Common conditions

Inherited Breast Cancer in Women

Cancer genetics

Cancer is a genetic disease, it is caused by alterations in genes that control the way cells grow and multiply. Cancer Research UK reports that 56,800 women are diagnosed with a breast cancer each year.

Factors that can affect the risk of developing breast cancer include increasing age, weight, drinking alcohol, not having a pregnancy or having your first child after 30 years, taking hormones.

Family history- you may have an increased risk of breast cancer if you have relatives with breast cancer, especially if they are close relatives to you and diagnosed at a young age. Sometimes we see a pattern of breast cancer, ovarian cancer and prostate cancer in families where there is an inherited breast cancer gene alteration.

Most cancers are caused by gene alterations that happen as we go through life and are not inherited. Some gene alterations can be inherited. Inheriting a gene alteration means that person has an increased risk of developing certain cancer(s) as they go through life.

Why am I being offered genetic testing?

 You are being offered a genetic test to see if your breast cancer might be due to an inherited Breast cancer gene alteration (variant).

What genes can I be tested for:


Two sets of genes that are known to give a high risk of breast cancer, are called BRCA1 and BRCA2,  this stand for BReast CAncer gene1 and BReast CAncer gene 2.

Inheriting a variant in BRCA1 or BRCA2 gives a woman a high chance of developing breast cancer over her lifetime.

Gene  Risk of breast cancer up to age 80 years
 BRCA1  72%
BRCA2  69%

BRCA gene carriers who have been diagnosed with a breast cancer are also known to have a significant risk of developing another new breast cancer in the future, up to 50% risk.

If you inherit a BRCA gene variant you will also have a higher risk of ovarian cancer.

Gene  Risk of ovarian cancer up to age 80 years
 BRCA1  44%
BRCA2  17%

BRCA variant carrier –risk of other cancers

There may be an increase risk to other cancers such as melanoma and pancreatic cancer, especially for BRCA2 variant carriers. No pancreatic surveillance is currently recommended.


Men who inherit a BRCA gene variant have a low- small risk of developing breast cancer, it is estimated to be <1% risk for BRCA1, and approximately 4% for BRCA2.

Men may also have a higher risk of developing prostate cancer over their lifetime.

Genes we can offer testing for include PALB2, PTEN, ATM, CHEK2, TP53, CDH1.

How are Breast cancer genes inherited?

Most breast cancer genes are inherited following a pattern known as autosomal dominant inheritance. If you have an alteration in a Breast cancer gene then each child, male or female, has a 50% chance of inheriting the Breast cancer gene with the alteration.

Breast cancer genes have an important job in the body

Most of the breast cancer genes work as tumour suppressor genes to protect you from getting breast cancer. If you inherit a tumour suppressor gene that is not working, this means you are more likely to develop certain cancers.

Does everyone who inherits a Breast cancer gene variant develop cancer?

No. Not everyone who carries a Breast cancer variant will go on to develop cancer. If you have a gene variant, your family members can opt for genetic testing to see if they also have inherited the same gene variant.

As the risk of developing breast and other cancers are higher than for a person who is not a Breast cancer gene carrier, certain surveillance procedures and follow up are recommended.

The risk of various cancer(s) and options available to manage risks, will vary depending if you are male or female.

Having a diagnosis of a cancer can be difficult. You may find yourself worrying more. It is important to know you are not alone and the team here in International Gene Clinic want to support you.