Breast cancer genes BRCA1 and BRCA2

and Maria Franz, M.Sc. Biochemistry and medical student

Martina Feichter studied biology with an elective subject pharmacy in Innsbruck and also immersed herself in the world of medicinal plants. From there it was not far to other medical topics that still captivate her to this day. She trained as a journalist at the Axel Springer Academy in Hamburg and has been working for since 2007 - first as an editor and since 2012 as a freelance writer.

More about the experts

Maria Franz has been a freelance writer in the editorial team since 2020. After completing a master's degree in biochemistry, she is currently studying human medicine in Munich. With her work at she would like to arouse her own great interest in medical topics among the readers as well.

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Hereditary breast cancer is often based on a change (mutation) in the BRCA1 or BRCA2 gene. There are also other breast cancer genes that can 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 process and consequences of the genetic test!

ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. D05C50

Familial breast cancer

Breast cancer is more common in some families. This can indicate a genetic cause. Almost a third of all breast cancer patients have a family history. That is, relatives in one line of the family have already developed breast cancer.

In around five to ten out of 100 people with breast cancer, a pathological genetic change (mutation) that they inherited from their mother or father can be identified. Then doctors speak of hereditary breast cancer (hereditary / genetic breast cancer). Those affected can in turn pass the breast cancer facility on to their children.

BRCA1 and BRCA2

In around a quarter of patients with familial history, the mutation is in one of two genes that have been known for a long time: BRCA1 (BReast-CAncer-1) and BRCA2 (BReast-CAncer-2). These genes contain the blueprint for enzymes that repair defects and damage in genetic material (DNA). This prevents the growth of tumors - BRCA1 and BRCA2 are therefore among the so-called tumor suppressor genes.

Increased risk of breast cancer

With mutations in BRCA1 and BRCA2, this repair mechanism no longer works - cancer can develop, especially breast cancer: Around 70 percent of women with a BRCA1 mutation and around 55 percent of women with a BRCA2 mutation will develop breast cancer in their lifetime.

This means that those affected are about ten times more likely to have breast cancer than women who do not carry either of the two gene mutations.In addition, the malignant breast tumor develops much earlier: women with a BRCA1 or BRCA2 mutation are on average 40 years old when diagnosed, i.e. 20 years younger than women without risk genes.

Those affected not only have an increased risk of developing breast cancer one day. After contracting breast cancer, you are also at great risk of developing breast cancer in the other breast as well.

Increased risk of ovarian cancer

A mutation in the BRCA1 or BRCA2 gene also carries an increased risk of ovarian cancer: Around 45 percent of all women with a mutated BRCA1 and around 15 percent of all women with a mutated BRCA2 develop ovarian cancer by the age of 70 (sometimes in addition to breast cancer).

BRCA1 and BRCA2: high risk genes for men too

The two breast cancer genes also increase the risk of malignant breast tumors in men: two out of 100 men with a BRCA1 mutation develop breast cancer. In the case of the BRCA2 mutation, this figure is as high as seven out of 100 men. In view of the otherwise rare occurrence of male breast cancer, this is a significant increase in risk.

Other risk genes for breast cancer

In addition to BRCA1 and BRCA2, researchers have now identified other genes that can increase the risk of breast cancer if mutated. These include the RAD51C and PALB2 genes. All of them are normally involved in repair processes in cells and thus protect against cancer. Mutations in PALB2 also significantly increase the risk of breast cancer; there are different data for RAD51C in the literature. Sometimes this results in a high risk, sometimes a moderate one.

Scientists are also researching other potential breast cancer genes. How strongly these actually influence the risk of breast cancer has not yet been conclusively clarified. It is possible that some mutations are only dangerous when other unfavorable factors are added.

Other genetic changes also play a role. Men with Klinefelter syndrome, who have at least one extra X sex chromosome, are more likely to develop breast cancer than men without an extra chromosome.

What are the signs of hereditary breast cancer?

There are several factors that suggest hereditary breast cancer (and ovarian cancer). This means that the suspicion of a BRCA1 or BRCA2 mutation in particular is likely if it is in the blood related family

• at least three women have breast cancer
• at least two women have developed 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 aged 35 or younger has breast cancer
• at least one woman aged 50 or younger has bilateral breast cancer
• at least one man has breast cancer and one woman has breast or ovarian cancer

Health professionals recommend women who have one or more of these factors that they seek advice and genetic testing from a specialized center. Experts from various fields work together in these centers, such as gynecologists, geneticists and psychologists. In each individual case, you can assess how high the risk of cancer is and explain the possibilities and consequences of the genetic test.

A list of the Familial Breast and Ovarian Cancer Centers can be found at:

German Cancer Aid: www.krebshilfe.de

Austrian Cancer Aid: www.krebshilfe.net

Swiss Cancer League: www.krebsliga.ch

Genetic test

For the genetic test (breast cancer) you only have to give a blood sample. The genetic makeup of the cells floating in the blood is then examined in a specialized laboratory for mutations, for example in the BRCA1 and BRCA2 genes. This can take a few weeks. Doctors will inform you of the result when you have another consultation at the specialized center.

Genetic test positive

A positive genetic test doesn't mean breast cancer will be safe to occur. Also, it cannot be used to predict how a possible disease will progress. It just says that the risk of breast and / or ovarian cancer is significantly increased.

However, if you have been found to have a BRCA1 and / or BRCA2 mutation, you can act early to prevent breast cancer:

• You can take part in an intensified breast cancer screening program.
• You can undergo preventive surgery, which means that both breasts and both ovaries and fallopian tubes can be removed preventively.

Genetic test negative

Even a negative test result does not “protect” against breast cancer. There may also be an increased familial breast cancer risk if no genetic change was found. If the genetic test is negative, discuss with your doctor what that means in your case.

Scientists assume that there are more risk genes than laboratories have so far been able to prove. If breast cancer occurs frequently in your family, intensified early detection makes sense, even if no mutations such as BRCA1 or BRCA 2 have been found. It is best to seek advice from a specialist doctor, with your gynecologist being a suitable first point of contact.

Intensified early detection program

Experts advise patients with a high familial risk to have more early detection. It involves a variety of exams and usually takes place in a specialized center for familial breast and ovarian cancer.

The following measures are part of the intensified early detection program (according to the guidelines of the Gynecological Oncology Working Group):

• Half-yearly palpation of the breast by the doctor and half-yearly ultrasound examination for women aged 25 and over
• Annually or every two years a mammogram of the breast from the age of 40 (possibly even earlier, depending on the respective risk analysis by a breast center)
• In the case of very high risk, annual MRI examination of the breast from the age of 25 up to menopause (possibly also in younger women with unclear ultrasound with dense breast tissue)

The costs

If certain requirements are met, many health insurance companies will cover the costs of the genetic test and the intensified early detection at a center for familial breast and ovarian cancer. The costs for preventive operations and breast augmentation are often reimbursed if there is evidence of a BRCA1 or BRCA2 mutation. In any case, you should discuss the assumption of costs with your health insurance company in advance.

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