Information for the public
Genetic counselling and genetic testing
If your estimated breast cancer risk suggests that you are at high risk of developing breast cancer, you should be offered genetic counselling before you are offered any genetic testing.
Genetic counselling can be very important in helping you understand how your family history, lifestyle and other factors affect your risk of breast cancer. Information about genetic counselling and what it involves should be provided before it starts.
During genetic counselling, a clinical genetic specialist (an expert in the links between genes and disease) should discuss your risks of carrying a faulty gene and developing cancer. They should present risk in a way that you can understand and should give you a written summary of this discussion. The more information you have been able to supply about your family history the more accurate the risk estimate will be. If it's appropriate, the genetic counsellor may tell you about genetic testing which can look for inherited faults in genes known to be linked to breast cancer. These genes are called BRCA1, BRCA2 and TP53. The discussion should include what genetic testing involves, what a positive, inconclusive or negative result means for you and other family members and how long it will take to get the results. The effects of knowing the results on you and other members of your family should also be discussed.
Genetic testing is performed to find out if there is a faulty gene (BRCA1, BRCA2 or TP53) in the family. Genetic testing is only offered if the family history suggests that cancers within a family might have happened because of a faulty gene. Many different gene faults are possible; some are common whereas others are rare and found in only a few families. Because healthcare professionals do not know exactly which fault they are looking for, the best chance of finding a faulty gene is to test a relative who has already had breast cancer or ovarian cancer (the same faulty genes can cause both types of cancer). If a faulty gene is found in this relative, healthcare professionals then know which genetic fault caused their cancers and can offer a test to family members who have not had cancer. The genetic test will show whether these family members have inherited the faulty gene and so have an increased risk of developing breast cancer in the future.
If a close relative (mother, father, daughter, son, sister, brother) with breast or ovarian cancer is not available for testing, you should be offered testing yourself if your family history suggests you have at least a 10% chance of having a faulty gene.
Genetic testing is carried out on a blood sample.
If you've had breast cancer or ovarian cancer you should be offered genetic testing if there is at least a 10% (1 in 10) chance of a faulty gene in your family. If you've been given a diagnosis of breast cancer within the past month and you have a family history of breast cancer, you may be offered immediate genetic testing (known as 'fast track' or 'rapid' testing) as part of a research trial. If you are offered 'fast track' testing but you decide against it, you can have genetic testing later on when you are ready.