Unfortunately, there are some things affecting your risk of breast cancer that you can’t do anything about.

How old you arecake illustration

As you get older, your chances of getting breast cancer increases.

Breast cancer is more common in women over the age of 50, which is when at least four out of five of all breast cancer cases in the UK occur. The older you get, the more likely it is that changes and damage occur in your cells, which in some cases can lead to cancer forming.

Your breast density

If you have dense breasts, your chance of getting breast cancer is increased.

Breast density is the amount of breast tissue compared to fat tissue in your breasts. It varies naturally between women and can only be measured on a mammogram. If you have a high amount of breast tissue compared to fat, you have a ‘high breast density’, which increases your risk of breast cancer.

The density of your breasts does fall gradually as you get older, but this doesn’t necessarily mean that your risk of breast cancer decreases as your breasts change. This is because as you get older, your risk increases. You can find out more about age above.

When you started your period

Your chance of developing breast cancer is slightly increased if you started your period at an early age. The earlier you began your periods, the higher your chance, but this increase is small.

This may be because you are exposed to the naturally occurring female hormone oestrogen for longer if you started your periods earlier than if you started your periods later. Although oestrogen is needed for our growth and development, in some cases it can encourage the growth of some breast cancers.

Your ethnicity

Your ethnic background can affect your chances of developing breast cancer.

If you’re a white woman, you’re more likely to develop breast cancer than if you are a non-white woman or from an ethnic minority.

If you’re a Black woman, research shows you may be more likely to get breast cancer under 50, although you are still less likely to develop cancer overall. You may also be more likely to develop triple negative breast cancer.

We’re not quite sure why different ethnic groups have different chances of developing breast cancer. These differences may be linked to genetics or lifestyle choices – for example, how many children you have or how much alcohol you drink. We need more research before we fully understand the reasons behind this.

We also know that certain ethnic groups, for example, Ashkenazi Jewish women, have a higher chance of developing breast cancer because they are more likely to carry certain faults in their genes such as in BRCA1 and BRCA2. You can find more information about faulty genes, including BRCA1 and 2 here.

When you go through the menopause

If you go through a late menopause, your chance of getting breast cancer is slightly increased. The later you go through menopause, the higher your risk, but this increase in risk is small.

This increase in breast cancer risk may be because you are exposed to the naturally occurring female hormone oestrogen for longer than women who go through the menopause earlier. Although oestrogen is needed for our growth and development, in some cases it can encourage the growth of some breast cancers.

Some women undergoing the menopause choose to take hormone replacement therapy (HRT) to treat their symptoms. HRT also slightly increases your chance of getting breast cancer while you take it, but it’s important to consider the risks and benefits to make the right decision for you. You can find out more about HRT and breast cancer here.

Having a benign breast condition

Your chance of getting breast cancer may be higher if you have a benign (non-cancerous) breast condition.

Most benign breast conditions (for example, cysts and simple fibroadenomas) do not increase your chance of getting breast cancer.

But your risk of breast cancer is increased if you have a benign breast condition where the breast cells are growing quickly, described as ‘proliferative’. How high your risk is depends on the exact type of proliferative benign breast disease you have. These types of breast conditions are generally uncommon.

If you have had a diagnosis of a benign breast condition and are unsure or worried about your increased chance of developing breast cancer, speak to your doctor. They will be able to give you more information and advice.

How tall you are

height illustrationThe taller you are, the higher your chance of getting breast cancer, although this is only a slight increase in risk.

We still don’t know exactly how your height is linked to your risk of breast cancer, but we do know that how tall you are as an adult depends on your genes, your levels of nutrition when you were growing up and the hormones you were exposed to.

It’s probably these factors that affect your chance of breast cancer – your height is more like a ‘marker’ of these combined influences.

Your size at birthbaby illustration

The bigger you were when you were born, the slightly higher your chances of developing breast cancer, especially before the menopause – although we still don’t know this for sure, and need more evidence to confirm this.

We’re not exactly sure why this might increase your risk, but like height, your size when you were born may be more of a ‘marker’ of combined influences.

It might be the different levels of hormones you were exposed to in the womb, or that being bigger at birth means you are more likely to be taller or go through puberty earlier, both of which are linked to a slight increase in breast cancer risk.

Want some more information?

If you are worried about any of the breast cancer risk factors mentioned here you should discuss your concerns with your doctor.

For more information on any of the factors likely to affect your breast cancer risk, download or order a copy of our booklet on knowing the facts.

What causes breast cancer? (PDF)

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Information last reviewed: November 2018

Next review: November 2021

Breast Cancer Now's health information is covered by NHS England's Information Standard quality mark. Find out how this resource was developed.