Being diagnosed with breast cancer or having a relative with the disease does not usually increase the risk for other family members.
Breast cancer is the most common cancer in the UK. Every year nearly 55000 people are diagnosed with breast cancer. Most of these develop it by chance and the biggest risk factors are being female and getting older.
Only a few breast cancers (5%) are because of genes passed on by your parents as in people who have inherited one of the known altered breast cancer genes – BRCA1 BRCA2 and TP53. This means routine genetic testing wouldn’t be helpful for most people diagnosed with breast cancer.
What is a family history of breast cancer
Being diagnosed with breast cancer or having relatives with breast cancer means you have a family history of breast cancer but not automatically a ‘significant’ family history.
A significant family history is when there is more than one blood relative (by birth not marriage) on the same side of the family (your mother’s side or your father’s) who has had breast cancer and some other cancers such as ovarian cancer.
Your family history may be significant if you have:
- one or more close relatives who have had breast cancer before the age of 40
- two or more close relatives on the same side of the family who have had breast cancer
- close relatives who have had breast cancer and others who have had ovarian cancer
- one close relative who has had breast cancer in both breasts (bilateral) or who has had breast and ovarian cancer
- a male relative who has had breast cancer
- Ashkenazi Jewish ancestry.
Assessment of risk – where to begin?
If you’re concerned that your breast cancer (or a relative’s breast cancer) was because of your family history talk to either your breast specialist or your GP. They will want to know:
- the number of relatives from the same side of the family that have developed cancer – your mother’s blood relatives and father’s blood relatives will be assessed separately
- what type of cancer each person had
- the age each person was when they were diagnosed and whether they are still alive
- what relationships the relatives with cancer have to each other (for example brother and sister sister and maternal aunt)
- what their relationships are to you.
If this information suggests you may have a significant family history you'll be referred to either the local family history clinic or regional genetic centre (depending what’s in your local area).
If you're assessed as being at high risk you'll be offered genetic counselling at a regional cancer genetic centre. The genetic counsellor can help you understand more about your family history your risk of developing another breast cancer (or of your relatives developing breast cancer) and ovarian cancer and the options available such as:
- genetic testing
- risk-reducing surgery
- possible drug treatment for those without breast cancer.
Telling your family you have a positive genetic result
It's possible that other family members (blood relatives) also have an altered gene and they will need to decide whether to go for a genetic test or not. So it’s important to find a way to talk to your relatives as knowing that you carry an inherited altered breast cancer gene will help them make choices; it could help reduce their risk of developing breast and ovarian cancer in the future.
There is no right way or time to tell them. Lots of things will influence when and how you do this.
For example you might feel guilty about passing on this news or you may not have a close relationship with the family members. How and when you tell children will depend on their age. Your genetic team can help you.
It's important to understand that everyone has two copies of each gene. When an altered BRCA1 BRCA2 or TP53 gene is found this means that only one of your two copies of that gene has been altered and the other copy is fine. When a baby is conceived you only pass on one copy of each gene. This means that a gene carrier has a 50% chance of passing on an altered gene to their baby (girl or boy). It’s out of your control but it could affect their future health.
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