Genetic testing for breast cancer: “We look at the whole family tree”

Genetics is an integral part of every medical specialisation today. Can genetic testing really stop people from developing breast cancer? 
It depends very much on whether the breast cancer is hereditary or a tumour that has formed spontaneously, as a result of exposure to environmental factors such as radiation or simply due to age. In the five to ten per cent of cases involving hereditary cancer, we can take preventative steps to help other family members.

How do you proceed in such cases? 
If we suspect that a person has a predisposition to breast cancer, we analyse certain genes that, if mutated, may trigger breast cancer. If we identify a mutation, we can offer other family members who do not yet have the disease the opportunity to be tested for this mutation in their family and tell them whether they have inherited the mutation or do not carry it at all and therefore do not have an increased risk of developing the disease. We can help allay these women's fears. You can also cut back on the need for frequent check-ups. A yearly check-up at the gynaecologist is enough. However, this screening does not make sense and is not necessary for all women.

In other words, does genetic testing not make sense for all women? 
No. This type of testing only makes sense if there is a history of cancer in the patient’s family. To analyse whether this kind of genetic predisposition exists, we look at the entire family tree. This is very important. If there are indications of a family history of cancer and a mutation that causes cancer has been identified in a person who already has the disease, a genetic analysis of family members can provide a reliable indication of whether someone has inherited this mutation or not. This makes it possible to take more intensive preventative measures in a timely manner or to just recommend the usual check-ups for the entire population.

Are there indications of a genetic predisposition without performing a DNA test?  
Yes. For one thing, of course, if other relatives also have breast cancer. But also if the patient had already developed breast cancer when she was under 50. Another warning sign is if the cancer occurs on both sides of the body or if the patient develops another cancer, for example ovarian cancer. These can all be signs of a genetic predisposition.

Can any woman undergo this kind of DNA test? 
The preference is for patients to be referred to Hirslanden Precise. However, in exceptional cases you can also register yourself. A genetic consultation is covered by health insurance and is a compulsory service. The consultation is very important and required by law in any event. A DNA test may not be carried out without a consultation and the results may not be given to the patient without one. An application for assumption of the costs is required for this testing.

It is now possible to buy DNA tests for breast cancer on the internet ...  
Yes, but tests like these are highly dangerous and, in my view, a waste of money. Patients receive several pages of findings that they don't know what to do with. For instance, a non-specialist would not understand what a risk assessment of three per cent means. Is it a lot? Or completely harmless? I recently had a consultation with a patient who received a very stressful diagnosis. She didn’t know what to make of it. We then repeated the test here, only to find that she did not have the mutation in question at all.

How is this kind of genetic testing carried out? 
In most cases, a blood sample is taken. A saliva sample can also be used. We then usually carry out what is known as a “clinical exome”, in which we single out the genes that are suspected to be cancerous for analysis. Should we have further specific questions later on, we can also analyse other genes. There is a whole range of genes that are associated with certain diseases. The list is updated each year as new findings emerge.

How high is the demand for it? 
It's relatively high, but we perform far fewer tests than consultations. In most cases, there is no genetic predisposition and an annual check-up is enough. However, genetic tests are often carried out on tumour tissue. This is in order to select the proper treatment.

In what way?  
If we know exactly what type of tumour it is and what stage the cancer has reached based on the genetic analysis, we can also say which type of treatment is appropriate. You can also test during treatment to see if it is actually working. If in doubt, you can then change it more quickly.

What are the chances of a cure for breast cancer? 
There are now a number of effective treatments and a fairly good prognosis. It is fair to say that breast cancer really can be cured in most cases nowadays. Nevertheless, women are still dying from it. Most of these women were diagnosed under the age of 50, or the cancer was discovered too late and has already metastasised.

The patient's genetic make-up also plays a role in choosing the right treatment. Why is that? 
Every person is different. Pharmacogenetics can tell us if a drug will work or if it may cause undesirable or even dangerous side effects. We get this information from the human DNA and not from the tumour’s DNA. This new approach can prevent a great many incorrect forms of treatment and serious side effects, for example with high blood pressure medication or blood thinners. The patient's genetic make-up is also important when it comes to anaesthesia to ensure that patients are not given an anaesthetic that they do not tolerate or to which they do not react. In the latter case, they suffer severe pain despite having an anaesthetic. Genetic testing makes perfect sense in such cases.