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Familial Breast Cancer

Key Points

  • the risk of breast cancer is higher in some women because of genetic influences. If you have one or more close relatives who have had breast cancer, you should ensure you speak to your doctor and have regular mammograms/checkups
  • many people have a family member who has had breast cancer. This may be due to inherited genetic factors, the family environment or just by chance. Most breast cancers do not have a genetic link.
  • less than 5% of all breast cancer is hereditary.

What is familial breast cancer?

This is where your family history shows one or more blood relatives who have, or have had, breast or ovarian cancer. These relatives could be on either side of your family. You should not count in-laws, adoptive parents or your step parents, sisters or brothers.

There are some features which potentially increase the risk. These are as follows:

  • A relative who has or has had cancer in both breasts
  • A relative who was diagnosed with breast cancer before the age of 40
  • A relative who has had both breast and ovarian cancer
  • A male relative who has or has had breast cancer.

What is hereditary breast cancer?

Breast cancer is normally called hereditary breast cancer where a woman has inherited a known genetic mutation such as BRCA1 or BRCA2. These genes control the growth of both breast cancer and ovarian cancer.

A genetic mutation is a faulty part of a gene which you have inherited from your mother or father. Only a small number of women- perhaps only 1 or 2 in 1000 are at increased risk of breast cancer from having inherited such a mutated gene. Ashkenazi Jews have a higher risk of having these faulty genes than any other group.

How do I know if I may have a higher risk?

The factors affecting your risk are:

  • the number of relatives with breast cancer
  • the number of close relatives (first degree) that have had breast cancer
  • the age at which their breast cancer was diagnosed

First degree relatives are mother, father, sister, brother, daughter, son. second degree relatives are grandparents, uncles, aunts, half-brothers and sisters, nephews and grandchildren.

What is my risk?

The following chart gives a summary of potential risk. If you are concerned see your doctor. He or she can refer you to a genetic counselling service. Just because you have a positive result does not mean you will develop breast cancer. Neither does a negative result mean you will not. However taking a genetic test can help you and others in your family plan a management program with the appropriate medical support.

Whichever group you are in you should:

  • Examine your breasts each month
  • Get your doctor to clinically examine your breasts annually, and every six months for high risk
  • See your doctor if you notice any changes in your breasts
Risk of developing cancer History (starting at the top, if you have any one of the following) Suggested Action

Low Risk

(less than 10%)

-no relatives with breast cancer

-one 1st or 2nd degree relative with breast cancer after 50 or two where one is on your mother's and one on your father's side

-one second degree relative at any age with breast cancer

After 50, have a mammogram every 2 years


Moderate risk


-one 1st degree relative with breast cancer before 50

-two 1st or 2nd degree relatives on the same side of your family with breast or ovarian cancer

After 50, have a mammogram every 2 years (or as advised)

Ask for a referral for a genetic test

Potentially high risk

(30% to 50%)

-three or more 1st or 2nd degree relatives on the same side of your family with breast or ovarian cancer

-two or more 1st or 2nd degree relatives on the same side of your family with breast or ovarian cancer with high risk features


Have a mammogram as advised by your doctor or genetic specialist

Ask for a referral for a familial cancer clinic and/or a cancer specialist

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