Hereditary breast cancer | Afrilatest.be

In Belgium, every woman has a risk of about 1 in 10 to get breast cancer during her life. The chance of getting the disease increases as one gets older. In 5 to 10% of women with breast cancer, it is a hereditary form of breast cancer. The hereditary form is usually diagnosed at a younger age – between 35 and 60 years. Patients with the hereditary form have an increased risk of developing cancer in both breasts (instead of one breast) and also an increased risk of ovarian cancer.

Hereditary breast cancer gene

Women who carry the breast cancer gene BRCA 1 or 2 have a 55 to 85% chance of developing breast cancer before the age of 80. The chance of ovarian cancer is 40-60% (for BRCA1) and 15-20% (for BCRA2). In certain population groups such as Ashkenazi Jews, the frequency is even higher. The chance that a man will develop breast cancer is around 5 percent, but the gene can be passed on by the man.

• Two or more first- and/or second-degree relatives (both male and female) on either the mother's or father's side with breast cancer and/or ovarian cancer.
• A first-degree relative (male or female) with breast cancer before the age of 50.
• A first-degree relative with breast cancer and ovarian cancer.
• A first-degree relative with breast cancer and a first-degree relative with ovarian cancer.

Also read: Which cancers are hereditary and how can they be detected?

How does hereditary breast cancer develop?

Our body is made up of cells. Each cell contains 46 chromosomes that are arranged in 23 pairs: 22 pairs of autosomes and one pair of sex chromosomes. Half of them come from the sperm cell of the father, the other half from the egg cell of the mother. Chromosomes are coiled DNA threads on which our genes or hereditary characteristics are located. They are located in the cell nuclei. Each chromosome is therefore a carrier of a series of genes that contain the information for our hereditary characteristics. In total, we have about 30,000 genes.

During fertilization, the fusion of an egg cell and a sperm cell takes place. In contrast to all other body cells, these reproductive cells contain only 23 chromosomes. After fertilization, a new cell (zygote) with 46 chromosomes is created. In this, half of the hereditary characteristics come from the father and the other half from the mother.

This zygote divides into two, four, eight cells, and so on. This process is called mitosis. During each mitosis, not only the cell divides, but also the nucleus (which contains the chromosomes). Before the nucleus divides, the chromosomes double, so that there are always 46 chromosomes in each new cell. These chromosomes are exact copies of the chromosomes of the very first cell.

Each body cell contains two copies of each chromosome, one from the father and one from the mother. This also means that each gene is present in duplicate. For each characteristic, such as hair colour, two genes are responsible. The hair colour of the child depends on the 'type' of gene.

• Dominant genes are always expressed in a certain trait, they dominate the other gene.
• Recessive genes are not expressed, they are suppressed by the other gene. When two genes for a certain trait are both recessive, this recessive trait does come forward.

Four possibilities

• the mother's gene is intact
• the mother's gene is defective
• the father's gene is intact
• the father's gene is defective

In a man, such an abnormal gene rarely leads to breast cancer. If he has the abnormal gene, each of his children – sons and daughters – has a 50% chance of inheriting it. His daughters therefore have a greatly increased risk of breast and/or ovarian cancer.

Also read: Breast cancer in men

Research: DNA test for hereditary breast cancer

BRCA1 is a gene on the long arm of chromosome 17 and BRCA2 is on chromosome 13.

When more than one woman in the same family is affected by breast cancer at a relatively young age and/or in which ovarian cancer also occurs, this may indicate a hereditary form of breast and/or ovarian cancer. This may be a reason for a predictive DNA test in other female family members to see if they have one of the abnormal genes.

The condition for starting DNA testing is that DNA from affected family members is available or that there are affected family members alive from whom blood can be taken for DNA testing. If the abnormality in the BRCA1 or BRCA2 gene has been detected in these family members, it is indisputably the hereditary form of breast and/or ovarian cancer. Predictive genetic testing of unaffected relatives (both men and women) is then possible.

In certain families with a clear history of breast cancer and/or ovarian cancer, no abnormality can be found in the DNA at this time (yet). However, this does not rule out the possibility that it may be a hereditary form of breast and/or ovarian cancer. These women probably have a greatly increased risk of breast and/or ovarian cancer and regular examination of the breasts and ovaries is indicated. However, no predictive test is possible for these women.

The decision to have a predictive DNA test for breast and/or ovarian cancer is a decision that can have far-reaching consequences. That is why these tests are handled by a specialized, multidisciplinary team that pays attention to all questions and concerns, both medical and psychological, that a confrontation with hereditary breast cancer can raise.

Preventive measures

Early detection of breast and/or ovarian cancer has a high chance of recovery. That is why it is important that women who are carriers of a genetic abnormality and therefore have a greatly increased risk of breast and/or ovarian cancer, undergo medical follow-up to detect early breast and/or ovarian cancer as early as possible.

• monthly breast self-examination
• clinical examination of the breasts and ovaries by a doctor every six months
• annual ultrasound of the ovaries and mammography and/or ultrasound of the breasts, or new techniques (magnetic scanner or NMR).

This is best done from the age of 30 or at least 5 years earlier than the age of onset of the youngest affected family member.

For a woman who belongs to a family with a clear family history of breast and/or ovarian cancer, but in whom genetic testing has not yet been able to identify an abnormality in the BRCA1 or BRCA2 gene, the same recommendations apply as for women in whom a genetic abnormality has been identified.

Also read: What are the symptoms of breast cancer in women?

Preventive mastectomy

This does mean an early menopause. The symptoms of menopause can be treated with hormone replacement therapy, but in women who still have their ovaries, such treatment increases the risk of heart disease, stroke and some cancers.

Sources:
https://erfelijkheid.nl
https://www.uzleuven.be