Breast cancer risk factors and causes

1. Many different things affect your risk of getting breast cancer, including some things you cannot control
2. There’s no single cause but your genes, lifestyle and environment all play a part
3. Things that increase your risk of breast cancer are called risk factors
4. We cannot say for certain who will get breast cancer or what caused someone’s breast cancer
5. You can reduce your risk of breast cancer by limiting alcohol, keeping to a healthy weight and being physically active regularly

Lifetime risk

In the UK 1 in 7 women will develop breast cancer in their lifetime.

Breast cancer is the most common cancer in women in the UK. And while it’s much rarer, men can get breast cancer too.

Around 55,000 women and 400 men are diagnosed with breast cancer every year in the UK.

Age

Your risk of breast cancer increases as you get older.

80 out of every 100 cases of breast cancer are diagnosed in women aged 50 and over. And the older you are, the higher your risk.

But younger women can get breast cancer too.

Most men who get breast cancer are over 60.

Family history

Most people who get breast cancer do not have a family history of the disease.

But sometimes, someone’s family history suggests they could be at increased risk of developing breast cancer. Their risk is likely to be higher the more relatives they have with breast cancer, particularly if they were diagnosed at a younger age.

This may be because there’s an altered gene in their family that increases the risk of breast cancer. 

If you’re concerned about breast cancer in your family, you can speak to your GP.

Alcohol

Regularly drinking alcohol increases your risk of breast cancer. And the more you drink, the higher your risk.

Limiting the amount of alcohol you drink can reduce your risk of breast cancer and has other health benefits too.

Weight

Your risk of breast cancer increases if you’re overweight or living with obesity after the menopause.

And the more weight you gain during adulthood, the higher your risk of breast cancer later in life.

Keeping to a healthy weight can help reduce your risk of breast cancer.

Physical activity 

You can reduce your risk of breast cancer by being physically active regularly. 

Being regularly active can also help you keep to a healthy weight and has many other health benefits too.

Smoking

There’s growing evidence that smoking slightly increases the risk of breast cancer. Stopping smoking also has other health benefits.

HRT

Taking hormone replacement therapy (HRT) can increase the risk of breast cancer.

For most people the risk of developing breast cancer because of taking HRT is small. The risk depends on the type of HRT and length of time you take it.

The pill

Taking the contraceptive pill slightly increases your risk of breast cancer. This small increase in risk disappears within a few years after you stop taking the pill.

Breast cancer is rarer in young women, who are more likely to take the pill.

Starting periods earlier

Starting your period early (before the age of 12) slightly increases your risk of breast cancer. However, the increased risk is small.

Going through the menopause later

Going through a later menopause (the average age is 51) slightly increases your risk of breast cancer.

Breastfeeding

Breastfeeding your children slightly reduces your risk of breast cancer. The longer you breastfeed, the more the risk is reduced.

Pregnancy

Having children has a complex effect on breast cancer risk.

In general, the risk of some types of breast cancer is higher for women who do not have children or who have them over the age of 30. Women who have multiple pregnancies at a younger age may have a lower risk of breast cancer.

Dense breasts

Having dense breasts increases the risk of breast cancer.

Breasts are described as dense if they have a high amount of breast tissue compared to fatty tissue.

This varies naturally between women and changes over time. It can only be seen on a mammogram and you will not know if you have dense breasts unless you are told.

Some benign (not cancer) conditions

Some benign breast conditions, such as hyperplasia or lobular neoplasia, slightly increase the risk of breast cancer.

However, most people who have them will not get breast cancer.

Body type

Your risk of breast cancer is slightly higher if:

• You’re tall
• You had a higher birthweight (your weight when you were born)
• You have higher bone density

Chest radiotherapy

Having radiotherapy to your chest area at a young age, for example to treat Hodgkin lymphoma, increases the risk of breast cancer in the future.

Environmental chemicals

Studies have looked at the relationship between breast cancer and chemicals in the environment or workplace such as pesticides, traffic fumes and plastics. But the evidence is unclear and more research is needed.

Diet

There’s no strong evidence that eating certain foods will increase or decrease your risk of breast cancer.

There’s limited evidence that eating non-starchy vegetables or a diet high in calcium may reduce the risk of some types of breast cancer.

Eating a healthy, balanced diet can help you keep to a healthy weight, which is one way to lower your risk of breast cancer.