient has a predisposition to cancer and what methods of treatment will be relevant in a particular case.

The FISH test does not require fully mature cells, so this analysis is much faster than other laboratory tests. In addition, the FISH method allows you to more clearly observe genetic damage, which is not possible with other types of analyzes. The FISH test is most often used specifically to detect breast cancer, but it also works to detect some other types of cancer.

The disadvantages of the FISH test include, in addition to its high cost, its impossibility to work on some parts of the chromosomes due to the specificity of the marks. In addition, the FISH test ignores certain types of mutations and breakdowns. genetic code, which can be an important omission in the diagnosis. Comparative studies of FISH with the cheaper IHC test did not reveal significant advantages in determining the susceptibility to Herceptin of cancer cells. However, the FISH test for this moment is the fastest among the high-precision methods for diagnosing cancer.