Breast density

Breast density is about how much fat and other kinds of tissue are in your breasts. 

Your breasts are made up of several types of tissue including fat, connective tissue and glandular tissue. Glandular tissue is the normal tissue in the breast that makes and carries milk.

Dense breast tissue is thicker (denser) than fat. It is sometimes called non-fatty tissue.

• People with dense breasts have more connective and glandular tissue, and less fat, in their breasts. 
• People with less dense breasts have more fat, and less connective and glandular tissue, in their breasts.

You can’t tell whether you have dense breasts just by feeling or looking at your breasts. Having firm or saggy breasts does not mean they are dense or less dense. 

Density can only be seen on a mammogram (breast X-ray).

In Ireland, breast density is not currently recorded during BreastCheck screening mammograms. This could change in the future. 

Dense breasts are common and normal. Everyone’s breasts have different density. 

About half of all women have dense or extremely dense breasts. Having dense breasts is normal, but it can slightly increase your risk of getting breast cancer. 

Why do I have dense breasts? 

You are more likely to have dense breasts if: 

• You are under 50 years old. Breasts tend to become less dense as you get older.
• You have a lower BMI or are underweight
• You are pregnant or breastfeeding
• You are taking hormone replacement therapy (HRT)

Breast density can change over time. Genetics can also affect your breast density. 

Does having dense breasts mean I will get cancer?

Breast density can affect your risk of cancer. If your breasts are denser, your risk of breast cancer is a bit higher. 

We don’t know exactly why breast density causes an increased risk of breast cancer. Researchers are working to try and answer these questions. 

Breast density makes no difference to how people respond to breast cancer treatment.

Dense breast tissue looks white on a mammogram. Breast cancer can also look white. This can make it harder to spot cancer in dense breast tissue. 

If your mammogram is hard to read, you will usually be called back for more assessments. This may include another mammogram, an ultrasound, or a physical breast examination.

Check your breasts

It's important to be breast aware. This means knowing what is normal for you, so that you can spot any changes. Everyone with breasts should check their breasts regularly.

We have advice on how to check your breasts here: Early detection of breast cancer

Attend your breast cancer screenings

It’s important to attend your breast cancer screenings.

BreastCheck is the name of the national breast screening programme. For more information contact BreastCheck directly at Freephone 1800 45 45 55 or visit the BreastCheck website.

Can I change my breast density?

Your breast density may change:

• As you get older
• If you become pregnant or breastfeed
• If you start taking hormone replacement therapy (HRT)

You can’t change your breast density with any known treatment, or through diet, weight loss or exercise. 

Other breast cancer risk factors

Breast density is just one risk factor for breast cancer. Other factors include your age or your family history of cancer.

There are also factors that you can change, like your lifestyle and diet.

You can read more about risk factors and prevention of breast cancer.