breast cancer genetics
family history
Only 5% of breast cancers are caused because a faulty gene has been inherited. Breast cancer is a common disease though, and it is not unusual for more than one family member to be affected. When we assess the risk of a family having a genetic cause for their breast cancer, there are a number of factors we need to take into account.Age at diagnosis
The younger someone is when they develop breast cancer, the more likely it is to be inherited. If you have more than one close relative who developed breast cancer before the age of 50, there may be a breast cancer gene mutation.
Pattern of inheritance
Breast cancer genes are passed from parent to child. Who can inherit them from either your father or mother. Therefore, if we see breast cancer in several generations (e.g. daughter, mother and grandmother), we are more suspicious of an inherited gene defect.
Other cancers
Breast cancer genes are associated with other cancers, particularly ovarian cancer. If you have a relative with ovarian cancer as well as relatives with breast cancer, there is likely to be a genetic cause.
Some other cancers are also associated with breast cancer, so it is important to have as full a family history as possible.
If there is a man in the family who has had breast cancer, this is very suggestive of a particular breast cancer gene defect.
If you are worried about your family history, one of our breast physicians can help you to assess it. If they feel it is in your interests to have regular checks because of your family history, this can be arranged. They can also refer you for further assessment or to a genetics counselor.
Inherited breast cancers are usually caused by two genes called BRCA1 and BRCA2. There are also some other genes which are strongly associated with breast cancer, as well as other cancers. In the future, we will certainly find other genes which cause breast cancer.
If you are found to have a gene defect, we can help you decide what to do next and what options are available for you.