1. What causes breast cancer?
2. Age
3. Risks you cannot control 
4. Lifestyle
5. The pill and HRT
6. Family history
7. Myths

1. What causes breast cancer? 

Many different things can affect your chances of getting breast cancer. 

There’s no single cause. It results from a combination of the way we live our lives, our genes and our environment. 

We can’t predict who will get breast cancer. And we can’t confidently say what might have caused someone’s breast cancer. 

There are, however, some things you can do to lower your chances of getting it.

2. Age and breast cancer risk

Getting older is the most significant risk for developing breast cancer. 

Most breast cancers (80%) occur in women over the age of 50. And the older you are, the higher your risk.

Most men who get breast cancer are over 60.

3. Risks you cannot control 

As well as getting older, some other things that you cannot do anything about can affect your risk of breast cancer.

When you started having periods

Women who started their periods at an early age (before 12) have a slightly increased risk of breast cancer. The earlier you began your periods, the higher your risk.

However, this increase in risk is small.

When you go through the menopause

If you go through a later menopause (the average age is 52), your chance of getting breast cancer is slightly increased.

Dense breast tissue

Breast density is the amount of breast tissue compared to fat tissue in your breasts. If you have a high amount of breast tissue compared to fat, you have a ‘high breast density’. This increases the risk of breast cancer. 

The denser the breast, the greater the risk.

Breast density varies naturally between women and can only be measured on a mammogram.

Some benign (not cancer) breast conditions 

Most benign breast conditions do not increase the risk of breast cancer. 

People who have atypical hyperplasia or lobular neoplasia have a slightly increased risk of breast cancer. 

4. Lifestyle and breast cancer risk 

By making small changes and living well now, you can lower your chances of getting breast cancer. 

It doesn’t guarantee that you won’t develop breast cancer, but leading a healthy lifestyle does give you a better chance.

Alcohol

Regularly drinking alcohol is associated with a higher risk of developing breast cancer. 

Limiting the amount of alcohol you drink can reduce your risk of breast cancer.

Read more about alcohol and breast cancer risk.

Being overweight or obese

Your risk of developing breast cancer increases if you are overweight or obese after the menopause. 

You can reduce your risk by maintaining a healthy weight.

Keeping active

You can reduce your risk of breast cancer by being physically active for around 20 minutes a day.

Smoking

There’s growing evidence that smoking slightly increases the risk of breast cancer. 

The risk is higher in women with a significant family history of breast cancer.

The younger a woman is when she begins smoking, the higher her risk. The increased risk remains for at least 20 years after stopping smoking.  

Pregnancy and breastfeeding

Having children has a complex effect on breast cancer risk. 

Overall, in the long term, pregnancy reduces the risk of breast cancer. 

Breastfeeding your children slightly reduces your risk of breast cancer.

5. The pill and HRT

The pill

Taking the combined contraceptive pill slightly increases your risk of breast cancer. Within a few years of stopping, however, this risk disappears. 

Hormone replacement therapy (HRT)

HRT increases your risk of breast cancer while you’re taking it and for a few years after stopping.

6. A family history of breast cancer

Having someone in your family with breast cancer doesn’t automatically mean your own risk is increased. For most people, having a relative with breast cancer does not increase their risk.

However, a small number of women and men have an increased risk of developing breast cancer because they have a significant family history.

7. Myths 

There are many myths about the causes of breast cancer. 

For example, some people worry about using deodorants or wearing an underwire bra, but these things do not increase the risk of breast cancer.

Find out more about these and other breast cancer myths

Last reviewed: September 2019
Next planned review begins 2020

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