Hereditary breast and ovarian cancer is most often caused by a mutation in the BRCA1 and BRCA2 genes. The BRCA1 and BRCA2 genes are anti-oncogens whose task is to prevent neoplastic disease. Mutations in these genes result in a loss of this function and can lead to cancer development. Find out when your genetic predisposition to cancer increases and how to reduce your risk of breast and ovarian cancer.

The BRCA1 and BRCA2 genes ensure that cells don't divide too quickly. The BRCA1 gene was discovered in 1994. It is located on the 17th chromosome and belongs to the suppressor genes (anti-oncogens). Mutations "turn off" the gene and lose its function.

For the record, we each have two sets of genes that we inherit (one each) from both our father and mother. When one of the BRCA1 genes is damaged, nothing bad happens because its function is taken over by the other pair. But when the second copy of the BRCA1 gene is also damaged in even one cell, cancer can develop.

Hereditary breast and ovarian cancer: family inclinations

With a hereditary tendency to breast and ovarian cancer, we come into the world with one gene already damaged. This means that we are at a higher risk of developing cancer from the start. The BRCA1 gene plays a role mainly in the tissues of the breast and ovary. If it is not working properly, the risk of breast cancer is around 80 percent and ovarian, fallopian tube, and peritoneal cancer is around 40 percent.

About 200,000 carriers of the mutated BRCA1 gene live in Poland, half of them are women.

Therefore, in families with an inherited gene mutation, numerous cases of the disease are observed, which are diagnosed in a relatively early adult age, and an additional characteristic feature is the presence of neoplasms in the same organs. Prostate cancer, colorectal cancer, laryngeal cancer and skin cancer are also more common in the families of carriers of the mutated BRCA1 gene.

Damaged BRCA1 and BRCA2 genes cause breast and ovarian cancer

The main guardian genes, such as BRCA1, are supported by other genes in certain organs. These include the BRCA2 gene, discovered in 1995. Damage to the BRCA2 gene in the Polish populationis a rare cause of breast and ovarian cancer, but has been associated with a family history of gastric cancer and male breast cancer.

The risk of falling ill is clearly lower than in the case of a mutation in the BRCA1 gene and amounts to 30-55%. for breast cancer, and 25 percent. for ovarian cancer. There are also other supporting genes in our body (eg NOD2, CHEK2), but the risk of getting sick when damaged is lower. Individuals are often ill or the neoplasms have different localization (e.g. prostate, thyroid, kidney).

If the facts are not brought together properly, which only an experienced geneticist can do, there is no suspicion of an inherited predisposition to cancer in a given family. The role of anti-oncogens can be illustrated on the example of a car. The BRCA1 gene plays the role of an engine that determines the ability to move efficiently. If it is damaged, the car will not start for a long time and we will face serious problems (general renovation and large expenses). The rest of the supporting genes seem a bit less important, but in the absence of fuel, low battery, rusty cables, the vehicle will not move. Of course, the trouble is smaller and easier to fix.

In addition, it happens that parts from one car model fit into another. Similarly, in nature there is an economical management of "spare parts" - supporting genes are common to more organs, hence the development of breast, thyroid, prostate and kidney cancer in carriers of mutations of the same genes.

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How to reduce the risk of breast cancer

Women who have been found to have mutations in their genes responsible for cancer development can reduce the risk of cancer by:

  • breastfeeding as long as possible (in a carrier of the mutated BRCA1 gene, breastfeeding for a total of one and a half years reduces the risk of breast cancer by approx. 50%);
  • delaying the first menstrual period due to intensive training (important for the daughters of the carrier);
  • proper use of hormonal contraception, i.e. avoiding oral preparations before the age of 30 and short use after the age of 30 (preferably via the percutaneous route);
  • lifestyle modification to help maintain a proper body weight, avoid stimulants (smoking!) And introduce Mediterranean diet elements to the daily menu.

Dangerous BRCA1 and BRCA2 mutations

Individual cancer risk is difficult to determine. In the case of carriers of the BRCA1 gene mutation, the risk increases by about 2-2.5 times if the woman also has a mutation in the MTHFR gene. In turn, mutations in the genes responsible for selenium metabolism(e.g. GPX1) may increase or decrease the risk of developing the disease depending on the level of selenium provided with food.

In Angelina Jolie, the risk of developing breast cancer was estimated at 87 percent and ovarian cancer at 50 percent, which is consistent with the observations in large populations of carriers of the BRCA1 gene mutation. Thanks to such observations, it can be expected that half of the carriers of the mutated BRCA1 gene will develop breast cancer before the age of 50, and this percentage increases with age. But your risk of developing breast cancer can be reduced (see box above).

Prevention of ovarian and breast cancer: what tests?

People with a positive family history should visit a genetic clinic - addresses of the centers can be found on the website of the International Hereditary Cancer Center in Szczecin (www.genetyka.com). The determination of the gene mutation can also be done in a private laboratory (marking the BRCA1 gene costs about PLN 300).

Early detection of a predisposition to developing cancer allows taking preventive measures. In Poland, there is a program financed by the Ministry of He alth, which covers women with a high risk of developing breast cancer with special oncological supervision. Women who are at risk are already in their 30s under the care of specialists.

One of the most important tests is breast ultrasound, which in the case of hereditary breast cancer caused by a mutation in the BRCA1 gene is even more detectable than mammography. In addition, the risk of developing the disease can be reduced by introducing short-term treatment with tamoxifen as soon as possible.

A similar treatment is also used after you develop breast cancer to protect your other breast. In addition, women at risk are recommended to remove the appendages, which is best done after the birth of all planned children, and before the menopause (usually around the age of 40). Only some women may be treated with a prophylactic mastectomy (removal of both breasts) before falling ill. However, it should be remembered that such surgery does not reduce the risk of ovarian cancer.

Medical statistics confirm that after successful breast cancer surgery, BRCA1 mutation carriers often die from ovarian cancer.

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Study of the BRCA1 and BRCA2 genes. Who should take the test?

The BRCA1 and BRCA2 gene testing should be performed by women with an increased risk (in relation to the population risk) of developing breast and / or ovarian cancer, that is:

  • have had at least 2 cases of breast cancer in their family (up to three generations ago),ovarian cancer or both, especially if the disease was diagnosed before the age of 50;
  • regardless of age, they either have breast or ovarian cancer themselves or have close relatives with breast or ovarian cancer (especially if they died earlier);
  • experienced an atypical form of the disease, e.g. when cancer was diagnosed at a young age (around 40), it was bilateral or it occurred in a related man;
  • in addition to breast cancer, among relatives there were cases of prostate cancer, larynx cancer, melanoma;
  • have been diagnosed with non-malignant changes, e.g. cysts in the breasts or ovaries, if they are planning or are already using hormone replacement therapy;
  • have family members who have been diagnosed with a BRCA1 or BRCA2 mutation.

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