Hereditary breast cancer is usually based on a mutation in the BRCA1 or BRCA2 gene. There are also other breast cancer genes that may be involved in the development of breast cancer. If familial breast cancer is suspected, a genetic test can detect mutations in the BRCA1 and BRCA2 genes. Find out more about BRCA1, BRCA2 and other breast cancer genes as well as the procedure and consequences of genetic testing!
Family breast cancer
In some families, breast cancer is more common. Hereditary breast cancer is relatively rare. Scientists estimate that about five to ten out of every hundred affected women have inherited the breast cancer device from their mother or father. You can pass the risk on to your children.
BRCA1 and BRCA2
In 25 to 50 percent of all cases of hereditary breast cancer, the pathological gene mutation is in one of two genes: BRCA1 (BReast-CAncer-1) and BRCA2 (BReast-CAncer-2). These genes contain the blueprint for enzymes that repair DNA defects and damage in DNA. This prevents the growth of tumors – BRCA1 and BRCA2 therefore belong to the so-called tumor suppressor genes.
Increased risk of breast cancer
However, with mutations in BRCA1 and BRCA2, this repair mechanism does not work anymore – cancer can develop, especially breast cancer:
About 65 to 75 out of 100 women with a BRCA1 mutation and 45 to 65 out of 100 carriers of a BRCA2 mutation get breast cancer before the age of 70. Thus, the female carriers have about ten times higher risk of breast cancer than women who do not carry either of the gene mutations. In addition, the malignant breast tumor develops much sooner in female carriers: the affected women are on average 40 years old at diagnosis (instead of 60 years, as patients without BRCA1 or BRCA2 mutation).
Increased risk of ovarian cancer
In addition, a mutation in the BRCA1 or BRCA2 gene also poses an increased risk of ovarian cancer: About 40 to 50 percent of all women with a mutant BRCA1 and 10 to 20 percent of all women with a mutant BRCA2 develop ovarian cancer by the age of 70 (sometimes in addition to breast cancer).
BRCA1 and BRCA2: high-risk individuals for men too
The two breast cancer genes also increase the risk of a malignant breast tumor in men: Two out of 100 men with a BRCA1 mutation develop breast cancer. In the BRCA2 mutation, there are even seven out of every 100 men. Given the otherwise rare occurrence of male breast cancer, this is a significant risk increase.
Other risk genes for breast cancer
In addition to BRCA1 and BRCA2, other genes are now known that can increase the risk of breast cancer in a mutation. These include the genes RAD51C and PALB2. All are usually involved in repair processes in cells and thus the protection against cancer. Science is exploring more potential candidates for breast cancer genes. How much they actually affect the risk of breast cancer needs to be further investigated. It is possible that some genetic mutations only have a risk-enhancing effect if other unfavorable factors are added.
What indicates hereditary breast cancer?
There are several factors that indicate hereditary breast cancer (and ovarian cancer). That is, the suspicion of a BRCA1 or BRCA2 mutation is obvious if in the blood-related family:
- at least three women have breast cancer
- At least two women have breast cancer, one of them before the age of 51
- At least one woman has breast cancer and one woman has ovarian cancer
- at least two women have ovarian cancer
- at least one woman has breast and ovarian cancer
- at least one woman with 35 years or younger is suffering from breast cancer
- at least one woman aged 50 years or younger has bilateral breast cancer
- at least one man has breast cancer and one woman has breast or ovarian cancer
Women who have one or more of these factors should seek advice and a genetic test from a specialized center. Experts from different disciplines work together in these centers, such as gynecologists, geneticists and psychologists. In individual cases, they can assess how high the risk of cancer is and explain the possibilities and consequences of genetic testing.
A list of centers for familial breast and ovarian cancer can be found at the German Cancer Aid at: www.krebshilfe.de/brustkrebszentren.html
Genetic test
For the genetic test (breast cancer) you only have to give a blood sample. The genome of the cells floating in the blood is then examined in a specialized laboratory for mutations in the BRCA1 and BRCA2 genes. This can take a few weeks. The result will be communicated to you at a renewed consultation in the specialized center.
Positive genetic test
If you have detected a BRCA1 and / or BRCA2 mutation, you have several options for further action:
- You can participate in a specialized breast cancer screening program at the specialized center.
- You can undergo a preventive surgery, so preventively remove both breasts and both ovaries and fallopian tubes.
Intensified early detection program
Intensified breast cancer screening in patients at high familial risk usually includes the following measures (individual differences are possible):
- Six-monthly palpation of the breast by the doctor and half-yearly ultrasound examination for women over 25 years
- breast mammography annually or every two years from the age of 30 (for very dense breast tissue from the age of 35 years)
- annual high-risk MRI examination of the breast at the age of 25 to 55 years (possibly also in younger women with unclear ultrasound in dense breast tissue)
The costs
If certain conditions are met, many health insurance companies cover the costs of the genetic test and intensified early detection at a center for familial breast and ovarian cancer. Also, the costs of preventive surgery and breast augmentation are often reimbursed, if proven a BRCA1or BRCA2 mutation. In any case, you should discuss a reimbursement in advance with your health insurance company.