Hereditary Breast Cancer

Breast Cancer that runs in a family is called ‘hereditary breast cancer’. The information on this page and the factsheet describes what hereditary breast cancer is, how it is passed on, and the importance of family history in guiding the search for changes in genes that can lead to cancer. Even though this factsheet is mainly aimed at women, it may also be relevant to men. If breast cancer runs in your family, your GP can refer you to the Specialist Breast Care Centre where you will be assessed by a consultant and advised of follow up surveillance and treatment where necessary.

How common is breast cancer?

Breast cancer is now the second most common cancer in Ireland. It affects over 2,000 women in Ireland every year. It is less common in women under the age of 30 and occurs more often in women over the age of 50. Men also develop breast cancer but this is very rare and about 15 men develop breast cancer each year in Ireland.

What causes breast cancer?

The cause of breast cancer is still not fully known. A woman has a 1 in 12 lifetime chance of developing breast cancer but some women are at higher risk of developing the disease. Experts believe that between 5–10% of breast cancer cases are caused by changes that have been passed on in certain key genes.

What are the risk factors for breast cancer?

There are some factors that increase a woman’s risk of developing breast cancer over which we have no control.
These include:

• Being female
• Getting older
• Family history of breast or ovarian cancer
• Early menarche (starting your periods before the age of 12)
• Late menopause (change of life after the age of 55)
• Other factors that can slightly increase risk include:
• Being overweight
• Not being physically active
• Hormone Replacement
• Therapy (HRT)
• Contraceptive pill use
• A history of benign breast disease
• First pregnancy after age of 30
• Too much alcohol use
• Smoking tobacco