Breast Density

Even with dense breasts, a screening mammogram every two years is still the most effective method of detecting breast cancer early in women over 50.

Breast Density: Overview

• Breasts are made up of a combination of fatty and dense tissue - some women have more dense tissue than others (around 40% of women in their 50s and 25% of women aged 60+ have dense breasts*)

• Dense tissue and breast cancer both appear white on a mammogram, so dense breasts can make it more difficult to detect breast cancer

• As there is currently no practicable way to measure breast density in the context of screening, BreastScreen Australia does not provide information about your breast density following your mammogram

• Currently, there is no definitive evidence to suggest that additional tests are needed for women with dense breasts

• It’s important for all women to regularly check their breasts for any unusual changes and talk to their GP about any concerns

*Based on international research

Even with dense breasts, a screening mammogram every two years is still the most effective way to detect breast cancer early in women aged over 50.

For more information, read BreastScreen Australia’s position statement on breast density

Breast Density FAQs

What is breast density?

How common are dense breasts?

How is breast density measured?

Does breast density affect the accuracy of a screening mammogram?

Should women with dense breasts have screening mammograms?

Does breast density increase the risk of breast cancer?

Should women with dense breasts be screened more frequently?

Should women with dense breasts have any additional tests?

Is BreastScreen Australia planning to report on breast density in the future?

What is breast density?

Breasts are made up of a combination of fatty and dense (fibroglandular) tissue.

Women with lower breast density have more fatty tissue, while woman with higher breast density have less fatty tissue.

How common are dense breasts?

Breast density refers to the amount of fibroglandular (dense) tissue present in your breasts. This is different for individual women, but is generally higher when you are younger and tends to reduce as you age.

Most women below the age of 50 have increased breast density compared with those aged over 50. International research shows that about 25% of women over the age of 60 continue to have dense breasts.

A range of other factors also contribute to breast density such as hormones, Body Mass Index and genetics.

How is breast density measured?

Breast density cannot be seen or felt, but can be measured by:

• a radiologist, who can analyse a mammogram and provide a density score

• computer software which can identify and score the amount of breast density present on a mammogram

There is currently no practicable method to measure breast density in a population-based screening program.

One of the problems with trying to measure breast density is that you may get different results depending on how your image is analysed, which can cause confusion and unnecessary anxiety.

For this reason, BreastScreen Australia does not provide you with information about the density of your breasts following your mammogram.

Does breast density affect the accuracy of a screening mammogram?

Detecting breast cancer using mammograms can be more difficult in women with dense breasts.

This is because dense breast tissue and breast cancer both appear white on a mammogram - as a result, the cancer can be ‘masked’ by dense tissue.

As breast density increases, the ability of mammograms to show cancers generally decreases, which means in some cases: 

• A normal mammogram result is given when cancer is present
• A woman is called for further tests when there is no cancer present

Even with dense breasts, a screening mammogram every two years is still the most effective way to detect breast cancer early in women aged over 50.

Should women with dense breasts have screening mammograms?

Yes. A screening mammogram is still the best method of detecting breast cancer early in women aged 50-74, even with dense breast tissue.

Did You Know? 

Mammograms are the only screening tool proven to improve the survival rate of women with breast cancer.

The BreastScreen Australia program has been found to reduce breast cancer mortality by almost a third in women aged 50-69.

Women who have their breast cancer detected early through a screening mammogram with BreastScreen NSW are half as likely to need a mastectomy.

Does breast density increase the risk of breast cancer?

Research shows that increased breast density is associated with an increased risk of breast cancer.

The risk of developing breast cancer is also influenced by a range of other factors, including age, a strong family history, being overweight, drinking alcohol, and other lifestyle and environmental impacts.

Age is the biggest risk factor for developing breast cancer, with most breast cancers occurring in women over 50. Importantly, most women who develop breast cancer have no known risk factors other than being female and getting older.

Should women with dense breasts be screened more frequently?

Even with dense breasts, a screening mammogram every two years is still the best way to detect breast cancer early in women aged 50-74 with no symptoms.

BreastScreen Australia constantly monitors and reviews evidence to ensure our program is delivering safe, high-quality and evidence-based care. We will continue to assess the evidence about breast density.

Should women with dense breasts have any additional tests?

There is no definitive evidence to suggest that additional tests are needed for women with dense breasts.

However, there are extra screening tests that can be considered by you and your doctor. These may include ultrasound, Magnetic Resonance Imaging (MRI) and 3D mammography (digital mammography tomosynthesis).

It’s important to be aware that there can be significant harm associated with having additional tests, including unnecessary and invasive procedures, false positive results (when a woman is told she has cancer when there is no cancer present), overdiagnosis, over-treatment, additional costs, and psychological distress.

Is BreastScreen Australia planning to report on breast density in the future?

BreastScreen Australia supports greater discussion, awareness and research into breast density.

We respect the rights of women to access their personal medical information and encourage their involvement in developing evidence-based approaches to breast cancer risk assessment, prevention and early diagnosis.

The benefits and drawbacks of routine reporting on breast density are complex issues that need to be evaluated, in discussion with women who participate in the BreastScreen program.

For more information, read BreastScreen Australia’s position statement on breast density

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