Find out more about our guide to UK services for people with a family history of breast cancer.

Our family history guide has been developed to help you understand what a family history of breast cancer is, and what it means for you and your family.

Most women in the UK have a one in eight chance of developing breast cancer in their lifetime. However, if you have a family history of breast cancer, you and some other members of your family may have a higher than average risk of developing the disease.  

It’s not easy to give a single definition of a family history of breast cancer, because there are many different patterns. However, you might have an increased risk of developing the disease if:

  • several blood relatives in your family have had breast cancer or ovarian cancer.
  • or, you have blood relatives who were diagnosed with breast cancer at a relatively young age (e.g. under 40).

Breast cancer is a common disease, so having one relative diagnosed over the age of 40 is not unusual and would not normally suggest that other family members are at increased risk. 

Visit our family history guide

However, about five to fifteen in every 100 women with breast cancer have a family history which is likely to have contributed to why they developed the disease. It’s important to look into any patterns of other cancers in the family too, because in some cases these can also indicate an increased risk of breast cancer in the family.

For each 100 women with breast cancer in the UK:

Family history of breast cancer

About 90 (estimates vary from 85 to 95) will not have a significant family history. About 10 will have a family history that may explain why they developed breast cancer. Of these:

Family history of breast cancer About five will have a fault in a gene known to be linked to breast cancer (eg BRCA1, BRCA2 or TP53)

Family history of breast cancer About five will have no known genetic reason for their family's increased risk

If you do have a family history, it doesn’t mean you will definitely get breast cancer, but it does mean your risk may be higher than for people without a family history. It may also mean you could develop breast cancer at a younger age.

NHS services are available to help women and men in this situation. Specialists are able to assess whether you are at increased risk and offer advice and support. If you do have an increased risk of developing breast cancer, there are options available to help reduce that risk and make sure the disease is spotted early if it does occur.

Gene faults and family history

Sometimes, faults in particular genes (such as BRCA1, BRCA2 and TP53) explain why a family has an unusually high number of relatives who have been diagnosed with breast cancer. About half of all women with a family history of breast cancer who have been diagnosed with the disease have a fault in a gene known to be linked to breast cancer, such as a BRCA1, BRCA2 or TP53. In the other half, the reason for their family’s increased risk of breast cancer is not known.

The BRCA1 and TP53 genes are found in everyone. BRCA genes play an important role in repairing damage to the DNA in our cells, while the TP53 gene normally controls when a cell divides.

When a fault occurs in one of these genes it can no longer function properly, resulting in DNA damage and uncontrolled cell growth which can lead to a cell becoming cancerous.

As well as increasing the risk of breast cancer, BRCA gene faults can increase the risk of some ovarian cancers too, which is why we mention both breast cancer and ovarian cancer when describing a family history. Gene faults also explain some cases of breast cancer in men too.

Even if a faulty gene is identified in a family member, this doesn’t mean that all other family members are at risk. Some (but unlikely all) family members may have inherited the gene from a parent, if they carried it. There is a 50:50 chance that a faulty gene will be passed from a parent (whether male or female) to their child.

Family history of breast cancer - managing your risk

For more information about family history and breast cancer, visit our dedicated guide.

Visit our family history guide

Information last reviewed: September 2015

Next review due: September 2018

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