The genetic test for breast cancer has as main objective to verify the risk of development of breast cancer, besides allowing the doctor to know which mutation is associated with the cancerous alteration.
This type of test is usually indicated for people who have close relatives who were diagnosed with breast cancer before the age of 50, ovarian cancer or male breast cancer. The test consists of a blood test that, using molecular diagnostic techniques, identifies one or more mutations associated with susceptibility to breast cancer, the main markers requested in the test being BRCA1 and BRCA2.
It is also important to have regular exams and be aware of the first symptoms of the disease so that the diagnosis is made early and, thus, treatment begins. Learn how to identify the early symptoms of breast cancer.
Genetic test price
Genetic testing is expensive, as it is done with the help of state-of-the-art equipment of high sensitivity and specificity. Thus, depending on the laboratory in which it is performed, genetic testing can cost between R $ 1500 and R $ 7000, 000 and is not included in health plans, however, it is possible to obtain authorization for the examination by SUS upon authorization Special.
When to do
The genetic examination for breast cancer is an examination indicated by the oncologist, mastologist or geneticist, made from the analysis of a blood sample and recommended for people who have family members diagnosed with breast cancer, female or male, before the age of 50 or ovarian cancer at any age. Through this test, it is possible to know if there are mutations in BRCA1 or BRCA2 and, thus, it is possible to check the chance of developing breast cancer.
Usually when there is an indication of the presence of mutations in these genes, it is likely that the person will develop breast cancer throughout life. It is up to the doctor to identify the risk of manifestation of the disease so that preventive measures are adopted according to the risk of developing the disease.
How is done
The genetic test for breast cancer is done by analyzing a small blood sample, which is sent to the laboratory for analysis. To do the exam, no special preparation or fasting is required and it does not cause pain, the most that can happen is slight discomfort at the time of collection.
This test has the main objective of evaluating the BRCA1 and BRCA2 genes, which are tumor suppressor genes, that is, they prevent cancer cells from proliferating. However, when there is a mutation in any of these genes, the function of stopping or delaying the development of the tumor is impaired, with the proliferation of tumor cells and, consequently, the development of cancer.
The type of methodology and mutation to be researched is defined by the doctor, and the performance of:
- Complete sequencing, in which the entire genome of the person is seen, making it possible to identify all the mutations he has; Genome sequencing, in which only specific regions of DNA are sequenced, identifying mutations present in those regions; Specific mutation research, in which the doctor indicates which mutation he wants to know and specific tests are carried out to identify the desired mutation, this method being more suitable for people who have family members with some genetic alteration already identified for breast cancer; Isolated research of insertions and deletions, in which changes in specific genes are verified, this methodology being more suitable for those who have already done the sequencing but need complementation.
The result of the genetic test is sent to the doctor and the report contains the method used for detection, as well as the presence of the genes and the identified mutation, if present. In addition, depending on the methodology used, it can be informed in the report how much the mutation or gene is expressed, which can help the doctor to check the risk of developing breast cancer. Learn more about molecular diagnosis.
Possible results
The results of the exam are sent to the doctor in the form of a report, which can be positive or negative. The genetic test is said to be positive when the presence of a mutation in at least one of the genes is verified, but it does not necessarily indicate whether or not the person will have cancer or the age at which it may happen, requiring quantitative tests.
However, when a mutation in the BRCA1 gene is detected, for example, there is a chance of up to 81% of breast cancer development, and it is recommended that the person undergo magnetic resonance imaging annually, in addition to being able to undergo mastectomy as a means of prevention.
The negative genetic test is one in which no mutation was verified in the analyzed genes, but there is still a chance of developing cancer, despite being very low, requiring medical monitoring through regular examinations. Learn about other tests that confirm breast cancer.
Oncotype DX exam
The Oncotype DX test is also a genetic test for breast cancer, which is done from the analysis of breast biopsy material, and aims to evaluate the genes related to breast cancer through molecular diagnostic techniques, such as RT-PCR. Thus, it is possible for the doctor to indicate the best treatment, and chemotherapy can be avoided, for example.
This test is able to identify breast cancer in the early stages and check the degree of aggression and how the response to treatment would be. Thus, it is possible that a more targeted treatment for cancer is made, avoiding the side effects of chemotherapy, for example.
The Oncotype DX exam is available in private clinics, it must be done after the oncologist's recommendation and the result is released, on average, after 20 days.
