Inherited cancers: breast cancer

Breast cancer is a common cancer. Most people with breast cancer do not have a strong family history of it. Less than 1 in 10 breast cancers may be linked to a change (alteration) in a gene running in a family. The two genes most often associated with breast cancer are BRCA1 and BRCA2.

Talk to your doctor if you are worried that your family history means you may be at increased risk of breast cancer. They may be able to reassure you, or refer you to a clinical genetics service or family cancer clinic.

Knowing your cancer risk can help you decide what to do to reduce the risk. This might include screening to find cancer early or having treatments to reduce the risk of the cancer developing.

Family history and breast cancer risk

Most breast cancers are not caused by inherited cancer genes, and most people who develop breast cancer don’t have a strong family history of it.

But sometimes breast cancer can run in families. In general, the chance of there being a family link is greater when:

  • a number of family members have been diagnosed with breast cancer or related cancers, such as ovarian cancer
  • the family members are closely related
  • the family members were diagnosed at a younger age.

Inherited genes and breast cancer

Less than 1 in 10 breast cancers are thought to be caused by a change (alteration) in a gene running in the family.

The two genes most often found to be altered in hereditary breast cancer are called BRCA1 and BRCA2.

If a family has an altered BRCA1 or BRCA2 gene, usually several relatives on the same side of the family may be diagnosed with breast cancer or related cancers. People in the family may also be diagnosed with cancers at a particularly young age.

BRCA gene alterations are more common in certain populations. If you have Ashkenazi Jewish ancestry and have relatives who’ve been diagnosed with ovarian or breast cancer, you may want to discuss your risk with your GP.

If you are concerned about your risk of breast cancer, talk to your GP. They can talk to you about your family history and your risk.

Assessing family history

A family history of cancer is usually based on your close relatives, including first-degree relatives.

First-degree relatives are your parents, brothers, sisters and children.

Close relatives are your first-degree relatives and second-degree relatives (grandparents, grandchildren, aunts, uncles, nieces and nephews).

You may have an increased risk of developing breast cancer if your family history includes:

  • one first-degree relative who developed breast cancer under the age of 40
  • one first-degree male relative (father, brother or son) who developed breast cancer at any age
  • one first-degree relative with cancer in both breasts when the first cancer was diagnosed under the age of 50
  • two first-degree relatives who developed breast cancer at any age
  • a first-degree relative and another close relative on the same side of your family who developed breast cancer at any age
  • three close relatives on the same side of your family who developed breast cancer at any age
  • close relatives with breast and ovarian cancer on the same side of the family.

If any of these apply to your family, or you are worried about your risk, talk to your GP. They may be able to reassure you, or refer you to a clinical genetics service or family cancer clinic.


Assessing breast cancer risk

A risk of breast cancer based on family history may be estimated as average, moderate or high.

If you have an increased risk of developing breast cancer because of your family history, you may be offered breast screening. This is separate from the national breast screening programme which is explained below.

Average risk (near population risk)

This is also sometimes called population risk. It means your risk is the same or very similar to the risk of people who don’t have a family history of breast cancer. You are more likely not to get breast cancer than to get it.

Moderate risk

This means your risk is higher than average but it’s unlikely there is a breast cancer gene in the family. You are still more likely not to get breast cancer than to get it.

Women with a moderate risk may be offered yearly mammograms (breast x-rays) between the ages of 40 and 49. Between the ages of 50 and 59, women either continue with yearly mammograms or have a mammogram every three years as part of the general national breast screening programmes. Your specialist will talk to you about this.

From age 60 onwards, you will then join the national breast screening programmes and have a mammogram every three years.

High risk

This means you have a high risk of developing breast cancer in your lifetime. However, it doesn’t mean that you will definitely get breast cancer. There may be a hereditary breast cancer gene in your family.

Most women at high risk are offered mammograms every 12 to 18 months. A smaller number will also have yearly MRI scans. The age that women may be first offered these scans depends on their estimated risk. Women who have an altered BRCA gene are offered MRI scans from the age of 30.


Genetic testing

If a genetics specialist thinks breast cancer could run in your family, they may offer you genetic testing. We have more information about genetic testing.


National breast screening programmes

In the UK, women aged between 50 and 70 who are registered with a GP are invited to have breast screening every three years. This aims to find breast cancer early when it’s easier to treat.

Screening involves having a mammogram (breast x-ray) every three years until you reach the age of 70. Each country in the UK has its own screening programme.

Women over 70 can continue to have regular mammograms by contacting their GP or their breast screening clinic to arrange an appointment.

There is currently no national breast screening programme for men. This is because an increased risk for men is still less than the average or population risk for women.

We have more information about breast screening.


Risk-reducing treatments

Women at increased risk of breast cancer may choose to have treatments using surgery or drugs, to help reduce the risk.

Risk-reducing surgery involves an operation to remove the ovaries or the breasts. This is a big step to take and is only suitable for a small number of women with a very high risk of breast cancer.

Having risk-reducing drug treatment involves taking a tablet (tamoxifen or raloxifene) every day for five years. It’s estimated that this reduces breast cancer risk by between 30% and 40%. However, these drugs can cause side effects similar to the menopause, such as hot flushes, vaginal discharge, urinary problems and weight gain. They also increase the risk of blood clots and womb cancer. The drugs are not suitable for women who are planning to get pregnant.

For most women with a high risk, the benefits of these drugs probably outweigh the risks. But women at moderate risk may have to think more carefully if they are offered this treatment.

Before deciding whether to have any risk-reducing treatment, you should have time to talk through all the possible benefits and disadvantages with a genetics or breast cancer specialist.

We have more information about risk-reducing breast surgery.


Research trials

Research is looking into treatments which may reduce the risk of breast cancer developing. You can discuss with your doctors the benefits and disadvantages of taking part in research trials.